Vol. 2, No. 10, 2007

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ISSN: 1559-3959
Dynamic failure of clamped circular plates subjected to an underwater shock

Sohrab Kazemahvazi, Darren Radford, Vikram S. Deshpande and Norman A. Fleck

Vol. 2 (2007), No. 10, 2007–2023
Abstract

Clamped circular copper plates have been subjected to exponentially decaying underwater blast waves with peak pressures in the range 10 MPa to 300 MPa and decay constants varying between 0.05 ms to 1.1 ms. The deformation and failure modes were observed by high-speed photography. For the thin plates considered in this study, the failure modes were primarily governed by the peak pressures and were reasonably independent of the blast wave decay constant. Three modes of deformation and failure were identified. At low pressures, the plates undergo bending and stretching without rupture (mode I). At intermediate pressures a range of tensile tearing modes were observed, from petalling failures to tearing at the supports with increasing blast pressures. These tearing modes are referred to as mode II failures. At the highest pressures investigated here, the plate tears at the supports in a manner that is reminiscent of a shear-off failure. This failure is labeled as mode III. Scanning electron micrographs of the failure surfaces showed that in all cases, the local failure mechanism was tensile necking. Finite element (FE) simulations employing a local shear failure criterion are used to model the rupture of the material. Appropriately calibrated FE models capture all failure modes with sufficient fidelity.

Keywords
dynamic fracture, petalling, underwater blast, FE simulation
Milestones
Received: 5 September 2007
Accepted: 7 September 2007
Published: 1 December 2007
Authors
Sohrab Kazemahvazi
Cambridge University Engineering Department
Trumpington Street
Cambridge
CB2 1PZ
United Kingdom
Darren Radford
Cambridge University Engineering Department
Trumpington Street
Cambridge
CB2 1PZ
United Kingdom
Vikram S. Deshpande
Cambridge University Engineering Department
Trumpington Street
Cambridge
CB2 1PZ
United Kingdom
Norman A. Fleck
Cambridge University Engineering Department
Trumpington Street
Cambridge
CB2 1PZ
United Kingdom