Improved Reliability Testing and Modeling of Electronics with Multi-DOF Vibration in Unmanned Army Ground Vehicles

The functionality of the next-generation Department of Defense platforms, such as the Small Unmanned Ground Vehicles (SUGV) and Small Unmanned Arial Vehicles (SUAV), requires strongly electronics-rich architectures. The reliability of these systems will be dependent on the reliability of the electronics. These electronic systems and the critical components in them can experience extremely harsh thermal and vibrations environments. Therefore, it is imperative to identify the failure mechanisms of these components through experiments and simulation based on physics-of-failure methods. One of the key challenges in recreating life-cycle vibration conditions during design and qualification testing in the lab is the re-creation of simultaneous multi-axial excitation that closely mimics what the product experiences in the field. Currently, there are two common approaches in the industry when testing a prototype or qualifying a product for multi-axial vibration environments. One approach is option is to use sequential single-axis excitation along each of the three axes, via a single axial electrodynamic shaker. The second approach relies on repetitive shock shakers that produce simultaneous multi-axial vibration but with uncontrolled power spectral density (PSD) profiles. Consequently, the dominant failure modes in the field are sometimes very difficult to duplicate in a laboratory test using the options stated above. The US Army Materiel Systems Analysis Activity (AMSAA) is currently collaborating with the Center for Advanced Life Cycle Engineering (CALCE) at the University of Maryland, to develop test methods that better capture unforeseen design defects in the prototyping and qualification stages, by better replication of the multi-axial life-cycle vibration conditions. This effort has led to the use of a novel multi degrees of freedom (M-DOF) electrodynamic shaker to ruggedize designs for fatigue damage due to random vibration. The PSD profiles can be controlled on this shaker simultaneously along all six DoF (three translation and three rotational).

This paper discusses the merits of vibration testing methods with a M-DoF shaker and the cost savings associated with such an approach. The M-DoF shaker may detect critical failures earlier in the development cycle than have been traditionally possible with existing shaker technologies; and therefore produce more cost effective and reliable systems for our warfighters.