Search Results

In most aspects of mechanical design related to a motor vehicle there are two ways to treat dynamic fatigue problems. These are the time domain and the frequency domain approaches. Time domain approaches are the most common and most widely used especially in the automotive industries and accordingly it is the method of choice for the fatigue calculation of welded structures. In previous papers the frequency approach has been successful applied showing a good correlation with the life and damage estimated using a time based approach; in this paper the same comparative process has been applied but now extended specifically to welded structures. Both the frequency domain approach and time domain approach are used for numerically predicting the fatigue life of the seam welds of a thin sheet powertrain installation bracketry of a commercial truck submitted to variable amplitude loading. Predicted results are then compared with bench tests results, and their accuracy are rated.

Mainly in the last 30 years so much research has been done on Fe-based calculation of seam welded thin-sheet structures fatigue life. However, available prediction methods have been developed for a limited range of geometries under ideal load conditions. Extrapolating to complex real world geometries and load conditions such those resultant from, for example, ground vehicles dislocation over rough surfaces, are least documented. One example of the application of seam welded thin-sheet structures in the ground vehicle industry is the powertrain installation bracketry. Such brackets are subject to variable amplitude loading sourced from powertrain and road surface irregularities and their fatigue strength is tightly dependent on the strength of their joints. In this paper, a FE-based force/moment method has been used for numerically predicting fatigue life of powertrain installation bracketry of a commercial truck submitted to variable amplitude loading.