Laser-Induced Spall in Silicon Carbide
Abstract
This article presents an alternative (or additional) test technique to investigate ceramic spall strength. The test uses a laser beam to produce the impact conditions for spall. The test configuration consists of a ceramic target covered by an opaque material (usually black tape) followed by a transparent material (usually water). The laser first passes through the water and vaporizes a thin layer of the black tape. The vapor absorbs the remaining laser pulse and creates a rapidly expanding plasma plume. The plume is trapped between the ceramic surface and the water creating a high-pressure, short-duration pressure pulse. The pressure pulse produces a compressive shock in the ceramic which travels through the specimen, creating a tensile (spall) stress near the rear surface after its reflection. Although there is substantial heat generated during this test, it is important to note that the applied stress is produced mechanically (like the plate-impact test) and not thermally. Some advantages of this technique are that it is relatively inexpensive to perform, the applied pressure profile (shock stress) is easily changed, the results are very reproducible, and the targets are not destroyed during testing. This paper presents a discussion of the experimental technique, including test results for silicon carbide. Computations of the experiments are also presented that further validate the JHB model and help analyze the data.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2007
- Accession Number
- ADA515739
Entities
People
- A. A. Wereszczak
- T. J. Holmquist