Reconstruction of the forces exerted by an engine on its engine mounts

The subject of this research is the reconstitution of the forces exerted by an engine on the engine mounts of an all terrain vehicle for numerical analyses. The frequency spectrum of the excitation produced by the engine is difficult to reproduce theorically. Yet, such data could be used in a numerical model, a finite element model for instance, to predict the vehicle structural response. Therefore, an experimental method was worked out which enables the reconstitution of the forces exerted by the engine on its supports from experimental data. The proposed method consists in placing triaxial accelerometers and force sensors under the engine, at the connexion points with the engine mounts. These four points are considered to be the only support points of the engine; it is assumed that forces are transmitted to the vehicle by the engine mounts exclusively. Approximation of the rotational inertias of the engine is possible if small translational displacements of the engine are considered. The results show that the method can work over a limited band of low frequencies, with the condition that the inertial characteristics of the engine are well known.