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Rapid Assessment Of The Role Of Microstructural Variability In The Fatigue Behavior Of Structural Alloys Using Ultrasonic Fatigue
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Book Synopsis Rapid Assessment of the Role of Microstructural Variability in the Fatigue Behavior of Structural Alloys Using Ultrasonic Fatigue by :
Download or read book Rapid Assessment of the Role of Microstructural Variability in the Fatigue Behavior of Structural Alloys Using Ultrasonic Fatigue written by and published by . This book was released on 2007 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrasonic fatigue (20kHz) has been used to investigate the role of microstructural variability on fatigue life variability for very long fatigue lives, between 10(to the 7th power) and 10(to the 9th power) cycles, in structural aerospace materials. This AFOSR program has been augmented by support from DARPA (Dr. Leo Christodoulou) and a summary of the results from the combined support is described in this report. Four distinctly different structural alloys have been studied: (1) a particle reinforced aluminum alloy, 2009Al/15SiCp, where clustering of SiC particles and the presence of processing-related inclusions is expected to control fatigue life, (2) an alpha/beta titanium disk alloy, Ti-6Al-2Sn-4Zr-6Mo, that has been processed to have a fine, homogeneous, two-phase microstructure that is essentially free of inclusions or other defects; (3) a polycrystalline nickel-base disk alloy, Rene 88DT which has a small but finite number of large grains that influence fatigue crack initiation; and a single crystal nickel-base superalloy for blade applications, PWA 1484. In this program, an advanced ultrasonic fatigue system capable of fatigue testing aerospace materials at 20 kHz and at temperatures form ambient to 1000 degrees C has been developed. For the polycrystalline materials, the magnitude of fatigue life variability was observed to be strongly dependent on the microstructure-dependent crack initiation processes, which, in turn, were different for each material. For 2009Al/15SiCp, crack initiation occurred in almost all cases at 20-30 micrometers diameter inclusions. Less than half an order of magnitude variation in fatigue life at 10(to the 9th power) cycles was observed and is explained by the absence of a significant crack initiation lifetime.
Book Synopsis Meeting of Board of Regents by : University of Michigan. Board of Regents
Download or read book Meeting of Board of Regents written by University of Michigan. Board of Regents and published by . This book was released on 2004-02 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mechanical Fatigue of Metals by : José A.F.O. Correia
Download or read book Mechanical Fatigue of Metals written by José A.F.O. Correia and published by Springer. This book was released on 2019-05-07 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of the XIX International Colloquium on Mechanical Fatigue of Metals, held at the Faculty of Engineering of the University of Porto, Portugal, 5-7 September 2018. This International Colloquium facilitated and encouraged the exchange of knowledge and experiences among the different communities involved in both basic and applied research in the field of the fatigue of metals, looking at the problem of fatigue exploring analytical and numerical simulative approaches. Fatigue damage represents one of the most important types of damage to which structural materials are subjected in normal industrial services that can finally result in a sudden and unexpected abrupt fracture. Since metal alloys are still today the most used materials in designing the majority of components and structures able to carry the highest service loads, the study of the different aspects of metals fatigue attracts permanent attention of scientists, engineers and designers.
Book Synopsis Fatigue Behavior of High-entropy Alloys by : Michael Alexander Hemphill
Download or read book Fatigue Behavior of High-entropy Alloys written by Michael Alexander Hemphill and published by . This book was released on 2012 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research was performed on the Al9Co1.2 Cr18.2Cu18.2Fe18.2Ni18.2 [subscripts atomic percent] and Al--.5Cr22.5Fe35Mn20Ni15 high-entropy alloys (HEAs) in an attempt to study their fatigue behavior. The present investigation shows encouraging fatigue-resistance characteristics due to their high fatigue lives of various samples at relatively high stresses. The current results indicate that the fatigue behavior of HEAs compares favorably to many conventional alloys, such as steels, titanium alloys, and advanced bulk metallic glasses with a fatigue-endurance limit of the Al9Co18.2Cr18.2Cu18.2Fe18.2Ni18.2 HEAs between 540 and 945 MPa and a fatigue-endurance limit to ultimate tensile strength ratio between 0.402 and 0.703. The Al--.5Cr22.5Fe35Mn20Ni15 HEAs were found to have a fatigue-endurance limit between 540 and 630 MPa. Some unpredictability in the fatigue life of the samples was observed by scattering in the stress versus life plot. Weibull models were applied to predict the fatigue data and to characterize the variability seen in Al99Co18.2Cr18.2Cu18.2Fe18.2Ni18.2 HEAs. A Weibull mixture predictive model was used to separate the data into two, strong and weak, groups. This model predicts that at stress ranges above 858 MPa, the median time to failure of specimens in the strong group will be greater than 107 cycles. Large oxide particles were found on the tensile surfaces of both samples with microcracks forming at these sites. It was shown that these microstructural defects may have a significant effect on the fatigue behavior of HEAs. A comparison of the endurance limits and fatigue ratios of HEAs to conventional structural alloys shows that HEAs may outperform many conventional alloys under fatigue conditions. It is believed that a reduction in the number of defects introduced during fabrication and processing may result in a superior fatigue behavior, which exceeds that of conventional alloys.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Iron & Steelmaker written by and published by . This book was released on 2003-07 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fatigue of Materials II by : T.S. Srivatsan
Download or read book Fatigue of Materials II written by T.S. Srivatsan and published by Springer. This book was released on 2016-12-06 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: The papers in this collection cover a diverse range of topics on the topic of fatigue of materials. The editors have grouped the papers into five sections. Sections 1 and 2 contain papers that (i) review the current state of knowledge both related and relevant to the subject of fatigue behavior of materials, and (ii) present new, innovative, and emerging techniques for experimental evaluation of the fatigue behavior. Sections 3 and 4 focus on advanced materials that are used in performance-critical applications in the aerospace and automotive industries, such as the alloys of titanium, nickel, aluminum, and magnesium. Section 5 presents papers relating to other materials of engineering interest, such as iron and steel, polymer, rubber, and composites.
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Microstructural effects on the fatigue behavior of fe-c-x alloys by : Gary J. Shiflet
Download or read book Microstructural effects on the fatigue behavior of fe-c-x alloys written by Gary J. Shiflet and published by . This book was released on 1986 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metals Abstracts written by and published by . This book was released on 1998 with total page 1076 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Microstructural Effects in the Fatigue Behavior of Metals and Alloys by : Norman S. Stoloff
Download or read book Microstructural Effects in the Fatigue Behavior of Metals and Alloys written by Norman S. Stoloff and published by . This book was released on 1974 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: This review examines the various stages of fatigue damage on the basis of changes in slip character and dislocation sub-structures resulting from solid solution alloying, thermomechanical treatments or precipitation hardening. Cyclic hardening and softening are related to fatigue life of a wide variety of alloy systems, including pure metals, commercial alloys, intermetallic compounds and directionally solidified eutectics. The influence on fatigue behavior of variations in structure produced by processing (e.g., casting defects, inclusions, surface notches) also are considered. Finally, the effects of temperature and aggressive environments on crack nucleation and propagation are related to metallurgical structure.
Book Synopsis Fatigue and Durability of Structural Materials by : Gary R. Halford
Download or read book Fatigue and Durability of Structural Materials written by Gary R. Halford and published by ASM International. This book was released on 2006 with total page 471 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue and Durability of Structural Materials explains how mechanical material behavior relates to the design of structural machine components. The major emphasis is on fatigue and failure behavior using engineering models that have been developed to predict, in advance of service, acceptable fatigue and other durability-related lifetimes. The book covers broad classes of materials used for high-performance structural applications such as aerospace components, automobiles, and power generation systems. Coverage focuses on metallic materials but also addresses unique capabilities of important nonmetals. The concepts are applied to behavior at room or ambient temperatures; a planned second volume will address behavior at higher-temperatures. The volume is a repository of the most significant contributions by the authors to the art and science of material and structural durability over the past half century. During their careers, including 40 years of direct collaboration, they have developed a host of durability models that are based on sound physical and engineering principles. Yet, the models and interpretation of behavior have a unique simplicity that is appreciated by the practicing engineer as well as the beginning student. In addition to their own pioneering work, the authors also present the work of numerous others who have provided useful results that have moved progress in these fields. This book will be of immense value to practicing mechanical and materials engineers and designers charged with producing structural components with adequate durability. The coverage is appropriate for a range of technical levels from undergraduate engineering students through material behavior researchers and model developers. It will be of interest to personnel in the automotive and off-highway vehicle manufacturing industry, the aeronautical industry, space propulsion and the power generation/conversion industry, the electric power industry, the machine tool industry, and any industry associated with the design and manufacturing of mechanical equipment subject to cyclic loads.
Book Synopsis TMS 2018 147th Annual Meeting & Exhibition Supplemental Proceedings by : The Minerals, Metals & Materials Society
Download or read book TMS 2018 147th Annual Meeting & Exhibition Supplemental Proceedings written by The Minerals, Metals & Materials Society and published by Springer. This book was released on 2018-02-03 with total page 898 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection features papers presented at the 147th Annual Meeting & Exhibition of The Minerals, Metals & Materials Society.
Book Synopsis Stochastic Energy-based Fatigue Life Prediction Framework Utilizing Bayesian Statistical Inference by : Dino Anthony Celli
Download or read book Stochastic Energy-based Fatigue Life Prediction Framework Utilizing Bayesian Statistical Inference written by Dino Anthony Celli and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fatigue life prediction framework developed and described in the proceeding chapters can concurrently approximate both typical stress versus cycle (SN) behavior as well as the inherent variability of fatigue using a limited amount of experimental data. The purpose of such a tool is for the rapid verification and quality assessment of cyclically loaded components with a limited knowledge-base or available fatigue data in the literature. This is motivated by the novelty of additive manufacturing (AM) processes and the necessity of part-specific structural assessment. Interest in AM technology is continually growing in many industries such as aerospace, automotive, or bio-medical but components often result in highly variable fatigue performance. The determination of optimal process parameters for the build process can be an extensive and costly endeavor due to either a limited knowledge-base or proprietary restrictions. Quantifying the significant variability of fatigue performance in AM components is a challenging task as there are many underlying causes including machine-to-machine differences, recycles of powder, and process parameter selection. Therefore, a life prediction method which can rapidly determine the fatigue performance of a material with little or no prior information of the material and a limited number of experimental tests is developed as an aid in AM process parameter optimization and fatigue performance qualification. Predicting fatigue life requires the use of a previously developed and simplistic energy-based method, or Two-Point method, to generate a collection of life predictions. Then the collected life predictions are used to approximate key statistical descriptions of SN fatigue behavior. The approximated fatigue life distributions are validated against an experimentally found population of SN data at 10^4 and 10^6 cycles failure describing low cycle and high cycle fatigue. A Monte Carlo method is employed to model fatigue life by first modeling SN distributions at discrete stress amplitudes using the predicted fatigue life curves. Then the distributions are randomly sampled and a life prediction model is obtained. The approach is verified by using Aluminum 6061 data due to ample material characterization and previous life prediction analysis available in literature. SN life prediction is modeled via a Random Fatigue Limit (RFL) model using least square regression to determine the model coefficients. The life prediction framework is further developed by incorporating Bayesian statistical inference and stochastic sampling techniques to estimate the RFL model parameters. In addition, digital image correlation (DIC) is leveraged during experimentation to collect hysteresis energy as a novel method to monitor hysteresis strain energy or the assumed critical damage variable. Fatigue life prediction is performed in a dynamic way such that the life prediction model is continually updated with the generation of experimental data. The life prediction framework is applied to conventional Aluminum 6061-T6 and AM Inconel 718 and Titanium 6Al-4V. The framework is validated for life prediction and forecasting SN high cycle fatigue behavior using only low cycle fatigue data. The culmination of this work enables the rapid characterization of fatigue of AM materials by concurrently approximating the variation of fatigue life as well as high cycle fatigue behavior with low cycle fatigue data. The benefit of this framework is the significant reduction in experimental testing time, effort, and cost necessary to accurately assess the fatigue behavior of materials with limited prior information and specimen availability, such as in the case with AM Alloys.
Book Synopsis Linking Enhanced Fatigue Life to Design by Modifying the Microstructure by : Kaimiao Liu
Download or read book Linking Enhanced Fatigue Life to Design by Modifying the Microstructure written by Kaimiao Liu and published by . This book was released on 2019 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural material fatigue is a leading cause of failure and has motivated fatigue-resistant design to eliminate risks to human lives. Intrinsic microstructural features alter fatigue deformation mechanisms so profoundly that, essentially, fatigue properties of structural materials become deviant. With this in mind, we initiated this project to investigate the microstructural effect on fatigue behavior of potential structural high entropy alloys. With a better understanding of the effect of microstructure features on fatigue properties, the ultimate goal was to engineer the microstructure to enhance the fatigue life of structural materials. The effects of two major deformation mechanisms presented here are twinning-induced fatigue crack retardation, and transformation-induced fatigue crack retardation. The fundamental principle of both mechanisms is to delay the fatigue crack propagation rate by altering the work hardening ability locally within the crack plastic zone. In ultrafine grained triplex Al0.3CoCrFeNi, nano-sized deformation twins were observed during cyclic loading in FCC matrix due to low stacking fault energy (SFE). The work-hardening ability of the material near the crack was sustained with the formation of twins according to Considere's criteria. Further, due to the ultrafine-grained (UFG) nature of the material, fatigue runout stress was enhanced. In a coarse-grained, dual-phase high entropy alloy, persistent slip bands formed in FCC matrix during cyclic loading due mainly to the slight composition change that affects the SFE in the FCC matrix and eventually alters the deformation mechanism. Another way known to alter an alloy's work hardening (WH) ability is transformation-induced plasticity (TRIP). In some alloys, phase transformation happens due to strain localization, which alters the work-hardening ability. iii In a fine-grained, dual-phase metastable high entropy alloy, gamma (f.c.c.) to epsilon (h.c.p.) transformation occurred in the plastic zone that was induced from cracks. Thus, we designed a Cu-containing FeMnCoCrSi high entropy alloy that exhibited a normalized fatigue ratio of ̃ 0.62 UTS (ultimate tensile strength). Our design approach was based on (a) engineering the gamma phase stability to attain sustained work hardening through delayed gamma (f.c.c.) to epsilon (h.c.p.) transformation to hinder fatigue crack propagation, (b) incorporating an ultrafine-grained microstructure to delay crack initiation, and (c) forming deformation twins to reduce the crack propagation rate. We verified that a UFG gamma dominant microstructure could provide opportunities for exceptional fatigue resistance, as sustained WH activity strengthened the material locally in the crack plastic zone, thereby validating our expectation that the combination of UFG and TRIP is a path to design the next generation of fatigue-resistant alloys.
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1044 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch Publisher : ISBN 13 : Total Pages :1080 pages Book Rating :4.E/5 ( download)
Book Synopsis Japanese Science and Technology, 1983-1984 by : United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch
Download or read book Japanese Science and Technology, 1983-1984 written by United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch and published by . This book was released on 1985 with total page 1080 pages. Available in PDF, EPUB and Kindle. Book excerpt:
