The current approach of hybrid RLDA is typically incapable of providing accurate dynamic loads coming on cab at chassis-to-cab load transfer locations, primarily due to the following two reasons. Firstly, all of the model parameters of the vehicle, which is put on the 4-post, are not known. Secondly, MBS (Multi-body System) Cab model is multi degree of freedom with rigid bodies, flex bodies, contacts and non-linear force elements. Therefore, if the system identification is to be performed manually it becomes an arduous and humanly impossible task.
Towards generating accurate dynamic loads on cab, an approach using FEMFAT LAB - VI & MI has been developed which involves a two-step process: a) Generating MBS excitation by back calculating from measured frame response – VI (Virtual iterations). b) Fine tuning modelling parameters to match measured cab response – MI (Model Improvement). To execute the VI & MI approach for calculating dynamic loads on cab through 4-poster & 7-poster simulation, measured road data (load, acceleration, displacement etc.) is required. Road data has been acquired on a Tata vehicle at strategically identified locations on various test tracks in two different loading conditions. The flexible MBS model had been created in MSC-ADAMS/Acar for 4-poster & 7-poster simulations. MBS excitation signal is back calculated from measured frame response through VI approach in FEMFAT Lab-VI tool and improvement in accuracy is demonstrated through correlation between simulated v/s measured cab & frame responses, in terms of relative damage. Furthermore, Model Improvement (MI) is done by updating relevant parameters identified by a diagnose tool to improve the correlation level. Finally, the improvement in accuracy of simulated outputs using VI & MI approach over existing process is also demonstrated.