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ASM Handbook, Volume 12: Fractography

ASM Handbook Committee, p 91-165 DOI: 10.1361/asmhba0001834

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Estimating the Fatigue Stress Concentration Factor of Machined Surfaces D

International Journal of Fatigue 24 (2002) 923–930 www.elsevier.com/locate/ijfatigue Estimating the fatigue stress concentration factor of machined surfaces D. Arola *, C.L. Williams 1 Department of Mechanical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA Received 18 December 2000; received in revised form 12 September 2001; accepted 19 December 2001 Abstract In this study the effects of surface texture on the fatigue life of a high-strength low-alloy steel were evaluated in terms of the apparent fatigue stress concentration. An abrasive waterjet was used to machine uniaxial dogbone fatigue specimens with speciﬁc surface quality from a rolled sheet of AISI 4130 CR steel. The surface texture resulting from machining was characterized using contact proﬁlometry and the surface roughness parameters were used in estimating effective stress concentration factors using the Neuber rule and Arola–Ramulu model. The steel specimens were subjected to tension–tension axial fatigue to failure and changes 3Յ Յ 6 in the fatigue strength resulting from the surface texture were assessed throughout the stress–life regime (10 Nf 10 cycles). It was found that the fatigue life of AISI 4130 is surface-texture-dependent and that the fatigue strength decreased with an increase in surface roughness. The fatigue stress concentration factor (Kf) of the machined surfaces determined from experiments was found to range from 1.01 to 1.08. Predictions for the effective fatigue stress concentration (K¯ f) using the Arola–Ramulu model were within 2% of the apparent fatigue stress concentration factors estimated from experimental results. 2002 Published by Elsevier Science Ltd.
Ebook Download Forensic Chemistry

FORENSIC CHEMISTRY PDF, EPUB, EBOOK David E. Newton | 208 pages | 15 Nov 2008 | Facts on File Inc | 9780816078004 | English | New York, United States Department of Chemistry and Biochemistry - B.S. Forensic Chemistry Degree Mass Spectrometry MS breaks samples apart and separates the ionized fragments by mass and charge. Generally, forensic chemists are trained in organic chemistry. This ensures that the forensic chemists can run analysis on blood and other body samples to identify DNA. They are also trained in organic chemistry so that they can run toxicology screenings. It is also important for a forensic chemist to have knowledge of physics. There are also forensic chemists who specialize in certain areas, such as chemicals that are tied to explosives or arson. These chemists will be called to a crime scene to look at fire patterns when determining if arson was involved in a fire or they will be called to investigate chemicals associated with a bomb. Once becoming a forensic chemist, there are many places where a forensic chemist could work. A forensic chemist might work for a private lab, or at a national agency like the FBI. Twitter Facebook Instagram Youtube. Back to Crime Library. A mysterious white powder, a blood smear, and a moldy ham sandwich—completely unrelated items to most. But they could be meaningful for forensic chemists, who analyze physical evidence and samples for clues to solve crimes. Television shows such as Bones, CSI, and Dexter have glamorized forensic scientists and made the field more popular, so competition can be intense. However, if you have a strong desire to shape the world of justice by using science to solve crime puzzles, then a career in forensic science could be worth pursuing.
On the Fractography of Impact-Tested Samples of Al-Si Alloys for Automotive Alloys Alloys for Automotive Alloys

Provisional chapter Chapter 2 On the Fractography of Impact-Tested Samples of Al-Si On the Fractography of Impact-Tested Samples of Al-Si Alloys for Automotive Alloys Alloys for Automotive Alloys Zheyuan Ma, Agnes M. Samuel, ZheyuanHerbert W. Ma, Doty Agnes and M. Fawzy Samuel, H. Samuel Herbert W. Doty and Fawzy H. Samuel Additional information is available at the end of the chapter Additional information is available at the end of the chapter http://dx.doi.org/10.5772/63409 Abstract Castings were prepared from both industrial and experimental 319.2, B319.2 and A356.2 alloy melts, containing Fe levels of 0.2–1.0 wt%. Stontium-modified (∼200 ppm) melts were also prepared for each alloy/Fe level. Impact testing of heat-treated samples was carried out using an instrumented Charpy impact testing machine. At low Fe levels and high cooling rates (0.4% Fe, dendrite arm spacing (DAS) of 23 μm), crack initiation and propagation in unmodified 319 alloys occur through the cleavage of β-Al5FeSi platelets (rather than by their decohesion from the matrix). The morphology of the platelets (individual or branched) is important in determining the direction of crack propagation. Cracks also propagate through the fracture of undissolved CuAl2 or other Cu interme- tallics, as well as through fragmented Si particles. In Sr-modified 319 alloys, cracks are mostly initiated by the fragmentation or cleavage of perforated β-phase platelets, in addition to that of coarse Si particles and undissolved Cu-intermetallics. In A356.2 alloys, cracks initiate mainly through the fracture of Si particles or their debonding from the Al matrix, while crack propagation occurs through the coalescence of fractured Si particles, except when β-Al5FeSi intermetallics are present, in which case the latter takes precedence.
Improved Fatigue Test Specimens with Minimum Stress Concentration Effects1

IMPROVED FATIGUE TEST SPECIMENS WITH MINIMUM STRESS CONCENTRATION EFFECTS1 Daniel de Albuquerque Simões2 Jaime Tupiassú Pinho de Castro3 Marco Antonio Meggiolaro3 Abstract The American Standard for Testing and Materials (ASTM) has standardized numerous mechanical tests such as the constant amplitude axial fatigue test of metallic materials (E 466–96), the strain-controlled fatigue testing (E 606–92) and the strain-controlled axial-torsional fatigue testing with thin-walled tubular specimens (E 2207–02). The specimens for such tests must have notches to connect their uniform test section to the larger heads required to grip them. The usual practice is to specify notches with as large as possible constant radius roots, since they can be easily fabricated in traditional machine tools. However, notches with properly specified variable radius may have much lower stress concentration factors than those obtainable by fixed notch root radii. The objective of this study is to analyze the stress distribution in these specimens using the finite element method and to quantify the stress concentration improvements achievable by optimizing variable radius notches for typical push-pull, rotary bending and alternate bending fatigue test specimens by redesigning the specimen geometry without changing their overall dimensions. Key words: Stress concentration factor; Shape optimization; Finite element methods. CORPOS DE PROVA DE FADIGA COM CONCENTRAÇÃO DE TENSÃO REDUZIDA Resumo A ASTM (The American Standard for Testing and Materials) padronizou inúmeros testes mecânicos, como por exemplo, o teste de fadiga de amplitude constante para materiais metálicos (E466–96), o teste de fadiga com deformação controlada (E 606–92) e o teste de fadiga de torção axial de corpos de prova tubulares (E 2207–02).
Improving Biometric and Forensic Technology: the Future of Research Datasets Symposium Report

NISTIR 8156 Improving Biometric and Forensic Technology: The Future of Research Datasets Symposium Report Melissa Taylor Shannan Williams George Kiebuzinski This publication is available free of charge from: https://doi.org/10.6028/NIST.IR.8156 NISTIR 8156 Improving Biometric and Forensic Technology: The Future of Research Datasets Symposium Report Melissa Taylor Shannan Williams Forensic Science Research Program Special Programs Office National Institute of Standards and Technology George Kiebuzinski Noblis, Inc. This publication is available free of charge from: https://doi.org/10.6028/NIST.IR.8156 March 2017 U.S. Department of Commerce Wilbur L. Ross, Jr., Secretary National Institute of Standards and Technology Kent Rochford, Acting NIST Director and Under Secretary of Commerce for Standards and Technology Table of Contents 1 Executive Summary .............................................................................................................................. 6 1.1 Background ................................................................................................................................... 6 1.2 Summary of Workshop Presentations and Discussions ............................................................... 6 1.3 Findings ......................................................................................................................................... 7 2 Introduction ........................................................................................................................................
Trace Materials Crime Scene Investigation Guide

This document is being made available so that the forensic science community and interested stakeholders can be more fully aware of the efforts and work products of the Organization of Scientific Area Committees for Forensic Science (OSAC). This document is a DRAFT which represents a work still in progress and is intended for future development into a web application. Therefore, please consider the content of the current version of the Trace Materials Crime Scene Investigation Guide but disregard the format, as the format will necessarily be overhauled upon adaptation of the document into a web application. Trace Materials Crime Scene Investigation Guide Draft Document 01.01 Table of Contents 01.02 Introduction 01.03 Evidence Collection and Packaging Overview 02 Sub-disciplines - 02.01 Airbags - 02.02 Explosives - 02. 03 Fibers - 02.03.01 Fabric damage and impressions - 02.03.02 Cordage - 02.04 Fire Debris - 02.05 Footwear and Tire Impressions - 02.06 Geological Material - 02.07 Glass - 02.08 Gunshot Residue - 02.09 Hairs - 02.10 Lamp/Filaments - 02.11 Paint - 02.12 Physical Fit - 02.13 Tape - 02.14 Other Types of Trace Evidence 03 Types of Crime Scenes - 03.01 Arson (TO BE INCLUDED) - 03.02 Shooting (TO BE INCLUDED) - 03.03 Stabbing (TO BE INCLUDED) - 03.04 Manual Strangulation (TO BE INCLUDED) - 03.05 Asphyxiation (TO BE INCLUDED) - 03.05 Blunt Force Trauma (TO BE INCLUDED) - 03.06 Sexual Assault - 03.07 Dumped Body (TO BE INCLUDED) - 03.08 Wrapped or Bound Victim (TO BE INCLUDED) - 03.09 Burglary (TO BE INCLUDED) - 03.10 Suspicious Death (TO BE INCLUDED) - 03.11 Explosion (TO BE INCLUDED) - 03.12 Hit-and-Run 04 Appendices - 04.01 Important Phone Numbers (TO BE INCLUDED) Introduction Trace evidence is a subset of forensic evidence that is scientifically analyzed to explore possible associations between people, places, and objects.
Fractography of Metals and Plastics

FRACTOGRAPHY OF METALS AND PLASTICS Ronald J. Parrington, P.E. IMR Test Labs 131 Woodsedge Drive Lansing, NY 14882 Abstract behavior; (2) use thermal spalling to detach bedrock from the working core; and (3) shape stone by pressure flaking. Fractography is critical to failure analysis of metals and th plastics. Fractography of plastics is a relatively new field Fractography as we know it today, developed in the 16 with many similarities to metals. Utilizing case histories, century as a quality control practice employed for ferrous various aspects of failure analysis and fractography are and nonferrous metal working. “De La Pirotechnia” compared and contrasted. published by Vannoccio Biringuccio (1) in 1540 is one of the first documents to detail fractographic techniques. Common failure modes include ductile overload, brittle fracture, impact and fatigue. Analogies can also be drawn Invention of the optical microscope in 1600 provided a between stress corrosion cracking (SCC)/stress cracking, significant new tool for fractography. Yet it was not th corrosion/chemical aging, dealloying/scission, residual utilized extensively by metallurgists until the 18 century. stress/frozen-in stress, and welds/knit lines. Stress raisers, In 1722, R.A. de Réaumur (2) published a book with microstructure, material defects, and thermo -mechanical engravings depicting macroscopic and microscopic history play important roles in both cases. Key fracture surfaces of iron and steel. Interestingly, the fractographic features for metals and plastics are described. categories of macroscopic features developed by de Réaumur have remained essentially unchanged through the Historical Perspective centuries. Plastics have been in existence for approximately 130 Partly due to the development of metallographic techniques for examining cross sections of metals, interest years.
73Rd Aafs Annual Scientific Meeting

AMERICAN ACADEMY OF FORENSIC SCIENCES 73RD AAFS ANNUAL SCIENTIFIC MEETING ADVANCE PROGRAM • FEBRUARY 2021 TABLE OF CONTENTS Registration Information . 1 Officers & Officials . 2 Program Committee . 3 Awards . 4 Business Meetings . 6 Financial Contributors . 7 Continuing Education . 8 Calendar of Events . 10 Student Academy . 14 Interdisciplinary Symposium . 16 Young Forensic Scientists Forum Special Session . 18 Standards Consortium . 21. Forensic Science Education Programs Accreditation Commission Session . 22 Keynote Address . 24 Plenary Session . 25 Case Break Sessions . 27 Workshops . 32 Humanitarian and Human Rights Resource Center Poster Session . 70 National Institute of Justice . 72 Scientific Sessions Anthropology . 77 Criminalistics . 87 Digital & Multimedia Sciences . 103 Engineering & Applied Sciences . 106 General . 109 Jurisprudence . 118 Odontology . 122 Pathology/Biology . 124 Psychiatry & Behavioral Science . 138 Questioned Documents . 141 Toxicology . 144 Last Word Society . 150 YFSF Poster Sessions . 151 Program Committee Financial Disclosure . 153 Presenting Author Financial Disclosure . 156 Key Word Index . 167 Presenting Author Index . 178 i REGISTRATION INFORMATION Your registration fee includes the opportunity to claim continuing education credits, access to live and pre-recorded content for up to 90 days, virtual networking, and admission to the virtual exhibit hall. All persons attending must be at least 18 years of age at the time of the meeting. THREE WAYS TO REGISTER 1. Register online at www.aafs.org through the AAFS Web Account (https://webdata.aafs.org/aafsweb/Security/SignIn.aspx). 2. Scan and email your registration form to: registration@aafs.org. 3. Mail your registration form, along with a check, money order, or purchase order, to: AAFS 410 North 21st Street Colorado Springs, CO 80904 (Checks must be drawn on a U.S.
A Short Review on Fracture Mechanisms of Mechanical Components Operated Under Industrial Process Conditions: Fractographic Analysis and Selected Prevention Strategies

metals Review A Short Review on Fracture Mechanisms of Mechanical Components Operated under Industrial Process Conditions: Fractographic Analysis and Selected Prevention Strategies George A. Pantazopoulos ELKEME Hellenic Research Centre for Metals S.A., 61st km Athens–Lamia National Road, 32011 Oinofyta, Viotias, Greece; gpantaz@elkeme.vionet.gr; Tel.: +30-2262-60-4463 Received: 9 January 2019; Accepted: 27 January 2019; Published: 29 January 2019 Abstract: An insight of the dominant fracture mechanisms occurring in mechanical metallic components during industrial service conditions is offered through this short overview. Emphasis is given on the phenomenological aspects of fracture and their relationships with the emergent fracture mode(s) with respect to the prevailed operating parameters and loading conditions. This presentation is basically fulfilled by embracing and reviewing industrial case histories addressed from a technical expert viewpoint. The referenced case histories reflected mainly the author’s team expertise in failure analysis investigation. As a secondary perspective of the current study, selected failure investigation and prevention methodological approaches are briefly summarized and discussed, aiming to provide a holistic overview of the specific frameworks and systems in place, which could assist the organization of risk minimization and quality enhancement. Keywords: metal components; fracture mechanisms; fractography; fracture mechanics; quality improvement 1. Introduction Failure analysis (FA) is a multidisciplinary, multifaceted scientific field, connecting areas of engineering from diverse backgrounds and bodies of knowledge; from applied mechanics to electrochemistry and corrosion and from numerical modeling, to the understanding of surface science and tribology. The complexity of the nature of the subject requires the embracing of various engineering disciplines, to succeed high process performance and effective root-cause analysis, which is the core and the central objective of the failure investigation process [1].
Forensic Failure Analysis

© 2005 ASM International. All Rights Reserved. www.asminternational.org Failure Analysis of Engineering Structures: Methodology and Case Histories (#05127G) CHAPTER 7 Forensic Failure Analysis FORENSIC SCIENCE refers to that part of science that is used is a written warranty or contract about its performance. The second in courts of law for administration of justice. Service failures of aspect of the contract that is implied is that the product should be machines and accidents to engineering structures result in serious, reasonably safe. Failure to perform its intended function satisfac- expensive, and prolonged litigations, affecting the credibility of torily and safely constitutes a breach of warranty and, hence, lia- the manufacturer and the reliability of its products. When defective bility. In courts of law, product liability is extended not only to the consumer products fail to perform their intended functions and manufacturer of the whole product but also to the designer, the thereby cause injuries to personnel or damage to property, the user maker of component parts, the assembler, the person who installs resorts to product liability litigations. Litigations also follow when it, the repairer, and also the distributor and the retail seller. The damages to structures, life, and property are caused by deliberate absence of privity of contract, i.e., direct connection between the acts of sabotage by antisocial elements. plaintiff and the defendant, does not preclude liability in tort. Thus, Investigations of such mishaps are of two kinds, preventive and in a product liability litigation, liability is imposed also on people punitive, i.e., inquisitorial and accusatorial. In the former, attempts behind the scenes.
Importance of SEM in the Study of Fractography: Camshaft Failure

2246 Microsc. Microanal. 24 (Suppl 1), 2018 doi:10.1017/S1431927618011716 © Microscopy Society of America 2018 Importance of SEM in the Study of Fractography, Camshaft Failure González-Mancera G.1 and González-González D. E.1 1. Universidad Nacional Autónoma de México, Facultad de Química. Departamento de Ing. Metalúrgica, Ciudad Universitaria, D. F. México. A camshaft is an important automotive part that automates car engine combustion. Most camshafts are made of cast irons to achieve large volume productions and others using CNC machining of steel to achieve a high-quality product but low volume production. In material science and engineering, fractography is one of the most relevant methods used in failure analysis and fracture mechanics. This technique is used to determine the cause of failure by examining the fracture surface. The fracture surfaces can be classified as ductile or brittle depending on the characteristics. In Ductile fracture present mostly, plastic deformation in the surroundings and a bright granular o fibrous surface. In the other hand, brittle fracture presents large crack propagation without plastic deformation and an opaque irregular surface. The current work examines the fracture of a camshaft using fractography. The sample was cleaned with water-based, organic solvent and acetic acid in ultrasonic baths to eliminate possible contamination and atmospheric oxidation. After the sample was analyzed by Scanning Electron Microscopy (SEM) observation, it shown this material is a nodular cast iron. At low magnification the characteristic fracture pattern indicates a torsion stress failure [1, 2]. It was observed v-shaped cracks known as Chevron marks and they converge in the fracture initial zone.
Effect of Stress Concentrations on Fatigue of Composite and Metallic Structures

Scholars' Mine Masters Theses Student Theses and Dissertations Spring 2014 Effect of stress concentrations on fatigue of composite and metallic structures Ross Henry Falen Follow this and additional works at: https://scholarsmine.mst.edu/masters_theses Part of the Mechanical Engineering Commons Department: Recommended Citation Falen, Ross Henry, "Effect of stress concentrations on fatigue of composite and metallic structures" (2014). Masters Theses. 7255. https://scholarsmine.mst.edu/masters_theses/7255 This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact scholarsmine@mst.edu. EFFECT OF STRESS CONCENTRATIONS ON FATIGUE OF COMPOSITE AND METALLIC STRUCTURES by ROSS HENRY FALEN A THESIS Presented to the Faculty of the Graduate School of the MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE IN MECHANCIAL ENGINEERING 2014 Approved by Dr. Lokeswarappa R. Dharani, Advisor Dr. K. Chandrashekhara Dr. Jeffery Thomas © 2014 Ross Henry Falen All Rights Reserved iii ABSTRACT The complex shapes of hydrokinetic turbine blades can include part features such as a fillet, step, or hole. Situations can arise where two part features, such as a hole and a fillet, may be in close proximity which can introduce stress concentrations within the blade structure, adversely affecting the structure’s life. Because the interaction between the part features isn't well known, fatigue data is needed to determine the proper analysis.