Residual Property Prediction for Damage Composite Structures

To address the U.S. Army"s need to predict the residual strength of composite material laminates that have suffered impacts, Texas Research Institute Austin (TRI/Austin) will integrate a set of new failure criteria into composite material laminate analysis programs that model the damage created by low and high velocity impacts. The failure analysis criteria will be based on properties from limited lamina mechanical tests. The Phase I effort will demonstrate that the new failure criteria can successfully predict the residual strength of laminated plates that have been impacted. For low velocity impacts, the algorithm proposed in the Phase I effort will analytically predict the total delamination area on the specimen for a given impactor geometry, weight, and lamination sequence of the composite. The analysis process can be integrated in spreadsheets or finite element programs. These analysis programs will make the use of composite materials less expensive because the design effort will be reduced, a lower level of testing will be required, and designs will be more efficient - thereby reducing deployment costs. The algorithm developed in the proposed effort will allow a go/no go decision with respect to the suitability of an impacted laminated composite material plate.