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Vibration testing is often carried out for automotive components to meet guidelines based on their operational environments. This is an iterative process wherein design changes may need to be made depending on an intermediate model’s dynamic behavior. Predicting the behavior based on modifications in boundary conditions of a well-defined numerical model imparts practical insights to the component’s responses. To this end, application of a general method using experimental free-free condition frequency response functions of a structure is discussed in the presented work. The procedure is shown to be useful for prediction of responses when kinematic boundary conditions are applied, without the need for an actual measurement. This approach is outlined in the paper and is applied to datasets where dynamic modifications are made at multiple boundary nodes.

Multileaf steel suspension springs are occasionally prone to failure through delayed hydrogen stress cracking, a brittle fracture that can occur even before the springs have been assembled into a vehicle. This failure mode is unusual, and problematic in respect of diagnosis and prevention. Jai Parabolic Springs Ltd (JPSL), the world's fourth largest leaf spring manufacturer, experienced early failures of this kind in springs produced for a truck vehicle program in 2005. The root cause was shown to be delayed hydrogen stress cracking, or hydrogen embrittlement. Tests were conducted to assess the conditions leading to this type of failure. Guidelines are presented that were developed, and proved in production, to prevent future recurrence.