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Innovative Methodologies for Modeling Fracture Under High Strain-rate Loading


Seek high fidelity modeling tools for fracture mechanics that are accurate and cost effective for post intercept debris prediction. Acceptable solutions potentially incorporate improved damage models, meshless methods, “peridynamics,” or any combination thereof. Use of first-principles codes to predict the characteristics of post-intercept debris requires prediction of fracture and cracking of aerospace structures. Prediction of crack initiation and propagation can be done using a mesh that follows the crack, but this is time-consuming since it involves re-building the model (re-meshing) in the region of interest. Finite element codes, or hydro-codes (e.g. Dyna, Paradyn, Zapotec, Velodyne, etc.), must capture events on extremely short time-scales for high-rate problems such as high-velocity impact or explosive loading of structures. Within this group of codes, methodologies that address fracture, crack growth, shear bands, and voids are all of interest. Fracture is a challenging problem in applied mechanics and both improved modeling and computational cost are critical to a successful approach. PHASE I: Investigate the feasibility of new damage models or modeling approaches in first-principles codes. Select a tractable problem on an appropriate scale with a known solution or experimental data for verification of the proposed methodology and demonstrate the feasibility of the approach using a representative structural model (incorporating materials commonly used in aerospace structures) with high-rate loadings (e.g. high-velocity impact or explosive loading) that would cause cracking or fracture on the time-scales (at least 20ms duration) of this type of problem. Demonstrate improvements to the fidelity of fracture predictions and assess the computational cost. PHASE II: Perform further demonstration of the methodology proposed in Phase I through application to more complex, larger-scale models of interest, and use of a broader range of experimental data sets. Include implementation of this methodology to predict fracture and crack-growth in full-scale testing, such as flight, sled, or arena tests. PHASE III: Transition the first-principle physics-based modeling capability developed under this program to lethality and debris prediction efforts. Execute model runs for design and analysis cases of interest to missile defense applications including flight test and engineering codes. Commercialization: An innovative application of generalized finite element methods or other fracture modeling approaches to first-principles codes or hydro-codes could then be applied in the defense and aerospace industries wherever high strain-rates appear due to high-velocity impact or explosive loadings, or in other applications such as mining or demolitions where explosive loadings are involved.
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