Dynamic Fracture Under Plane Wave Loading
- Creators
-
Ravichandran, G.
- Clifton, R. J.
Abstract
A new plate impact experiment is presented for studying dynamic fracture processes that occur under sub-microsecond loading. The experiment is designed to provide comparatively straightforward interpretation within the framework of fracture mechanics. A disc containing a mid-plane, pre-fatigued, edge crack that has been propagated halfway across the diameter is impacted by a thin flyer plate of the same material. A compressive pulse propagates through the specimen and reflects from the rear surface as a step, tensile pulse with a duration of 1μs. This plane wave loads the crack and causes initiation and propagation of the crack. The motion of the rear surface is monitored during this event using a laser interferometer system. The location of the crack front is mapped before and after the experiment using a focussed ultrasonic transducer. Experiments have been conducted on a hardened 4340 VAR steel at temperatures ranging from room temperature to — 100°C. Crack advance increases monotonically with increasing impact velocity and with decreasing temperature. Critical values of the stress intensity factor K_Ic are inferred from known elastodynamic solutions and the assumption that the measured crack advance occurs at a constant energy release rate. Fracture modes are characterized by means of scanning electron microscopy of the fracture surfaces. A finite difference method is used for numerical simulation of the experiments. The loading is modelled as that of a plane, square, tensile pulse impinging at normal incidence on a semi-infinite crack. Crack advance is assumed to initiate when the crack-tip stress intensity factor reaches the critical value K_Ic. Crack velocities are prescribed corresponding to various fracture models. The predicted motion of the rear surface is found to be in good agreement with the measured motion when the crack velocity is taken to be a constant.
Additional Information
© 1989 Kluwer Academic Publishers. Received 16 October 1987; accepted in revised form 26 July 1988. The authors are grateful to Professor L.B. Freund for providing many valuable insights during the course of this investigation. The research support of the Army Research Office through the grant DAAG-29-85-K0003 and the NSF Materials Research Laboratory at Brown University is gratefully acknowledged. The calculations described here were carried out in the Computational Mechanics Facility at Brown University and on a CRAY X-MP computer at the National Center for Supercomputing Applications at the University of Illinois, Urbana-Champaign. The Computational Mechanics Facility was made possible by grants from the National Science Foundation (Solid Mechanics Program), the General Electric Foundation, and the Digital Equipment Corporation. Access to the CRAY at NCSA was made possible by a National Science Foundation grant to the Materials Research Laboratory at Brown University.Additional details
- Eprint ID
- 55210
- DOI
- 10.1007/BF00960599
- Resolver ID
- CaltechAUTHORS:20150225-144722141
- DAAG-29-85-K0003
- Army Research Office (ARO)
- NSF Materials Research Laboratory
- NSF Solid Mechanics Program
- General Electric Foundation
- Digital Equipment Corporation
- Created
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2015-03-02Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field
- Caltech groups
- GALCIT