Accession Number:

AD0684077

Title:

AN INVESTIGATION ON PROPAGATING CRACKS BY DYNAMIC PHOTOELASTICITY.

Descriptive Note:

Technical rept.,

Corporate Author:

WASHINGTON UNIV SEATTLE DEPT OF MECHANICAL ENGINEERING

Personal Author(s):

Report Date:

1969-02-01

Pagination or Media Count:

30.0

Abstract:

A 16-spark gap, modified Schardin type camera was constructed for use in dynamic photoelastic analysis of fracturing plastic plates. Using this camera system, dynamic photoelastic patterns in fracturing Homalite-100 plates were recorded. The Homalite-100 material was calibrated for static and dynamic properties of modulus of elasticity, Poissons ratio, and stress optical coefficient. For dynamic calibration, a Hopkinson bar setup was used to record the material response under constant strain-rate loading conditions. The precise location of the dynamic isochromatic patterns in relation to the crack tip was determined by a scanning microdensitometer. This information was then used to determine dynamic stress intensity factors which were compared with corresponding static stress intensity factors determined by the numerical method of direct stiffness. While the dynamic stress intensity factors varied in accordance with the corresponding static stress intensity factors, the former values were generally 40 per cent higher than the latter for constant velocity cracks. For decelerating cracks, the peak values of dynamic stress intensity factors were 40 per cent higher than the corresponding static values. Author

Subject Categories:

  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE