Download or read book Thermal Effects on the Dynamic Damage and Fracture of a Dual Phase Automotive Steel written by Sarath Chandran and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Causes of shear Fracture of Dual phase Steels written by Ji-Hyun Sung and published by . This book was released on 2010 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Dual Phase (DP) steels are a class of advanced high strength steel (AHSS) in increasing use for sheet formed automotive parts. In spite of attractive combinations of high strength, high ductility, and low cost, the widespread adoption of DP steels has been limited because practical die tryouts exhibit forming failures far earlier than predicted by standard industrial methods. These failures, often referred to as "shear fractures," occur in regions of high curvature and with little apparent necking, in contrast to "normal" or tensile fractures. Conventional wisdom attributes shear fractures to a postulated damage mechanism related to the special microstructure of DP steels. In order to reproduce, characterize, and analyze such fractures in a laboratory setting and to understand their origin of the inability to predict them, a novel draw-bend formability (DBF) test was devised based on displacement control. DP steels from several suppliers with tensile strengths ranging from 590 to 980 MPa were tested over a range of rates and bend ratios (R/t, inner bend radius / sheet thickness). The new DBF test reliably reproduced three kinds of fractures identified as Type I, II, and III, corresponding to tensile fracture, transitional fracture, and shear fracture, respectively. These tests revealed a surprising result: the occurrence of shear fractures increased at higher deformation rates. This degradation of formability was shown to be principally a result of deformation-induced heating, which is greatly accentuated for AHSS because of their high plastic energy absorption and commensurate high temperature increases, up to 100 degrees C. In order to understand and quantify the role of deformation-induced heating on plastic localization, temperatures were measured and simulated using a novel new empirical plasticity constitutive form describing the flow stress as a function of strain, strain-rate, and temperature. Designated the "H/V model", the new constitutive model consists of three multiplicative functions describing (a) strain hardening and its temperature sensitivity, (b) strain-rate sensitivity, and (c) temperature sensitivity. This form allows a natural transition from unbounded strain hardening at low temperatures toward saturation behavior at higher temperatures, consistent with many observations. Thermo-mechanical finite-element simulations using the H/V model confirmed its accuracy and the magnitude of the role on shear fracture. Failure types were predicted, as well as quantitative. For most of the DP steels tested, heating induced by deformation was identified as the dominant effect in producing unpredicted fractures. This is a result of standard industrial techniques that do not take non-isothermal effect into account, in particular constructing forming limit diagrams from low-speed / isothermal testing, and use of isothermal finite element modeling to analyze industrial sheet forming operations. Microstructural damage can also contribute to shear fracture, but it was a secondary factor for all but one of the alloys tested, in one test direction.
Download or read book Dynamic Behavior of Materials written by Mikko Hokka and published by Elsevier. This book was released on 2023-11-21 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic Behavior of Materials: Fundamentals, Material Models, and Microstructure Effects provides readers with the essential knowledge and tools necessary to determine best practice design, modeling, simulation and application strategies for a variety of materials while also covering the fundamentals of how material properties and behavior are affected by material structure and high strain rates. The book examines the relationships between material microstructure and consequent mechanical properties, enabling the development of materials with improved performance and more effective design of parts and components for high-rate applications. Sections cover the fundamentals of dynamic material behavior, with chapters studying dynamic elasticity and wave propagation, dynamic plasticity of crystalline materials, ductile fracture, brittle fracture, adiabatic heating and strain localization, response to shock loading, various material characterization methods, such as the Hopkinson Bar Technique, the Taylor Impact Experiment, different shock loading experiments, recent advances in dynamic material behavior, the dynamic behaviors of nanocrystalline materials, bulk metallic glasses, additively manufactured materials, ceramics, concrete and concrete-reinforced materials, geomaterials, polymers, composites, and biomaterials, and much more. - Focuses on the relationship between material microstructure and resulting mechanical responses - Covers the fundamentals, characterization methods, modeling techniques, applications and recent advances of the dynamic behavior of a broad array of materials - Includes insights into manufacturing and processing techniques that enable more effective material design and application
Download or read book Effects of Strain Rate on the Mechanical Properties and Fracture Characteristics of a Dual Phase 980 Steel written by Sukanya Sharma and published by . This book was released on 2019 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dual phase (DP) steels are being increasingly used as structural components in the automotive industry owing to their combination of high strength and moderate ductility.Formability and crash resistance are important mechanical properties that expose the steel to high strain rates.Fracture characteristics of a DP steel at strain rates spanning seven orders of magnitude are investigated using quantitative fractography.The DP steel investigated in this study is comprised of a continuous matrix of martensite with interspersed ferrite islands.The data reveal that the flow stress, uniform strain, and ductility are substantially higher at the higher strain rates.Quantitative fractography, employed to understand the fracture characteristics, shows an increase in the extent of ductile fracture at high strain rates.In this presentation, the results demonstrating high strain rates facilitating dimpled ductile fracture and/or increased resistance to faceted fracture are discussed.
Download or read book Design of an Experimental Program to Assess the Dynamic Fracture Properties of a Dual Phase Automotive Steel written by Sarath Chandran and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Thermo mechanical and Thermal Treatments on the Structure property Relationships of Dual Phase DP and Transformation induced Plasticity TRIP Steels written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigation of thermo-mechanical and thermal treatments on the microstructure and mechanical behavior of DP590 and TRIP680 steels revealed several critical aspects of the materials' responses to different testing. Various thermo-mechanical treatments were carried out to identify the responses to the said treatments. Following these preconditioning protocols, quasi-static, and high strain-rate tests showed how the materials reacted under tensile testing to fracture. Ensuing heat treatments on the as-received materials were performed to bring about phase fraction changes to each of the steels. These heat-treated DP and TRIP steels were examined to discover microstructural characteristics and mechanical responses through quasi-static and high strain-rate testing. The responses of the steels were analyzed and compared to the as-received testing results to observe the significant changes of mechanical behavior that occurred.
Download or read book Ductile Damage Characterization in Dual Phase Steels Using X ray Tomography written by Caroline Landron and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of the current context of requiring ever more efficient grades of steels in terms of resistance to stress and to damage, the Dual-Phase steels (DP) present an acceptable strength/ductility compromise. It is nevertheless necessary to have a better understanding of the mechanisms leading to the fracture of such steels. Damage mechanisms were studied in this PhD using X-ray tomography. In-situ tensile tests were carried out on several grades of DP steel, a ferritic steel and a martensitic steel in order to characterize each step of ductile damage. Qualitative observations and quantitative data on the nucleation of damage, the void growth and the coalescence of cavities were collected during these tests. This quantitative data was then used for the development and/or the validation of damage models. A prediction of the kinetic of nucleation was proposed and the Huang's correction of the void growth model of Rice and Tracey accounting for the triaxiality was experimentally validated. For the first time, the step of void coalescence leading to fracture of materials was quantitatively characterized in an industrial material and coalescence criteria were locally applied on couples of neighboring cavities present in the studied specimen. The use of analytical models enabled a better understanding of the properties influencing the studied damage phenomena. The effect of the kinematic part of the strain hardening on void nucleation and void growth was notably emphasized and validated by performing complex loading tests.
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:
Download or read book Automotive Steels written by Radhakanta Rana and published by Woodhead Publishing. This book was released on 2016-11-26 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Automotive Steels: Design, Metallurgy, Processing and Applications explores the design, processing, metallurgy, and applications of automotive steels. While some sheet steels are produced routinely in high volume today, there have been significant advances in the use of steel in the automotive industry. This book presents these metallurgical and application aspects in a way that is not available in the current literature. The editors have assembled an international team of experts who discuss recent developments and future prospects for automotive steels, compiling essential reading for both academic and industrial metallurgists, automotive design engineers, and postgraduate students attending courses on the metallurgy of automotive materials. - Presents recent developments on the design, metallurgy, processing, and applications of automotive steels - Discusses automotive steels that are currently in the early stages of research, such as low-density and high modulus steels that are driving future development - Covers traditional steels, advanced high strength steels, elevated Mn steels and ferrous composite materials
Download or read book Technical Abstract Bulletin written by Defense Documentation Center (U.S.) and published by . This book was released on 1963 with total page 1032 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 14th International Conference on the Technology of Plasticity Current Trends in the Technology of Plasticity written by Katia Mocellin and published by Springer Nature. This book was released on 2023-09-19 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume highlights the latest advances, innovations, and applications in the field of metal forming, as presented by leading international researchers and engineers at the 14th International Conference on Technology of Plasticity (ICTP), held in Mandelieu-La Napoule, France on September 24-29, 2023. It covers a diverse range of topics such as manufacturing processes & equipment, materials behavior and characterization, microstructure design by forming, surfaces & interfaces, control & optimization, green / sustainable metal forming technologies, digitalization & AI in metal forming, multi-material processing, agile / flexible metal forming processes, forming of non-metallic materials, micro-forming and luxury applications. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster multidisciplinary collaboration among different specialists.
Download or read book Modelling of Plasticity and Fracture Behaviors of Dual phase Steel written by Yuliang Hou and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dual-phase (DP) steel has been developed by automotive industry for the purpose of weight reduction, improvement in safety performance and fuel efficiency. Usually, DP steel contains hard martensite islands embedded in a soft ferrite matrix. Synergy between these two phases with the inhomogeneous microstructure exhibits excellent mechanical properties. The mechanical properties (plasticity and damage behaviors) of DP steel are mostly derived from its microstructure, e.g., volume fraction, size, distribution and morphology of each constituent phase. Micromechanical approaches are vastly applied to predict plasticity and other mechanical properties of DP steel under various loading scenarios. In this work, micromechanical modelling of DP steel has been performed using real or artificial microstructures. A real microstructure is obtained from metallographic image, while an artificial microstructure generator with an enhanced phase assignment algorithm based on material topology optimization is proposed to investigate the mechanical properties. In this artificial generator, phase assignment process is performed on a modified Voronoï tessellation to achieve the tailored representative volume element (RVE) with a good convergence. The proposed method also includes a proper orthogonal decomposition (POD) reduction of flow curves (snapshots), which are computed using the asymptotic extension homogenization (AEH) scheme, to identify the optimal controlling parameters for DP steel. This numerical method is verified using DP590 and DP980 steels that indicate a good agreement with the flow stress from measurements and RVE prediction based on real microstructures. Predictions of plastic strain patterns including shear bands using the artificial microstructure closely resemble the actual mechanical behavior under similar loading conditions. Moreover, an interpolation has been adopted to obtain a correlation between these controlling parameters based on the identification for various DP steels. Additionally, a bi-level reduced surrogate model is developed and presented to identify the material parameters of the Mohr-Coulomb (MMC) fracture criterion. Using this method, the identification process becomes feasible with a limited number of experimental tests. The method combines local critical elements associated with global models. The surrogate model of fracture strain constructed using the diffuse approximation and the local elements, reduced the computational cost for searching material parameters. Global fracture simulations are performed to update the target fracture strain and to compute the corresponding failure onset displacement. Convincing results are obtained via successive application of design of experiment (DOE) and enhanced design space transformation algorithms. The proposed identification protocol is validated with DP590 steel. Robustness of the method is confirmed with different initial values. These numerical investigations provide new direction for multiscale simulations of the plasticity and damage behaviors of DP steel. Moreover, they efficiently contribute to bridge the gap between scientific research and engineering application of heterogeneous materials.
Download or read book Damage in Dual Phase Steels written by Emon Erkan Asik and published by . This book was released on 2019 with total page 150 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:
Download or read book NBS Special Publication written by and published by . This book was released on 1968 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2566 pages. Available in PDF, EPUB and Kindle. Book excerpt:
