bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Elastic-Plastic Fracture Toughness Testing in the Transition Region through Japanese Interlaboratory Tests
Authors: Iwadate T , Yokobori T 
Published: March 2009

International cooperative interlaboratory test programs on elastic-plastic fracture toughness in the transition region have been conducted under the 129th Committee, Japan Society for the Promotion of Science (JSPS), and the Materials Properties Council (MPC). The objective of the tests is to obtain basic information regarding the measurement of lower-bound fracture toughness of steels using small specimens. The test program used ASTM A508 Class 3 steel. The 19 laboratories participated in these programs. Tests were carried out with 25.4-mm (1-in.) thick compact tension (1T-CT) specimens at three temperatures, -100°C (T1), -75°C (T2), and -50°C (T3). In addition to the interlaboratory tests, the effect of strain rate on small-specimen fracture toughness behavior was also investigated.
The Japanese test results provided some information to standardize a method for measuring the lower-bound fracture toughness of steels. Small-specimen fracture toughness KJc values indicated a wide scatter, especially in the higher temperature or in the lower strain rate or both. The causes of the scatter of KJc values typically depend on the stable crack growth, Δa0, the distance from stable crack front to trigger point, X, and the distance from fatigue crack front to trigger point, Δa0 + X. No effect of grain size and material cleanliness and slight effect of sampling location of the specimens and difference of the testing conditions between laboratories were observed. The KJc value at Δa0 = 0, X = 0, and Δa0 + X = 0 was defined as a lower-bound fracture toughness KJci, because additional study using A470 Ni-Cr-Mo-V rotor steel showed that the KJci value coincides well with the lower bound of large-specimen fracture toughness KIc per the ASTM Standard Test Method for Plane-Strain Fracture Toughness of Metallic Materials (E 399). Test results also indicated that the KJci value corresponds to 3% fracture probability toughness of the steel.
Based on these test results, the guidelines on the measurement of Δa0, X and Δa0 + X were established, and the tentative test procedure for the determination of the lower-bound fracture toughness using a fractographic data analysis has been developed by the JSPS 129th Committee.
Simpler JIc Test and Data Analysis Procedures for High-Strength Steels
Authors: Underwood JH , Troiano EJ , Abbott RT 
Published: March 2009

Tests of five medium- and high-strength steels were used to investigate some prospective simplifications in JIc test and data analysis procedures. Three-point bend specimens with material strengths of 500 to 1500 MPa and a nominal thickness of 10 mm were tested at room temperature. The investigation included: (1) JIc tests using measured crack-mouth displacement to calculate load-line displacement based on an expression that relates the two displace ments; (2) a simple zero-point adjustment for J versus Δa curves, whereby certain intermediate Δa values are shifted to the blunting line to correct for errors at low values of Δa; (3) a comparison of Δa and JIc results from the load-drop method, which gives a simple measure of crack growth after maximum load, with results from the usual unloading compliance method.
The various results and comparisons are discussed in relation to their usefulness as a general JIc test procedure for a variety of materials or a limited use test for certain materials. Two specific test and data analysis procedures are proposed for general use in JIc testing, as follows: 1. A new expression is described that calculates load-line displacement for the bend specimen from measured crack-mouth displacement, for a range of a/W values and strain-hardening exponents. The expression makes possible a single-displacement unloading compliance JIc test for the bend specimen, using a single, standard, crack-mouth clip gage. 2. A simple zero-shift procedure is proposed for general use with JIc tests and for addition to ASTM Test Method for JIc, a Measure of Fracture Toughness (E 813). The procedure adjusts the zero point of Δa so that on average the Δa values lie on the blunting line over the J range of 20 to 60% of the provisional fracture toughness, JQ. The adjustment calculations can be done with a calculator or a few lines of computer code.
Dislocation Emission and Dynamics Under the Stress Singularity at the Crack Tip and Its Application to the Dynamic Loading Effect on Fracture Toughness
Authors: Yokobori AT , Iwadate T , Isogai T 
Published: March 2009

In previous work, computer simulation of dislocation emission and motion was carried out considering the stress singularity near the crack tip. It was found that there is a region in which no dislocation exists along the slip plane near the stressed source, namely, a dislocation free zone (DFZ), and that there is an inverse pileup of dislocations against the tip of this DFZ. A formula was obtained correlating the maximum dislocation density with the DFZ length.
Based on those results, an evaluation has now been attempted for fracture toughness within the brittle-ductile transition range of steel. The effect of dynamic loading on the fracture toughness and trigger point observed in the experimental results reported in the literature is explained.
Effects of Cyclic Loading on the Deformation and Elastic-Plastic Fracture Behavior of a Cast Stainless Steel
Authors: Joyce JA , Hackett EM , Roe C 
Published: March 2009

The objective of this program was to develop the appropriate material properties to characterize the cyclic tensile deformation, cyclic elastic-plastic crack growth, and the ductile tearing resistance of a pipe elbow made from a cast stainless steel equivalent to ASME SA-351CF8M. This material was used for large-scale tests in the high level vibration test program, which applied intense cyclic loadings to reactor piping system components and revealed that fatigue crack growth could be a serious problem in these components. The tests conducted included monotonic and cyclic tension tests, monotonic J-R curve tests, and cyclic elastic and elastic-plastic fatigue crack growth rate tests. The cyclic elastic-plastic fracture behavior of the stainless steel was of primary concern and was evaluated using a cyclic J-integral approach.It was found that the cast stainless steel was very resistant to ductile crack extension. J-resistance curves essentially followed a blunting behavior to very high J levels. High cycle fatigue crack growth rate data obtained on this stainless steel was typical of that reported in standard textbooks. Low cycle fatigue crack growth rate data obtained on this material using the cyclic J-integral approach was consistent with the high cycle fatigue crack growth rate and with a standard textbook correlation equation typical for this type of material. Evaluation of crack closure effects was essential to determine accurately the crack driving force for cyclic elastic-plastic crack growth in this material.
General Purpose Software for Fatigue Testing
Authors: Dharmavasan S , Peers SMC 
Published: March 2009

Recently, most manufacturers of servohydraulic materials test equipment have developed digital control systems. Digital systems have several advantages over the more mature analog controllers, in particular, the availability of features that allow more realistic tests to be carried out. Also, the ability to interface and communicate with computers easily makes it possible to perform not only realistic but also very complex control and data acquisition tasks. However, the software required to define these complex tasks and communicate with digital controllers is demanding.
The development of digital controllers has been made possible by the tremendous advances in microprocessor technology. These developments have also given rise to computers with everincreasing capabilities at lower costs. The software architectures controlling these computers have also given rise to sophisticated developments in order to make the computers easier to use. Most computers now have some form of graphical user interface (GUI). The downside of most GUIs is that the development of application software is much more complex. In addition, most of these operating systems are not ideally suited for real-time control that is absolutely vital for automated fatigue testing.
The difficulties associated with developing software for specific fatigue tests may be somewhat alleviated by the development of suitable tools within an integrated architecture that allow the scientist/engineer to define the required test in the form of functional blocks. This type of general-purpose software can then take the test definition provided by the scientist and convert it into a form suitable for the digital controller.
A suitable test description paradigm is proposed in terms of general requirements; a test-description language with elements such as objects, functional blocks, time, events, and data presentation; and some specific requirements for a software development environment. From this, general-purpose software for automated fatigue testing can be developed and used at a high level of abstraction. In addition, the paper reviews the development of an integrated general-purpose program for automated fatigue testing that implements the functional blocks required but without the full test description language. The paper also uses the example of testing offshore structural components using realistic sea-state sequences, such as WASH, to illustrate the problems that must be solved.
Some implications of this approach in future fatigue testing applications are also discussed in the paper.
Automated Fatigue Test System for Spectrum Loading Simulation of Railroad Rail Cracks
Authors: Jablonski DA 
Published: March 2009

A digital servohydraulic test system has been utilized to apply stress spectra, which represented the railhead stress cycles caused by passage of a train, on laboratory compact tension specimens. The system was designed so that tasks that required immediate action were built into the machine controller firmware. Tasks that did not require immediate action were generally performed in the control software on a personal computer. This system was utilized to measure fatigue life of railroad rails under real-life stress spectra that represented the reconstructed railhead stresses for various types of trains. A stress intensity mapping procedure was utilized to simulate the railhead “detail fracture” in laboratory compact tension specimens.
This test system was used to measure fatigue crack growth rate under five different stress spectra. Two of the stress spectra were ordered according to decreasing maximum stress (DMS). The fatigue crack growth rate and crack closure behavior were different for the real sequence ordered (RSO) and decreasing maximum stress ordered (DMS) spectra. Constant amplitude fatigue crack growth rate was measured at three different stress ratios to develop a fatigue crack growth rate model for the material. The fatigue crack growth rate could be modeled with either a modified Walker equation that accounted for stress ratio effects or with an effective ΔK model that accounted for crack closure effects. The constant amplitude test data were used to predict the spectrum load crack growth rates using a modified Palmgren-Miner's rule. The predictions based upon the modified Walker equation were nonconservative. Predictions based upon constant amplitude test data, when corrected for crack closure effects, compared well with the experimental results.
Crack Closure Measurements and Analysis of Fatigue Crack Propagation Under Variable Amplitude Loading
Authors: Amzallag C , Le Duff J-A , Robin C , Mottet G 
Published: March 2009

An experimental program has been conducted on a Type 316L stainless steel to analyze the behavior of surface and embedded metallurgical defects in components.
Crack closure measurements have been performed under plane stress and plane strain conditions, under constant amplitude loading, and after overloads.
The crack opening load was measured by four different methods including surface, center, and bulk measurements.
Fatigue crack growth rates were determined, at different R ratios, under constant amplitude and under random loading conditions, using a stationary Gaussian sequence (I = 99%). Numerical analysis of the crack closure phenomenon has been carried out.
The principal results obtained are: 1. Immediately after overload, crack blunting occurs, and there is no crack closure: this fact is observed using both the different experimental measurement techniques and the calculations. 2. Under plane stress conditions, calculations have shown that crack closure decreases after overload over a distance of ∼1 mm, then increases; good agreement was found between experiments and calculations. 3. Under plane strain conditions, calculations have shown that crack closure rapidly increases after overload, the initial value is reached after ∼1 mm propagation; this was not detected experimentally because a pure plane strain state did not exist in the tested specimens. 4. The fatigue crack growth rates, da/dN, under random loading were expressed in terms of ΔKrms and ΔKeq. A better correlation of fatigue crack growth rates under constant amplitude loading and random loading was found using ΔKeq compared to ΔKrms.
The equivalent load approach is appropriate for describing the crack growth under this narrow band sequence that does not present a strong interaction between cycles. It may not be applicable to other load spectra.
A Fatigue Crack Propagation Model Under Variable Loading
Authors: Gerald J , Menegazzi A 
Published: March 2009

In order to understand the behavior of metallic structures in service it is necessary to be careful in both the experimental analysis and the analytical modeling of the fatigue crack propagation under variable loading.
A relatively general model to simulate crack propagation under variable loadings is proposed. It describes the cycle-by-cycle progression of the crack. The propagation law formulation is actually a Paris law type model, transient effects are introduced through a concept of an effective SIF range, as did Elber, whose approach it generalizes.
This model offers some advantages: it remains simple, it generalizes well-know models, and the transient effect predictions are encouraging as shown in some proposed applications.
Sensitivity of Equivalent Load Crack Propagation Life Assessment to Cycle-Counting Technique
Authors: Le Pautremat E , Olagnon M , Bignonnet A 
Published: March 2009

The purpose of the present study is to assess a simple prediction method for the fatigue life of structures subjected to variable amplitude loading, and to validate it in the whole range of possible irregularity factors.
This method based on an equivalent load concept (reducing the load history to constant amplitude cycles) leads to a fair prediction of fatigue life with few parameters.
Five cycle-counting methods were compared as to the determination of the equivalent load amplitude. The tests were carried out with several histories chosen either for their specific irregularity factors or to be relevant to offshore structures (WASH(W) sequence).
Material Data Banks: Design and Use, an Example in the Automotive Industry
Authors: Diboine A 
Published: March 2009

Today's engineering requires fast and easy access to various types of information, including economical, process, technical, and material data. A large number of databases that cover these fields have been launched recently. However, where the mechanical behavior material data are concerned, engineers often deal with those materials specific to their industry. Such is the case in the automotive industry. Therefore, data for these materials are often not available from large national or international databases. This is one of the reasons for developing an inhouse PC-based materials database.
This paper describes the process of designing, testing, and implementing this database. The design of the database proved to be quite difficult according to the needs for calculation, material selection, and component fatigue life assessment.
The selection and acquisition of the data to be stored is a critical problem. This project has clearly shown the importance of testing standards to guarantee the homogeneity and the reliability of the data.
Finally, the significance of the distribution and follow-up of the database is discussed.
Further Studies of Cure and Durability of Building Sealants
Authors: Beech J , Beasley J 
Published: March 2009

Some results from the second phase of a two year experimental study are reported and discussed. A range of well cured commercial sealants products was exposed to natural weather and to various laboratory simulations of the factors in weather which cause degradation or changes in properties, for up to 12 months. These include heat (70°C), with and without UV(B) radiation, and artificial weathering including UV(B) radiation and moisture condensation (QUV apparatus).
The cure properties of polyurethane, silicone and poly sulphide sealants over a two year period are described. For these materials, the majority of which were well cured in the second year of the study, the effects of heat and of UV(B) radiation are discussed. Polyurethane sealants showed significant correlations between changes in modulus and in extensibility, after exposure to UV and to artificial weather. The effect of heat was more significant for polysulphides and for some silicone sealants.
As in the earlier phase of this work it was possible to demonstrate significant correlations between modulus changes in the full range of sealants after exposure to weather for twelve months and to artificial weathering for eight weeks. In addition, heat aging caused changes in extensibility that correlated highly with the effects of natural weather.
Expansion Joints in Deck Waterproofing Systems
Authors: Rutila DA , Ruggiero SS 
Published: March 2009

Structural expansion joints that interrupt plaza and traffic bearing waterproofing membranes are often a source of leakage. Most joint seals in plaza type waterproofing systems are “buried,” making them difficult and expensive to maintain. Exposed joint seals in traffic bearing waterproofing systems are subject to severe loading conditions, such as vehicular traffic, but are generally accessible.
This paper presents design concepts for waterproofing expansion joints in building decks. We review assemblies commonly used to waterproof expansion joints and we examine several design concepts. Membrane/waterproofing continuity across joints and joint maintenance are of particular concern. An estimate of the joint movement is necessary to select a joint seal. Adequate drainage away from the joints remains the most important design consideration
Test Method for Evaluating Pavement Sealants Under Simultaneous Cyclic Shear and Normal Deflections
Authors: Al-Qadi IL , Abo-Qudais SA 
Published: March 2009

A new method to evaluate the performance of sealants, used in rigid pavement joints, was developed. A special fixture was designed to transfer cyclic in-line deflection, applied by a testing machine, to simultaneous cyclic normal and shear deflections, at a specific ratio, on a sealant sandwiched between two-51 mm portland cement mortar cubes. The developed fixture was used to evaluate the performance of three commercially available one-component sealant types (A, B, and C): A is a low modulus silicone, B is a self leveling silicone, while C is a polyurethane used with primer.
The sealants were evaluated under both cyclic compression/shear and tension/shear tests at 25 Hz. Each sealant was evaluated at two joint widths, 6.5 mm and 19 mm. Analysis of test results indicated that sealant C performed the best with no failure after 500,000 cycles in all tests, while the performance of sealant B was the worst with cohesive failure in most cases. Sealant A, on the other hand, failed adhesively at a joint width of 6.5 mm. All sealants, not surprisingly, performed better in cyclic compression/shear than in cyclic tension/shear.
Selecting Rehabilitation and Replacement Bridge Projects
Authors: Weissmann J , Harrison R , Burns NH , Hudson WR 
Published: March 2009

Evaluating the cost-effectiveness of new techniques, materials, and systems to extend bridge life frequently requires some form of life cycle analysis at the project level. Where networks are concerned, life cycle analysis can be useful in determining budgetary levels and the scheduling of activities which will ensure that maximum bridge life is obtained. As part of this latter process, a procedure developed for the state of Texas is reported, which allocates a budget for bridge replacement and rehabilitation projects using multi-attribute criteria and user-friendly computer programs. The system is a two-level closed loop procedure based on standard bridge inventory data and addresses the concerns of both state and district levels within the state. One state level program determines those bridge projects meeting FHWA financing criteria while a second program takes this subset and applies specific state criteria for project ranking and prioritization. The user of this module can rank the candidate projects using a multi-attribute technique and can complement this with an automatic qualification process based on user-defined threshold values. The multi-attribute approach uses statistical techniques applied to the entire state bridge population. Therefore, as this data set is regularly updated in accordance with FHWA requirements, it captures information on both recent deterioration and improvements to structures. A district reporting program incorporates regional knowledge of structures and their condition into the decision-making process.
The system methodology can be useful to any state officials engaged in ranking bridge projects since it incorporates managerial experience and uses statistics derived from current national bridge survey data. It also fits into the latest research findings on the development of a comprehensive bridge management system.
Retrofit of Cracked Welded Steel Bridge Girders
Authors: Pullaro JJ 
Published: March 2009

A welded plate girder bridge on a main interstate highway in service for over 25 years suddenly develops a through crack in the web and flange of a fascia girder. An in-depth inspection and metallographic examination reveal the crack started in the vicinity of a welded diaphragm. The crack propagated quickly and was characteristic of a brittle fracture. Further analysis, including strain gauging and Charpy V-notch (CVN) tests, does not conclusively identify the cause for the propagation of the crack.
Fatigue analysis reveals it is very unlikely the crack could have been initiated by fatigue within the 25-year life span of the structure. The problem is traced to a 3-mm (1/8-in.) porosity defect at the root of a weld at the diaphragm connection. Propagation is attributed to out-of-plane bending in the web of the girder, high residual stresses, low toughness of steel, and cold weather.
A method for retrofitting the structure via “softening the connections” and repairing the cracked girders is selected as the course of action.