Critical Growth Stress for Spallation,
Abstract
The slip line field analysis of ductile void development is applied to the problem of fracture with stress waves, i.e., spallation, and an expression is developed for the prediction of the critical growth stress sigma go of voids in an elastic-plastic material. Comparison of experimentally measured values of sigma go with predictions based on the initial state of the material indicates it is important to account for the change in yield point of the material caused by the shock compression of the stress wave that eventually causes fracture. Application of standard yield point measurements of preshocked samples reveals that recovery processes can be important. If the critical void growth stress is expressed in terms of the shock compression effects prior to spallation, it does not appear to be a constant characteristic of the material since the shock effects are reflected in the result. The formulation presented describes shock effects and explicitly states how sigma go should depend on the extent of prior plastic strain, the plastic strain rate of this compression and recovery prior to and during the spallation process. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1977
- Accession Number
- ADA045413
Entities
People
- Gerald L. Moss
Organizations
- Ballistic Research Laboratory