Clamped sandwich beams with thick weak cores from central impact: A theoretical study

A theoretical model is obtained to predict the dynamic response of a clamped sandwich beam with thick weak core impacted centrally by a projectile. The core is weak and thick enough that only part or all of the front face sheet and the core undergo permanent plastic deformations, while the back face sheet undergoes an elastic vibration. The core is taken to be rigid-plastic and the front face sheet is treated as an individual rigid-plastic beam resting on a foundation. The back face sheet is modeled as an Euler-Bernoulli beam. Based on the rigid-perfectly theory and Galerkin method, two types of the sandwich beam response are given, i.e., intermediate strength and low strength core type responses. The critical kinetic energy of the projectile as the back face sheet reaches its elastic limit is studied. The localized indentation and response history of the sandwich beam are presented. It is found that the dynamic response of the sandwich beam is sensitive to the core strength, mass ratio, breadth and impact velocity of the projectile. The finite element (FE) simulation is also carried out to verify the analytical predictions and a good agreement is achieved.