Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session U5: Inelastic Deformations, Fracture and Spall XI |
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Chair: Avinash Dongare, University of Connecticut Room: Regency Ballroom B |
Thursday, July 13, 2017 2:15PM - 2:30PM |
U5.00001: Numerical Simulation and Validation of Damage In AA1100 Aluminum Symmetric Taylor Impact (ROR) Nicola Bonora, Neil K. Bourne, Serafina C. Garcea, Andrew Ruggiero, Domenico Gentile, Gianluca Iannitti, Gabriel Testa Impact velocities for incipient and developed damage condition for AA1000-O aluminum alloy in symmetric Taylor impact tests (rod-on-rod, ROR) were predicted by means of numerical simulation. The material plastic flow was modelled using a modified version of the Rusinek-Klepaczko model and damage calculations were made using a continuum damage mechanics model updated to account for pressure effect on material damage model parameters. There were identified independently using traction test results. 3D numerical simulations of ROR, using a stochastic variation of the damage parameters, were performed to predict development of the damage pattern at different impact velocity. Successively, ROR tests were performed at several impact velocities. Soft recovered samples were scanned using X-ray tomography and analysed to produce 3D maps of nucleated voids that were then used to validate numerical simulation results. [Preview Abstract] |
Thursday, July 13, 2017 2:30PM - 2:45PM |
U5.00002: A modified Non-local GTN damage model for high strain rate loading Nisha Mohan With local continuum damage models, the results are inherently highly sensitive with respect to the spatial discretization length. Therefore to overcome mesh dependence, a modified non-local formulation of GTN damage model is proposed here, to work under an Eulerian explicit finite volume framework. The GTN model also takes advantage of the equations of states to evolve the material properties under high pressures and temperatures. The model is applied to simulate the fracture mechanical test of a typical metallic pressure vessel. It captures the salient features of damage propagation, such as porosity led shear band-like structures and fragmentation under ductile failure. Hence, it is seen to capture damage realistically compared with experimental results. Post-processing is based on the porosity and stress state development at various stages of crack initiation and propagation. [Preview Abstract] |
Thursday, July 13, 2017 2:45PM - 3:00PM |
U5.00003: Expanding rings of stainless steel 304L using a gas gun Russell Amott, Ernest Harris, David Chapman, Daniel Eakins An intrinsic material property of interest is fail under rapid tensile loading. Expanding cylinder experiments using a gas gun have been successfully used in the past to generate high fidelity failure data but were limited to one data point per experiment. By re-designing the expanding cylinder geometry it was instead possible to expand a series of rings. By comparison, large numbers of rings can be launched in a single experiment (with each ring achieving a different radial velocity) generating fragmentation and failure strain data across a range of different radial strain-rates. This new geometry has recently been used to expand rings of stainless steel 304L at radial strain-rates of between 103 and 104 s-1 with precise measurements of a rings expansion velocity and failure strain using a combination of high speed photography and Het-V. The increased amount of data that was collected using the new expanding ring technique enabled a dependence of failure strain on radial strain-rate to be observed. In addition a novel soft recovery system was fielded on a series of identical experiments to enable metallographic analysis on how failure affects the materials micro-structure. [Preview Abstract] |
Thursday, July 13, 2017 3:00PM - 3:15PM |
U5.00004: The dynamic ductile fracture of high purity copper Sarah Ward, Christopher Braithwaite, Andrew Jardine Ductile fracture is widely accepted to proceed through the nucleation, growth and coalescence of voids to form a failure plane. Ductile fracture voids form at grain boundaries, and it has been shown that impurities and secondary phase particles are often found at the centre of these voids. In pure metals, without impurities, theories suggest that void nucleation and growth is governed by dislocations and their substructures, which in turn are underpinned by the plasticity behavior, which is often highly strain rate and history dependent. Here, we describe research which aims to understand the effects of material microstructure and plasticity behavior upon the dynamic fracture properties of high purity copper, by means of high-rate loading of ring samples. Rings of OFHC copper in both the `as-received' and annealed conditions are investigated, at strain rates between 10$^{\mathrm{3}}$ and 10$^{\mathrm{4}}$~s$^{\mathrm{-1}}$. The fragments are studied using Scanning Electron Microscopy, where the characteristic nature of the fracture surface is used to understand the failure mechanism. The effect of the initial microstructure of the material on the fragmentation can then be elucidated through comparisons with the fracture surfaces. [Preview Abstract] |
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