John Z. Gyekenyesi

N&R Engineering and Management Services Corporation, Parma Heights, Ohio

Pappu L.N. Murthy

Glenn Research Center, Cleveland, Ohio

Subodh K. Mital

University of Toledo, Toledo, Ohio

NASALIFE—Component Fatigue and Creep

Life Prediction Program

NASA/TM—2005-213886

September 2005
The NASA STI Program Office . . . in Profile

Since its founding, NASA has been dedicated to

the advancement of aeronautics and space

science. The NASA Scientific and Technical

Information (STI) Program Office plays a key part

in helping NASA maintain this important role.

The NASA STI Program Office is operated by

Langley Research Center, the Lead Center for

NASA’s scientific and technical information. The

NASA STI Program Office provides access to the

NASA STI Database, the largest collection of

aeronautical and space science STI in the world.

The Program Office is also NASA’s institutional

mechanism for disseminating the results of its

research and development activities. These results

are published by NASA in the NASA STI Report

Series, which includes the following report types:

• TECHNICAL PUBLICATION. Reports of

completed research or a major significant

phase of research that present the results of

NASA programs and include extensive data

or theoretical analysis. Includes compilations

of significant scientific and technical data and

information deemed to be of continuing

reference value. NASA’s counterpart of peerreviewed formal professional papers but

has less stringent limitations on manuscript

length and extent of graphic presentations.

• TECHNICAL MEMORANDUM. Scientific

and technical findings that are preliminary or

of specialized interest, e.g., quick release

reports, working papers, and bibliographies

that contain minimal annotation. Does not

contain extensive analysis.

• CONTRACTOR REPORT. Scientific and

technical findings by NASA-sponsored

contractors and grantees.

• CONFERENCE PUBLICATION. Collected

papers from scientific and technical

conferences, symposia, seminars, or other

meetings sponsored or cosponsored by

NASA.

• SPECIAL PUBLICATION. Scientific,

technical, or historical information from

NASA programs, projects, and missions,

often concerned with subjects having

substantial public interest.

• TECHNICAL TRANSLATION. Englishlanguage translations of foreign scientific

and technical material pertinent to NASA’s

mission.

Specialized services that complement the STI

Program Office’s diverse offerings include

creating custom thesauri, building customized

databases, organizing and publishing research

results . . . even providing videos.

For more information about the NASA STI

Program Office, see the following:

• Access the NASA STI Program Home Page

at http://www.sti.nasa.gov

• E-mail your question via the Internet to

help@sti.nasa.gov

• Fax your question to the NASA Access

Help Desk at 301–621–0134

• Telephone the NASA Access Help Desk at

301–621–0390

• Write to:

 NASA Access Help Desk

 NASA Center for AeroSpace Information

 7121 Standard Drive

 Hanover, MD 21076
John Z. Gyekenyesi

N&R Engineering and Management Services Corporation, Parma Heights, Ohio

Pappu L.N. Murthy

Glenn Research Center, Cleveland, Ohio

Subodh K. Mital

University of Toledo, Toledo, Ohio

NASALIFE—Component Fatigue and Creep

Life Prediction Program

NASA/TM—2005-213886

September 2005

National Aeronautics and

Space Administration

Glenn Research Center
Acknowledgments

Thank you to D.N. Brewer, U.S. Army Aviation Systems Command, Glenn Research Center, for providing the

support for this effort, and also to D.C. Slavik, R. Vanstone, J.R. Engebretsen, O.C. Gooden,

and R.D. McClain, General Electric Aircraft Engines, for the initial program.

Available from

NASA Center for Aerospace Information

7121 Standard Drive

Hanover, MD 21076

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22100

Available electronically at http://gltrs.grc.nasa.gov
NASA/TM—2005-213886 1

NASALIFE—Component Fatigue and Creep 

Life Prediction Program 

John Z. Gyekenyesi 

N&R Engineering and Management Services Corporation 

Parma Heights, Ohio 44130 

Pappu L.N. Murthy 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Subodh K. Mital 

University of Toledo 

Toledo, Ohio 43606 

Abstract

NASALIFE is a life prediction program for propulsion system components made of ceramic matrix 

composites (CMC) under cyclic thermo-mechanical loading and creep rupture conditions. Although, the 

primary focus was for CMC components the underlying methodologies are equally applicable to other 

material systems as well. The program references empirical data for low cycle fatigue (LCF), creep 

rupture, and static material properties as part of the life prediction process. Multiaxial stresses are 

accommodated by Von Mises based methods and a Walker model is used to address mean stress effects. 

Varying loads are reduced by the Rainflow counting method or a peak counting type method. Lastly, 

damage due to cyclic loading and creep is combined with Minor’s Rule to determine damage due to 

cyclic loading, damage due to creep, and the total damage per mission and the number of potential 

missions the component can provide before failure. 

1. Introduction

Engine companies are constantly striving to improve the performance and life of their gas turbine 

engines. Materials are pushed to new limits as new materials and concepts are applied to gas turbines to 

increase operating temperatures, reduce weight, and improve aerodynamic efficiencies. Also, there is the 

need to reduce maintenance costs and down time making life prediction with increased accuracy an 

important issue. The method of accurately determining the fatigue life of an engine component in service 

has become increasingly complex. This results, in part, from the complex missions which are now 

routinely considered during the design process. These missions include large variations of multiaxial 

stresses and temperatures experienced by critical engine parts. 

NASALIFE was written in an attempt to provide a convenient software package to the designer for 

determining the life of a component under cyclic thermo-mechanical loading. The program was 

developed at General Electric Aircraft Engines (GEAE) under the National Aeronautics and Space 

Administration’s (NASA) Enabling Propulsion Materials (EPM) program. The EPM program and its 

objectives were summarized by Brewer (1999) and NASALIFE was briefly covered by Levine, et al. 

(2000). NASALIFE was developed further by N&R Engineering under NASA’s Ultra Efficient Engine 

Technology (UEET) program. It should be noted that NASALIFE is not a final and all inclusive program 

for predicting component life, but is the part of the continuing process to improve life prediction 
NASA/TM—2005-213886 2

techniques. Empirical data is used as a reference for predicting the fatigue life of a component. As a 

result, the definition of failure is the same as the failure criteria of the empirical data. This code utilizes 

specific methods which are intended to provide conservative life predictions. In some cases these may be 

excessively conservative. The lives predicted by NASALIFE should be examined carefully by the design 

engineer in view of engineering judgment and experience. The output information from NASALIFE has 

been designed to provide the design engineer a quick assessment of the most damaging portion of each 

cycle. It is the user's responsibility to seek guidance on correct choices or options for calculating life. 

2. Technical Background 

High temperature structural components of a gas turbine engine are placed under severe 

environmental conditions during engine operation. The components experience thermal cycling, body 

forces, and extraneous loads from the gas flow. In addition, there are issues with creep, corrosion, and 

erosion. The conditions can cause crack initiation and propagation through a component at highly stressed 

locations. The cracks, if undetected, would eventually result in the component failing to perform as 

required. NASALIFE is a tool which the engineer can use when combining operating conditions, heat 

transfer analysis, stress analysis, and materials data to establish the minimum predicted life to failure due 

to crack initiation or complete fracture. 

NASALIFE requires as input a complete mission stress and temperature history. Stresses can be 

uniaxial or, in the case of isotropic materials, multiaxial. Also required for input are a number of material 

related data items, such as the appropriate family of pseudo-stress versus life curves, a Walker exponent, 

as presented by Walker (1970), and its variation with temperature determined for low cycle fatigue (LCF) 

applications, and the nonlinear stress-strain curve information. The program itself will then compute the 

major LCF cycle, identify all subsequent minor cycles, and finally produce a calculated LCF life for the 

given mission. All calculations in NASALIFE are performed using elastic stresses. In addition, 

NASALIFE can also estimate life relative to creep rupture and the combined life due to LCF and creep. 

Figure 1 shows a flow chart for NASALIFE. 

Stress

And

Temperature

Data

Combine

Multiaxial

Stresses

Identify

Major/Minor

Damage

Cycles

Mean

Stress

Effects

Calculate

Cyclic

Life

Calculate

Creep

Rupture

Life

Calculate

Time

Dependent

Life

Damage

Accumulation

Rule

Component

Life

Select

Time

Method

Materials Data

LCF/HCF

Mean Stress

Constitutive

Rupture

NASALIFE

Figure 1.—A flow chart for NASALIFE. 
NASA/TM—2005-213886 3

2.1. LCF Data 

The fatigue data input contains a series of values for stress and a corresponding life which describe a 

series of isothermal LCF curves. Extrapolation beyond either the maximum temperature or maximum 

stress of the fatigue data is not permitted and will be indicated by an error flag and assigned a life of zero 

cycles or missions. Also, the lowest temperature LCF data is used to determine failure when the mission 

temperature is below the lowest available data temperature. The LCF life is determined for a given stress 

amplitude by a log-log interpolation between adjacent stress-life points given in the data file. The 

interpolation between temperatures is performed in a linear fashion. 

The fatigue data series of stress and corresponding life does not permit inclusion of an absolute 

endurance limit, so the last point in the file is the life for zero stress. This is necessary so that a life can be 

calculated for very small stress amplitudes. NASALIFE does not permit the termination life to exceed 

1031 cycles due to exponent overflow errors. NASALIFE checks the selected data for the termination life 

and prints an error flag if the 1031 value is exceeded. 

2.2. Multiaxial Fatigue Methods 

Critical locations in engine components often experience significant multiaxial stress fields. The 

multiaxial stresses consist of the three orthogonal normal stresses, σx, σy, σz, and three shear stresses, τxy, 

τyz, τzx. Also, with a cyclic load there is a minimum stress and maximum stress per cycle which are 

indicated with the subscripts min and max, respectively. Figure 2 illustrates the load cycle and the 

variables to describe it. Multiaxial methods are used to convert the multiaxial stresses into an equivalent 

uniaxial stress. This conversion must include the treatment of both the mean stress, σm, and the stress 

amplitude, also referred to as the alternating stress, σa. The mean stress and the stress amplitude are 

defined by the following equations 

2

σmax + σmin σm =

(1) 

2

σmax − σmin σa =

Time

Stress

σmax

σm

σmin

σa

Figure 2.—The illustration shows the stress variables and 

subscripts to describe a load cycle. 

Upon rearranging the above equations we have 
NASA/TM—2005-213886 4

σmax = σm + σa

(2) 

σmin = σm − σa

Two other terms are commonly used for describing fatigue loads. These are the R-ratio, R, and the 

A-ratio, A, as defined by the following equations 

max

min

σ

σ R = (3) 

m

a A

σ

σ = (4) 

There are several methods described in the literature for calculating a single effective stress from the 

multiaxial stresses. A few of the methods are utilized in NASALIFE. In addition, the Manson-McKnight 

and Modified Manson-McKnight multiaxial stress methods are introduced here. The methods, used in 

NASALIFE, are based on the Von Mises method, also known as the octahedral shear stress method and 

distortion energy method. The multiaxial methods are restricted to proportional loading of the multiaxial 

stresses. Isotropic material properties are assumed. The subsequent sections describe the methods used 

within NASALIFE. 

The following equations are used throughout the next section. These are the mean stresses and stress 

amplitudes in the orthogonal directions, x, y, and z. 

2

x max x max xm

σ + σ

σ = 2

x max x min xa

σ − σ

σ =

2

y max y min

ym

σ + σ

σ = 2

max min y y

ya

σ − σ

σ = (5) 

2

z max zmin zm

σ + σ

σ = 2

zmax zmin za

σ − σ

σ =

Also, the shear stresses are defined as 

2

xy max xy min

xym

τ + τ

τ = 2

xy max xy min

xya

τ − τ

τ =

2

yz max yz min

yzm

τ + τ

τ = 2

ya max yz min

yza

τ − τ

τ = (6) 

2

zx max zx min zxm

τ + τ

τ = 2

zx max zxmin zxa

τ − τ

τ =

As noted above, the subsequent sections describe the various Von Mises based methods available in 

NASALIFE. These methods are used to convert the multiaxial stresses to a single effective stress. The 

user decides which method is appropriate for the desired analysis, although, the program does use the 

Manson-McKnight method as the default method for reducing a multiaxial stress to a uniaxial stress. 
NASA/TM—2005-213886 5

2.2.1. The Manson-McKnight Method.—A method used in NASALIFE is known as the MansonMcKnight method. The equations for the mean stress and the stress amplitude of the Manson-McKnight 

method are described below:

(7)

( )( ) ( ) ( ) 2 2 2 2 2 2 6

2

2

σa = σxa − σya + σya − σza + σza − σxa + τxya + τ yza + τzxa (8) 

The stress amplitude and the mean stress are defined by the Von Mises criteria. In addition, the mean 

stress is modified where the sign of the mean stress is the sign of the sum of the normal stresses with the 

use of the SIGN term. 

The major limitation of this method is for cases which are dominated by shear stresses. Consider the 

plane stress case where a material is cycled under a normal stress and a proportional shear stress. The 

loads are 

σx min = 0.0 ksi τxy min = 0.0 ksi 

σx max = 0.1 ksi τxy max = 100 ksi 

The resulting stress amplitude and mean stress are 

σa = 86.6 ksi 

σm = 86.6 ksi 

If the sign is changed on the applied normal stress such that 

σx min = 0.0 ksi τxy min = 0.0 ksi 

σx max = -0.1 ksi τxy max = 100 ksi 

The resulting stress amplitude and mean stress are 

σa = 86.6 ksi 

σm = -86.6 ksi 

In this case, a change of 0.2 ksi results in a change of the mean stress by 173.2 ksi due to the SIGN 

term in the mean stress equation. 

2.2.2. The Modified Manson-McKnight Method (Shaft Life Option).—The Modified MansonMcKnight method changes the sign calculation for the mean stress. The sign term, SIGN(σxm+σym+σzm), 

of the Manson-McKnight mean stress equation is replaced with a function of the largest and smallest 

principal stresses, σ1 and σ3, respectively for each loading condition. The principal stresses are found by 

solving for σ with the following determinant.

( )

( )

( )

= 0

τ τ σ − σ

τ σ − σ τ

σ − σ τ τ

zx yz z

xy y yz

x xy zx

 (9)

         2 2 2 2 2 2 6

2

2

m  SIGN xm  ym  zm xm  ym  ym  zm  zm  xm  xym   yzm  zxm
NASA/TM—2005-213886 6

The substitution is for the case when the sign of the largest principal stress, σ1, is different from the 

sign of the smallest principal stress, σ3. The function is as follows 

1 3

1 3

σ − σ

σ + σ

The resulting equation for the mean stress is 

( )( ) ( ) ( ) ⎟

⎟

⎠

⎞ ⎜

⎜

⎝

⎛

σ + σ

σ + σ

σ = σ + σ + σ + σ + σ + σ + τ + τ + τ

1 3

2 2 2 2 2 2 1 3 6 * 2

2 m xm ym ym zm zm xm xym yzm zxm (10)

The stress amplitude remains the same as the one presented with the Manson-McKnight method. The 

equation for the stress amplitude is 

( )( ) ( ) ( ) 2 2 2 2 2 2 6

2

2

σa = σxa − σya + σya − σza + σza − σxa + τxym + τ yzm + τzxa (11) 

In the example used with the Manson-McKnight method where 

σx min = 0.0 ksi τxy min = 0.0 ksi 

σx max = 0.1 ksi τxy max = 100 ksi 

with the resulting stress amplitude and mean stress of 

σalt = 86.6 ksi 

σmean = 86.6 ksi 

If the sign is changed on σx max so that σx max = –0.1, these values would remain the same, that is 

σalt = 86.6 ksi 

σmean = 86.6 ksi 

2.2.3. The Sines Method.—The Sines method, as noted by Sines and Ohgi (1981), calculates the 

mean stress as the sum of the mean stresses in each orthogonal direction as illustrated with the following 

equation

σm = σxm + σym + σzm (12) 

In addition, the Sines method stress amplitude, σa, modifies the alternating stress derived from the 

distortion energy method. Here, the stress amplitude is also a function of a constant, C1, and the mean 

stress as illustrated in the following equation 

( )( ) ( ) ( ) 1 mean 2 2 2 2 2 2 6

2

2

σa = σxa − σya + σya − σza + σza − σxa + τ xya + τ yza + τzxa + C σ (13)

The constant, C1, is assigned the following values under the given conditions within NASALIFE 
NASA/TM—2005-213886 7

C1 = 0.5 for uniaxial loading conditions 

C1 = 1.0 for multiaxial loading conditions 

Lastly, the Sines method adjusts the LCF data to A-ratio = ∞. This theory implies that a mean shear 

stress has no effect on fatigue life. 

2.2.4. The Smith Watson Topper Method.—The Smith-Watson-Topper (1970) method does not use 

the Walker mean stress model. The mean stress is assumed to be zero.

σm = 0 (14) 

The stress amplitude, σa, is a function of the largest principal stress, σ1 with the 

Smith-Watson-Topper method. The maximum value of the largest principal stress, σ1 max, is calculated 

from stresses σx max, σy max, σz max, τxy max, τyz max, τzx max. The minimum value of the largest principal stress, 

σ1 min, is calculated from the stresses σx min, σy min, σz min, τxy min, τyz min, τzx min. The resulting equation for the 

stress amplitude is 

1max ( ) 1max 1min 2

1

σa = σ σ − σ (15) 

2.2.5. The R-Ratio Sines Method.—The R-ratio Sines method uses the mean stress from the Sines 

method presented above. The equation for the mean stress is

σm = σxm + σym + σzm (16) 

The stress amplitude, σa, calculation, similar to the distortion energy method, is 

( )( ) ( ) ( ) 2 2 2 2 2 2 6

2

2

σa = σxa − σya + σya − σza + σza − σxa + τxya + τ yzm + τzxa (17) 

2.2.6. Effective Method.—The Effective method, presented here, derives its mean stress by doubling 

the mean stress from the distortion energy method and reducing it by the magnitude of the stress 

amplitude. The equation for the mean stress follows

σm = ( )( ) σxm + σym + σym + σzm + ( ) σzm + σxm + (τxym + τ yzm + τzxm ) − σa 2 2 2 2 2 2 2 6 (18) 

The Effective method determines the scalar stress amplitude, σa, from the distortion energy method, 

that is the same as the one presented with the Manson-McKnight method. The equation for the stress 

amplitude is 

( )( ) ( ) ( ) 2 2 2 2 2 2 6

2

2

σa = σxa − σya + σya − σza + σza − σxa + τxya + τ yza + τzxa (19)

2.2.7. Other Methods.—New subroutines can be added to future versions of NASALIFE to 

accommodate different stress reduction methods.
NASA/TM—2005-213886 8

Most components operate with a varying mean stress occurring during their cyclic mission. There 

may be purely elastic mean stress effects due to the complex missions, or there may be a mean stress 

which is generated by local plastic yielding at sharp stress concentrations. The Walker (1970) model may 

be used in NASALIFE to address the influence of mean stresses on fatigue lives. To reiterate, NASALIFE 

only treats elastic stresses. 

It was noted in the previous section but the parameters designated by R-ratio, R, and A-ratio, A, are 

commonly used to describe the level of mean stresses or stress. Reiterating, if we use stress as the 

parameter, 

max

min

σ

σ R = (3) 

m

a A

σ

σ = (4)

or upon substituting variables, we get 

m a

m a R

σ + σ

σ − σ = (19)

max min

max min

σ + σ

σ − σ A = (20) 

Also, it can be shown that 

A

A R

+

− = 11 (21)

R

R A

+

− = 11 (22) 

For example, most specimen testing is with the minimum stress, σmin, at zero and the maximum stress, 

σmax, greater than zero resulting in R = 0 and A = 1. With the R-ratio being zero the stress amplitude is one 

half of the maximum stress. 

The Walker equation can be presented for the modified stress amplitude or Walker stress amplitude, 

σaw, as a function of the maximum stress; R-ratio; and the Walker exponent, m. The equation is 

( )m σaw σ 1− R

2

1 max (23) 

For fatigue lives, this expression is converted to a function of the stress amplitude using the identity: 

R

a

−

σ

σ = 1 max 2 (24) 

2.3. The Walker Mean Stress Model 
NASA/TM—2005-213886 9

Substitution of the maximum stress, σmax, into the equation for the Walker stress amplitude, σaw, 

equation and rearranging results in 

( )

( 1) 1 − σ = σ − m aw a R (25) 

This approach results in increased damage for R>0 (A<1), life benefit when R<0 (A>1), and no effect 

when R = 0 (A = 1). 

2.3.1. Walker Exponents Within NASALIFE.—One of the major difficulties with using the Walker 

mean stress model is the unavailability of Walker exponents. If Walker exponents have not been 

determined for a particular condition, then default Walker exponents can be invoked in NASALIFE. The 

default values with the given loading conditions are 

 m = 1.0 when R<0 and as a result A>1.0 

 m = 0.5 when R≥0 and as a result A≤1.0 

The Walker modified stress amplitude is the same as the applied stress amplitude when the default 

Walker exponent, m, is 1.0 when the minimum stress is negative. When R≥0 the use of m = 0.5 results in 

lower lives relative to the use of the stress amplitude. If the life of a component is low when the default 

Walker exponents are used, it may be possible to increase the life using Walker exponents determined 

from experimental data. 

NASALIFE reads temperature dependent Walker exponents from the materials data and interpolates 

values linearly with temperature. When the Walker exponents are not known, a value less than –1 should 

be entered in the material to invoke the use of default Walker exponents. No extrapolation is permitted 

outside the temperature range in the material’s data. 

2.3.2. Restrictions on the Walker Mean Stress Model.—Two restrictions have been placed on the use 

of the Walker model: 

(1) No additional benefit will be taken when the mean stress is negative. 

The first restriction is based on the frequently observed behavior in LCF curves that little to no 

improvement in life will occur in test specimens with mean stresses less than zero, that is R<–1 (A<0), 

relative to mean stresses greater than or equal to zero, R≥–1 (A≥0), tests. This approach permits taking 

benefit for the mean stress effects up to mean stresses of zero, but does not permit any additional benefit. 

(2) When the stress amplitude exceeds yield, the higher of σa or σaw will be used to assess life. 

This is why the user inputs the stress strain curve. 

2.3.3. A-Ratio Correction.—The A-ratio is initially assumed to be one or R = 0 for the LCF data 

within NASALIFE. If the value for the A-ratio is other than one then NASALIFE corrects the Walker 

calculation. NASALIFE adjusts the A-ratio when A≤0.900. The adjusted Walker calculation is

( )

1

1

2

1 −

⎟

⎠

⎞ ⎜

⎝

⎛ − +

σ = σ

m

aw a R

A

A (26) 

The A-ratio, A, is taken from the test conditions used to generate the LCF data that is used with 

NASALIFE. Under the condition that the A-ratio is less than or equal to zero, or greater than 107

 then the 

term (1+A)/2A is set to 1⁄2, the value for A = ∞, such that the equation becomes 
NASA/TM—2005-213886 10

( )

1

1

2

1 −

⎟

⎠

⎞ ⎜

⎝

⎛

σ = σ −

m

aw a R (27) 

2.4. Load Cycle Counting Methods 

The application of a varying load over time requires the use of a technique for counting the different 

cycles. This section describes the methods available in NASALIFE. 

2.4.1. Rainflow Counting.—The simplest method of considering the full damage content of a mission 

is through the use of a rainflow counting technique as presented by Endo (1967, 1968). The rainflow 

counting technique is a standardized cycle counting method as per American Society for Testing and 

Materials (ASTM) (2004) E 1049–85. A common rainflow approach is to use the effective stress at the 

end points of a particular cycle. This will properly calculate the magnitude of the stress amplitude, but 

does not take into account the influence of the mean stress of the cycle or the variation of temperature 

during the cycle. As a result, NASALIFE uses a damage rainflow approach.

Damage counting schemes identify the most damaging cycle based on the stress and temperature data. 

In NASALIFE, a damage counting algorithm is used to identify the most damaging major cycle. The most 

damaging major cycle is determined by evaluating every combination of mission points, 

N*(N-1) permutations for N mission points, to find the combination which will produce the lowest life. 

The life for each subcycle is calculated using the multiaxial method (section 2.2), and the mean stress 

model (section 2.3). All subsequent minor cycles are then identified using the more traditional stress 

rainflow techniques. 

This damage rainflow approach can select any point in a mission, not necessarily a maximum or 

minimum stress. A good example of this would be a relatively slow loading ramp where the temperature 

goes through a large maximum. If the fatigue life of the material in question decreases with increasing 

temperature, an intermediate stress point at a high temperature might be one of the points in the most 

damaging cycle. 

2.4.2. Rainflow Stresses.—NASALIFE reduces stress tensors to scalar values in preparation for 

applying the rainflow counting method. The program uses one of the previously described methods for 

reducing a multiaxial stress state to an effective uniaxial stress state along the maximum octahedral shear 

stress axis. As noted earlier, material isotropy is assumed. The rainflow counting method is used to reduce 

a complex variable amplitude mission loading to a more manageable effective mission loading. The 

method finds the most damaging cycles.

2.4.3. Rainflow Process.—NASALIFE uses a 6 step process:

1. Use a multiaxial method with a mean stress model and find the most damaging cycle of each mission 

and the most damaging mission. 

2. The stress range for the most damaging cycle of the most damaging mission is used to identify the 

orientation which produces the maximum octahedral shear stress. 

3. All 6 components of stress for each mission point of all missions are resolved into the critical plane 

and the component in the direction of the maximum octahedral shear stress direction is saved for all 

subsequent minor cycle identification. 

4. A rainflow counting procedure is applied to the mission stresses to eliminate intermediate stress 

points and to pair the appropriate minimum and maximum stress points. Eliminate small cycles based 

on a tolerance of the largest applied stress in the mission. 

5. The multiaxial fatigue method, and the mean stress model is then used to calculate the effective stress 

for each paired subcycle. The paired cycles are sorted on the minimum life, the maximum Walker 

stress and then the input order. 
NASA/TM—2005-213886 11

6. If the first two points from step 5 are not the same ones identified as the most damaging cycle in Step 

1, these points are replaced with the most damaging cycle identified in step 1. This process may 

reduce the life relative to that determined for a pure stress rainflow analysis. 

2.5. Cumulative Fatigue Damage 

The fatigue life for a particular stress can be determined from the appropriate LCF curve. The 

durability life for the mission is obtained by combining the LCF damage of each of the individual cycles. 

NASALIFE estimates the LCF damage using Miner's (1945) rule: 

i

i

i N

X

N = Σ 1 (28)

where Xi is number of cycles of one magnitude and environmental condition and Ni is the life with those 

cycles at the same environmental condition. 

2.6. Rupture Calculations 

NASALIFE will provide a calculated rupture life if rupture data is included in the input file. The 

stresses are converted from tensors to scalars using effective stress. A very simple integration over the 

mission is then performed. The step size is determined based on the larger of the time increment or the 

stress increment. 

Rupture time is calculated for each increment. The rupture data may either be tables of temperature 

and stress versus life, or Larson-Miller (1952) parameters. 

2.6.1. Larson-Miller Parameter for Creep.—The basic Larson-Miller equation is: 

P = T (C + logt) (29) 

where: 

T temperature 

C material constant 

t time 

P Larson-Miller parameter 

The Larson-Miller parameter is a function of the log of the stress. For NASALIFE the Larson-Miller 

parameter is entered as a polynomial function of stress with simple adjustments as presented by Conway 

(1969). As a result, it is assumed that the Larson-Miller parameter has a normal distribution or, 

equivalently, the rupture time follows a lognormal distribution as noted by Zuo, et al. (2000). 

NASALIFE uses the above equation solved for time as shown by the following equation 

⎟

⎠

⎞ ⎜

⎝

⎛ −

= C

T

p

t 10 (30) 

It was noted above that the Larson-Miller parameter is entered as a polynomial function. The function is 

illustrated below 
NASA/TM—2005-213886 12

i P = P0 + P1σ + P2σ2 + ... + Piσ (31) 

where: 

Pi polynomial coefficients 

σ applied effective stress 

2.7. Combined LCF and Rupture Life 

In NASALIFE, the total damage caused by a mission is the sum of the damage due to cyclic fatigue 

and the damage due to creep. Damage is the life used by a mission divided by the total available life. As a 

result, damage that is greater than or equal to unity constitutes failure. Initially the life is determined for 

the creep life under a given loading condition. Damage, Dcreep, is taken as the inverse of the life, Lcreep as 

shown by the following equation 

creep

creep L

D 1 = (32) 

Also, NASALIFE converts the LCF life, LLCF, to LCF damage, DLCF, as illustrated by the equation below 

LCF

LCF L

D 1 = (33) 

The total damage, D, is 

D = DLCF + Dcrreep (34) 

NASALIFE can utilize an exponential creep damage rate leading to the following equation 

b D = DLCF + Dcreep (35) 

where b is the exponent for the creep damage. 

2.8. Stress-Strain Properties 

NASALIFE uses the Ramberg-Osgood (1947) curve fitting method for modeling the stress-strain 

curve of a material. As described by Dowling (1999) the Ramberg-Osgood method considers the elastic 

and plastic strain separately and sums them. The elastic strain is linearly related to the stress while the 

plastic strain has the exponential relationship with the stress. The equation is 

n

E K

1

⎟

⎠

⎞ ⎜

⎝

⎛ σ

+

σ

ε = (36) 

The variables for the above equation are defined as 

σ stress 

ε strain 

E Young’s modulus 
NASA/TM—2005-213886 13

K Ramberg-Osgood constant 

n Ramberg-Osgood exponent 

The Ramberg-Osgood constant, K, is the value of the stress, σ, at the initiation of plastic strain. εy. With 

strain at the initiation of yielding the above equation becomes 

n σy = K ε y (37) 

At the current time NASALIFE uses the material constants and Ramberg-Osgood parameters to 

calculate a 0.2 percent offset yield strength as the cutoff point for the Walker mean stress model. 

NASALIFE performs a linear interpolation on the constants K, and n with temperature. Extrapolation 

beyond the maximum temperature is not permitted and will be indicated by an error flag. 

2.9. Other Issues Not Included In NASALIFE 

Design engineers must often consider factors other than those discussed in this document in 

determining the fatigue life of their components. Some of these issues are: 

• Time dependent deformation 

• LCF/HCF Interaction 

• Role of feature testing 

• Composite material failure mechanisms 

• An elastic plastic Walker model 

These factors may be important, but until methods are established and verified for these they will not 

be included in NASALIFE. When those methods are developed, they will be included in future releases 

and the corresponding updated manual. 

Another failure issue, particularly, with CMCs is pesting as presented by Ogbuji (2002). Pesting is the 

oxidative degradation of CMCs in a service environment at intermediate temperatures. As mentioned 

above as models become available they can be incorporated into NASALIFE. 

3. User Manual 

This section provides the information necessary for creating a mission input file and using 

NASALIFE. The mission file consists of keywords, flags, and data describing desired outputs, material 

properties, and loading conditions. The mission file uses keywords placed on the first line of each section 

with flags, parameters, or data on the following lines. Delimiters may consist of a space, comma, or 

ampersand. The program uses a free format entry method. The program will accept lower and upper case 

letters for the keywords. Any lower case alpha characters are converted to upper case within the program. 

3.1. Output and Print Options 

NASALIFE sets up the desired output with the print command, PRIN. The command line is followed 

by a line of ten numeric flags to set options. An example is shown below 

PRIN 

3 1 1 0 0 2 2 2 2 1 
NASA/TM—2005-213886 14

The first option has four choices as follows 

0 Only the mission fatigue life and flags are printed to the terminal screen. No information is 

printed to an output file. 

1 The fatigue life and flags are printed to the terminal screen. The mission rainflow, times, stresses, 

temperatures, life, and flags are printed to an output file. 

2 The mission rainflow, times, stress, temperatures, life, and flags are all printed to the terminal 

screen and to an output file. 

3 or greater The mission rainflow, times, stress, temperatures, life, and flags are all printed to an 

output file. 

When results are directed to an output file NASALIFE creates an output file that uses the input file’s 

name but replaces the input file’s extension with the extension of “out”. If the input file name does not 

have an extension then NASALIFE just appends the “.out” extension on to the input file name for the 

output file. In the case an output file exists with the same name the program prompts the user to quit the 

run or overwrite the file with a new output file. NASALIFE uses the input file’s drive and directory 

location for the output file. 

The remaining 9 numeric print flags and their respective options are 

Flag 2 is for file names 

1 print file names 

not 1 do not print file names 

Flag 3 is for mission echo 

0 do not echo mission data 

not 0 echo mission data 

Flag 4 is for critical damage plane information 

0 no critical damage plane information printed 

greater than 0 critical damage plane information printed 

Flag 5 is for rainflow/mission edit information 

0 rainflow/edit information suppressed 

not 0 rainflow/edit information printed 

Flag 6 is for rupture data 

 0 no rupture data printed 

 1 reserved 

 2 or greater print rupture data 

Flag 7 is for LCF data 

 0 no LCF data printed 

 1 reserved 

 2 or greater print LCF data 

Flag 8 is for material file data 

0 no material data is printed 

not 0 material data is printed 

Flag 9 is for minor load cycle printout 
NASA/TM—2005-213886 15

0 no information on minor cycles printed 

 1 reserved 

 2 or greater information on minor cycles printed 

Flag 10 is for program options 

 0 No internal stress handling information printed 

 not 0 Internal stress handling information printed 

3.2. Material Data 

NASALIFE references material and mechanical properties data as part of the life prediction process. 

The data is usually empirically derived. The properties include LCF data, creep rupture data or LarsonMiller parameters for creep, and static properties. The following sections described the format for 

entering the data in the mission file. 

One important restriction is that no extrapolations beyond values defined in the input file are 

permitted. Any extrapolations to a higher or lower temperature or to a higher stress will result in a life of 

0.1 for that cycle, resulting in a negligible life for the entire mission. Therefore, the reference data utilized 

must cover the entire range of temperatures and stresses for the mission being analyzed. This safeguard 

has been placed in the code so that data base extrapolations and/or issues are performed by the 

appropriate engineering personnel and not arbitrarily performed in NASALIFE. 

NASALIFE does not contain a model for matching an LCF curve with an endurance limit. The 

program provides a finite life for low amplitude loading cycles. In addition, lives beyond 1031 cycles are 

not permitted due to difficulties with exponential overflow. Lives longer than 1031 cycles will be assumed 

to have a life of 1031 cycles. 

3.2.1. LCF Properties Data.—NASALIFE requires LCF data as a reference for estimating life under 

various loads. The LCF properties are the maximum stress and the resulting life at various temperatures 

and a given A-ratio. The LCF data entry is selected with the keyword LCF followed by other keywords 

and their respective information and the actual LCF data. As described in previous sections the keyword 

is place on one line followed by the required information on the next line. 

The keys used under the LCF command are 

TITL LCF data title 

ARAT A-ratio (stress amplitude or alternating stress divided by mean stress) by which LCF data was 

generated 

FLIF SMAX FLAG TEMP 

where 

FLIF life in cycles 

SMAX Maximum stress in ksi 

FLAG described below 

TEMP temperature in °F 

The keywords, FLIF, SMAX, FLAG, and TEMP can be in any order within the line. The data following 

the command line has to be in the same order as the keywords within the keyword line. 

EOF Line to indicate the end of LCF data section 

NASALIFE calls for some restrictions in the LCF data. The restrictions are as follows 
NASA/TM—2005-213886 16

• Data is in order of increasing temperature. 

• Next, data is in order of increasing life. 

• At least two stress levels are required at each temperature. 

• The LCF data set can only be at one A-ratio. 

The flags determine the validity and applicability of the LCF data for a given mission. If this 

information is important to the quality of the analysis, information will be printed in the NASALIFE 

output. The flags are defined with a three digit integer (X1 X2 X3). The integers are not separated by 

delimiters. A single digit entry would set X1 and X2 to zero with X3 set to the given single digit entry. 

Similarly, a two digit entry sets X1 to zero and X2 and X3 to the given values. The values for the integers 

are as follows 

Deviation flag (X1) 

0 No deviation required 

1 Deviation required 

Temperature Extension Flag (X2) 

0 within valid range of data 

1 extended to high temperature outside data 

2 extended to low temperature outside data 

Stress amplitude Extension Flag (X3) 

0 within valid range of data 

1 extended to low stress amplitude outside data 

2 extended to high stress amplitude outside data 

An example of the LCF data section is presented below 

LCF 

TITL 

Example NASALIFE LCF data 

ARAT 

1 

FLIF SMAX FLAG TEMP 

 1000 400 20 60 

 10000 51 20 

100000 50 121 

 1000 300 0 300 

 10000 21 0 

100000 20 0 

 1000 300 0 1000 

 10000 21 0 

100000 20 0 

 1000 300 12 1300 

 10000 11 10 

100000 10 11 

 EOF 

The flag, 20, in the example above is read as 020. The blanks in the temperature column lead the 

program to use the previous temperature. 
NASA/TM—2005-213886 17

3.2.2. Static Material Properties.—NASALIFE requires static material properties. The material 

properties consist of stress and strain deformation data at different temperatures. The program is informed 

of the initiation of the material data entry section with the keyword MATL followed by other relevant 

keywords and information and, finally, the material data. Keywords in the material section are as follows:

TITL material title 

CURV curve number 

GS grain size 

RKT thermal conductivity, Kt 

MATN material data set number 

FORM material form 

RORI material orientation 

ILIF type of life data 

Many of the above keywords are used to describe the material for the user. As a result, they are optional. 

The keyword, TITL, is to be by itself in a line with the actual title of the material section on the next line. 

The remaining keywords can be placed on a single line with the respective values in the same order on the 

next line. 

In addition, the following commands set options within the program. 

IOP1 uniaxial mean stress option 

0 .02 percent strain used for yield stress 

1 0.2 percent strain used for yield stress (default) 

IOP2 material option (unused) 

IOP3 material option (unused) 

IOP4 material option 

0 program does not allow low temperature extrapolation (default) 

1 allow low temperature extrapolation 

IOP5 material option (unused) 

TEMP M FLAG walker exponent data where 

 TEMP is temperature in °F 

 M is the Walker exponent 

 FLAG is described further down below 

TEMP E K N V FLAG are stress-strain data (E and V are ignored at this time) where 

TEMP is temperature in °F 

E is Young’s modulus of elasticity in ksi 

K is the Ramberg-Osgood constant 

N is the Ramberg-Osgood exponent 

V is Poisson’s ratio 

FLAG is described further down below: 

EOF end of material data key 

Default values for the Walker exponent are activated by using any value less than of –1 with the 

exponent keyword, M. As noted earlier in the theoretical section, the default Walker exponent, m, is 

m = 1 when R<0, A>1 
NASA/TM—2005-213886 18

m = 0.5 when R≥0, A≤1 

All data must be represented in units of °F and KSI. 

The input options for the keyword, FLAG, are 

000 = valid regime 

010 = extrapolated to high temperature 

020 = extrapolated to low temperature 

The options for the keyword, ILIF, are 

0 for 95/99 curve 

1 for three standard deviations curve 

2 for average properties 

No extrapolations beyond values defined in the input files are permitted. Any extrapolations to a 

higher or lower temperature will result in a life of 0.1, resulting in a negligible life for the entire mission. 

Therefore, the materials data must cover the entire range of temperatures for the mission being analyzed. 

The following lines demonstrate the material entry section 

MATL 

TITL 

Example NASALIFE material file 

IOP1 IOP2 

 1 1 

TEMP M FLAG 

 60 .5 20 

1300 .5 10 

TEMP E K N V FLAG 

 60 30000 100 0 .3 20 

1300 30000 100 0 .3 10 

EOF 

3.2.5. Creep Rupture Information.—The use of creep rupture information in the input file for 

NASALIFE is optional. If creep rupture information is available then NASALIFE will calculate the life 

due creep and the combined effects of LCF and creep. Creep rupture data may be entered as a table of 

empirical data or in equation form. Entry of tabular form of creep rupture data is initiated with the

keyword, RUPT. Alternatively, creep rupture information may be entered with Larson-Miller parameters. 

The Larson-Miller equation form of data entry is initiated with the keyword, RUPD. 

First, the method for entering creep rupture information using Larson-Miller parameters is covered 

here. As noted, the keyword, RUPD, is used to initiate equation parameters entry for creep rupture 

behavior. The keys that follow are: 

TITL material title 

REXP the rupture damage exponent (used with summing of damage) 

SOFF stress offset 

ISTY stress type for applying the stress offset 
NASA/TM—2005-213886 19

0 offset σ = logσ − σ

1 σ = σ − σoffset

TADD temperature adder or offset (default 459.67 for °F to °R) 

TMUL temperature multiplier for converting to Rankine (default 1.) 

NASALIFE is setup to read temperature in degrees Fahrenheit. Internally, the program converts the 

temperature to Rankine. In the event other units for temperature are provided the keywords, TMUL and 

TADD, can be included for the program to convert the given temperatures to units of Rankine. The 

program uses the following equation for the conversion 

TRankine = (T + TADD)TMUL

The following table provides values for TADD and TMUL that should be used with the given data 

temperature units 

data units TADD TMUL

°F 459.67 1.00

°C 273.15 1.80

°R 0.00 1.00

K 0.00 1.80

The entry of the Larson-Miller parameter polynomial coefficients is initiated with the keyword, PM. 

The lines following the keyword line include the coefficients with one coefficient per line. The example 

at the end of this section illustrates a Larson-Miller polynomial and its entry in a mission file. 

The Larson-Miller parameter can be set to change upon exceeding a threshold temperature. The 

program will look for the change with the keyword, LMFM and its value set to one. 

LMFM–Larson-Miller form 

0 for no change in the Larson-Miller parameter polynomial with temperature (default) 

1 for change upon exceeding a threshold temperature 

The Larson-Miller parameter varies exponentially with temperature and user defined constants upon 

exceeding the threshold temperature. The keywords for the constants are 

PTEM temperature above which the exponential form of the Larson-Miller parameter becomes 

active 

PBAS base for the exponential component 

PEXP exponent 

The equation form being 

( )

PEXP Pmodified = P + PBAS T − Tthreshold

The modified Larson-Miller parameter can be further modified. The following equation is used 
NASA/TM—2005-213886 20

Pmodified 2 = Pmodified + PAVG *T

The above equation becomes active with the keyword, IRUP, and its value set at 1. This in addition to the 

first modified Larson-Miller being active. Also, the constant PAVG is entered with the keyword of the 

same name followed by its value in the next line. 

PAVG minimum to average factor 

Other parameters for the Larson-Miller equation are as follows 

C Larson-Miller constant 

RMUL rupture time multiplier 

TMLO the low temperature for this equation 

TMHI the high temperature for this equation 

STLO the low stress for this equation 

STHI the high stress for this equation 

EOF end of rupture equation key 

A user defined adjustment to the rupture life may be entered into NASALIFE. The keyword for the 

multiplier is RMUL with its value on the following line. The multiplier adjusts the Larson-Miller 

equation as illustrated by the following equation 

10 *RMUL

⎟

⎠

⎞ ⎜

⎝

⎛ −

= C

T

p

t

These all default to zero. TMHI and STHI should be greater than zero for the equation format to 

work. Temperatures below TMLO and stresses below SMLO will be converted to the low value before 

calculating the life. 

The following lines provide an example for entering creep rupture equation data. The polynomial 

form of the Larson-Miller parameter, P, for the example is 

2 P = 40 −15σ − 7σ

RUPD 

TITL 

Example NASALIFE creep rupture equation data 

TMLO TMHI STLO STHI C SOFF TMUL TADD 

1200 1300 55 150 20 2.00 1 459.67 

PM 

40 

-15 

-7 

EOF 

As noted at the beginning of this section, creep-rupture data may be entered as a table of empirical 

data or in equation form. This section covers data entry in tabular form. The key, RUPT, is used to initiate 

the entry of creep-rupture information within the mission file. The keys that follow are: 
NASA/TM—2005-213886 21

TITL material title 

REXP rupture damage exponent 

IRUP flag: 1 average, 2 minimum 

RLIF RSTR FLAG TEMP creep-rupture data where 

 RLIF life in hours 

 RSTR rupture stress in ksi 

 FLAG described below 

 TEMP temperature in °F 

 EOF end of rupture table key 

As with the LCF data NASALIFE calls for some restrictions with the creep rupture data. The 

restrictions are as follows 

• Data is in order of increasing temperature 

• Next, data is in order of increasing life 

• Resulting stress must be in decreasing order 

The rules for the flags are similar to the ones presented with the LCF data entry section. The flags 

determine the validity and applicability of the rupture data for a given mission. If this information is 

important to the quality of the analysis, information will be printed in the NASALIFE output. The flags 

are defined with a three digit integer (X1 X2 X3). The integers are not separated by delimiters. A single 

digit entry would set X1 and X2 to zero with X3 set to the given single digit entry. Similarly, a two digit 

entry sets X1 to zero and X2 and X3 to the given values. The values for the integers are as follows 

Deviation flag (X1) 

0 No deviation required 

1 Deviation required 

Temperature Extension Flag (X2) 

0 within valid range of data 

1 extended to high temperature outside data 

2 extended to low temperature outside data 

Stress Extension Flag (X3) 

0 within valid range of data 

1 extended to low stress outside data 

2 extended to high stress outside data 

Rupture data is interpolated linearly in stress, log in Rankine temperature, and log in life. 

Temperatures and stresses below the table values will be raised to the appropriate minimum table value. 

Temperatures and stresses above the table values will generate 10–31 for the life used. 

An example of the rupture data section of the mission file is presented here 

RUPT 

TITL 

Example NASALIFE creep rupture data 

IRUP 

 1 

 RSTR RLIF TEMP FLAG 
NASA/TM—2005-213886 22

 150.000 239.269 1200.00 0 

 145.000 341.125 1200.00 0 

 140.000 490.251 1200.00 0 

 135.000 710.526 1200.00 0 

 130.000 1038.96 1200.00 0 

 125.000 1533.55 1200.00 0 

 120.000 2286.10 1200.00 0 

 115.000 3443.91 1200.00 0 

 110.000 5246.18 1200.00 0 

 105.000 8086.78 1200.00 0 

 100.000 12623.4 1200.00 0 

 95.0000 19971.7 1200.00 0 

 90.0000 32055.0 1200.00 0 

 85.0000 52248.4 1200.00 0 

 80.0000 86582.7 1200.00 0 

 75.0000 146058. 1200.00 0 

 70.0000 251170. 1200.00 0 

 65.0000 440988. 1200.00 0 

 60.0000 791858. 1200.00 0 

 55.0000 1.456930E+06 1200.00 0 

 150.000 12.7974 1300.00 0 

 145.000 17.8811 1300.00 0 

 140.000 25.1737 1300.00 0 

 135.000 35.7232 1300.00 0 

 130.000 51.1203 1300.00 0 

 125.000 73.8044 1300.00 0 

 120.000 107.553 1300.00 0 

 115.000 158.296 1300.00 0 

 110.000 235.436 1300.00 0 

 105.000 354.098 1300.00 0 

 100.000 538.931 1300.00 0 

 95.0000 830.713 1300.00 0 

 90.0000 1297.94 1300.00 0 

 85.0000 2057.66 1300.00 0 

 80.0000 3313.34 1300.00 0 

 75.0000 5425.69 1300.00 0 

 70.0000 9047.24 1300.00 0 

 65.0000 15384.5 1300.00 0 

 60.0000 26721.3 1300.00 0 

 55.0000 47489.7 1300.00 0 

EOF 

Note, 0 is the same as 000 for the flag in the example above. 

3.3 Stress Conversion Method 

The default method, within NASALIFE, for converting a multiaxial stress load to an effective 

uniaxial stress is with the use of the Manson-McKnight method. With the use of the keyword, MNMD, 

the user can specify the Manson-McKnight method or the other available methods described in the 
NASA/TM—2005-213886 23

Multiaxial Fatigue Methods section. The keyword, MNMD, is placed on one line with the method 

keyword on the following line. The keywords for the methods are 

blank line Manson-McKnight method 

SHAF Modified Manson-McKnight method 

SINE Sines method 

SWT Smith-Watson-Topper method 

RSIN R-Ratio Sines method 

EQVL Effective method 

3.4. Mission Loads 

Finally, the mission loading conditions are added to the input file for NASALIFE. The loading 

information consists of time, temperature, and six components of stress. 

The mission points are identified by the keywords, TIME, TEMP, S11, S22, S33, S12, S23, S31, and 

NULL. TIME corresponds to time in seconds. The final time in the mission is considered to be the 

mission duration and is used to calculate the fatigue lifetime (predicted cycles to failure x mission time). 

The keyword, TEMP, refers to the temperature in degrees Fahrenheit. Additionally, the keyword, TCON, 

will set the temperatures for the next mission to a constant. The stresses S11, S22, and S33 correspond to 

the normal stresses, σxx, σyy, and σzz, respectively. The stresses S12, S23, and S31 correspond to the shear 

stresses σxy, σyz, and σxz, respectively. All the stresses are in units of ksi. 

Only those keywords that have data need to be used. An example is to use S11 only for a normal 

uniaxial case. The keyword NULL will ignore a column of data. 

An example of typical mission loading data is provided below. Also, Figure 3 illustrates the stress, 

S22, with respect to time from the same mission loading data. 

 TIME TEMP S11 S22 S12 

 1 1250 0 -31 2 

 2 1250 0 -77 2 

 3600 1250 0 -140 0 

Figure 3.—A plot of stress, S22, with respect to time. 
NASA/TM—2005-213886 24

3.5. Input File 

All the sections of the mission input file described are compiled into a single file. Optionally, the sections 

can be stored in separate files. With the use of the FILE command within the main input file the user can 

direct the main input file to the smaller files for the required data. As an example, a file containing rupture 

equation data may be created. For now, the rupture information file can be called testn.rupd. Any file 

name is acceptable. The file, testn.rupd, will contain the example provided previously, that is 

RUPD 

TITL 

Example NASALIFE creep rupture equation data 

TMLO TMHI STLO STHI C SOFF TMUL TADD 

1200 1300 55 150 20 2.00 1 459.67 

PM 

40 

-15 

-7 

EOF 

The following is an example of a mission input file for NASALIFE with the call for the rupture 

information from another file, that is, testn.rupd 

PRIN 

3 1 1 0 0 2 2 2 2 1 

FILE 

testn.rupd 

LCF 

TITL 

Example NASALIFE LCF data 

ARAT 

1 

FLIF SMAX FLAG TEMP 

 1000 400 20 60 

 10000 51 20 

100000 50 121 

 1000 300 0 300 

 10000 21 0 

 100000 20 0 

 1000 300 0 1000 

 10000 21 0 

 100000 20 0 

 1000 300 12 1300 

 10000 11 10 

 100000 10 11 

 EOF 

MATL 

TITL 
NASA/TM—2005-213886 25

Example NASALIFE material file 

IOP1 IOP2 

 1 1 

TEMP M FLAG 

 60 .5 20 

1300 .5 10 

TEMP E K N V FLAG 

 60 30000 100 0 .3 20 

1300 30000 100 0 .3 10 

EOF 

TIME TEMP S11 S22 S12 

 1 1250 0 -31 2 

 2 1250 0 -77 2 

 3600 1250 0 -140 0 
NASA/TM—2005-213886 26

3.6. Keyword Definitions 

KEYWORDS DEFINITIONS 

PRIN Indicates which way the output is to be displayed. This must be the only key on a 

line. The next line will have 10 integer values. (see section 3.1) 

ARAT A-ratio used with LCF data. 

TMF The Thermal mechanical fatigue option: 

1 Most damaging temperature 

2 Maximum temperature 

3 Average temperature 

MNMD mutiaxial material option 

' ' Manson-McKnight (default) 

SHAF Modified Manson-McKnight 

SINE Sines 

SWT Smith Watson Topper 

RSIN R-Ratio Sines 

EQVL Effective 

LCF The LCF data follows this key. 

LCFO The old format LCF data follows this key. 

MATL The material data follows this key. 

MATO The old format material data follows this key. 

RUPD The rupture equation data follows this key. 

RUPT The rupture table data follows this key. 

FILE The next line is a filename to be read. 

TIME The mission time. 

TEMP The temperature in degrees Fahrenheit. 

S11, S22, S33 The six components of stress. The minimum 

S12, S23, S31 input can be 1 stress component. 

NULL This will ignore a column of mission data. 

XVIB The mission mix fraction or percent usage the composite mission occurred 

relative to the overall mission. 

SA11, SA22, SA33 The stress adder, these value are added to stress components 

SA12, SA23, SA31 
NASA/TM—2005-213886 27

SM11, SM22, SM33 The stress multiplier, stress components are scaled by these 

SM12, SM23, SM31 

TMPA The temperature adder or offset, this value is added to all temperatures. 

TMPM The temperature multiplier, all temperatures are scaled by this 

TMEA The time adder or offset. This value is added to all times. 

TMEM The time multiplier. All times are scaled by this. 

FRUP, PRUP, TRUP The rupture Pesting data. 

 if PRUP is positive 

 RLIFE=RLIFE*10.**(FRUP+PRUP*TEMP) 

 if PRUP is negative 

 RLIFE=RLIFE*(FRUP+PRUP*(TEMP-TRUP)*(TEMP-TRUP)) 

FLCF, PLCF, TLCF The LCF Pesting data. Note, these variables are read but not utilized by the 

program at this time. These may be incorporated in future versions of 

NASALIFE. 

TSIG, TTEM, TTIM The tolerances for stress, temperature, and time for rupture. 

MXNI The maximum number of increments per sub-cycle for rupture. 
NASA/TM—2005-213886 28

3.7. Executing NASALIFE 

Upon executing NASALIFE the first terminal screen is 

The full name of the mission file and its path is entered. If there is a need to terminate the program at 

this point then the command QUIT may be entered. Once the mission file is entered the program 

calculates the number of missions that can be accomplished under the given loading conditions. The 

image below illustrates a part of the output window one would observe when the PRIN command directs 

output to the terminal. 

A simpler terminal output is displayed with the PRIN command directing output to a file. The 

resulting terminal display is shown below. 
NASA/TM—2005-213886 29

NASALIFE creates an output file that replaces the input file’s extension with the extension of “.out”. In 

the case an output file exists with the same name the program prompts the user to quit the run or 

overwrite the file with a new output file. The terminal window shows the output file’s full path and name. 

Also, the user has the option of running the program again with the default value being to terminate the 

program. 

3.8. Glossary of Flags

Section 3.8.1 lists the flags which can be printed out within NASALIFE and section 3.8.2 describes in 

more detail the meaning of those flags. Section 3.8.3 lists rupture flags and section 3.8.4 describes the 

rupture flags. 

3.8.1. List of NASALIFE Output Flags (LCF)

 1.a ZERO LIFE: Mission temperatures above material temperatures 

 1.b ZERO LIFE: Mission temperatures below material temperatures 

 1.c ZERO LIFE: Mission temperatures above and below material temperatures 

 

 2.a Mission temperatures above Walker exponent curve 

 2.a Mission temperatures below Walker exponent curve 

 2.c Mission temperatures above and below Walker curve 

 

 3.c High temperature extrapolated walker curve used 

 3.c Low temperature extrapolated walker curve used 

 3.c Low and high temperature extrapolated walker curve used 

 4.a Mission temperatures above material curves 

 4.b Mission temperatures below material curves 

 4.c Mission temperatures above and below material curves 

5.a High temp extrapolated material curve used 
NASA/TM—2005-213886 30

 5.b Low temp extrapolated material curve used 

 5.c Low and high temp extrapolated material curve used 

 6.a Mission temperatures above LCF curve 

 6.b Mission temperatures below LCF curve 

 6.c Mission temperatures above and below LCF curve 

 7.a High temp extrapolated LCF curve used 

 7.b Low temp extrapolated LCF curve used 

 7.c Low and high temp extrapolated LCF curve used 

 8.a High life extrapolated LCF curve used 

 8.b Low life extrapolated LCF curve used 

 8.c Low and high life extrapolated LCF curve used 

 9.a Pseudo stress extrapolation performed on life calculation 

 9.b ZERO LIFE: Walker stress extrapolation not permitted above LCF data 

11. Non approved LCF curve point used 

12. Low temperature extrapolation used 

13.a These results may have a large step change in the 

 mean stresses and fatigue life. 

13.b ZERO LIFE: Shaft life mean stresses have a non-zero middle principal stress 

14. The stress R-ratio less than -1 was reset to -1 

15. Used default walker exponents. (R<0, M=1; R≥0, M=.5) 

16.a Yield strength exceeded. Used stress amplitude (higher than Walker.) 

16.b Yield strength exceeded. Used Walker stress (higher than alternating.) 
NASA/TM—2005-213886 31

3.8.2. Interpretation of NASALIFE Output Flags (LCF)

Flag No. 

1. At least one of your mission points exceeds a temperature condition; other flags will be more 

specific. (Zero life) 

2. You are outside of the range of Walker temperatures. 

3. Your mission uses points on a temperature extrapolated Walker curve. 

4. You are outside of the range of your material temperatures. 

5. Your mission uses points on a temperature extrapolated material curve. 

6. You are outside of the range of LCF temperatures. 

7. Your mission uses points on a temperature extrapolated LCF curve. 

8. Your mission uses points on a life extrapolated LCF curve. 

9. Your Walker stress amplitude was: 

 a, lower than the lowest value supplied in your LCF curve (extrapolation to low stress is 

permitted) 

 b, higher than the highest value supplied in your LCF curve (Zero life) 

10. Not used. 

11. You are using material data flagged for special purposes. 

12. Your mission contains points below room temperature. 

13.a You experienced a mean stress shift. 

13.b Your stress state is not applicable for shaft life, this is not a torsion controlled problem. (Zero life) 

14. You have an R-ratio that is less than one (see section 2.3.2). 

15. Your material file specified default Walker exponents. 

16. Your alternating stress was greater than your yield strength (see section 2.3.2) 
NASA/TM—2005-213886 32

3.8.3. List of NASALIFE Output Flags (Rupture) 

1.a Mission temperatures below rupture data 

1.b Mission temperatures above rupture data 

1.c Mission temperatures above and below rupture data 

2.a High temperature extrapolated rupture data used 

2.b Low temperature extrapolated rupture data used 

2.c Low and high temperature extrapolated rupture data used 

3.a High life extrapolated rupture data used 

3.b Low life extrapolated rupture data used 

3.c Low and high life extrapolated rupture data used 

4.a Mission stresses below rupture data 

4.b Mission stresses above rupture data 

4.c Mission stresses above and below rupture data 

5.a Non approved rupture data point used

3.8.4. Interpretation of NASALIFE Output Flags (Rupture)

Flag No. 

1. You are outside of the range of rupture temperatures. 

2. Your mission uses points on a temperature extrapolated rupture curve. 

3. Your mission uses points on a life extrapolated rupture curve. 

4. Your effective stress was: 

a, lower than the lowest value supplied in your rupture curve (extrapolation to low stress is 

permitted) 

 b, higher than the highest value supplied in your rupture curve (Zero life) 

5. You are using rupture data flagged for special purposes. 
NASA/TM—2005-213886 33

3.9. NASALIFE Output Example 

An example of an output from NASALIFE is provided in this section. The lines have been numbered 

for this example so that the lines can be addressed to describe the individual output lines. 

 1 NASALIFE Version I.32 2005-02-04 on JAN. 13, 2005 at 14:46:13.993 

 2 WARNING: This code is subject to change. 

 3 The user is responsible for proper life methods. 

 4 Mission 1 in file 

 5 c:\jg\mytest18a.dat 

 6 User defined fatigue curves utilized. 

 7 Idealized LCF data table for MI SiC/SiC 

 8 Curve A-Ratio = 1.00000 

 9 Life (Cycles) Stress (KSI) Flag Temperature 60.0 

 10 1000 400.0 20 

 11 10000 51.0 20 

 12 100000 50.0 121 

 13 Life (Cycles) Stress (KSI) Flag Temperature 300.0 

 14 1000 300.0 0 

 15 10000 21.0 0 

 16 100000 20.0 0 

 17 Life (Cycles) Stress (KSI) Flag Temperature 1000.0 

 18 1000 300.0 0 

 19 10000 21.0 0 

 20 100000 20.0 0 

 21 Life (Cycles) Stress (KSI) Flag Temperature 1300.0 

 22 1000 300.0 12 

 23 10000 11.0 10 

 24 100000 10.0 11 

 25 Example NASALIFE material file 

 26 Curve Number = .000000E+00 

 27 Material Number = .000000E+00 

 28 Material Form = .000000E+00 

 29 ASTM Grain Size = .000000E+00 

 30 Specimen Orientation = .000000E+00 

 31 Specimen RKT = .000000E+00 

 32 Temp (°F) Walker Exp Temp Flag 

 33 60.0 .50 20 

 34 1300.0 .50 10 

 35 Temp (°F) Modulus (KSI) K (KSI) N Gnu Temp Flag 

 36 60.0 30000.0 100.0 .00000 .30000 20 

 37 1300.0 30000.0 100.0 .00000 .30000 10 

 38 Conservative Walker mean stress model utilized 

 39 Time Temp XVIB S11 S22 S33 S12 S23 S31 

 40 1.0 1250.0 1.000 .0 -31.0 .0 2.0 .0 .0 

 41 2.0 1250.0 1.000 .0 -77.0 .0 2.0 .0 .0 
NASA/TM—2005-213886 34

 42 3600.0 1250.0 1.000 .0 -140.0 .0 .0 .0 .0 

 43 Damaging temperature at maximum or minimum stress used in fatigue calculation 

 44 Manson-McKnight Multiaxial Mean Stress model utilized 

 45 Isothermal method used 

 46 Low and high temperature extrapolated Walker curve used 

 47 Low and high temperature extrapolated material curve used 

 48 High temperature extrapolated LCF curve used 

 49 Low life extrapolated LCF curve used 

 50 Pseudo stress extrapolation performed on life calculation 

 51 The stress R-ratio less than –1 was reset to –1 

 52 Temperature extremes of 1250.0 to 1250.0 

 53 Cycle Time Temperature Stress Walker Calculated 

 54 Number Min Max Min Max Min Max Alt Life 

 55 1 1.0 3600.0 1250.0 1250.0* -140.0 -31.0 38.6 4423 

 56 * Indicates most damaging temperature. 

 57 Rupture Calculations 

 58 Time Temp Stress Rupture Life Delta Time Rupture Damage 

 59 .0 1250.0 54.1 250195. 1.388889E-04 5.551218E-10 

 60 .0 1250.0 77.1 21677.9 1.388889E-04 1.576840E-09 

 61 .0 1250.0 79.0 17776.8 3.123264E-02 1.584792E-06 

 62 .1 1250.0 81.0 14616.5 3.123264E-02 3.513134E-06 

 63 .1 1250.0 83.0 12049.0 3.123264E-02 5.855685E-06 

 64 .1 1250.0 84.9 9957.53 3.123264E-02 8.694171E-06 

 65 .2 1250.0 86.9 8249.21 3.123264E-02 1.212506E-05 

 66 .2 1250.0 88.9 6850.25 3.123264E-02 1.626198E-05 

 67 .2 1250.0 90.8 5701.70 3.123264E-02 2.123852E-05 

 68 .3 1250.0 92.8 4756.40 3.123264E-02 2.721142E-05 

 69 .3 1250.0 94.8 3976.55 3.123264E-02 3.436425E-05 

 70 .3 1250.0 96.7 3331.69 3.123264E-02 4.291149E-05 

 71 .3 1250.0 98.7 2797.23 3.123264E-02 5.310338E-05 

 72 .4 1250.0 100.6 2353.27 3.123264E-02 6.523139E-05 

 73 .4 1250.0 102.6 1983.70 3.123264E-02 7.963437E-05 

 74 .4 1250.0 104.6 1675.40 3.123264E-02 9.670558E-05 

 75 .5 1250.0 106.5 1417.68 3.123264E-02 1.169007E-04 

 76 .5 1250.0 108.5 1201.82 3.123264E-02 1.407470E-04 

 77 .5 1250.0 110.5 1020.65 3.123264E-02 1.688533E-04 

 78 .6 1250.0 112.4 868.310 3.123264E-02 2.019219E-04 

 79 .6 1250.0 114.4 739.978 3.123264E-02 2.407615E-04 

 80 .6 1250.0 116.4 631.666 3.123264E-02 2.863019E-04 

 81 .7 1250.0 118.3 540.090 3.123264E-02 3.396111E-04 

 82 .7 1250.0 120.3 462.526 3.123264E-02 4.019134E-04 

 83 .7 1250.0 122.3 396.722 3.123264E-02 4.746110E-04 

 84 .8 1250.0 124.3 340.800 3.123264E-02 5.593072E-04 

 85 .8 1250.0 126.2 293.197 3.123264E-02 6.578334E-04 

 86 .8 1250.0 128.2 252.613 3.123264E-02 7.722785E-04 

 87 .8 1250.0 130.2 217.957 3.123264E-02 9.050221E-04 

 88 .9 1250.0 132.1 188.319 3.123264E-02 1.058773E-03 

 89 .9 1250.0 134.1 162.937 3.123264E-02 1.236607E-03 

 90 .9 1250.0 136.1 141.162 3.123264E-02 1.442018E-03 

 91 1.0 1250.0 138.0 122.460 3.123264E-02 1.678967E-03 

 92 1.0 1250.0 140.0 106.372 3.123264E-02 1.951941E-03 

 93 107.1 1250.0 140.0 106.372 106.164 1.00000 
NASA/TM—2005-213886 35

 94 Rupture Ident 

 95 Example NASALIFE rupture data 

 96 Average rupture data used 

 97 Functional rupture data used 

 98 Rupture data valid from 1200.0 to 1300.0 °F 

 99 and from 55.0 to 150.0 KSI 

 100 Stress Offset 2.00000 

 101 Temperature Adder 459.670 

 102 Temperature Multiplier 1.00000 

 103 Larson-Miller Constant 20.0000 Polynomials 

 104 40.0000 –15.0000 –7.00000 

 105 Mission stresses below rupture data 

 106 Rupture Missions to Failure 512, Damage/Mission 1.952E-03, 90% 

 107 Fatigue Missions to Failure 4423, Damage/Mission 2.261E-04, 10% 

 108 Combined Missions to Failure 459, Damage/Mission 2.178E-03, 100% 

Referring to the NASALIFE sample output above the individual output lines are described here. The 

numbers presented here refer to the line numbers above. The printout format is described, including how 

it is to be interpreted. 

1. The name of the computer code is NASALIFE. The release number and the date of its 

release are as shown. 

2. The technical contents in NASALIFE will be changed or added to as directed and with 

the appropriate documentations. 

3. Use of this program does not insure proper life calculations. As noted, it is the user 

responsibility to have an understanding of the problem and its modeling. NASALIFE is a 

tool to assist in the modeling process. 

4.–5. The load case number and the mission file with its path used for the run. 

6.–24. The fatigue curve data used and its title. 

25.–38. The material property data. 

39.–42. The chronological mission mechanical and thermal loading data used in this run. 

43.–45. Program message on options and data utilized for analysis. 

46.–51. Flags which are discussed in section 3.8 

52. The minimum and maximum temperature after the mission loading has been reduced to a 

simplified equivalent load by rainflow counting. 

53.–55. The time, temperature, and stress for a cycle pair after the rainflow counting method has 

been applied. 

56. The asterisk indicates the temperature used to determine the fatigue life. As per the message, it is 

the temperature where the most damage takes place. 
NASA/TM—2005-213886 36

Minor cycles which have a fatigue life greater than 1E7 cycles are not printed out. The 

total number of minor cycles not printed noted in the output when they are present. This 

particular example does not have any suppressed minor cycles. 

57.–92. These lines present the results of the rupture life calculation. The unit of time is 

hours. 

93. The time where damage reaches one is always printed on a separate line. In this case the 

damage is less than one at the end of the mission. The time to damage of one is calculated 

using the last time point’s stresses and temperature. 

94.–104. The creep rupture data and other rupture related properties and settings are presented 

here. 

105. This line has any creep rupture related flags. 

106.–108. The life, damage per mission and percent of total damage for rupture, fatigue, and the 

combination are presented at the end of the output. 

References

1. American Society for Testing and Materials, “E 1049–85 (Reapproved 1997) Standard Practice 

for Cycle Counting in Fatigue Analysis.” ASTM International, West Conchohocken, PA, 2004. 

2. Brewer, D., “HSR/EPM Combustor Materials Development Program.” Materials Science and 

Engineering, A261, 1999. pp. 284–291. 

3. Conway, J.B., “Stress-Rupture Parameters: Origin, Calculation and Use.” Gordon and Breach 

Science Publishers, New York, NY, 1969. 

4. Dowling, N.E., “Mechanical Behavior of Materials.” Prentice-Hall, Upper Saddle River, NJ, 

ISBN 0–13–905720–X, 1999. 

5. Endo., T.; Mitsunaga, K.; and Nakagawa, H.; “Fatigue of Metals Subjected to Varying Stress–

Prediction of Fatigue Lives.” Preliminary Proceedings of the Chugoku-Shikoku District Meeting, 

The Japan Society of Mechanical Engineers, Nov., 1967, pp. 41–44 and The Rainflow Method in 

Fatigue. Ed. By Murakami, Y. Butterworth-Heinemann Ltd, Boston, ISBN 0 7506 0504 9. 1992. 

p. vii. 

6. Endo., T.; Mitsunaga, K.; Nakagawa, H.; and Ikeda, K.; “Fatigue of Metals Subjected to Varying 

Stress–Low Cycle, Middle Cycle Fatigue.” Preliminary Proceedings of the Chugoku-Shikoku 

District Meeting, The Japan Society of Mechanical Engineers, Nov., 1967, pp. 45–48 and The 

Rainflow Method in Fatigue. Ed. By Murakami, Y. Butterworth-Heinemann Ltd, Boston, ISBN 0 

7506 0504 9. 1992. p. xi. 

7. Larson, F.R. and Miller, J., “A Time-Temperature Relationship for Rupture and Creep Stresses.” 

Trans. ASME, vol. 74, 1952, p. 765. 

8. Levine, S.R.; Calomino, A.M.; Ellis, J.R.; Halbig, M.C.; Mital, S.K.; Murthy, P.L.; Opila, E.J.; 

Thomas, D.J.; Ogbiji, L.U.; Virrilli, M.J.; “Ceramic Matrix Composites (CMC) Life Prediction 

Method Development.” NASA Technical Memorandum, NASA/TM—2000-210052, May, 2000. 

9. Minor, M.A., “Cumulative Damage in Fatigue.” Journal of Applied Mechanics, vol. 12, no. 3, 

1945, pp. A159–A164. 

10. Mitsunaga, K. and Endo., T., “Fatigue of Metals Subjected to Varying Stress–Fatigue Lives 

Under Random Loading.” Preliminary Proceedings of the Kyushu District Meeting, The Japan 

Society of Mechanical Engineers, Mar., 1968, pp. 37–40 and The Rainflow Method in Fatigue. 

Ed. By Murakami, Y. Butterworth-Heinemann Ltd, Boston, ISBN 0 7506 0504 9. 1992. p. xv. 
NASA/TM—2005-213886 37

11. Ogbuji, L.U.J.T., “Recent Developments in the Environmental Durability of SiC/SiC 

Composites.” NASA Contractor Report, NASA/CR—2002-211687, July, 2002. 

12. Ramberg, W. and Osgood, W.R., “Description of Stress-Strain Curves by Three Parameters.” 

National Advising Committee for Aeronautics, Technical Note no. 902, 1947. 

13. Sines, G. and Ohgi, G., “Fatigue Criteria Under Combined Stresses and Strains.” Journal of 

Engineering Materials and Technology. vol. 103, 1981, pp. 82–90. 

14. Smith, K.N.; Watson, P.; and Topper, T.H.; “A Stress-Strain Function for the Fatigue of Metals.” 

Journal of Materials, vol. 5, no. 4, Dec., 1970, pp. 767–778. 

15. Walker, K., “The Effect of Stress Ratio during Crack Propagation and Fatigue for 2024-T3 and 

7075-T6 Aluminum,” Effects of Environment and Complex Load History on Fatigue Life. ASTM 

STP 462, American Society for Testing and Materials, Conshohocken, PA, 1970, 

pp. 1–14. 

16. Zuo, M.; Chiovelli, S.; and Nonaka, Y.; “Fitting Creep-Rupture Life Distribution Using 

Accelerated Life Testing Data.” Transactions of ASME, vol. 122, Nov., 2000. 

NASA/TM—2005-213886 39

Appendix A 

Subroutine/Function Description/Purpose Called by Subroutine

IZTRAS zeros out ATRASH (int.) RDMISS, KEYLCF, KEYMAT, XXUSRM

KEYLCF read in LCF curve RDMISS

KEYMAT read material property file in keyword format RDMISS

KEYRPD read rupture data in equation form RDMISS

KEYRPT read rupture data, tabular? RDMISS

RDMISS reads mission file MAIN

RMDATA rupture life from data RMLIFE

RMLIFC calculates time to rupture MAIN

RMLIFE RMLIFC

RMPRNF print rupture tripped flags XXPRNO

RMPRNO print rupture life calculation information MAIN

RMTABL rupture life from tabular data RMLIFE

SYDAHR get date and time from system clock XXPRNV

SYEXIT siesta exit handler

MAIN, RDMISS, KEYLCF, KEYMAT, XXLIFC, RMLIFE,

 XXUSRM, XXUSRL, UTSFIL, SYFILE

SYFILE siesta file operations MAIN, RDMISS

SYLUIF siesta UIF format line reader XXUSRM, SYRUIF

SYPARS parses a character string SYLUIF

SYRDNB read & strip leading blanks MAIN, RDMISS, KEYLCF, KEYMAT, XXUSRL

SYRUIF siesta UIF format file reader RDMISS, KEYLCF, KEYMAT, XXUSRM, XXUSRL

SYSCON sets siesta constants MAIN

SYUCAS converts character string to upper string SYFILE, SYLUIF

UTJCBI

calculates eigenvalues & eigenvectors of square

symetric matrix using Jacobi method UTSPRN

UTMMPY performs matrix multiplication XXROT3, XXCRTP

UTRASH sets an array to a 'TRASH' value XXUSRL

UTSEFF calculate effective stress XXMSHF, RMLIFC, XXMSIN, XXMRSN, XXMEQV, XXMMMM

UTSFIL sets siesta file codes MAIN

UTSPRN calculate principal stresses & direction vectors XXMSHF, XXMSWT, XXCRTP

UTSRTA sorts sets of FLT. data UTSPRN

XXCRTP life calculation XXLIFC

XXDAMG perform damage & multiaxial stress rainflow XXLIFC

XXFLAG flag adder XXDAMG, RMDATA, RMTABL, XXINTR, XXWALK, XXLCFC

XXFLIP reverses cycles based on temperature then original order XXLIFC, XXSORT

XXINTR linear temperature interpolation XXSNSL, XXDAMG

XXLCFC calculate LCF life from stress & temperature XXPAIR

XXLIFC life calculation MAIN

XXMEQV multiaxial mean stress, equivalent XXMNMD

XXMINE mission life calculation with Minor's fatigue damage rule XXLIFC

XXMMMM multiaxial mean stress, Manson-McKnight XXMNMD

XXMNMD convert multiaxial stresses to uniaxial XXLIFC, XXDAMG, XXPAIR

XXMRSN multiaxial mean stress, R ratio sines XXMNMD

XXMSED edits the mission XXLIFC, XXXVIB

XXMSHF multiaxial mean stress, shaft life Manson-McKnight XXMNMD

XXMSIN multiaxial mean stress, sines XXMNMD

XXMSWT multiaxial mean stress, Smith Watson Topper XXMNMD

XXNXPT finds the next rainflow point in a mission XXRAIN

XXPAIR evaluate the life for a mission pair XXDAMG, XXSORT

XXPRNE debug mission output XXLIFC

XXPRNF print tripped flags XXPRNO

XXPRNV prints xlife version information MAIN, XXLIFC, XXPRNO

XXPRNO print fatigue life calculation information XXLIFC

XXRAIN rainflows the mission XXLIFC, XXXVIB

XXRDFL reads ted zeh special title line XXLIFC

XXROT3 rotates a stress matrix XXMSWT

XXSNSL converts an A ratio LCF curve to an A=INF curve MAIN

XXSORT sort mission/barry kalb damage replacement XXLIFC

XXUSRL read user LCF curve information RDMISS

XXUSRM read material property file RDMISS

XXWALK calculate Walker alternating stress XXPAIR

XXWALP emulates XXWALK for printout XXPRNO

XXXSRT sorts rainflowed life data XXSORT

XXXVIB adds XVIB & XBLOCK information, deletes small cycles XXLIFC

ZTRAS zeros out ATRASH (FLT.) RDMISS, KEYLCF, KEYMAT, XXUSRM, XXUSRL
This publication is available from the NASA Center for AeroSpace Information, 301–621–0390.

REPORT DOCUMENTATION PAGE

2. REPORT DATE

19. SECURITY CLASSIFICATION

 OF ABSTRACT

18. SECURITY CLASSIFICATION

 OF THIS PAGE

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources,

gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this

collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson

Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)

Prescribed by ANSI Std. Z39-18

298-102

Form Approved

OMB No. 0704-0188

12b. DISTRIBUTION CODE

8. PERFORMING ORGANIZATION

 REPORT NUMBER

5. FUNDING NUMBERS

3. REPORT TYPE AND DATES COVERED

4. TITLE AND SUBTITLE

6. AUTHOR(S)

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT

13. ABSTRACT (Maximum 200 words)

14. SUBJECT TERMS

17. SECURITY CLASSIFICATION

 OF REPORT

16. PRICE CODE

15. NUMBER OF PAGES

20. LIMITATION OF ABSTRACT

Unclassified Unclassified

Technical Memorandum

Unclassified

National Aeronautics and Space Administration

John H. Glenn Research Center at Lewis Field

Cleveland, Ohio 44135–3191

1. AGENCY USE ONLY (Leave blank)

10. SPONSORING/MONITORING

 AGENCY REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546–0001

Available electronically at http://gltrs.grc.nasa.gov

September 2005

NASA TM—2005-213886

E–15257

WBS–22–714–30–20

44

NASALIFE—Component Fatigue and Creep Life Prediction Program

John Z. Gyekenyesi, Pappu L.N. Murthy, and Subodh K. Mital

NASALIFE; Life; Life prediction; Fatigue; Low cycle fatigue; Creep rupture; Ceramics; Ceramic matrix

composites; CMC; Probabilistic analysis; CMC vane; Cumulative distribution function; Probability density

function; Scatter; Weibull distribution; Strength; Proportional limit; Design requirements

Unclassified -Unlimited

Subject Categories: 24 and 39

John Z. Gyekenyesi, N&R Engineering and Management Services Corporation, 6659 Pearl Road, Suite 400,

Parma Heights, Ohio 44130; Pappu L.N. Murthy, NASA Glenn Research Center; and Subodh K. Mital, University

of Toledo, 2801 W. Bancroft Street, Toledo, Ohio 43606. Responsible person, Pappu L.N. Murthy, organization code

RSL, 216–433–3332.

NASALIFE is a life prediction program for propulsion system components made of ceramic matrix composites (CMC)

under cyclic thermo-mechanical loading and creep rupture conditions. Although the primary focus was for CMC

components, the underlying methodologies are equally applicable to other material systems as well. The program

references empirical data for low cycle fatigue (LCF), creep rupture, and static material properties as part of the life

prediction process. Multiaxial stresses are accommodated by Von Mises based methods and a Walker model is used to

address mean stress effects. Varying loads are reduced by the Rainflow counting method or a peak counting type

method. Lastly, damage due to cyclic loading and creep is combined with Minor’s Rule to determine damage due to

cyclic loading, damage due to creep, and the total damage per mission and the number of potential missions the

component can provide before failure.