Bonded Joint Analysis Method Navy STTR FY2012.A Sol No.: Navy STTR FY2012.A Topic No.: N12A-T004 Topic Title: Bonded Joint Analysis Method Proposal No.: N12A-004-0051 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 combined discrete cohesive interface fracture and continuum damage mechanics initiation and propagation toolkit for Abaqus will be developed for the residual strength prediction of adhesively bonded composite structures subjected to multi-axial loading. This tool will allow us, for the first time, to be able to simulate concurrently both the continuum and discrete damage progression at the bonded interface and in the adhesive, respectively, under multiaxial loading. To capture the highly nonlinear material constitutive response and the environmentally-driven mechanical properties along the bondline, the adhesive layer will be characterized explicitly without introducing a smearing procedure. An advanced cohesive fracture model will be developed to account for the combined energy dissipation from decohesion, frictional sliding, and yielding. A hydrostatic stress dependent plasticity model coupled with a continuum shell description will be implemented to capture the damage accumulation in a thin adhesive layer subjected to a combined tension/compression/shear loading. Testing will be performed to identify model parameters and to validate the toolkit at coupon and component levels. GEM has secured commitments for technical support from Virginia Tech, Lockheed Martin, 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 failure sequence and residual strength of jointed composite structures under mixed mode loading. Our team members Lockheed Martin and Sikorsky have already indicated interest in applying the toolkit to optimize the bonded composite structure design and plan cost-effective maintenance of their existing composite structures. Once developed, the 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 under combined tension/compression/shear loading? 3) How tolerant is a proposed design of a crack without the risk of catastrophic failure? 4) If damage is found in service, how long is it safe to leave the damage before repair? and 5) If the vessel�_s mission and operational profile have changed, what are the implications for fracture 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