Showing papers in "International Journal of Crashworthiness in 2004"
TL;DR: In this paper, a comprehensive approach for predicting failure in a component based on macroscopic strains and stresses is presented, which requires the use of a number of different failure mechanism representations, such as necking and local instabilities, as well as ductile and shear fracture.
Abstract: A correct representation of the plastic deformation and failure of individual component parts is essential to obtaining accurate crashworthiness simulation results The aim of this paper is to present a comprehensive approach for predicting failure in a component based on macroscopic strains and stresses This approach requires the use of a number of different failure mechanism representations, such as necking (due to local instabilities), as well as ductile and shear fracture All failure criteria have been developed in a way to include the influence of non-linear strain paths The effectiveness of this approach in predicting failure is then discussed by comparing numerical results with test data by three point bending and axial compression tests of double chamber extrusion components All studies presented in this paper were carried out on extrusions made from aluminium alloy EN AW-7108 T6
550 citations
TL;DR: The results indicate that, despite the fundamental differences between these six model formulations, the comparisons with the experimentally measured pressures and relative displacements were largely consistent and in good agreement and may prove useful for those attempting to model real life accident scenarios.
Abstract: In order to create a useful computational tool that will aid in the understanding and perhaps prevention of head injury, it is important to know the quantitative influence of the constitutive properties, geometry and model formulations of the intracranial contents upon the mechanics of a head impact event. The University College Dublin Brain Trauma Model (UCDBTM) [1] has been refined and validated against a series of cadaver tests and the influence of different model formulations has been investigated. In total six different model configurations were constructed: (i) the baseline model, (ii) a refined baseline model which explicitly differentiates between grey and white neural tissue, (iii) a model with three elements through the thickness of the cerebrospinal fluid (CSF) layer, (iv) a model simulating a sliding boundary, (v) a projection mesh model (which also distinguishes between neural tissue) and (vi) a morphed model. These models have been compared against cadaver tests of Trosseille [2] an...
216 citations
TL;DR: In this paper, a series of quasi-static and dynamic axial crushing tests have been performed on three materials: 304 stainless steel, aluminium alloy 6063-T6, and mild steel.
Abstract: Quasi-static and dynamic axial crushing tests have been performed on circular thin-walled sections made of three materials: 304 stainless steel, aluminium alloy 6063-T6, and mild steel. The tests were arranged to investigate the mode transitions during the impact crushing of thin-walled tubes and the three materials were chosen for their distinctive individual characteristics, such as strain rate sensitive properties, pronounced strain hardening, etc. The stainless steel, aluminium alloy and mild steel shells have moderate diameter-to-thickness ratios, 2R/H, of 22, 33 and 26, respectively, and were examined over a range of different axial lengths that encompassed both classical progressive buckling and the global bending modes of failure. The tests were conducted at a standardised energy of 9 kJ, approximately, with a few tests repeated at a higher energy of 18 kJ. The shells were impacted at velocities up to 13.4 m/s with masses up to 502 kg. Standard collapse modes developed in the tubes and the associated energy absorbing characteristics have been examined and compared with previous studies on mild steel. Quasi-static and dynamic tensile test results on the materials are also reported and the critical slenderness ratios at the transition between the two principal modes of failure are identified. The effects of strain hardening, strain rate as well as inertia effects due to the individual characteristics of the three materials are explored.
135 citations
TL;DR: In this paper, a quasi-static compressive testing of extruded aluminum alloy 6061-T4 and 6061 T6 square cross-sectional tubular specimens, with and without the presence of dual centrally located circular hole discontinuities, was completed to investigate the load management and energy absorption characteristics of these structural members.
Abstract: Quasi-static compressive testing of extruded aluminum alloy 6061-T4 and 6061-T6 square cross-sectional tubular specimens, with and without the presence of dual centrally located circular hole discontinuities, was completed to investigate the load management and energy absorption characteristics of these structural members. The tubular geometries selected (tube lengths of 200 mm and 300 mm, wall thickness of 3.15 mm, and nominal side width of 38.1 mm) had parameters which result in predicted global bending collapse under compressive loading. Centrally located circular holes, machined into the two opposing walls of the tubes, were used as crush initiators to commence the plastic buckling process. Holes with diameters of 7.1 mm and 14.2 mm were considered. In addition to progressive buckling, collapse modes involving cracking and splitting were observed in many tests and are characterized using photographs of the experimental process. The collapse modes and energy absorption of the crush test specimens were found to be dependent largely on material properties and to a lesser extent on the diameter of the discontinuity. Significant increases in the crush force efficiency, up to a maximum of approximately 22%, were observed for the shorter length tube geometry. However, the presence of the circular discontinuity within the AA6061 T4 300 mm tubes slightly degraded the crush force efficiency compared to the same length tubular member without any discontinuity. Energy absorption capabilities were substantially improved for all AA6061- T6 specimens containing a circular discontinuity relative to the specimens without any crush initiators. With the addition of the discontinuity, energy absorption was improved for the 200 mm length AA6061-T4 specimens but slightly decreased for the 300 mm length members.
76 citations
TL;DR: The goal of the current study was to perform dynamic bending experiments on legs and thighs from post mortem human surrogates and combine the failure data with that of previous applicable studies to perform an injury risk analysis.
Abstract: The goal of the current study was to perform dynamic bending experiments on legs and thighs from post mortem human surrogates (PMHS) and combine the failure data with that of previous applicable studies to perform an injury risk analysis. Four leg and 12 thigh specimens were loaded dynamically (∼1.5 m/s) in latero-medial 3-point bending. The four leg specimens and six of the thigh specimens were loaded at the mid-diaphysis and the other 6 thigh specimens were loaded at a third of the length from the distal end. Data from four other studies were used with data from the current study to develop injury risk functions for the human thigh loaded at the distal third (50% probability of femur fracture = 372 Nm), and at the mid shaft (50% probability of femur fracture = 447 Nm) and for the human leg loaded at the mid shaft (50% probability of tibia fracture = 312 Nm).
70 citations
TL;DR: In this article, a numerical model for the crushing simulation of fiber-reinforced composite materials is proposed, where the progression of the main cracks is modelled using a new formulation of finite decohesion elements, that allows to correctly account for the energy involved in the cracking process.
Abstract: Components in composite materials are progressively replacing metals for crashworthy applications in the automotive, railway and aeronautical industries. The numerical simulation of the crushing process for composite structures is a recent research area. Due to the complex mechanical behaviour of advanced composites, the capability of the existing analytical and numerical models to predict the crushing behaviour of composite materials is still limited. A numerical model for the crushing simulation of fibre-reinforced composite materials is proposed in this work. The progression of the main cracks is modelled using a new formulation of finite decohesion elements, that allows to correctly account for the energy involved in the cracking process. The intralaminar damage is modelled taking into account the specificities of each material system, degrading the elastic properties in accordance with the different predicted physical damage phenomena. After the validation of the decohesion element, this is ...
69 citations
TL;DR: In this paper, a method to obtain optimum topologies of structures subject to impact loads that produce geometric and material nonlinear behavior, surface contact, friction, and other phenomena in shell and three-dimensional structures is presented.
Abstract: This paper presents a method to obtain optimum topologies of structures subject to impact loads that produce geometric and material nonlinear behavior, surface contact, friction, and other phenomena in shell and three-dimensional structures. The main feature of this method is an algorithm that does not use sensitivity (gradient) information and does not require large number of iterations. A criterion called prescribed plastic strain/stress is used to circumvent the lack of sensitivity information. Additionally, a controlled crash behavior (CCB) feature is included in the simulation phase allowing design engineers to prescribe an improved structural behavior. An application of this method in a vehicle front rail is presented.
57 citations
TL;DR: Both rotational and translational effects are important when predicting the strain levels in the human brain, and the change in rotational velocity and the head injury criterion (HIC) value were chosen as appropriate measurements.
Abstract: The most frequently sustained severe injuries in motorcycle crashes are injuries to the head, and many of these are caused by rotational force Rotational force is most commonly the result of oblique impacts to the head Good testing methods for evaluating the effects of such impacts are currently lacking There is also a need for improving our understanding of the effects of oblique impacts on the human head Helmet standards currently in use today do not measure rotational effects in test dummy heads However rotational force to the head results in large shear strains arising in the brain, which has been proposed as a cause of traumatic brain injuries like diffuse axonal injuries (DAI) This paper investigates a number of well-defined impacts, simulated using a detailed finite element (FE) model of the human head, an FE model of the Hybrid III dummy head and an FE model of a helmet The same simulations were performed on both the FE human head model and the FE Hybrid III head model, both fitted with helmets Simulations on both these heads were performed to describe the relationship between load levels in the FE Hybrid III head model and strains in the brain tissue in the FE human head model In this study, the change in rotational velocity and the head injury criterion (HIC) value were chosen as appropriate measurements It was concluded that both rotational and translational effects are important when predicting the strain levels in the human brain
54 citations
TL;DR: In this article, failure loads of self-piercing rivets have been investigated under combined opening and shear static loading conditions using a new test set-up and simple specimen geometry with only a single rivet.
Abstract: The paper presents a study on identification and modelling of self-piercing rivet connections in aluminium. Failure loads of self-piercing rivets have been investigated under combined opening and shear static loading conditions using a new test set-up and simple specimen geometry with only a single rivet. These results were used to identify rivet model parameters in the code LS-DYNA using inverse modelling. Static and dynamic tests were conducted on double-hat sections made of aluminium sheets jointed with self-piercing rivets at the flanges to validate the chosen rivet model. The numerical analyses of these components provided a direct check of the accuracy and robustness of the numerical model.
51 citations
TL;DR: In this paper, the authors investigated the energy absorption response of straight and tapered rectangular tubes under axial impact loading using dynamic finite element techniques and found that tapered tubes have a higher crush force efficiency than straight tubes.
Abstract: This paper investigates the energy absorption response of straight and tapered rectangular tubes under axial impact loading using dynamic finite element techniques. The parameters in the study are the number of tapers, taper angle, wall thickness, impact velocity and impact duration. The results show that tubes with three tapered sides have the highest energy absorption capacity, followed by straight tubes and tubes with four tapered sides. Impact velocity has less effect on the absorbed energy for tapered tubes compared with straight tubes. Furthermore, the amplification of absorbed energy with increasing velocity can be controlled using the number of tapered sides. Finally, it was found that tapered tubes have a higher crush force efficiency than straight tubes. Overall, the results highlight the advantages of using tapered tubes for impact energy absorbers such as in crashworthiness applications. The research findings can be used to quantify energy absorption in the design of energy absorbers ...
50 citations
TL;DR: In this article, a detailed finite element model of the guardrail was developed and the crash response simulated when impacted by a pick up truck traveling at 100 km/hr was evaluated.
Abstract: Crashworthiness of a modified W-beam guardrail design is evaluated in this paper. In this analysis, a detailed finite element model of the guardrail was developed and the crash response simulated when impacted by a pick up truck traveling at 100 km/hr. A finite element model of a Chevrolet C2500 pickup truck was combined with the guardrail model to simulate the crash test. The combined model evaluation focuses on comparison of actual crash test data with the simulation results in terms of roll and yaw angle measurements. Simulation results were found to be in good agreement with the crash test data. Additionally, simulations were also performed to evaluate the effect of certain guardrail design parameters, such as rail mounting height and routed/non-routed blockouts, on the crashworthiness and safety performance of the system.
TL;DR: In this article, the peak impact load of a car crashing into a rigid concrete safety barrier was determined using full-scale crash tests carried out by different research institutions including Monash University.
Abstract: This paper presents equations for determining the peak impact load of a car crashing into a rigid concrete safety barrier. The equations were validated using full-scale crash tests carried out by different research institutions including Monash University. Comparisons between theory and test results indicate that the equations provide reasonable accuracy when predicting peak impact loads of a car crashing into a rigid concrete barrier for different impact speeds and angles. In particular, these equations can provide bridge engineers a useful means of determining realistic peak impact service loads when designing bridge deck barriers.
TL;DR: In this paper, the effects of adhesion and friction between the aluminium tube and the composite overwrap were examined, and a modified Chang-Chang failure model was used for the composite layers.
Abstract: In this paper, we have used finite element method to study the quasi-static axial crush behaviour of aluminium-composite hybrid tube containing filament wound E glass-fibre reinforced epoxy over-wrap around an aluminium tube. The fibre orientation angle in the overwrap was ±45° to the tube axis. A modified Chang-Chang failure model was used for the composite layers. The effects of adhesion and friction between the aluminium tube and the composite overwrap were examined. Excellent correlation was observed between the numerical and experimental results.
TL;DR: In this article, a new method has been used regarding data collection of vehicle deformations, which allows a detailed analysis of actual load paths acting on the vehicle during the crash event.
Abstract: This paper provides results from in-depth real world crash investigations of fatal frontal crashes with belted occupants. A new method has been used regarding data collection of vehicle deformations. This method allows a detailed analysis of actual load paths acting on the vehicle during the crash event. By using this method it was identified that small overlap crashes accounted for 48% of the belted fatalities which corresponds to an overlap < 30% and not including the drive train as an active load path. Crashes that correspond to load paths usage similar to the Euro & US NCAP crash test protocols accounted for 23% of the fatalities. A comparison of the new data collection methodology to the existing SAE J224 practice indicates that the SAE J224 practise overestimates the width of front structural involvement. These results points out the necessity to identify actual load paths involved in crashes in order to evaluate current crash test standards and future vehicle compatibility issues.
TL;DR: This study aimed to understand the dynamic response of the pelvis and establish its fracture threshold, using a three-dimensional finite element model, with 13,070 tetrahedral (trabecular bone) and 5,820 shell (cortical bone) elements through 3,704 nodes.
Abstract: The pelvis is most susceptible to severe fractures in side impacts, arising from motor vehicle crashes. In recent years, car manufacturers are providing more importance to the protection of occupants in lateral impacts. This study was aimed to understand the dynamic response of the pelvis and establish its fracture threshold, using a three-dimensional finite element model, with 13,070 tetrahedral (trabecular bone) and 5,820 shell (cortical bone) elements through 3,704 nodes. These elements take care of bending stress due to out of plane loading. After a detailed modal analysis, thirty-eight load cases were simulated by varying the intensity of impact load, impact duration and density ( i.e . inertia effect) of bones, with 65% of the body weight acting on the sacrum. It was observed that the failure threshold load was near 3 kN. With better design of car-door and hippad, if side impact force was brought down to 3 kN (approximately), then the peak stress (162 MPa at 5 ms of impact time to peak load), within the pelvis, would not exceed the average compressive strength for the cortical bone.
TL;DR: In this article, the fundamentals of friction modelling between solid elements in LS-DYNA are discussed, and the discussion is applicable to most nonlinear finite element analysis codes used for crashworthiness analysis.
Abstract: In recent years, analysts have been adding considerable detail to their finite element models in order to replicate actual physical behaviour with greater accuracy. One such detail is the connections between parts. Meshing of such models, although not quick, can be done without much difficulty. What can be difficult, however, is accurately capturing the interaction of all of the parts that compose the connection. Friction plays an important role in that interaction. Therefore, this paper discusses the fundamentals of friction modelling between solid elements in LS-DYNA. However, the discussion is applicable to most nonlinear finite element analysis codes used for crashworthiness analysis. Understanding the details behind friction modelling will improve an analyst's modelling skills and thus, lead to quicker and better designs.
TL;DR: In this paper, new child and adult head-form impactors according to the requirements of the ISO and IHRA subsystem test procedures have been designed and developed, including the moment of inertia, the location of the centre of gravity, the position of the seismic mass of accelerometers, and the natural frequency of the impactors.
Abstract: Head injuries are the most common cause of pedestrian deaths in car-pedestrian accidents. To reduce the severity of such injuries, the International Organization for Standardization (ISO) and International Harmonized Research Activities (IHRA) have proposed subsystem tests in which child and adult headform impactors are impacted upon a car bonnet top. The ISO and IHRA designated the mass of the child headform impactor as 3.5 kg (i.e., the average mass of a 6-year-old child's head), and that of an adult as 4.5 kg. However, such headform impactors have not been developed so far. Therefore, in the present study, new child and adult headform impactors according to the requirements of the ISO and IHRA subsystem test procedures have been designed and developed. The technical specifications, including the moment of inertia, the location of the centre of gravity, the location of the seismic mass of accelerometers, and natural frequency of the impactors, are determined. Then, the results of biofidelity certification tests of the skin of these newly developed impactors are investigated. The results show that the technical specification of the manufactured child and adult headform impactors fulfilled the ISO and IHRA requirements.
TL;DR: In this article, a quasi-static roof crush simulation based on FMVSS 216 has been carried out successfully on a small European car, and different loading conditions have been tested.
Abstract: Quasi-static roof crush simulations based on FMVSS 216 have been carried out successfully on a small European car, and different loading conditions have been tested. Results show that bonded windscreens contribute at least 30% of roof strength based on FMVSS 216. This confirms experimental test results carried out by other researchers. Furthermore, results show that the roll and pitch angles are a function of roof strength and greatly influence the overall behaviour. For instance, with the same pitch angle, the roof strength greatly drops as the roll angle goes up from 15° to 45°; but the magnitude of roof strength drop is minimal as the pitch angle increases. While for the same roll angle, the roof strength is seen to decrease as the pitch angle increases from 0° to 10°; but it does not mean that the bigger the pitch angle, the weaker the roof strength becomes. In fact in the case of a 10° pitch angle, the roof strength exhibits worst results. The recommendations on the updated FMVSS 216 are a r...
TL;DR: The Volpe Center is supporting the Federal Railroad Administration in performing rail passenger equipment crashworthiness research as mentioned in this paper, and the overall objective of this research is to develop strategies for improving structural crashworthiness and occupant protection.
Abstract: The Volpe Center is supporting the Federal Railroad Administration in performing rail passenger equipment crashworthiness research. The overall objective of this research is to develop strategies for improving structural crashworthiness and occupant protection. A field study of passenger train accidents is being conducted to investigate the causal mechanisms of how train occupants are injured during accidents. The investigation of the April 23, 2002 collision in Placentia, CA is being used to develop occupant protection strategies. This process first required the development of two simulation models: a collision dynamics model and an occupant response model. These models suggested that workstation tables brought about fatal thoracic and abdominal injuries in two occupants. Improved crashworthiness performance workstation tables, which limit the abdominal load imparted by the table, are currently under investigation through modelling and full-scale testing with advanced anthropomorphic test devices.
TL;DR: In this paper, a multibody dynamics based methodology that combines optimization with efficient analysis techniques is proposed for the design of train crashworthy components, where the components of the trains are described as rigid bodies that have their relative motion constrained by kinematic joints and among which there are nonlinear spring-damper type elements that represent the structures of trains that deform under normal operating conditions or during the train crash.
Abstract: Advanced train crashworthiness design requires not only numerical simulation tools capable of describing the dynamic response of train sets during general crash scenarios, but also, optimization procedures that can be used efficiently in the earlier design stages. A multibody dynamics based methodology that combines optimization with efficient analysis techniques is proposed in this work, for the design of train crashworthy components. In this methodology, the components of the trains are described as rigid bodies that have their relative motion constrained by kinematic joints and among which there are nonlinear spring-damper type elements that represent the structures of the trains that deform under normal operating conditions or during the train crash. Interaction between the colliding trains components are described by contact detection and contact force models. A planar dynamics formulation is used to access out-of-direction dynamics of the train cars. Through the use of an optimization algor...
TL;DR: In this article, beam elements are used to model structural components that absorb most of the crash energy, and all nonlinearities (plasticity, breakable attachments and intermittent contacts) are concentrated in plastic hinges and nonlinear contact spring elements, respectively.
Abstract: The paper presents a simplified method to analyze the crashworthiness of vehicles. This is especially aimed at guiding designs in the early stages when a decision has to be made from a fairly large number of ideas. The object of the method is to drastically reduce the size of the finite element model and the C.P.U computing time, while preserving a sufficient degree of accuracy for an efficient selection between different designs. With this purpose in mind, beam elements are used to model structural components that absorb most of the crash energy. All non-linearities (plasticity, breakable attachments and intermittent contacts (shocks) are concentrated in plastic hinges and nonlinear contact spring elements, respectively. Rigid parts (engine block, gear box etc.) are modelled as rigid solids. Furthermore, computation of the dynamic response of the vehicle is performed by using a substructuring method, based on modal synthesis. The method was successfully applied in analyzing several crash tests c...
TL;DR: In this article, a detailed suspension model has been added to the C2500 pickup truck model to validate the rear suspension system of the vehicle and the results are compared to the pendulum tests in terms of deformation, displacement and acceleration at various locations.
Abstract: Finite element models, based on a Chevrolet C2500 pickup truck vehicle, were developed at the FHWA/NHTSA National Crash Analysis Center (NCAC). These models have been used by several transportation safety researchers to analyze vehicle safety issues as well as to evaluate and improve roadside hardware. Over the past few years, modifications and more details have been incorporated in the models to add capabilities of these models to be used in different impact scenarios. In this study, a detailed suspension model has been added to the C2500 pickup truck model. Pendulum tests have been conducted at The Federal Highway (FHWA) Federal Outdoor Impact Laboratory (FOIL) and used in the validation of the suspension model. The focus in this study was on the rear suspension system of the vehicle. Simulations were conducted and the results are compared to the pendulum tests in terms of deformation, displacement and acceleration at various locations. To ensure the accuracy of the newly upgraded vehicle model...
TL;DR: In this paper, a combined experimental, analytical and numerical/FEM study on the quasi-static axial crushing of thin-walled aluminum S-rails is presented.
Abstract: A combined experimental, analytical and numerical/FEM study on the quasi-static axial crushing of thin-walled aluminum S-rails is presented. Quasi-static test was performed on S-rails with a prescribed cross-head speed 10 mm/sec. Finite element models were developed and found to reproduce the crushing response to a significant degree of accuracy with respect to the onset of collapse, the subsequent localization of plastic deformation and the overall energy absorbing capability. With the failure parameters calibrated from uniaxial tensile tests, FEM simulation can also be used to predict the fracture onset. Based on a simplified model, an analytical solution for the force-deflection response was developed, which can be applied to an early design stage of the “S” frame. Finally, the same problem was solved by means of CrashStudio and comparisons were made with some known solutions.
TL;DR: In this paper, the authors focused on the injury potential of children in forward and rearward facing child restraint seats in frontal collisions and performed a sled test with a Hybrid III 3-year-old dummy.
Abstract: This research focuses on the injury potential of children in forward and rearward facing child restraint seats in frontal collisions. Experimental sled tests were completed following the guidelines outlined in the Federal Motor Vehicle Safety Standard 213 using a Hybrid III 3-year-old dummy in a convertible forward/rearward facing child restraint seat. The seat was equipped with a five point child safety belt and the experimental test was completed in the forward facing configuration. The Hybrid III 3-year-old dummy was equipped with three uniaxial accelerometers arranged in mutually perpendicular directions in the head and chest. A numerical model employing a subset of the apparatus used in the forward facing experimental sled test was developed and numerically simulated using LSDYNA. To verify the numerical simulations, the head and chest accelerations were compared to the experimental findings and it was observed that a reasonable correlation between the data existed. Further numerical simulat...
TL;DR: In this article, the influence of reduced variability of the input parameters on the predicted range of impact velocities was analyzed for both wet and dry road conditions and confidence levels for impact speed prediction.
Abstract: A key element of study of the biomechanics of pedestrian injuries from vehicle collisions is the determination of pre-impact vehicle speed. Pedestrian projection distances are an important means to determine collision speed, particularly as tyre brake marks are not readily observable with ABS brakes. A number of models have been developed by the authors, which include recent analytical models for forward [1] and wrap projection [2] impact. These models are novel as they include explicit modeling of the impact phase. They have been validated against the available test data, showing very good comparisons, and are therefore ideal for further statistical analysis. Confidence limits for speed estimates are set out for various purposes including injury research and litigation. The models show that the distribution of predicted collision speeds from projection distance can be large when a high degree of confidence is required. Some of this uncertainty is due to the impact phase where parameters such as duration and restitution are unknown for individual collisions, in addition to other confounding factors that are difficult to quantify. However the effects of the coefficient of retardation during the projection phase and the mass ratio between pedestrian and the striking vehicle can be readily determined. This paper analyses the influence of reduced variability of the input parameters on the predicted range of impact velocities. Analysis for known coefficients of retardation and mass ratio values yields the minimum prediction uncertainty due to the variability of the impact phase parameters alone. Results show that significant improvements in prediction uncertainty can be achieved by exact knowledge of the pedestrian to vehicle mass ratio and of the coefficient of retardation between the pedestrian and the road surface. In practice, while the mass ratio can be determined for individual collisions there is significant uncertainty as to the coefficient of retardation values, as these are influenced by the kinematics of the pedestrian during projection and ground impacts, in addition to factors such as road surface condition and contamination. However, overall data is available for wet and dry road conditions. Tables are presented for impact speed prediction from projection distance for various conditions and confidence levels.
TL;DR: In this article, a series of experiments loosely based upon the Concorde incident was conducted to assess whether the probable failure mode in the crash of the aircraft could occur in land-based vessels.
Abstract: Following the accident involving the Air France Concorde in 2000 the effects of fluid structure interactions resulting from the impact of a fluid filled tank has become a cause for concern. The work reported here relates to the design of a series of experiments loosely based upon the Concorde incident which aimed to assess whether the probable failure mode in the Concorde accident could occur in land based vessels. Preliminary numerical analyses were undertaken for two of the nine cases that were investigated experimentally in which an empty tank was impacted by a projectile with a velocity of 14m/s and 21.9m/s Initial numerical results for the acceleration at two points on the tank surface and the deformation at the impact zone showed good agreement with test data. Future work is discussed including further numerical modelling incorporating fluid structure interactions for the analysis of the cases when the tank is partially full or completely full.
TL;DR: In this article, a 3D finite element model of the head-neck sub-assemblies of the THOR 50th percentile male dummy is presented, in conjunction with the use of the physical dummy, a computational tool for headneck injury studies related to motor vehicle, rail, or aircraft crashes.
Abstract: Development, calibration and validation of a three-dimensional finite element model of the head-neck sub-assemblies of the THOR 50th percentile male dummy are presented. The model provides, in conjunction with the use of the physical dummy, a computational tool for head-neck injury studies related to motor vehicle, rail, or aircraft crashes. Physical dummy CAD data is used to construct the finite element mesh. Mass and inertia properties of the model are consistent with those of the hardware. The THOR head spring-cable system, designed to produce a neck that gives more biofidelic head trajectories, is properly represented in the model. Several modelling methods are discussed in detail. The deformable components of the model include head skin (vinyl), face foam (Confor foam), face pad (silicone rubber), head springs, neck cables and neck discs (neoprene rubber). The material properties are determined, or calibrated, mainly from system identifications with data from material tests, head and face impact tests on a full dummy and sled tests on stand-alone head-neck sub-assemblies. The model is validated with the remaining sled test data and head-neck pendulum test data. Key simulation results such as head spring forces, motion trajectories, accelerations at head centre of gravity, and neck forces and moments are compared with the corresponding experimental data, and error analyses are conducted for the presented results.
TL;DR: In this article, a mathematical model was developed to explore and demonstrate the injury reducing potential of an adaptable frontal stiffness system for full frontal collisions, which was validated by means of crash tests and was found to predict the peak accelerations of the crash test vehicles well.
Abstract: A mathematical model was developed to explore and demonstrate the injury reducing potential of an adaptable frontal stiffness system for full frontal collisions. The model was validated by means of crash tests and was found to predict the peak accelerations of the crash test vehicles well, whereas correlation concerning mean acceleration or residual crush was not found. Vehicles were divided into three mass classes, and a test matrix was established in order to evaluate different combinations of vehicles involved in frontal crash at three closing velocities. In a baseline simulation setup, constant stiffness values were used and the results were compared to the corresponding simulations using adaptable frontal stiffness. Results show promising acceleration peak reductions at low speeds, implying that injury risk reductions are possible.
TL;DR: In this article, an extruded aluminum truss-work bridge railing for NCHRP Report 350 test levels three and four conditions was designed and analyzed using the nonlinear dynamic finite element program LS-DYNA.
Abstract: This report describes the design and analysis of an extruded aluminum truss-work bridge railing for NCHRP Report 350 test levels three and four conditions. The objective of this research is to determine if the barrier will pass the NCHRP Report 350 full-scale crash tests for test levels three and four by using the nonlinear dynamic finite element program LS-DYNA. A subsequent AASHTO LRFD analysis supported the LS-DYNA results. The design documented in this report was found to be of comparable strength to other F-shaped bridge railings so that successful crash test results are highly likely.
TL;DR: A reflection was initiated on a laboratory test coupled fluid/structure in order to develop a reference experimental database and to use it to evaluate the most recent capacities of the crash codes.
Abstract: In the field of fluid/structure interactions, one question concerns the relevance of structural tests carried out for the validation of the physical models and numerical formulations implemented in the codes. In the "SEAWORTH" programme, simulations 2D were confronted to experimental tests in the elementary structures. Even more, the different tools gave different results, and none of them proved to predict all the different experimental cases properly. These tests were already too complex for a physical model validation exercise. So, a reflection was then initiated on a laboratory test coupled fluid/structure in order to develop a reference experimental database and to use it to evaluate the most recent capacities of the crash codes. The paper presents the experimental part of this work.