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The present study had two aims: (1) to develop a model which reproduced the dummy lower leg kinematics observed in a high-speed test, and (2) to develop a methodology to assess various theoretical design parameters of a heel foam pad to reduce the risk of the lower extremity injuries. To address the first aim, a MADYMO sled simulation model was developed. The interior parts were represented mainly with finite element (FE) models, with intent to capture deformations and the reaction force directions. Moreover, the occupant responses were estimated from the refined version of the dummy model (i.e., the Hybrid III model; Q dummy model). The model was acceptably correlated to experiments. To address the second aim, the model was simplified for subsequent optimization of the heel foam pad.

Continuous improvement of side airbag safety performance is an important step because it is associated with many public domain tests and regulations. Thus, occupant restraint with a side airbag is critical and it is necessary to develop tools that can be utilized to help in design of side airbags. Though many papers on side impact safety have been published, only a few papers are related to MADYMO simulations of side airbags. This paper describes an improved injury prediction and optimization approach using a MADYMO model for side impact. This model consists of 3 parts: dummy, trim and airbag in FEM. In this study, a side impact with a ES-2, EuroSID-2, was simulated in MADYMO as follows: First, component tests were conducted for trim and airbag respectively to establish correlation. Second, these component models were then integrated into a MADYMO model, which has high correlation with a crash simulator that is capable of replicating physical vehicle tests.

Driver fatality rate of a passenger vehicle is considerably high when struck on the side by an LTV (light truck and van). Aggressivity of LTVs, particularly in side crashes, needs to be reduced to improve this incompatible situation. Crash energy absorption share of a passenger car struck on the side by an LTV was measured through component tests. As a result, B-pillar of the struck passenger car was found to receive most of the crash energy intensively. This intensive energy triggered large B-pillar deformation. Computer simulation proved that B-pillar deformation was closely related to occupant injury. The key to mitigate the injury of side-struck car occupant, therefore, is to disperse crash energy to other structural parts than B-pillar. Front-end structures of LTVs that realize crash energy dispersion were designed and examined. The structures include (a) optimization of the vehicle height, and (b) adoption of a forward-extended sub-frame.

Development of anti-whiplash technology is one of the hottest issues in the automotive safety field because of the frequent occurrence of rear impact accidents. We analyzed the whiplash mechanism and conducted a study to seek the optimized seat characteristics with BioRID II and MADYMO simulations. A parameter study was made to construct a conceptual theory to decrease NIC, Neck Injury Criteria, with the MADYMO model. As a result of the study, head restraint position and seatback stiffness were found to affect dummy movement and injury values. Applying the NIC mechanism and the influential parameters to the MADYMO model, the optimized seat characteristics for whiplash prevention were obtained.

This paper clarifies aggressivity reduction approach for MPV, Multi-Purpose Vehicles, derived from large passenger vehicles toward small passenger vehicles. The effects of aggressivity-reducing approach were measured through full-frontal rigid barrier crash simulations with TRL aluminum honeycomb by Finite Element Method. The front-end structures of large vehicles studied in this paper based on this aggressivity reduction approach show good front-end homogeneity and low average height of force. The structures were also found to effectively reduce aggressivity toward small vehicles by car-to-car simulation. However, there are some cases where the effect was influenced by overlap ratios. From this result, overlap ratio is considered to be one of the important factors to improve compatibility performance.

With an aim to improve compatibility performance, vehicle-to-vehicle frontal impact simulations have been conducted between large car and small car. Focusing on sub-frame structure that disperses applied force with multiple load paths, a large saloon car with sub-frame was selected and three different front structures were studied: original, forward-extended sub-frame, and original with 25%-stiffness reduced structures. The types of collision contained four different crash modes in a combination of lateral overlap rate difference and side member height difference. As a result, it was found that the front structure with forward-extended sub-frame improved aggressivity by preventing override effect through structural interaction enhancement. Height of Force (HOF) was also improved.

A structure which effectively improves compatibility in a vehicle-to-vehicle frontal impact has been considered focusing on sub-frame structure that disperses applied force with multiple load paths. Evolved sub-frame structure has been studied by CAE with RADIOSS to search the possibility to reduce aggressivity and to improve self-protection at the same time. Vehicle models used for this compatibility study were a large saloon car with sub-frame and a small family car without sub-frame. The large saloon car had three different front structures: original, forward-extended sub-frame, and original with 25%-stiffness reduced structures. The types of collision contained four different crash modes in a combination of lateral overlap rate difference and side member height difference.

To reduce real world fatal/serious/minor injuries, factors causing such injuries should be investigated in depth from wider perspectives. The aim of this paper is to clarify the factors based on Japanese accident database compiled by ITARDA (Institute for Traffic Accident Research and Data Analysis). ITARDA database has data for injury rates, seatbelt use rate of driver and age of driver involved in crashes, etc. by vehicle model. As a result of an elaborate statistical analysis, the most influential and essential factors on all injuries including fatality were quantitatively found to be seatbelt use rate and vehicle weight. The increase by 1% in seatbelt use rate makes injury rate decrease by 7%. The influence of vehicle weight is 1.7 times higher than seatbelt use rate. Multiple regression analysis on these two parameters was also conducted. The present analysis successfully predicted all injury rates by model per 10,000 units.

Of the injuries sustained by belted rear occupants in a frontal collision event in Japan, the neck and the head are the regions of the body most likely to be injured, while children and female occupants are accounting for the highest rate of injuries. For the purpose of reducing rear seat occupant injuries, the occurrence mechanism of neck and head injuries is clarified by sled tests with the current rear seat belt system. When a high load is applied to the occupant via the seat belt, the occupant experiences sudden deceleration of the chest, resulting in a great relative velocity difference between the head and the chest. This causes injury to the occupant's neck and head. To reduce occupant injuries, therefore, it is important to minimize the relative velocity difference by control of belt load.

Recently, computational fluid dynamics (CFD) has made great progress. This paper reviews published papers on aerodynamic noise simulated by CFD and studies to what level CFD can predict aerodynamic noise for basic models and for applied models of automobiles. Based on noise generation mechanisms, aerodynamic noise is basically classified into two types, that is, noise induced by two-dimensional flow and by three-dimensional flow. As typical examples of noise generated by two-dimensional flow, wind throb at opened sliding roof, edge tone at the end of liftgate and aeolian tone generated by a cylindrical antenna are simulated by several computational schemes. As typical examples of three-dimensional flow, noise generated by A-pillar longitudinal vortex and noise from a side view mirror are computed by using a wing model and a actual vehicle, respectively.