Monday  |  Salon 13  |  04:10 PM–04:30 PM

#15790, High-Rate Ductile Fracture of Al 7075 Alloy at a Range of Stress Triaxialities

Engineering materials are intrinsically heterogeneous owing to their processing history. For heat-treatable lightweight aluminum alloys, e.g., 7XXX alloys, the fracture behavior is governed by the size and distribution of second phase particles. Modern empirical and micro-mechanically motivated computational failure models used for ductile fracture calculations do not include spatially heterogeneous microstructural information in any meaningful manner, despite recent significant advances in high-throughput, three-dimensional in-situ and ex-situ characterization techniques. Our hypothesis is that direct numerical simulations of particle-initiated failure, which will be informed by advanced testing and characterization, will provide the most realistic prediction of failure to date. This paper will focus on high-rate ductile fracture experiments using the mini-tension Kolsky bar with sample geometries that induce a wide range of stress triaxialities—from pure shear to plane strain tension. Samples are cut from near the surface and at the midplane of a thick plate because the size and distribution of the second phase particles, and the texture of the matrix Al, are different at these locations. Deformation of the different geometries is recorded at 1 mfps, where the total loading time is approximately 100 µs. The experiments show there is a clear difference in the flow response between the two locations, but a clear strain to failure difference is not clear from these initial experiments.

Christopher Meredith   DEVCOM Army Research Laboratory
Jeffrey Lloyd   DEVCOM Army Research Laboratory
Daniel Magagnosc   DEVCOM Army Research Laboratory