Residual Property Prediction for Damage Composite Structures

Advanced composite material systems are vital to the development of lightweight, multi-functional Army missile systems. In addition to reducing the weight of the structure, composite materials provide the ability to expand the function of the structure by tailoring stiffness and strength characteristics for numerous applications such as solid rocket motor cases, missile airframes, missile guidance housings, as well as many launch tubes and launcher primary structures. The AMRDEC Weapons Development and Integration Directorate has identified a need to understand the operational fitness of such structures following impact events from a wide range of energy levels. The objective of the proposed Phase II research program is to develop and demonstrate an analysis tool that allows designers to evaluate post impact residual strength of composite structures. A user element (UEL) subroutine for use with commercially available analysis codes is proposed. A new shell element that offers advantages in both the economy and reliability of computations is to be demonstrated. This approach will link the UEL subroutine to a nonlinear material model to evaluate progressive damage and a shear correction model that accurately predicts the transverse response of impacted composite structures. Concurrently, material characterization and database development will be conducted to support implementation.