Strength Evaluation and Validation of Structural Joints

Many methods have been developed to evaluate the fatigue life of structures when the joints are as per ideal case. But if the joints are loosening, it leads to increase in loading on the other members which causes failures. Most commonly in commercial vehicle segment welding joint & bolting joints are most popular ones. It is very easy to find out bolts strength & loosening effect in static conditions. But when vehicle is moving (i.e. dynamic condition), same method cannot be used. For this we have developed methodology to predict the bolts loosening in dynamic condition using vibration data. Similarly, loading may differ on the structural members if the welds are failing in dynamic conditions. To overcome this problem, in our organization we have a solution. Of course to simulate welding failures fatigue analysis is mandatory. We are using notch-stress approach for evaluating the welding strength of the joint. This method does not need weld material data instead it increases the amplitude stress appearing on nodes representing welding joint. We have correlated both the methods with the rig test and/or Accelerated endurance testing. We have achieved almost 80% correlation between the real life testing and virtual testing.