Fracture Evaluation and Design Tool for Welded Aluminum Ship Structures Subjected to Impulsive Dynamic Loading Navy STTR FY2010.A Sol No.: Navy STTR FY2010.A Topic No.: N10A-T041 Topic Title: Fracture Evaluation and Design Tool for Welded Aluminum Ship Structures Subjected to Impulsive Dynamic Loading Proposal No.: N10A-041-0527 Firm: Global Engineering and Materials, Inc. 11 Alscot Drive East Lyme, Connecticut 06333 Contact: Jim Lua Phone: (860) 367-4970 Web Site: www.GEM-Consultant.com Abstract: A software tool for fracture evaluation and load deflection prediction of welded aluminum ship structures subjected to impulsive loading will be developed by enhancing and integrating an existing extended finite element method (XFEM) for dynamic fracture of thin shells in Abaqus. The software package will be able to model arbitrary crack paths as dictated by the physics of the scenario, completely independent of the mesh. This will be accomplished by adding discontinuous displacement and velocity fields arbitrarily within the shell elements via two superposed elements with a set of phantom degrees of freedoms. Explicit time integration with one point quadrature scheme and an hourglass control will be implemented to further simplify the treatment of cracked elements and provide consistent history variables for nonlinear material models. A modified Johnson-Cook model coupled with a nonlocal fracture criterion will be implemented to capture an anisotropic and rate dependent nonlinear material behavior and its associated damage initiation. Global Engineering and Materials, Inc. (GEM) has secured commitments for technical support from the University of Texas at El Paso (UTEP) and Professor Ted Belytschko from Northwestern University (NWU). Dr. Belytschko will provide GEM his stand alone explicit dynamic XFEM tool for shells. Benefits: The results from this research will have significant benefits and a wide range of commercial applications in the ship, marine, offshore, automotive and aerospace industries. It will result in 1) a commercially viable, accurate, computationally efficient, and user-friendly tool for fracture damage and residual strength assessment of large scale welded aluminum structures subjected to extreme dynamic loading; 2) a standardized test matrix at the coupon level for quantification of material properties used in the material and fracture models; 3) a virtual testing tool to reduce current certification and qualification costs that are today heavily driven by costly sub-element and full-scale component testing for design certification, and 4) innovative design and fabrication procedures for designing blast resistant structures. The software tool will be of great benefit to 1) ship builders to aid in designing reliable and cost effective aluminum weldments to meet the operating requirements; 2) DOD labs to assess the shock resistance capabilities of welded aluminum structures; and 3) the automotive and aerospace industries to evaluate impact damage and explore new hardening strategies for crashworthiness and other applications. Through a close interaction and alliance partnership with SIMULIA, we will facilitate commercialization of the developed technology and extend its use by the oil industry and civil/architectural engineering firms for the design of lightweight protection system. Return