Simulations with LS-DYNA for Registration Approval of a Coach according to ECE R66 Regulation

During the last years the increasing number of fatal coach accidents with tragic consequences for passengers showed the importance of passive safety in addition to the driver’s competence and active safety. In the European countries the certification of sufficient deformation strength when overturning is compulsory for the approval of a coach according to the ECE R66 regulation. The certification is granted after positive results from crash tests or computer simulations with partial or full bus structure. The ECE R66 regulation defines a survival space for the passengers which must remain intact after the accident. The tests specify either the overturning of the vehicle structure from a tilting platform or the impact of a plate on the coach structure as it would correspond to the crash of the structure when falling onto the ground. Since such tests with real vehicle structures are costly and computer efficiency, on the other hand, is becoming increasingly better and cheaper, crash simulations will play a more important role for the approval in the future. This paper will present different LS-DYNA – time simulations of the overturning test with a segment of a bus structure according to ECE R66 and time simulations with a pivoted plate hitting with the same kinetic energy against the structure as the model falling from the tilting platform and crashing onto the floor. Several modelling configurations with deformable and rigid undercarriage, with different friction coefficients of the contact ground-structure, are simulated. These calculations shall serve as a preparation for future calculations to obtain the necessary certification. Unfortunately no experimental results are available at present to enable the comparison between hardware test and computer simulation. However, the experience gained with tilting tests of similar coach structures in the past indicates the trustworthiness of the calculations. As these experiences are published on the panel of a users’ meeting, this paper goes more then usual into detail regarding the modelling and the difficulties in simulations which the authors, until that time unfamiliar with LS-DYNA, has to overcome. A short introduction to the variable test possibilities explained in regulation ECE R66 is given