Heinz Hoschopf

VALIDATION OF THE PC-CRASH PEDESTRIAN MODEL

The pedestrian model in PC-Crash is based on a multi-body system, where several bodies are interconnected by joints. This paper describes in detail the validation process for the pedestrian model. A significant number of crash tests (approx 30) was used as a basis to compare the results of the simulations and the real movement of the test subjects. Different test configurations were selected to provide a set of crash tests, which represents real cases as close as possible. To show the difference between dummy movement and the movement of human test subjects some tests with human test subjects and some real cases, which were very well documented, have been used. Each of the different tests was reconstructed using PC-Crash and the pedestrian model and the significant difference between simulation results and crash tests are pointed out. A special interest has been focused on the pedestrian trajectories and the contact locations between the pedestrian and other objects. All tests and simulations are compared in the conclusion and the usability of the pedestrian model in different accident configuration is discussed. Typical parameter ranges for the different input parameters like pedestrian geometry, weight and stiffness parameters are presented as well. (A) For the covering abstract see ITRD E106540.

Reconstruction of occupant kinematics and kinetics for real world accidents

A detailed study of vehicle and occupant movement during an accident is often of great interest. When reconstructing car accidents, quiet often questions arise regarding occupant movement and loading. This paper discusses the numerical results compared to experimental test results. For two selected full scale car to car collisions (frontal and side impact) three dimensional vehicle movement as well as dummy accelerations were compared. Additional emphasis were set on the influence of the crash pulse on the occupant behaviour. For the approach used a constant acceleration during the crash phase was assumed for the occupant simulation, which was performed by coupling the three dimensional car behaviour from PC Crash with a simplified MADYMO model of car interior, restraint system and 50% tile Hybrid III dummy model.

Required length of guardrails before hazards

One way to protect against impacts during run-off-road accidents with infrastructure is the use of guardrails. However, real-world accidents indicate that vehicles can leave the road and end up behind the guardrail. These vehicles have no possibility of returning to the lane. Vehicles often end up behind the guardrail because the length of the guardrails installed before hazards is too short; this can lead to a collision with a shielded hazard. To identify the basic speed for determining the necessary length of guardrails, we analyzed the speed at which vehicles leave the roadway from the ZEDATU (Zentrale Datenbank Tödlicher Unfälle) real-world accidents database. The required length of guardrail was considered the length that reduces vehicle speed at a maximum theoretically possible deceleration of 0.3g behind the barrier based on real-world road departure speed. To determine the desired length of a guardrail ahead of a hazard, we developed a relationship between guardrail length and the speed at which vehicles depart the roadway. If the initial elements are flared away from the carriageway, the required length will be reduced by up to an additional 30% The ZEDATU database analysis showed that extending the current length of guardrails to the evaluated required length would reduce the number of fatalities among occupants of vehicles striking bridge abutments by approximately eight percent.

Case study of a frontal car accident involving three fatally injured children

Rear occupants are generally considered to sustain less severe injuries in frontal car impacts compared with front occupants. Contrary to this thesis, in 2009, in a serious accident involving two passenger cars took place in Austria in which three children seated in the rear were fatally injured in a frontal collision. Based on this car accident, the present study was performed to gain a better understanding of rear occupants’ injury mechanisms and potential improvements to rear-seat restraint system. The study employed a validated numerical model that shows that loads and injury criteria can be reduced by up to 70%. Also, national accident databases have been analysed. The accidentology indicates that children restrained by the vehicle rear belt are fatally injured only approximately two times more frequently than children using a child restraint system. The investigation indicates that the protection level offered to children aged 6–14 does not match the high protection level available for adults and for children up to six.

Methods to Prevent or Mitigate Accidents with Large Animals

Although accidents with animals represent a small portion in the official statistics, these accidents have an economic effect. The regulatory costs in Germany added up to an average of 370–464 million Euros annually in the years between 2000 and 2005. The insurance companies registered between 210,000 and 235,000 deer accidents on average every year. The largest part of the data collected by the insurance companies is accidents with damage to property. But accidents with large animals are a danger to vehicle occupants. German statistics for accidents with animals for this period show between 18 and 28 fatally injured persons and between 580 and 750 severely injured and 2,100–2,600 light casualties every year. Accidents that are caused by evasive maneuvers causing running-off track and finally colliding with the infrastructure or causing a cross-over collision have not been taken into account. The aim of this investigation is to evaluate typical accident scenarios and accident simulation with large animals. In particular, the effects on the vehicle occupants are investigated by multi-body simulation methods. The occupant load for accidents with animals is determined and influencing factors on the load are derived. Based on these investigations, avoidability scenarios are developed and methods are introduced that are relevant to the vehicle (active and passive safety) and also to the infrastructure and the driver. The objective is to develop effective counteractions in order to avoid accidents with animals or at least mitigate the accident aftermath.

Safety Measures for Avoiding or Mitigating the Occupant Exposure in Collisions with Large Animals

Road accidents involving large animals are responsible for a considerable number of fatalities; these are e.g. elk in Northern Europe or camels in Middle East, Horn of Africa and Maghreb. In order to address this topic, investigations concerning active and passive road safety have been launched at the King Saud University and at Graz University of Technology. Data of real accidents or accident statistics are not available in the required quality to gather typical accident scenarios. Therefore generic accidents types were derived and critical load cases were determined by means of multi body and finite element simulations. It was found that the vehicle acceleration due to the impact is not a safety issue, but the finite element simulations showed that massive local intrusions into the passenger compartment are the main cause for severe occupant injuries. Therefore, concepts for the prevention of critical intrusions were examined. In a first step the space required for the occupant movement due to the rather mediocre acceleration levels in car-to-large animal accidents was determined by multi-body simulation. In a second step different approaches preventing intrusions into the occupant-movement-space were analyzed by finite element simulation. In addition, the possible effects and requirements of active systems have been studied to demonstrate the potential of combined measures.