Equating severity in qualification testing

Abstract

Understanding how damage progresses in engineering materials is of the utmost importance for ensuring safety and reliability. Mechanical components and structures must often perform safely and reliably for much longer than can be reasonably tested, or the components must operate in severe environments that are difficult to reproduce. The capability to perform real-time, real-scenario testing is not always present or attainable however, and failure to adequately test components can lead to catastrophic consequences or high preventative-maintenance costs resulting from the use of weaker presumptive models. As a solution, a criterion for ductile metals for equating high-stress single shock damage, to periodic, low-stress, multiple shock damage is presented. The correspondence in damage, exhibited as an equivalency in deformation, is derived and experimentally validated. To accomplish this process, we relate the plastic deformation a test coupon experiences under a shock input, to the shock parameters under both single shock and multiple shock regimes. We then compare the proposed theoretical damage model against the experimental data.