Development Of Simplified Models For Crashworthiness Analysis

Simplified modeling generates a great deal of interest in the area of crashworthiness analysis. Modeling methods used to create simplified computer models for crashworthiness have been well developed. In advanced simplified models, researchers develop simplified elements that can correctly predict structure's crash behavior based on the existing collapse theories. These developed simplified elements then are applied to develop the simplified models. Nevertheless, most of the exiting collapse theories are regarding the thin-walled box section beams. However, in addition to the box section member, the channel section member is another popular member and is widely used in engineering for architectural structures, vehicles, and etc. Therefore, to simplify the thin-walled channel section beams, new collapse theory is required to predict the crash behavior for such beams. This topic is the focus of this dissertation. This dissertation develops a mathematical model to predict the crash behavior of the thin-walled channel section beams based on their real collapse mechanisms. The derived math formulae are verified through several basic applications. After that, both the existing collapse theories and the developed collapse theory regarding the thin-walled channel section beams are applied to simplify the detailed truck chassis model. The developed simplified model is used for crashworthiness analysis and the results are compared to those from the detailed model. The developed theory and the modeling method are then validated through the comparison. Additionally, in developing the simplified truck chassis model, the cross members that were modeled using coarse shell elements in previous simplified models are remodeled using simple elements. Two of the simplified modeling methods, the superelement method and the equivalent beam method, are utilized to generate the simplified models for the cross members of the truck chassis model. The principle of both methods is to use simple elements to transfer the original members' mass and stiffness matrices. The equivalent beam method is recommended after comparison of the results of the crashworthiness analyses of each method. The primary contributions of this work are first, the derivation of crash theory that can predict the crash behavior of thin-walled channel section beams. The second is the use of equivalent beams to simplify the cross members within truck chassis models. Finally, a simplified modeling methodology is presented and evaluated. All the theory and modeling method developed in this work are applied for creating simplified models. Both the simplified and detailed models are used for crashworthiness analyses, results show that the errors caused by the simplified models are fewer than 10% and the simplified models only take less than 10% of the computer time of the corresponding detailed models.

This book studies the crash response of thin-walled beams with different cross sections. Two collapse behaviors are studied in this book, the axial collapse and the bending collapse. Mathematical equations are derived to predict and describe the thin-walled beams' collapse mechanisms. Based on the present collapse theories, simplified finite element (FE) models and modeling methodologies are developed for different types of thin-walled beams. The developed models are validated through crashworthiness analysis and the results agree very well to those obtained from the detailed FE models. As demonstrated in this book, compared to the detailed models, the developed simplified models have reduced size and consist of less number of elements thereby can save much more modeling labors and computing time. Such advantages make the simplified models most suitable for computer simulation and product design. For an example, the simplified models and modeling methods presented in this book can be applied in optimum design of the thin-walled beams.

Advances in Computational Algorithms and Data Analysis offers state of the art tremendous advances in computational algorithms and data analysis. The selected articles are representative in these subjects sitting on the top-end-high technologies. The volume serves as an excellent reference work for researchers and graduate students working on computational algorithms and data analysis.

In this research, two types of smart front-end structure are proposed to improve vehicle crashworthiness. The first type consists of two non-extendable hydraulic cylinders parallel to the longitudinal members. The second type consists of two extendable hydraulic cylinders integrated with the front-end structure. The literature review shows that little has been done for the development of simplified models for automotive crash problems in general, and smart front-end structures in particular. The development of such models is desirable for use in the initial concept design stage of automotive structures. The work carried out in this research includes developing and analyzing mathematical models of vehicle-to-vehicle and vehicle-to-barrier in different frontal collision events. In these models, vehicle components are modeled by lumped masses and nonlinear springs. Moreover, the hydraulic cylinders are represented by nonlinear dampers elements. Two types of nonlinearity forms, piecewise and cubic, are used to define the characteristics of both nonlinear springs and dampers. In this research, the dynamic responses of the crash events are obtained with the aid of analytical and numerical approaches. Moreover, the intrusion injury and occupant deceleration are used for interpreting the results. It is demonstrated from simulation results that significant improvements to both intrusion and deceleration injuries are obtained using the smart front-end structures. Furthermore, the vehicle compatibility and the crash severity have been significantly minimized.

Developments in the Analysis and Design of Marine Structures is a collection of papers presented at MARSTRUCT 2021, the 8th International Conference on Marine Structures (by remote transmission, 7-9 June 2021, organised by the Department of Marine Technology of the Norwegian University of Science and Technology, Trondheim, Norway), and is essential reading for academics, engineers and professionals involved in the design of marine and offshore structures. The MARSTRUCT Conference series deals with Ship and Offshore Structures, addressing topics in the fields of: - Methods and Tools for Loads and Load Effects; - Methods and Tools for Strength Assessment; - Experimental Analysis of Structures; - Materials and Fabrication of Structures; - Methods and Tools for Structural Design and Optimisation; and - Structural Reliability, Safety and Environmental Protection. The MARSTRUCT conferences series of started in Glasgow, UK in 2007, the second event of the series took place in Lisbon, Portugal in March 2009, the third in Hamburg, Germany in March 2011, the fourth in Espoo, Finland in March 2013, the fifth in Southampton, UK in March 2015, the sixth in Lisbon, Portugal in May 2017, and the seventh in Drubovnik, Croatia in May 2019. The ‘Proceedings in Marine Technology and Ocean Engineering’ series is dedicated to the publication of proceedings of peer-reviewed international conferences dealing with various aspects of ‘Marine Technology and Ocean Engineering’. The Series includes the proceedings of the following conferences: the International Maritime Association of the Mediterranean (IMAM) conferences, the Marine Structures (MARSTRUCT) conferences, the Renewable Energies Offshore (RENEW) conferences and the Maritime Technology (MARTECH) conferences. The ‘Marine Technology and Ocean Engineering’ series is also open to new conferences that cover topics on the sustainable exploration and exploitation of marine resources in various fields, such as maritime transport and ports, usage of the ocean including coastal areas, nautical activities, the exploration and exploitation of mineral resources, the protection of the marine environment and its resources, and risk analysis, safety and reliability. The aim of the series is to stimulate advanced education and training through the wide dissemination of the results of scientific research.

As part of an electric vehicle consortium, LLNL and Kaiser Aluminum are conducting experimental and numerical studies on crashworthy aluminum spaceframe designs. They have jointly explored the effect of heat treat on crush behavior and duplicated the experimental behavior with finite-element simulations. The major technical contributions to the state of the art in numerical simulation arise from the development and use of advanced material model descriptions for LLNL's DYNA3D code. Constitutive model enhancements in both flow and failure have been employed for conventional materials such as low-carbon steels, and also for lighter weight materials such as aluminum and fiber composites being considered for future vehicles. The constitutive model enhancements are developed as extensions from LLNL's work in anisotropic flow and multiaxial failure modeling. Analysis quality as a function of level of simplification of material behavior and mesh is explored, as well as the penalty in computation cost that must be paid for using more complex models and meshes. The lightweight material modeling technology is being used at the vehicle component level to explore the safety implications of small neighborhood electric vehicles manufactured almost exclusively from these materials.

Among all the fields in solid mechanics the methodologies associated to multibody dynamics are probably those that provide a better framework to aggregate different disciplines. This idea is clearly reflected in the multidisciplinary applications in biomechanics that use multibody dynamics to describe the motion of the biological entities, or in finite elements where the multibody dynamics provides powerful tools to describe large motion and kinematic restrictions between system components, or in system control for which multibody dynamics are the prime form of describing the systems under analysis, or even in applications with fluid-structures interaction or aeroelasticity. This book contains revised and enlarged versions of selected communications presented at the ECCOMAS Thematic Conference in Multibody Dynamics 2003 that took place in Lisbon, Portugal, which have been enhanced in their self-containment and tutorial aspects by the authors. The result is a comprehensive text that constitutes a valuable reference for researchers and design engineers and helps to appraise the potential of application of multibody dynamics to a wide range of scientific and engineering areas of relevance.