Engineering design analysis (Physics of Failure)

In December 2007, the Army Acquisition Executive approved the new Army Reliability Policy. The policy was developed to cost-effectively increase the reliability of Army systems. The new policy encourages use of cost-effective reliability best practices and provides a mechanism to alert key Army leaders when weapon systems are off track with respect to meeting their reliability requirements. One of the policy\´s key elements is early engineering design in order to "design-in reliability." Physics of Failure (PoF) is a science-based approach to reliability that uses modeling and simulation to design-in reliability. The approach models the root causes of failure such as fatigue, fracture, wear and corrosion. PoF analyses are used to address long-term wear-out issues due to random vibration, thermal overstress or repetitive shock. Computer-Aided Design (CAD) tools have been developed to address various failure mechanisms and sites. Examples of failure mechanisms include things such as metal fractures on various vehicle components or fatigue cracking of electronic solder joints. The US Army Materiel Systems Analysis Activity (AMSAA) conducts PoF analyses to support contractors, program managers (PMs) and engineers on systems in all stages of acquisition from design, to test and evaluation (T&E) and fielded systems. In the design stage system level dynamics models, component finite element models and fatigue-life models are used to reveal the underlying physics of the hardware in its mission environment. Outputs of these analyses include forces acting on a system, displacements of components, accelerations, stress levels, weak points in the design and probable component life. This information is used during the design process to make design changes early in the acquisition process when it is easier and more cost effective. Design decisions and corrective actions made early in the acquisition phase lead to improved efficiency and effectiveness of the T&E process.- - The intent is to make fixes prior to T&E which will reduce test time and cost, allow more information to be obtained from test, and improve test focus. PoF analyses can be conducted for failure occurring during test to better understand the underlying physics of the problem and identify the root cause of failures which leads to better fixes for problems discovered, reduced test-fix-test iterations and reduced decision risk. The same analyses and benefits mentioned above can be applied to systems which are exhibiting failures in the field.