01025040

Component

The crash test scenario of a small passenger car (total mass of 900 kg) striking a rigid Round Robin barrier at a speed of 100 km/hr and with an angle of 20 deg. was considered. The impact conditions comply with the European Committee for Standardization (CEN) specifications for the homologation of a roadside safety barrier. In order to collect the acceleration and velocity-time histories of the vehicle and to consequently assess the occupant risk factors during the impact simulation, an accelerometer sensor was included in the vehicle model. For this purpose, a standard element is available in LS-DYNA, defined by the card *ELEMENT_SEATBELT_ACCELEROMETER. This element is represented by a rigid brick that must be properly connected to the vehicle (at the centrum of gravity of the vehicle), usually by means of a rigid link to a massive part in the model in order to attenuate the high elemental frequencies. With this built-in features, the user can collect the acceleration-time histories in a local coordinate system moving with the sensor, defined by three nodes of the element-accelerometer. This device proves to be very useful when comparing the simulation results with data measured in a full-scale crash test, where accelerometers are mounted similarly on the test vehicle. The output nodes are set in the card *DATABASE_HISTORY_NODE, while the output frequency is specified with the card *DATABASE_NODOUT. Nodal accelerations, velocities and displacements are written in the NODOUT ASCII file as they are computed by the solver without any data filtering or processing. According to these considerations, it is responsibility of the user to choose a reasonable output frequency to avoid aliasing phenomena. A practical rule to determine a suitable output frequency is to refer to the maximum frequencies in the model and, therefore, to the integration timestep, related for stability reasons to the upper bound of the frequencies of the model. If no other methods can guarantee the absence of aliasing phenomena at a chosen output frequency, it is advisable to set a sampling period of the same order of magnitude of the timestep. In this paper the results of the impact simulation are reported, evaluating the influence of the output frequency on the computation of the acceleration-time histories and occupant risk factors. The same impact scenario and finite element model were used to evaluate the effect of the location of the accelerometer sensor.

01020180

06-0846

English

21p

2006

Transportation Research Board 85th Annual Meeting

CD-ROM

Figures (12) ; References; Tables (4)

Accelerometers; Crash tests; Data analysis; Data collection; Finite element method; Velocity

Angle of impact; Impact speed; Occupant risk; Rigid barrier tests; Roadside safety; Round robin barrier; Safety barriers

Highways; Research; Vehicles and Equipment; I95: Vehicle Inspection

Transportation Research Board Annual Meeting 2006 Paper #06-0846

TRIS, TRB

Mar 3 2006 10:29AM