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Applications - Virtual Prototype Analysis

Vehicles and other manufactured products have to be durable. They are commonly subjected to tests involving repeated loads and one-off extreme loads to assess their durability performance. The tests are sometimes modelled using linear finite element analysis, in which the loading is estimated from experience. This technique gives poor results, because the stiffness and strength of the structure often controls the applied force, so design changes intended to reduce deformation can instead lead to unexpected failures. In the vehicle industry, durability tests may be modelled by a multi-step analysis process involving simplifying assumptions at each stage.

The errors that arise from this type of analysis process are becoming unacceptable in today's shorter product development cycles, because there is no longer time to find and correct problems by testing. Many advantages can be obtained by simulating the tests as they are done in practice, including all the dynamic and nonlinear effects, in a single simulation. LS-DYNA is ideally suited to simulate many of these tests.

An example is the modelling of events from accelerated durability tests and suspension abuse loads on cars. The loading is determined by tyre behaviour, suspension response, and the flexibility of the suspension members, bushes, and body. By including all of these items in the calculation, a potentially more accurate simulation can be achieved. In the abuse load cases, damage to the body and suspension can be predicted.

The modelling techniques are very similar to those for crash analysis, except that the suspension and tyres are modelled more accurately. The tyres each contain around 1500 orthotropic shell elements; often, solid elements are added to represent the tread. The LS-DYNA airbag feature is used to control the internal pressure.

The analyses shown in the pictures on this page were all run using standard LS-DYNA 940 on a 64-bit Cray computer. It is recommended that a double precision version of LS-DYNA should be used for this type of calculation if the solver normally uses 32-bit word length, as is the case with most unix workstations.

More details on Virtual Prototype Analysis