Accession Number:

AD0870792

Title:

Investigation of Dynamic Mechanical Stress with Photoelastic Techniques

Descriptive Note:

Technical rept. 1 Apr-3 Sep 1969

Corporate Author:

HUGHES AIRCRAFT CO FULLERTON CA

Report Date:

1970-04-01

Pagination or Media Count:

54.0

Abstract:

The technique of dynamic photoelasticity has been applied to a study of hypervelocity impact phenomena. The target consisted of a cadmium front plate, followed either by a void or a foam filled space, and a rear plate of steel or aluminum. Two series of tests were carried out. The first, employing a Plexiglas rod, acting as a Hopkinson pressure bar in a transmission polariscope arrangement, sensed the pressure time history resulting from debris stagnation in the second plate. In the second series, the rear plate was provided with a photoelastic coating as part of a reflection polariscope. Dynamic stress patterns, produced by a debris impact, were photographed as they developed in time and provided a whole field view of the nature of the pattern. The experimental results indicate that Plexiglas can be used successfully as a pressure bar for dynamic stress measurements in the range of several kilobars. Analysis of dynamic plate motion indicates the presence of elastic extensional waves and shows that second plate deformation and rupture are accompanied by elastic effects.

Subject Categories:

  • Test Facilities, Equipment and Methods
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE