High-Fidelity Residual Strength and Life Prediction Tool for Adhesively Bonded Composite Structures Navy SBIR FY2012.1 Sol No.: Navy SBIR FY2012.1 Topic No.: N121-042 Topic Title: High-Fidelity Residual Strength and Life Prediction Tool for Adhesively Bonded Composite Structures Proposal No.: N121-042-0497 Firm: Global Engineering and Materials, Inc. 1 Airport Place, Suite 1 Princeton, New Jersey 08540 Contact: Jim Lua Phone: (860) 398-5620 Web Site: www.GEM-Innovation.com Abstract: A hybrid damage initiation and propagation toolkit for Abaqus will be developed for residual strength and life prediction of adhesively bonded composite structures. This tool will for the first time be able to simulate concurrently both the continuum and discrete damage based progressive failure within the mesh independent computational framework for the solution domain away and near the bondline, respectively. To capture the highly nonlinear material response and the process and environment driven mechanical properties along the bondline, the adhesive layer will be characterized explicitly without introducing a smearing procedure. Given the thin thickness of both the adhesive layer and individual plies above and below the bondline, a continuum shell element along with its phantom pair will be developed to capture the discrete matrix cracking without remeshing. An adaptive fracture process zone model will be developed for an accurate extraction of fracture parameters along the moving crack front within individual plies and at their interface. A unified damage initiation and propagation model will be implemented for both the composite laminate and adhesive to perform the total life prediction under the thermal/mechanical/environmental loading. GEM has secured commitments for technical support from LM, Sikorsky, and Air Force Research Lab. Benefits: The research will result in a versatile, user-friendly, and computationally efficient toolkit for ABAQUS that is capable of evaluating processing dependent bonded structure performance, its environment induced degradation, residual strength, and life expectancy under monotonic and cyclic loading. Our team members LM and Sikorsky have already shown their interests in applying the developed toolkit for optimizing the bonded composite structure design and cost effective maintenance of their existing composite structures. The developed prediction toolkit for Abaqus can be used effectively and efficiently to assist a designer and rule-maker to answer the following questions: 1) is the proposed fabrication and processing procedure rational; 2) does a proposed design have an acceptable risk of failure; 3) how tolerant is a proposed design of a crack without the risk of catastrophic failure; 4) if an initial damage is found in service, how long is it safe to leave the damage before repair; 5) the vessel�_s mission and operational profile have changed, what are the implications for fatigue and fracture risks; 6) how often should the vessel be inspected; 7) what damage size does a structural health monitoring system need to be able to detect to reduce the risk of fracture; and 8) how can measured loads from a structural health monitoring system be used to update the fatigue risks? The tool can be used to assist commercial and military industries to reduce the cost of test-driven design and process iterations with the use of the virtual testing tool. Return