The objective of this research is to simulate crashworthiness for Out-of-Position (OOP) occupants incorporating a 50th percentile Hybrid III dummy and a side curtain airbag in a 1996 Dodge Neon under side impact scenarios. Two different methods of airbag techniques namely, the uniform pressure (UP) and the smooth particle hydrodynamics (SPH) were compared. This study revealed that there is minimal difference between UP and SPH methods when the dummy’s head impacts the airbag after it has fully inflated. However, when the dummy’s head impacts the airbag during the inflation process, the modeling of the airbag gas dynamics becomes critical in predicting the dummy response. The SPH method, which models the gas dynamics in the airbag, causes the airbag to unroll more uniformly. Depending on the timing of the dummy’s head impact with the airbag these differences in inflation can produce significant differences in dummy head accelerations.

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Finite element analysis with explicit time integration is widely used in commercial crash solvers to accurately simulate transient structural problems involving large-deformation and nonlinearity. Technological advances in computer software and hardware have expanded the boundaries of computational expense, allowing designers to analyse increasingly complex structures on desktop computers. This dissertation is a review of the use of finite element analysis for crash simulation, the principles of crashworthy design and a practical application of these methods and principles in the development of a concept energy absorber for a sailplane. Explicit nonlinear finite element analysis was used to do crash simulations of the glass, carbon and aramid fibre cockpit during the development of concept absorbers. The SOL700 solution sequence in MSC Nastran, which invokes the LS-Dyna solver for structural solution, was used. Single finite elements with Hughes-Liu shell formulation were loaded to failure in pure tension and compression and validated against material properties. Further, a simple composite crash box in a mass drop experiment was simulated and compared to experimental results. FEA was used for various crash simulations of the JS1 sailplane cockpit to determine its crashworthiness. Then, variants of a concept energy absorber with cellular aluminium sandwich construction were simulated. Two more variants constructed only of fibre-laminate materials were modelled for comparison. Energy absorption and specific energy absorption were analysed over the first 515 mm of crushing. Simulation results indicate that the existing JS1 cockpit is able to absorb energy through progressive crushing of the frontal structure without collapse of the main cockpit volume. Simulated energy absorption over the first 515 mm was improved from 2232 J for the existing structure, to 9 363 J by the addition of an energy absorber. Specific energy absorption during the simulation was increased from 1063 J/kg to 2035 J/kg. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

Finite element analysis with explicit time integration is widely used in commercial crash solvers to accurately simulate transient structural problems involving large-deformation and nonlinearity. Technological advances in computer software and hardware have expanded the boundaries of computational expense, allowing designers to analyse increasingly complex structures on desktop computers. This dissertation is a review of the use of finite element analysis for crash simulation, the principles of crashworthy design and a practical application of these methods and principles in the development of a concept energy absorber for a sailplane. Explicit nonlinear finite element analysis was used to do crash simulations of the glass, carbon and aramid fibre cockpit during the development of concept absorbers. The SOL700 solution sequence in MSC Nastran, which invokes the LS-Dyna solver for structural solution, was used. Single finite elements with Hughes-Liu shell formulation were loaded to failure in pure tension and compression and validated against material properties. Further, a simple composite crash box in a mass drop experiment was simulated and compared to experimental results. FEA was used for various crash simulations of the JS1 sailplane cockpit to determine its crashworthiness. Then, variants of a concept energy absorber with cellular aluminium sandwich construction were simulated. Two more variants constructed only of fibre-laminate materials were modelled for comparison. Energy absorption and specific energy absorption were analysed over the first 515 mm of crushing. Simulation results indicate that the existing JS1 cockpit is able to absorb energy through progressive crushing of the frontal structure without collapse of the main cockpit volume. Simulated energy absorption over the first 515 mm was improved from 2232 J for the existing structure, to 9 363 J by the addition of an energy absorber. Specific energy absorption during the simulation was increased from 1063 J/kg to 2035 J/kg. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

<div>Thin walled structures find wide applications in automotive industry as energy absorption devices. A great deal of research has been conducted to design thin walled structures, where the main objective is to reduce peak crushing forces and increase energy absorption capacity. With the advancement of computers and mathematics, it has been possible to develop 2D patterns which when folded turn into complex 3D structures. This technology can be used to develop patterns for getting structures with desired properties. </div><div>In this study, square origami tubes with folding pattern (Yoshimura pattern) is designed and studied extensively using numerical analysis. An accurate Finite Element Model (FEM) is developed to conduct the numerical analysis. A parametric study was conducted to study the influence of geometric parameters on the mechanical properties like peak crushing force, mean crushing force, load uniformity and maximum intrusion, when subjected to dynamic loading. </div><div>The results from this analysis are studied and various conclusions are drawn. It is found that, when the tube is folded with the pattern having specific dimension, the performance is enhanced significantly, with predictable and stable collapse. It is also found that the stiffness of the module varies with geometrical parameters. With a proper study it is possible to develop origami structures with functionally graded stiffness, the performance of which can be tuned as per requirement, hence, showing promising capabilities as an energy absorption device where progressive collapse from near to end impact end is desired.</div><div><br></div>

There is no international regulation for the frontal collision of the buses, protecting their occupants and partners in traffic. There are some regulation such as ECE R-80 which deals with strength of seat structure of the coaches and their anchorages strength. There is increasing need to focus issues like occupant protection and full scale crash testing regulation for buses. This thesis attempts to collect possible subjects required for international regulation required for crashworthiness of transit buses. This research attempts to develop and validate a model of transit bus for all three impact conditions. The full finite element model is developed with help hypermesh software and its validation and analysis is done with help Ls-Dyna nonlinear finite element solver. The cost of actual testing and secrecy maintained by manufacturers make research process difficult and increase the importance of computer simulations. To boost the research of crash worthiness of transit need for computer model is felt. This thesis examines several frontal crash test procedures and evaluates how well each procedure meets the objective. This validated model is used to analyze various real world impact scenarios and its analysis with European and federal regulation. This validated model is used to extract crash pulses of various impact scenarios at the center of gravity of the bus. These extracted crash pulses are applied to the madymo model to estimate the injuries to occupants of the bus. This thesis discusses the design aspects of bus frontal impact behavior as one of the main subjects of bus crashworthiness and results of previous full scale tests comparing the Fem simulation results carried out on the transit bus. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering / "December 2006."

Mitigating injury in side impact has been an important topic of research for decades. In the mid 1980’s the American government began a program intended to improve the crashworthiness of vehicles in side impact. This program ultimately led to the introduction of a dynamic side impact test (Federal Motor Vehicle Safety Standard (FMVSS) 214), which new vehicles must pass, along with a very similar test aimed at consumer awareness (New Car Assessment Program (NCAP) side impact test). The work presented in this thesis involved the study and simulation of these tests to evaluate occupant response in side impact, with a focus on the thoracic response. In the first portion of the work presented here, an in-depth study of the National Highway Traffic Safety Administration (NHTSA) crash test database was performed. In this study the results of the side impact crash tests of 72 vehicles were examined to understand the general trends seen in this type of testing with regards to vehicle velocity, side intrusion, and occupant injury prediction. A series of average velocity profile curves was created from accelerometer data at 18 measurement points on each vehicle crash tested. Additionally the injury criterion measured by the front seat occupant was plotted against several vehicle variables (such as mass and occupant arm to door distance) to study the effect these variable had on the injury predicted by the occupant. No single variable was shown to have a strong correlation to injury, although increasing door intrusion distance, peak lateral velocity, the Head Injury Criterion (HIC), and pelvic acceleration were found to positively correlate to thoracic injury. In addition, increasing vehicle model year, vehicle mass, and arm to door (AD) distance showed negative correlations with thoracic injury. Following the survey of the NHTSA database, a finite element model of the NHTSA side impact test was developed. This model included a full scale Ford Taurus model, a NHTSA barrier model and three side impact anthropometric test device (ATD) occupant models, each representing a different 50th percentile male dummy. Validation of this model was carried out by comparing the simulated vehicle component velocity results to the corridors developed in the NHSTA crash test database study as well as comparing these velocities, the vehicle deformation profile, and the occupant velocity, acceleration and rib deflection to several Ford Taurus crash tests from a similar vintage to the finite element model. As this model was intended as a ‘baseline’ case to study side impact and occupant kinematics in side impact, side airbags were not included in this model. A lack of experimental data and a lack of consensuses within the automotive crash community on the proper method of modeling these devices and their effectiveness in real world impacts also led to their exclusion. Following model validation, a parametric study was carried out to assess the importance of the initial position of the occupant on the vehicle door velocity profile and the predicted occupant injury response. Additionally the effect of the door trim material properties, arm rest properties and the effect of seat belt use were studied. It was found that the lateral position of the occupant had an effect on the door velocity profile, while the vertical and longitudinal position did not. The use of seatbelts was shown to have no significant effect in these simulations, due to minimal interaction between the restraint system and occupant during side impact. Furthermore, there was a general decreasing trend in the injury predicted as the initial position of the occupant was moved further inboard, down and forward in the vehicle. Stiffer interior trim was found to improve the injury prediction of the occupant, while changing the material of the foam door inserts had no effect. It was found that in general the occupant remained in position, due to the inertia of the occupant, while the seat began moving towards the centerline of the vehicle. Future considerations could include more advanced restraint systems to couple the occupant more effectively to the seat, or to develop side interior trim that engages the occupant earlier to reduce the relative velocity between the occupant and intruding door. Overall, the model correlated well with experimental data and provided insight into several areas which could lead to improved occupant protection in side impact. Future work should include integrating side airbags into the model, widening the focus of the areas of injury to include other body regions and integrating more detailed human body models.

Lighter structural and energy absorbing materials are essential to increase fuel efficiency in transportation systems and have provided a motivation to investigate the use of new joining techniques based on the use of high strength and high tenacity adhesives. Current joining techniques, such as spot-welding, limit the possible weight reduction that can be achieved if lighter sections, dissimilar materials and/or novel geometries were to be used. Adhesive materials can address many limitations of current joining techniques. To take advantage of the available numerical codes for the simulation of bonded structures during dynamic crash events, a constitutive model for structural adhesive material using cohesive elements was assembled from the measured properties of two structural adhesives; DP-460NS and EC-2214 (3M, Canada). To verify that the proposed cohesive model accurately describes the behavior of the materials a two stage approach was used. First, a cohesive element formulation of the adhesive material was implemented to investigate a Double Cantilever Beam (DCB) (ASTM test D3433-99). The results of the simulation were compared against available experimental data. Second, using sub-size crush tube structures assembled from steel sections that were adhesively bonded, quasi-static and impact events were performed. The results from the experiment were compared against the numerical simulation of the same structure using cohesive elements to describe the adhesive joint. Later, Tie-Breaks were implemented to reduce computational times. Both types of elements successfully represented the adhesive joint and the numerical model of the crush tube was in good agreement with the overall load-displacement behavior of the experimental crush tubes. The use and testing of sub-size structures not only permitted the validation of the numerical models; it also investigated the feasibility of adhesive-only joints in automotive structures that may be exposed to crash scenarios. Sub-sized tubes were used due to equipment capacity limits, but an analysis was undertaken to demonstrate appropriate structural scaling. Even though the results between the experiments and the simulations were in very good agreement, it is clear that current cohesive material models and Tie-Breaks cannot incorporate strain rate effects, which may be important under dynamic impact conditions. Although testing in the literature has reported that the mechanical properties of the bond are affected by the properties of the joined materials as well as the geometry of the joint, these effects in the case of crush tube structures seem perhaps negligible in view of the simulation results.

Mitigating injury in side impact has been an important topic of research for decades. In the mid 1980’s the American government began a program intended to improve the crashworthiness of vehicles in side impact. This program ultimately led to the introduction of a dynamic side impact test (Federal Motor Vehicle Safety Standard (FMVSS) 214), which new vehicles must pass, along with a very similar test aimed at consumer awareness (New Car Assessment Program (NCAP) side impact test). The work presented in this thesis involved the study and simulation of these tests to evaluate occupant response in side impact, with a focus on the thoracic response. In the first portion of the work presented here, an in-depth study of the National Highway Traffic Safety Administration (NHTSA) crash test database was performed. In this study the results of the side impact crash tests of 72 vehicles were examined to understand the general trends seen in this type of testing with regards to vehicle velocity, side intrusion, and occupant injury prediction. A series of average velocity profile curves was created from accelerometer data at 18 measurement points on each vehicle crash tested. Additionally the injury criterion measured by the front seat occupant was plotted against several vehicle variables (such as mass and occupant arm to door distance) to study the effect these variable had on the injury predicted by the occupant. No single variable was shown to have a strong correlation to injury, although increasing door intrusion distance, peak lateral velocity, the Head Injury Criterion (HIC), and pelvic acceleration were found to positively correlate to thoracic injury. In addition, increasing vehicle model year, vehicle mass, and arm to door (AD) distance showed negative correlations with thoracic injury. Following the survey of the NHTSA database, a finite element model of the NHTSA side impact test was developed. This model included a full scale Ford Taurus model, a NHTSA barrier model and three side impact anthropometric test device (ATD) occupant models, each representing a different 50th percentile male dummy. Validation of this model was carried out by comparing the simulated vehicle component velocity results to the corridors developed in the NHSTA crash test database study as well as comparing these velocities, the vehicle deformation profile, and the occupant velocity, acceleration and rib deflection to several Ford Taurus crash tests from a similar vintage to the finite element model. As this model was intended as a ‘baseline’ case to study side impact and occupant kinematics in side impact, side airbags were not included in this model. A lack of experimental data and a lack of consensuses within the automotive crash community on the proper method of modeling these devices and their effectiveness in real world impacts also led to their exclusion. Following model validation, a parametric study was carried out to assess the importance of the initial position of the occupant on the vehicle door velocity profile and the predicted occupant injury response. Additionally the effect of the door trim material properties, arm rest properties and the effect of seat belt use were studied. It was found that the lateral position of the occupant had an effect on the door velocity profile, while the vertical and longitudinal position did not. The use of seatbelts was shown to have no significant effect in these simulations, due to minimal interaction between the restraint system and occupant during side impact. Furthermore, there was a general decreasing trend in the injury predicted as the initial position of the occupant was moved further inboard, down and forward in the vehicle. Stiffer interior trim was found to improve the injury prediction of the occupant, while changing the material of the foam door inserts had no effect. It was found that in general the occupant remained in position, due to the inertia of the occupant, while the seat began moving towards the centerline of the vehicle. Future considerations could include more advanced restraint systems to couple the occupant more effectively to the seat, or to develop side interior trim that engages the occupant earlier to reduce the relative velocity between the occupant and intruding door. Overall, the model correlated well with experimental data and provided insight into several areas which could lead to improved occupant protection in side impact. Future work should include integrating side airbags into the model, widening the focus of the areas of injury to include other body regions and integrating more detailed human body models.