bluuebunny/crossref_metadata_2025 huggingface dataset:
Elimination of high frequencies in the absolute nodal coordinate formulation
Authors: Matikainen M K , von Hertzen R , Mikkola A , Gerstmayr J
Published: September 2009

The performance of the coordinate partitioning method, the method of Lagrangian multipliers with Baumgarte's stabilization, and the penalty method to account for non-linear constraints of a linear beam element based on the absolute nodal coordinate formulation is studied. Proper non-linear constraints are selected to avoid high-frequency transverse or shear oscillations of the beam. The results show that harmful oscillations can be successfully eliminated from the beam response and efficiency of the numerical solution improves when these constraints are used in the solution procedure. In case of a swinging pendulum, the calculation speed could be improved, when compared to the non-constrained case. It was found that the overall performance of the Lagrange multiplier method with Baumgarte's stabilization and carefully selected stabilization parameters was the best approach.
A new criterion for assessment of train derailment risk
Authors: Durali M , Jalili M M
Published: September 2009

A new criterion for prediction of train derailment is presented in this article. A three-degrees-of-freedom (3 DOF) wheelset model is used to identify the main dynamic parameters that affect wheelset derailment. Using these parameters and conventional definition of derailment coefficient, a new criterion for prediction of wheelset derailment is introduced. The proposed criterion, in addition to providing the required precision in prediction of wheel set derailment, requires measurements that are easy to perform. To evaluate the capability of the new criterion in prediction of derailment, a full wagon model with 48 DOF moving on a track with different random irregularities was used. The track is assumed to be mounted on a viscoelastic foundation. The wagon model is a three-dimensional, non-linear model of a train passenger car. The model includes non-linear elements for primary and secondary suspension systems. Friction and slack between elements, the centre pivot with kinematics constraints, forces between pads, and bolster are also included in this model.

The motion of the wagon on tangent and curved tracks is simulated for different travel speeds. Derailment coefficient and a new derailment criterion are used to investigate the possibility of wheelset derailment in each case. The study shows that the new criterion can very well predict wheelset derailment and can duplicate the predictions by conventional derailment coefficient ( Y/ Q).
Effect of injection timing on gasoline homogeneous charge compression ignition particulate emissions
Authors: Misztal J , Xu H M , Wyszynski M L , Price P , Stone R , Qiao J
Published: September 2009

Particulate emissions from homogeneous charge compression ignition (HCCI) engines are often considered as negligible and the measurement of particulate matter (PM) with HCCI combustion systems has been rare. An earlier publication in the literature and the authors' own recently published work suggest that PM emissions from gasoline direct injection (DI) HCCI engines should not be neglected. It has been shown that PM emissions from HCCI engines, although generally lower, can be similar to spark ignition (SI) levels for certain engine conditions, especially in the accumulation mode. The present work shows that although injection timing is effective for control of HCCI, it can have a significant impact on PM emissions. Engine speed also appears to have an impact on PM emissions for the HCCI combustion mode. Typically for HCCI operating at 1500 r/min, the total mass and total number of the PM emissions could be up to six times higher when the fuel is injected during the recompression period compared with the case for injection during the inlet valve open period. Similarly, when the engine was operated in SI mode, an attempt to inject fuel close to induction top dead centre (TDC) made the PM emission noticeably higher, reaching unacceptable levels. The split injection strategy for HCCI mode has been investigated for its effect on PM emissions. It has been found that the PM number concentration for split injection lies between the maximum concentration measured for very early injections (near TDC at recompression) and the minimum concentration measured for the latest injections used (at crank angles near to the inlet valve maximum opening time), with the magnitude of number density varying approximately from 0.2 to 1.2 million/cm3. It is also observed that for split injection the number of particulates in nucleation mode varies less, while the number in accumulation mode level varies within a limit of one order of magnitude; both are dependent on the injection strategy. The shape of the PM distribution is such that the nucleation mode exceeds the number concentration of 1×107 (d N d log Dp) and the accumulation mode falls parabolically to approximately 1×106. For comparison, it can be said that the PM number concentration measured in the authors' engine is approximately one order of magnitude lower in accumulation mode than the level for a typical modern diesel engine.
A theoretical investigation of thermodynamic performance for a ramjet based on a magnesium—water reaction
Authors: Yang Y , He M
Published: September 2009

A preliminary study on the operating performance of a certain kind of water ramjet engine was implemented theoretically. With regard to this proposed powerplant operating in an available water environment, inspiration drawn from a supercavitation phenomenon coupled with a hydroreactive characteristic of several metals was the inducement for its attractive development. In terms of the requirement to provide the highest possible performance, a multiple water-injection mechanism was employed; i.e. the introduction of sufficient ambient water was suggested in order to maintain a successful combustion, while in the meantime not being too large to avoid a potential condensation phenomenon at the nozzle exit. Then against a ramjet carrying a metal fuel grain with a 50 per cent magnesium mass fraction, a performance analysis proceeded on the basis of a proposed thermodynamic calculation theory. The upper limit of the primary water—fuel ratio was predicted as 2.4 when considering the conditional temperature of the main magnesium—water reaction. Peak values of both specific impulse and thrust exist on the order of 4695.86 N s/kg and 2.57kN respectively, while the water—fuel ratio approached 4.2. Furthermore, rules governing the characteristic velocity along with the water—fuel ratio were also examined. Then, altering physical conditions such as metal fuel formation and chamber pressure, a conclusion was drawn that a higher performance was related to a relatively higher chamber pressure and a higher magnesium mass fraction as long as normal working conditions were guaranteed.
Copper-Catalyzed Allylation of Alkyl Halides with Allylic Grignard Reagents
Authors: Sai Masahiro , Yorimitsu Hideki , Oshima Koichiro
Published: September 2009

Treatment of alkyl halides, including secondary and tertiary alkyl bromides, with allylic Grignard reagents in the presence of a catalytic amount of copper(II) triflate in diisopropyl ether at 25 °C yielded the corresponding allylated products in high yields. The coupling reactions of tertiary alkyl halides lead to construction of allylated quaternary carbon centers. The active species is likely to be allylcuprate.
Interventions to Improve Medication Reconciliation in Primary Care
Authors: Bayoumi Imaan , Howard Michelle , Holbrook Anne M , Schabort Inge
Published: September 2009

Objective:

To systematically review all primary care intervention studies designed to implement medication reconciliation for effects on medication discrepancies, clinical outcomes, and patient knowledge of their medications.

Data Sources:

We searched MEDLINE (1988–March 2008); Healthstar (1966–March 2008): CINAHL (1982–March 2008); EMBASE (1980–March 2008); Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Cochrane Methodology Register, and Health Technology Assessments; and unpublished material. No language restrictions were applied. Search terms included medication reconciliation, medication errors, prescribing error, medication systems, adverse drug events, drug utilization review, medication list, medication record, and medications management.

Study Selection And Data Abstraction:

Randomized controlled trials or before-and-after studies that examined the effect of various interventions on medication discrepancies either in ambulatory settings or at hospital discharge among community-dwelling adults were included. Two reviewers independently assessed studies to determine inclusion. Level of agreement between the reviewers was good, with unweighted Cohen's κ of 0.71. Two of 3 independent reviewers abstracted data and evaluated validity from included studies. Disagreements between reviewers were resolved by consensus.

Data Synthesis:

Four trials met the inclusion criteria. Two before-and-after studies (n = 275) in ambulatory care examining systematic medication reconciliation at each visit produced conflicting results. One study showed a reduction in the proportion of medication discrepancies from 88.5% to 49.1% (OR 0.13; 95% CI 0.07 to 0.21); the other showed no benefit. One randomized controlled trial and one before-and-after study (n = 202) evaluated pharmacist medication review at hospital discharge. Neither showed a benefit. Heterogeneity precluded pooling of studies. All included studies had significant design flaws.

Conclusions:

There is no good quality evidence demonstrating the effectiveness of medication reconciliation in the primary care setting. Further research is needed.
Contemporary Issues in the Prevention and Management of Postthrombotic Syndrome
Authors: Vazquez Sara R , Freeman Andrew , VanWoerkom Ryan C , Rondina Matthew T
Published: September 2009

Objective:

To provide an evidence-based review and clinical summary of postthrombotic syndrome (PTS).

Data Sources:

A literature review was performed via MEDLINE (1950–July 1, 2009) and International Pharmaceutical Abstracts (1970–June 2009) searches using the terms post-thrombotic syndrome, post-phlebitic syndrome, deep vein thrombosis, and compression stockings.

Data Synthesis:

PTS is best characterized as a chronic syndrome of clinical signs and symptoms including pain, swelling, parasthesias, and ulceration in the affected limb following deep vein thrombosis (DVT). It occurs in up to hall of patients with symptomatic DVT, usually within the first 2 years. Although the pathophysiology of PTS is not well understood, a thrombus may cause venous hypertension and valvular incompetence resulting in edema, tissue hypoxia, and in severe cases, ulceration. Risk factors for PTS include recurrent ipsilateral DVT, obesity, and poor quality of anticoagulant therapy. PTS diagnosis is based on the presence of typical signs and symptoms and may be made using one of several clinical scoring systems. Prevention of PTS should focus on DVT prevention and the use of elastic compression stockings following DVT, while fibrinolysis remains under investigation as an effective method for PTS prevention. The treatment of PTS may include either pharmacologic or mechanical modalities, although none of these regimens has been rigorously tested. Pharmacists have the opportunity to provide more comprehensive antithrombotic management by educating patients and providers on PTS, recommending appropriate preventive therapy, assisting patients in obtaining and adhering to this therapy, and assisting providers with the management of PTS.

Conclusions:

Providers should be proactive in preventing PTS, with pharmacists taking an active role in optimal DVT prevention, identifying patients at risk for PTS, and counseling and directing preventive therapies.
Arousal Loss Related to Safer Sex and Risk of Pregnancy: Implications for Women's and Men's Sexual Health
Authors: Higgins Jenny A. , Tanner Amanda E. , Janssen Erick
Published: September 2009

CONTEXT: Few studies have examined arousal loss associated with safer‐sex practices or the perceived risk of unintended pregnancy, let alone its associations with sexual risk practices.

METHODS: An Internet survey conducted in 2004–2006 among 2,399 men and 3,210 women asked respondents about arousal loss related to the use of condoms or other safer‐sex products and perceived unintended pregnancy risk. Regression analyses gauged associations between arousal profiles, unprotected sex in the last year and lifetime experience of unintended pregnancy.

RESULTS: Many respondents reported arousal loss related to the use of safer‐sex products (34%) or the risk of unintended pregnancy (46%). Participants who strongly agreed that use of safer‐sex products can lessen their arousal were significantly more likely to have had unprotected sex in the last year than were those who strongly disagreed (odds ratios, 1.8 for men and 3.7 for women); those who strongly disagreed that pregnancy risk can lessen their arousal were significantly more likely to have been involved in an unintended pregnancy than were those who strongly agreed (2.0 for men and 1.4 for women). Arousal loss related to safer‐sex practices was more strongly associated with unprotected sex among women than among men, whereas arousal loss related to pregnancy risk was more strongly associated with unintended pregnancy among men than among women.

CONCLUSIONS: Some men and women are turned off by safer‐sex practices or by pregnancy risk. Given arousal profiles' potential contributions to unintended pregnancies and STD transmission, they should be integrated into sexual health behavioral models, research and programming.
Women's Perspectives on Family Planning Service Quality: An Exploration of Differences by Race, Ethnicity and Language
Authors: Becker Davida , Klassen Ann C. , Koenig Michael A. , LaVeist Thomas A. , Sonenstein Freya L. , Tsui Amy O.
Published: September 2009

CONTEXT: Despite calls to make family planning services more responsive to the values, needs and preferences of clients, few studies have asked clients about their experiences or values, and most have used surveys framed by researchers', rather than clients', perspectives.

METHODS: Forty in‐depth interviews exploring lifetime experiences with and values regarding services were conducted with 18–36‐year‐old women who visited family planning clinics in the San Francisco Bay Area in 2007. Women were categorized as black, white, English‐ or Spanish‐speaking Latina, or of mixed ethnicity to allow examination of differences by racial, ethnic and language group. Interviews were audiotaped, transcribed and coded thematically; matrices were then used to compare the themes that emerged across the subgroups.

RESULTS: Eight themes emerged as important to women's views of services: service accessibility, information provision, attention to client comfort, providers' personalization of care, service organization, providers' empathy, technical quality of care and providers' respect for women's autonomy. Women reported that it was important to feel comfortable during visits, to feel that their decision‐making autonomy was respected, to have providers show empathy and be nonjudgmental, and to see the same provider across visits. The only notable difference among racial, ethnic and language groups was that Spanish‐speaking Latinas wanted to receive language‐appropriate care and contraceptive information.

CONCLUSIONS: Future surveys of family planning service quality should include measures of the factors that women value in such care, and efforts to improve providers' communication and counseling skills should emphasize the personalization of services and respect for clients' autonomy.
Decomposing Trends in Nonmarital Fertility Among Latinas
Authors: DeLeone Felicia Yang , Lichter Daniel T. , Strawderman Robert L.
Published: September 2009

CONTEXT: For Latinos, high rates of nonmarital fertility reinforce economic inequality and slow the pace of social and economic incorporation into American society.

METHODS: Changes in the nonmarital fertility ratio—nonmarital births as a percentage of all births (NMFR)—among women aged 15–44 over the period 1994–2005 were partitioned into three components: changes in marital and in nonmarital fertility, and in the proportion of women who were married. Annual birth data were drawn from the national Natality Detail File, and population estimates were drawn from the Current Population Surveys. Analyses were conducted for blacks, whites and Latinas, as well as for selected subgroups of Latinas; differences in NMFRs between racial and ethnic groups were also calculated.

RESULTS: NMFRs were largely unchanged between 1994 and 2002, and then began to rise; they averaged 43% for Latinas, 69% for blacks and 23% for whites over the study period. In 2005, 48% of births to Latinas were nonmarital. Most of the rise in Latinas' NMFR was linked to a decline in marriage. Among foreign‐born Latinas, a six‐percentage‐point increase in the NMFR was due mostly to a rise in nonmarital fertility and a decline in marital fertility, which offset the beneficial effects of a rising marriage rate. The difference between Latinas' and whites' NMFRs was largely attributed to Latinas' higher nonmarital fertility, whereas the difference between blacks' and whites' NMFRs was driven mostly by lower marriage rates among blacks.

CONCLUSIONS: Efforts to reduce out‐of‐wedlock childbearing among Latinas are needed, and programs should promote healthy marriages, especially among foreign‐born Latinas.
Fully Traceable Absolute Protein Quantification of Somatropin That Allows Independent Comparison of Somatropin Standards
Authors: Pritchard Caroline , Quaglia Milena , Mussell Chris , Burkitt William I , Parkes Helen , O'Connor Gavin
Published: September 2009

Background: Measurement traceability in clinical chemistry is required to standardize clinical results irrespective of the measurement procedure and laboratory. The traceability of many protein substances is maintained by reference to the first standard produced, which may no longer exist, with values assigned by consensus. Independent methods that provide traceability to the Système d’Unité International for all relevant properties of a protein standard could remove reliance on the original standard preparations.

Methods: We developed a method based on the traceable quantification of tryptic peptides released from the protein by isotope dilution mass spectrometry to compare 2 standard preparations of somatropin (recombinant human growth hormone), WHO 98/574 and Ph.Eur.CRS S0947000. Relative quantification using isotope-coded affinity tagging, isobaric tagging for relative and absolute quantification, and standard additions were also performed to validate the digestion method used and to determine whether any modifications were present.

Results: The total somatropin content in both materials was determined and an uncertainty estimation undertaken [WHO 2.19 ± 0.21) mg/vial, European Pharmacopeia 2.06 ± 0.21 mg/vial]. Each uncertainty in this paper is a fully estimated uncertainty, with 95% CI (k = 2). Isotope coded affinity tag and standard addition results fully validated the robustness of the digestion method used. In addition, iTRAQ (isobaric tagging for relative and absolute quantification analysis) identified 2 modifications, neither of which impacted the quantification.

Conclusions: An independent method that does not rely on a preexisting protein standard has been developed and validated for the traceable value-assignment of total somatropin. The methods reported here address the amount of substance (mass fraction) of the standard materials but address neither biological activity nor other characteristics that may be important in assessing suitability for use as a calibrator.
Towards new diagnostic criteria for diagnosing GDM – the HAPO study
Authors: Hadar Eran , Oats Jeremy , Hod Moshe
Published: September 2009

Gestational diabetes mellitus (GDM) is defined as a carbohydrate intolerance, with onset or first recognition during pregnancy. The prevalence of GDM, and the occurrence of related complications, depends upon the definition of normal glucose values during gestation. The diagnostic criteria for GDM are controversial mainly because they lack correlation to outcome, be it maternal or perinatal. To date, there are no risk based guidelines to make the diagnosis of GDM and determine practice guidelines that are extrapolated from perinatal and maternal outcome and endpoints. To answer some of the above-mentioned controversies, the hyperglycemia and adverse pregnancy outcome study (HAPO) was planned and executed. This review outlines the results of the HAPO study, which demonstrates that fasting glucose levels and post 75 g OGTT are correlated to maternal, perinatal and neonatal outcomes. It is anticipated that the international recommendation for GDM diagnosis, will be shortly published.
Correlation Between Static Initiation Toughness KJC and Crack Arrest Toughness Kla 2024-T351 Aluminum Alloy
Authors: Wallin K
Published: September 2009

The Master Curve method, developed for brittle fracture initiation estimation, has enabled a consistent analysis of fracture initiation toughness data. The method has been modified to also describe crack arrest toughness. Here, this “crack arrest master curve” is further validated and used to develop a simple, but yet adequately accurate correlation between the two fracture toughness parameters. The correlation enables the estimation of crack arrest toughness from small Charpy-sized static fracture toughness tests.

If a more accurate description of the crack arrest toughness is required, it can either be measured experimentally or estimated from instrumented Charpy-V crack arrest load information.
Physical Reasons for a Reduced ΔK as Correlation for Fatigue Crack Propagation
Authors: Marci G , Lang M
Published: September 2009

It is generally acknowledged that a reduced ΔK, namely ΔKeff, is the best correlation between cyclic mechanical loading conditions and fatigue crack propagation rates. Yet, there are differing opinions among scientists as to the cause for such a reduction, and different concepts are proposed for the transfer of ΔK into ΔKeff. In this work, it is demonstrated that the highly constrained compressive deformation around the crack front during the unloading part of a fatigue cycle leads to a high hydrostatic stress field that needs to be overcome during the loading part of the following cycle before a crack can further extend. The stress intensity factor, K, describes the loading part of the fatigue cycle, while the unloading part of a cycle follows completely different rules with respect to stresses and strains in the plastic zone. A rigorous separation of these two parts of a fatigue cycle is conducted, leading to a new view at the problem. The crack growth increment of a cycle depends on Kmax and the crack propagation stress intensity factor, KPR, set by the previous cycle. KPR itself depends on Kmax and the unloading level, Kmin (or — σmin) and thus solely on the unloading part of the previous cycle. The crack propagation stress intensity factor, KPR, represents the load level where the hydrostatic stresses in the vicinity of the crack tip are released, thus dividing the loading part of a cycle into an effective and a noneffective part.
Influence of Specimen Geometry on the Random Load Fatigue Crack Growth
Authors: Radon JC , Nikbin K
Published: September 2009

The aim of this study was to evaluate and compare, using linear elastic fracture mechanics (LEFM), the fatigue behavior of a low alloy steel using compact-type and surface-crack bend specimens at constant amplitude and random loading. The material tested is relevant to offshore oil platforms and other large structures. It was found that the crack growth rate in the compact type specimens was substantially higher than in surface crack bend specimens. The crack growth results under constant amplitude loading showed a small mean-stress effect. There was much greater effect of mean stress on crack propagation results under random loading than under constant-amplitude. The triple-peaked spectrum signal produced faster growth rate results compared with the other two signals. The random-load crack-growth results were faster in the steady-state (regime II) than in constant amplitude loading. The results suggest that the use of data from constant amplitude tests do not necessarily reflect fatigue crack growth rates data from random loading particularly where there are changes also involved in geometry, thickness, R-ratio, mean load, frequency and material condition.
Fatigue Behavior of SA533-B1 Steels
Authors: Huang J-Y , Li R-Z , Chien K-F , Kuo R-C , Liaw PK , Yang B , Huang J-G
Published: September 2009

High-cycle and low-cycle fatigue tests were conducted on SA533-B1 steels with four levels of sulfur content at room temperature. For high-cycle fatigue (HCF) tests, the fatigue limit was observed around the yield stress (650 MPa) and showed little or no dependence on sulfur content. The lower the applied maximum stress (around the fatigue limit), the more scattered the fatigue life data. From the low-cycle fatigue (LCF) results, an excellent correlation between the SWT (Smith, Watson, and Topper) stress parameter versus reversals to failure was obtained. Fatigue life could be predicted from either the SWT parameter or Coffin-Manson equation for a specimen under constant strain amplitude loading conditions. A comparison of scanning-electron-microscopy (SEM) fractographic features of HCF- and LCF-tested specimens has been made. Obscured crack-initiation sites, wider striation spacing, and quasi-cleavage were observed to be characteristic of LCF, in contrast to the fractographic features of HCF-tested specimens.

To predict the fatigue residual life of a plate containing surface cracks, the associated stress intensity factor must be known. In this work, the stress intensity factor for surface-cracked plates was calculated by a three-dimensional finite-element method (FEM). As a verification practice, fatigue tests were conducted on surface-cracked specimens of SA533-B1 steels to study the crack growth behavior under a constant amplitude loading condition. The results show that it is feasible to calibrate the calculated stress intensity factor of a surface crack by the experimental backtracking method. From both FEM and experimental results, the empirically obtained stress intensity factors for surface cracks are reasonably with the numerical solutions with a maximum deviation of 21 % in the range of stress intensity studied. The crack-closure effect is proposed to account for discrepancies between the predicted and measured stress intensities.
Compliance Ratio Method of Estimating Crack Length in Dynamic Fracture Toughness Tests
Authors: Joyce JA , Albrecht P , Tjiang HC , Wright WJ
Published: September 2009

Crack extension during fracture toughness tests of ferritic structural steels cannot be determined from measurements of unloading compliance or electric potential change when the specimen is dynamically loaded. Measurements of crack extension in fracture toughness tests are also very difficult when the test temperature is high or the test environment is aggressive. To circumvent this limitation, researchers for years have been developing key curve and normalization function methods to estimate crack extension in standard elastic-plastic fracture toughness test geometries.

In the key curve method [1,2] a load-displacement curve is measured for a so-called “source” specimen that is subsize or has a blunt notch so that the crack will not initiate during elastic-plastic loading. The load and displacement are then converted to normalized stress-strain units to obtain a key curve that can be used to predict crack extension in geometrically similar “target”specimens of same material loaded at similar loading rates and tested under similar environmental conditions.

More recently, Landes and coworkers [3,4] proposed the normalization method. During the past three years the ASTM Task Group E 08.08.08 has prepared a draft Appendix H for the ASTM E 1820 specification that presents the normalization method as an alternative to the standard E 1820 unloading compliance procedure. Although the normalization method works well in many cases, it has serious drawbacks: the load, displacement, and crack length at the end of the test must be measured; the prescribed functional form that is fitted to the initial and final data may not be accurate for all materials; and the iterative method of inferring crack length from the combination of the data and the normalization function is complex.

The compliance ratio (CR) method developed in Ref 5 is used in this paper to determine key curves for predicting crack extension in dynamically loaded specimens. It consists of first testing a statically loaded source specimen using the unloading compliance procedure as specified in ASTM 1820. Then the so-called CR load-displacement curve is calculated for the source specimen, which is the load-displacement record that would have been obtained if the crack had not extended. Nondimensionalizing the CR load by the maximum load and the displacement by the elastic displacement at the maximum load, P*i/Pmax and vi/velmax from the source specimen yields the rate adjusted key curve. Assuming that the key curves of the statically and dynamically loaded specimens are one and the same, the compliance is calculated with a reverse application of the compliance ratio method and the crack length is obtained using the equations in ASTM E 1820. The CR method is found to be much simpler than the normalization method described in the draft Appendix H of ASTM 1820.
Modeling Multilayer Damage in Composite Laminates Under Static and Fatigue Loading
Authors: Soutis C , Kashtalyan M
Published: September 2009

The failure process in composite laminates under quasi-static or fatigue tensile or thermal loading involves sequential accumulation of damage in the form of matrix cracking in the off-axis plies of the laminate, matrix crack-induced local and edge delaminations, fiber-matrix debonding and fiber breakage. Accurate prediction of the laminate strength and stiffness response to damage must consider the above-mentioned damage mechanisms. In this paper, a model is developed for the analysis of cross-ply laminates, damaged by transverse and longitudinal matrix cracks and transverse and longitudinal delaminations growing along them. The model is based on the Equivalent Constraint Model (ECM) of the damaged ply and employs an improved 2-D shear lag method to determine the stress field in the damaged ply. The model is then applied to predict stiffness reduction in T300/914 cross-ply laminates using experimentally observed damage patterns under thermal fatigue loading.
Development of ASTM C 1421-99 Standard Test Methods for Determination of Fracture Toughness of Advanced Ceramics
Authors: Bar-On I , Quinn GD , Salem J , Jenkins MJ
Published: September 2009

An ASTM standard test method for determination of fracture toughness has been created for advanced ceramics. Standard C 1421-99 includes three test methods and is suitable for ceramics with flat R-curve behavior, but includes some provisions for materials with rising R-curve. The three methods are: chevron notch, single-edge precracked beam, and surface crack in flexure, all of which use beams in bending. Supporting data have been collected through several major international round robin programs conducted under the auspices of the Versailles Advanced Materials and Standards program.

This paper presents the historical evolution of the standard and reflects on the strategies used to overcome the interferences of slow crack growth, R-curve, and stability. It draws parallels to the development of ASTM E 399, and it presents data that show good precision and accuracy for well-behaved materials. Materials with R-curve and susceptibility to slow crack growth have been analyzed following the recommendations in the standard, and the procedure fulfills the objective of identifying such behavior. Standard Reference Material 2100 with certified values of fracture toughness directly complements C 1421.
An Experimental Study of the Growth of Surface Flaws Under Cyclic Loading
Authors: McDonald V , Daniewicz SR
Published: September 2009

Fatigue crack growth studies were carried out using 7075-T651-aluminum alloy specimens with a semi-elliptical surface crack. Multiple experiments were conducted under constant amplitude loading with a stress ratio R = 0.1, which inherently included the effects of fatigue crack closure, and R = 0.7, which was assumed closure free. Crack length measurements on the free surface were made with a traveling microscope. To allow crack depth measurements, marker bands were used.

The aspect ratio evolutions for the two stress ratios tested were compared to determine whether crack closure affects aspect ratio or crack shape evolution. It was found that closure impacts this evolution in a significant manner. In addition, the fatigue crack growth data collected from the multiple specimens was used to perform uncertainty analyses on the crack lengths, crack depths, and the aspect ratio. This was done to determine if crack growth models are best validated using the aspect ratio as the measured quantity or the individual measured crack length and crack depth. The measured aspect ratio was found to exhibit a smaller percentage of experimental uncertainty, and thus should be used for model validations. Finally, the observed crack growth rate-stress intensity factor range relationships for R = 0.7 at the free surface and the deepest point of penetration were compared to existing through-crack data, with a good correlation being observed.
Development of Mechanical Properties Database of A285 Steel for Structural Analysis of Waste Tanks
Authors: Duncan AJ , Subramanian KH , Sindelar RL , Miller K , Reynolds AP , Chao YJ
Published: September 2009

A statistically-designed test matrix has been developed to govern test conditions for measurement of the fracture toughness properties of A285 carbon steel. The effects of several variables on ductile tearing were investigated. The results of initial J-Integral testing are presented along with preliminary observations and data analysis. These results will contribute to a database of J-resistance (J-R) curves, which will be used for flaw stability analyses in waste storage tanks constructed in the 1950s at the Savannah River Site (SRS). J-Integral toughness tests were conducted to evaluate fracture behavior as functions of composition and orientation around the minimum operating temperature of waste storage tanks at SRS (294 K). The selected ranges of composition and grain size were based on available heats of new and vintage material from archival site sources. The specimen dimensions were designed to represent the thickness of tank wall regions in the structure and to a width that ensured back end constraint after crack extension up to several millimeters. The loading rate was held constant at 8.2 × 10-3 (MPa-√m)/s.
Application of the Local Approach to Fracture in the Brittle-to-Ductile Transition Region of Mismatched Welds
Authors: Minami F , Katou T , Jing H
Published: September 2009

This paper predicts the cleavage resistance of steel welds in the ductile-to-brittle transition region by the Local Approach. Attention is payed to the strength mismatch effect on the ductile tearing and subsequent cleavage fracture. Welded joints of pipeline steels, X65 and X80 steels according to API 5L, are made with the same electrode under the same heat input condition. The resultant weld metals are matched for the X80 steel welds and overmatched for the X65 steel welds in terms of the yield strength. The fracture behavior is investigated with 3-point bend specimens and tension plate specimens with a notch in the weld metal close to the fusion line. The strength mismatch and specimen geometry exert a large influence on the cleavage toughness and prior ductile tearing; CTOD toughness and crack growth resistance for the X65 tension welds increased significantly. This is due to a loss of constraint induced by the strength overmatch and tension geometry. The fracture driving force is evaluated by the Weibull stress as a function of the crack growth. The computational cell model is applied for the analysis of crack growth, where the independence of the cell parameters on the strength mismatch and specimen geometry is verified. Using the Weibull stress fracture criterion coupled with the crack growth analysis, 3-point bend toughness results can be transferred to the fracture strength evaluation of tension loaded welds with strength mismatch in the ductile-to-brittle transition region.
Prediction of Residual Stress Effects on Fracture Instability Using the Local Approach
Authors: Yamashita Y , Sakano K , Onozuka M , Minami F
Published: September 2009

Effects of residual stresses induced in a three-point bend CTOD specimen on brittle fracture initiation are studied on the basis of the Local Approach. Compressive residual stresses are produced near the crack tip by preloading at room temperature. The material used is a 780 MPa class high-strength steel. Fracture tests are conducted at low temperatures (-75 and -40°C) after preloading. The preloading apparently increases the fracture load and critical CTOD levels at the onset of brittle fracture from the reference levels at monotonic loading, which is due to the compressive residual stress field around the crack tip. The present study employs the Weibull stress fracture criterion to evaluate the brittle fracture resistance of the preloaded specimen. The Weibull stress is calculated by a 3D elastic-plastic FE analysis. Under the assumption that the critical Weibull stress at brittle fracture initiation is a material property independent of preloading, the critical CTOD of the preloaded specimens can be predicted from the fracture test results of monotonically loaded specimens.
Dimension Stone Use in Building Construction
Authors: Hoigard Kurt R. , Scheffler Michael J.
Published: September 2009

Description

Twelve peer-reviewed papers demonstrate the continuing advancement in the understanding of dimension stone used in building construction. Topics cover:

Strength Testing—addresses testing to determine strength characteristics of dimension stone cladding panels.

Design—covers a wide range of topics, including the advantages and disadvantages of three common dimension stone paving installation techniques; the relationships between stone material strength, anchorage strength, and induced stress states for four common dimension stone cladding anchorage configurations; and more.

Evaluation and Investigation—provides observations regarding investigations into the causes of dimension stone cladding deterioration and failure.

Durability—discusses the complex issue of dimension stone durability using three different approaches; a large-scale European research project to investigate the causes of marble and limestone cladding panel bowing, develop preconstruction testing parameters to assess bowing potential, and assess proposed remedial efforts to reduce or inhibit ongoing bowing; and more.
A Stable Internal Standard Flame Photometer for Sodium, Potassium, Lithium and Calcium Analyses in Biological Fluids and A Study of Ion Interference
Authors: Fox CL , Freeman EB , Lasker SE
Published: September 2009

A description is given of the design, construction, and operation of an improved internal standard flame photometer that burns city illuminating gas and requires no electronic equipment. Sodium and potassium analyses are performed with lithium as the internal standard, lithium analyses with potassium as the internal standard, and calcium analyses with sodium as the internal standard. Data on the interference of high concentrations of sodium on potassium analyses and vice versa are presented together with comparisons of these and other interference effects that occur in several different types of flame photometers. The internal standard technique appears to reduce or eliminate errors due to interference as well as those due to variations in operating conditions. Considerably greater precision is attained with the internal standard instrument. This technique provides a satisfactory method for calcium analyses of inorganic samples rich in sodium. Some of the difficulties that prevent accurate results for calcium in biological samples are presented, and criteria for evaluating flame photometers are suggested.
Determination of Tetraethyllead in Gasoline by Flame Photometry
Authors: Gilbert PT
Published: September 2009

A very rapid method of determining lead in gasoline without preliminary treatment is provided by the new flame photometry attachment with integral burner-atomizer for the Beckman Model DU quartz spectrophotometer. At 405.8 mμ in the oxy-hydrogen or oxy-acetylene flame, the instrument is sensitive to 0.001 ml of tetraethyllead per gal and precise to 0.01 ml. Linearity is exact and the instrument can be made direct-reading. Accurate comparisons may, according to the procedure here described, be made only between gasolines of the same base stock or of not more than two different stocks. A technique is suggested whereby it should become possible, with modified burners, to use the spectral background as internal standard in comparing different stocks, without recourse to unleaded blanks or more than one standard; alternatively, viscosity measurements made with the burner itself should also make possible such internal standardization. With a suitable single standard, routine determinations accurate to 0.01 ml per gal can be carried out at the rate of 30 or more samples per hr.
The Flame Photometer in The Analysis of Water and Water-Formed-Deposits
Authors: Scott RK , Marcy VM , Hronas JJ
Published: September 2009

Salts of sodium and to a lesser extent potassium occur in most water supplies. Any chemical treatment process is likely to increase the ratio of sodium or potassium to the dissolved solids in the water. Modern practices of boiler feedwater treatment result in the conversion of practically all soluble constituents of the boiler water to sodium and potassium salts. The determination of alkali metal concentrations in water supplies for a number of industrial processes may be useful.
Why Test Building Constructions
Authors: Whittemore HL
Published: September 2009

Building construction has progressed a long way from the days of the crude dwellings of our ancestors. Methods of analyses of structures and stress determinations in building members have been developed to replace the building “art” that once governed. Testing equipment has fostered research, testing procedures, and specifications for building materials. Building constructions are being tested according to specified procedures, although there is great need for means to establish allowable loads from test data.

Houses are not being designed to take full advantage of our present knowledge, and materials are being wasted. If the construction industry and the public are to receive maximum benefits, it must be through further imaginative research and proper application of this research to better and more economical house design.

Are standard procedures for evaluating the properties of building constructions necessary or desirable? What tests are required on a particular construction, and what type of loading should be imposed? Given the results of a specific test program, how can one determine whether the construction is suitable or even safe?

These are the questions that must be considered and discussed if we are to obtain worth-while results from standard methods of testing building constructions. Indeed these questions need to be answered as each standard is conceived if it is to receive widespread use and prove of benefit to the construction industry. It is time to reanalyze the results of tests of building components made during the past quarter century and to reassess the value of this research and its effect on construction practices. A review of our progress would indicate not only the value of past research but would aid us in being more objective in future studies.
Structural Performance Requirements in Housing Codes
Authors: Wood LW
Published: September 2009

Although housing performance codes based on standard test methods are a modern development, it is known that performance requirements in codes were in effect several thousand years ago. Standard performance tests on the structural elements of houses include vertical compression and racking on walls, transverse bending and concentrated load on walls, floors, or roofs, and sandbag impact on walls and roofs. Performance requirements related to these tests have been developed. At the same time codes without these performance test provisions have included “alternative methods” clauses that are essentially performance requirements. Most codes are thus doing a good job of protecting public health and safety and at the same time permitting progress in the building arts.
Glued and Nailed Roof Trusses for House Construction
Authors: Luxford RF , Heyer OC
Published: September 2009

To simplify house construction and thereby to save on costs, the use of light-weight roof trusses is becoming a more standard practice. By using lightweight trusses, the exterior walls and roof can be erected without the placement of any interior partitions. Thus, the interior becomes one big workshop. The entire ceiling and walls can be finished as one unit without interruption of partitions. If dry-wall construction is used, it means that sheets as large as 4 by 12 ft can be placed without any cutting. Similarly, the finish floor can be laid over the entire area without the cutting and fitting necessary when partitions are in place.
Experience with Pozzolanic Materials in Kansas
Authors: Scholer CH , Peyton RL
Published: September 2009

Serious cement-aggregate reaction betwen certain cements and the “sand gravel” aggregate of the gravel producing streams of Kansas has caused the Engineering Experiment Station of Kansas State College, in cooperation with the Kansas State Highway Commission and the Portland Cement Association, to study various procedures to control or eliminate this reaction. The results of these studies have been partially reported by Scholer and Gibson (1), and Scholer (2), as well as by several unpublished progress reports during the several years the project has been under formal study.