Residual Property Prediction for Damaged Composite Structures (MSC P 4091)

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, these material systems provide the ability to expand the function of the structure by tailoring stiffness and strength characteristics for numerous applications. Carbon fiber-reinforced epoxy structures have become very attractive for applications such as solid rocket motor cases, missile airframes, missile guidance housings, as well as many launch tubes and launcher primary structures. The Weapons Development and Integration Directorate within AMRDEC have identified a need to understand the operational fitness of these types of structures following impact events for a wide range of energy levels. The overall objective of the proposed Phase I research program is to develop 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, in particular an improved shell element that offers advantages in both the economy and reliability of computations, is proposed. This novel approach will link the UEL subroutine to a nonlinear material model to evaluate progressive damage of composite materials and a shear correction model that accurately predicts the transverse response of impacted composite structures.