Experimental And Numerical Investigation Of Crash Structures Using Aluminum Alloys

Lightweight Composite Structures in Transport: Design, Manufacturing, Analysis and Performance provides a detailed review of lightweight composite materials and structures and discusses their use in the transport industry, specifically surface and air transport. The book covers materials selection, the properties and performance of materials, and structures, design solutions, and manufacturing techniques. A broad range of different material classes is reviewed with emphasis on advanced materials. Chapters in the first two parts of the book consider the lightweight philosophy and current developments in manufacturing techniques for lightweight composite structures in the transport industry, with subsequent chapters in parts three to five discussing structural optimization and analysis, properties, and performance of lightweight composite structures, durability, damage tolerance and structural integrity. Final chapters present case studies on lightweight composite design for transport structures. Comprehensively covers materials selection, design solutions, manufacturing techniques, structural analysis, and performance of lightweight composite structures in the transport industry Includes commentary from leading industrial and academic experts in the field who present cutting-edge research on advanced lightweight materials for the transport industry Includes case studies on lightweight composite design for transport structures

In an increasingly globalised world, despite reductions in costs and time, transportation has become even more important as a facilitator of economic and human interaction; this is reflected in technical advances in transportation systems, increasing interest in how transportation interacts with society and the need to provide novel approaches to understanding its impacts. This has become particularly acute with the impact that Covid-19 has had on transportation across the world, at local, national and international levels. Encyclopedia of Transportation, Seven Volume Set - containing almost 600 articles - brings a cross-cutting and integrated approach to all aspects of transportation from a variety of interdisciplinary fields including engineering, operations research, economics, geography and sociology in order to understand the changes taking place. Emphasising the interaction between these different aspects of research, it offers new solutions to modern-day problems related to transportation. Each of its nine sections is based around familiar themes, but brings together the views of experts from different disciplinary perspectives. Each section is edited by a subject expert who has commissioned articles from a range of authors representing different disciplines, different parts of the world and different social perspectives. The nine sections are structured around the following themes: Transport Modes; Freight Transport and Logistics; Transport Safety and Security; Transport Economics; Traffic Management; Transport Modelling and Data Management; Transport Policy and Planning; Transport Psychology; Sustainability and Health Issues in Transportation. Some articles provide a technical introduction to a topic whilst others provide a bridge between topics or a more future-oriented view of new research areas or challenges. The end result is a reference work that offers researchers and practitioners new approaches, new ways of thinking and novel solutions to problems. All-encompassing and expertly authored, this outstanding reference work will be essential reading for all students and researchers interested in transportation and its global impact in what is a very uncertain world. Provides a forward looking and integrated approach to transportation Updated with future technological impacts, such as self-driving vehicles, cyber-physical systems and big data analytics Includes comprehensive coverage Presents a worldwide approach, including sets of comparative studies and applications

There exists considerable motivation to reduce vehicle weight through the adoption of lightweight materials, such as aluminum alloys, while maintaining energy absorption and component integrity under crash conditions. To this end, it is of particular interest to study the crash behaviour of lightweight tubular hydroformed structures to determine how the forming behaviour affects the axial crush response. Thus, the current research has studied the dynamic crush response of both non-hydroformed and hydroformed EN-AW 5018 and AA5754 aluminum alloy tubes using both experimental and numerical methods. Experiments were performed in which hydroforming process parameters were varied in a parametric fashion after which the crash response was measured. Experimental parameters included the tube thickness and the hydroformed corner radii of the tubes. Explicit dynamic finite element simulations of the hydroforming and crash events were carried out with particular attention to the transfer of forming history from the hydroforming simulations to the crash models. The results showed that increases in the strength of the material due to work hardening during hydroforming were beneficial in increasing energy absorption during crash. However, it was shown that thinning in the corners of the tube during hydroforming decreased the energy absorption capabilities during axial crush. Residual stresses resulting from hydroforming had little effect on the energy absorption characteristics during axial crush. The current research has shown that, in addition to capturing the forming history in the crash models, it is also important to account for effects of material non-linearity such as kinematic hardening, anisotropy, and strain-rate effects in the finite element models. A model combining a non-linear kinematic hardening model, the Johnson-Cook rate sensitive model, and the Yld2000-2d anisotropic model was developed and implemented in the finite element simulations. This combined model did not account for the effect of rotational hardening (plastic spin) due to plastic deformation. It is recommended that a combined constitutive model, such as the one described in this research, be utilized for the finite element study of materials that show sensitivity to the Bauschinger effect, strain-rate effects, and anisotropy.

The use of aluminum alloys for light-weighting purposes in energy absorbing components of automobiles is hindered by the relatively low ductility and more complicated constitutive behavior of these alloys. This study presents results from series of quasi-static and dynamic axial crushing experiments on extruded Al-6061-T6 circular tubes of varying D/t ratios. A custom drop-weight testing facility was used to perform the dynamic experiments. Crushing led to axisymmetric, mode-2, and mode-3 concertina folding. In the quasi-static experiments, the folding was monitored using time-lapse photography; dynamic crushing was monitored using high-speed photography. The crushing responses and energy absorption capacities are evaluated and failures were recorded. Failure was observed in most of the experiments with the severity depending on the D/t and mode of folding. The experiments are simulated with three-dimensional, nonlinear finite element analysis using the von Mises, the non-quadratic Hosford, and the calibrated anisotropic Yld04-3D models. The Yld04-3D model was found to most accurately reproduce the structural response under both quasi-static and dynamic loadings. This model was used to the monitor the strains induced in two example cases: axisymmetric folding under quasi-static loading, and mode-2 folding under dynamic loading. The analysis predicted maximum strains to develop at locations on the model tube where failure is observed on the specimen in the experiments. It is concluded that the Yld04-3D constitutive model is most suitable for the prediction of the structural response and failure in tube crushing of this aluminum alloy

Biocomposites for Industrial Applications: Construction, Biomedical, Transportation and Food Packaging reviews the properties and performance of these materials, with a focus on their intended applications. Sections cover their properties and performance, including processing conditions, structure and property relations. For biomedical applications, researchers need a broad understanding of conceptual design, physico-chemical properties, and cytotoxicity (orthopedic implants). As the usage of biocomposites has increased significantly over recent years, mainly due to the advantages these materials have when compared to synthetic composites, such as (i) renewability (ii) eco-friendly components, (iii) biodegradable aspects, and (iv) non-toxicity, this book provides a great update on the technology. These advantages will help to attract wider use in more lightweight-based applications such as (i) construction and building (ii) biomedical (iii) transportation (automotive, marine, and aerospace), and (iv) in food packaging. Covers recent applications in construction, transportation, food packaging and biomedical sectors Focuses on materials requirements, factors governing the properties of these materials and durability Discusses factors effecting processing conditions and recent advancements in design and fabrication Provides a detailed outline of experimental research in each chapter

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.

In a broad sense, the work described herein addresses either extreme of a traditional da/dN vs. dK plot. The first chapter addresses the uppermost limit of such plot, where tearing represents the limit state of structural failure. Subsequent chapters address the lower limit, where emphasis is placed on nucleation and early propagation of microstructurally small fatigue cracks (MSFCs). A common theme throughout the dissertation is the development of new tools and techniques (be they experimental or numerical) to enable unprecedented interrogation of crack evolution in 3D, with applications to various aluminum-alloy structures. Each chapter represents a separate body of work providing novel contributions in one or more areas involving fracture mechanics (viz. structural prognosis, corrosion science and engineering, and materials characterization). A brief overview of each chapter is described next. In Chapter 1, a methodology is described for predicting in real time the residual strength of structures with discrete-source damage. An artificial neural network (ANN) is trained using linear-elastic fracture mechanics (LEFM)-based data from numerical models; the ANN predicts residual strength given a set of damage parameters. Section 1.3 focuses on augmenting the existing LEFMbased modeling toolset to simulate ductile tearing and thereby improve resid- ual strength values used to train an ANN. Validation results are presented for two ductile-tearing simulations. Chapters 2 through 4 focus on MSFC initiation and propagation in an Al-Mg-Si alloy used to line composite-overwrapped pressure vessels. Chapter 2 describes an experimental study regarding the effect of an alkaline-based chemical milling treatment used to dimensionally reduce the Al-Mg-Si pressure-vessel liners. 3-D scanning electron microscopy is employed to quantify surface pitting caused by the chemical-milling treatment. The 3-D surface characteristics, along with high-magnification fractographs, are used to explain the observed 50% reduction in low-cycle fatigue lives among the chemically-milled specimens compared to a control group. In Chapter 3, an experimental methodology based on post-mortem measurements is developed to quantify 3-D rates of propagation and crack-surface crystallography for a naturally nucleated MSFC in an Al-Mg-Si specimen. The measurements are made possible through recent developments in 3-D characterization methods. Findings from the study demonstrate: 1) the complexity and variability of 3-D MSFC evolution in the Al-Mg-Si alloy and 2) the viability of the post-mortem characterization approach for quantifying 3-D MSFC evolution in polycrystalline alloys. The dissertation culminates with Chapter 4, which, for the first time, demonstrates the 3-D digital reconstruction and numerical simulation of a sequence of directly measured MSFCs, where both MSFC geometry and individual grain morphologies and orientations are explicitly represented at the polycrystalline length scale. The numerical reconstruction is demonstrated using 3-D measurements from Chapter 3. Work from Chapters 1 and 2 is published in [1, 2, 3, 4] and [5], respectively. The combined work from Chapters 3 and 4 is described in [6, 7, 8] and is currently in preparation for additional journal publication.

This dissertation, "Behaviour and Design of Aluminium Alloy Structural Elements" by Meini, Su, 蘇玫妮, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Aluminium alloys are nonlinear metallic materials with continuous stress-strain curves that are not well represented by the simplified elastic, perfectly plastic material model used in most existing design specifications. The aims of this study are to develop a more efficient design method for aluminium alloy structures by rationally exploiting strain hardening. The key components of this study include laboratory testing, numerical modelling and development of design guidance for aluminium alloy structures. As part of the present study, the experimental programme included tests on 11 stub columns, 40 simply supported beams, 46 continuous beams and corresponding tensile coupon tests. Numerical investigations of aluminium alloy simply supported beams and continuous beams were also conducted. The validated finite element models were used for extensive parametric studies, generating 96 results for beams under three-point bending, 96 under four-point bending and 210 for continuous beams. The experiments and numerical simulations have shown the following key features of the inelastic behaviour of aluminium alloy structural elements: (1) the significance of strain hardening, indicated by the ultimate stress over the yield stress, could be up to 50%; (2) non-slender section capacities could be generally up to 40% higher than the yield limits in compression, and 50% greater than the plastic moments in bending; (3) the experimental and numerical ultimate loads of continuous beams on non-slender sections go beyond the calculated loads corresponding to the occurrence of the first hinge by more than 10%. Previous experimental data on aluminium alloy stub columns and simply supported beams were also collected. These collected test data were used together with the newly generated experimental and numerical results obtained from this study, totalling about 900 data, to assess the design predictions of the American, Australian/New Zealand and European specifications. On average, the existing design methods under-estimated the capacity of aluminium alloy stub columns by around 15% 22%, simply supported beams by around 18% 40% and continuous beams by around 27% 50%. Existing section classification limits in Eurocode 9 (2007) were also assessed, and while they were found to be safe, some improved limits were proposed. The combined experimental and numerical results were used to develop and calibrate a new design method, termed the continuous strength method (CSM). Two key components of the CSM - a base curve and a bi-linear material model for aluminium alloys have been proposed in this study. Global plastic analysis allowing for moment redistribution has also been adopted in the CSM. Unlike current practices, the CSM has the merits of adopting the continuous treatment for the cross-section deformation response, rationally exploiting the available capacity beyond the yield limit and reasonably allowing for redistributing the internal forces. The capacity predictions of aluminium alloy structural members have been improved by more than 30% using the CSM. Reliability analyses have also been performed to assess the reliability level of different design methods according to the American Institute of Steel Construction (2010) and European Standard EN1990 (2002) approaches. The CSM has been shown to be safe, efficient and consistent for aluminium alloy structural members. DOI: 10.5353/th_b5328036 Subjects:

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.