FE based method for simulation of rock-loading on a truck

Sammanfattning: Volvos trucks are used to carry boulders of varying sizes from different mining sites or construction sites. These boulders are loaded onto the dumper of the truck by a wheel-loader which drops the boulders from various heights causing an impulse like force which distributes throughout the frame and to the rest of the truck. Depending on the size and what height the boulders are being dropped from, the distributed forces can cause damage to important parts of the truck. An experiment done by Volvo has shown that a two-ton weight dropped from 3.5 meters caused some truck components to crack, such as flywheel housing. Since this is alerting and it is costly to do the experiment on all trucks that Volvo manufactures it is our objective to come up with a method based on Finite Element which would evaluate the rock loading case. By using ANSA as the pre-processor which helps set up the model before running a simulation, and Nastran and LS-DYNA as the FEM solvers, a result was obtained that is somewhat comparable with the measurements. In the Nastran model, no non-linearities such as contact were considered, while in LS-DYNA nonlinear contact between the weight and the dumper body was defined, which improved the results considerably. The key conclusion from the two results was that the contact definition used in LS-DYNA is necessary if accurate results are important. Since LS-DYNA uses an explicit numerical method the model can be made more complicated by including more nonlinearities in the model and it would not affect the computation to much or at all. Hence the method would be future proof.