Modeling Fracture in Z-Pinned Composite Co-Cured Laminates Using Smeared Properties and Cohesive Elements in DYNA3D
Master's thesis, Aug 2005-Sep 2006
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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The purpose of the present research was three-fold 1 gain a more sophisticated understanding of the response of co-cured composite joints with and without through-thickness reinforcement TTR, 2 compare the behavior of specimens reinforced with various sizes and densities of reinforcement, and 3 use experimental data to verify the existing DYNA3D smeared property model. Double cantilever beam, end-notch flexure and T-section specimens reinforced with 0.011 diameter z-pins at 2 and 4 volume densities were tested to determine the mode I, mode II and mixed mode I and II behavior. Results were added to preliminary research in which tests were conducted on previously mentioned specimen geometries reinforced with 0.022 diameter z-pins at similar densities. Experiments were modeled in DYNA3D using shell and cohesive elements. The energy release rate, G, determined through a curve fit developed from beam theory, was smeared across the region of reinforcement treating it as a separate material. The research validated Z-pinning as an effective means of improving the fracture toughness of polymer matrix laminated composites in mode I and mixed mode loading conditions and determined that the existing model works well in simulating the behavior in mode I tests.
- Laminates and Composite Materials
- Numerical Mathematics