MEASUREMENTS OF STRESS AND STRAIN ON CYLINDRICAL TEST SPECIMENS OF ROCK AND CONCRETE UNDER IMPACT LOADING
Abstract
A test method to determine the minimum dynamic tensional stress required to rupture materials that have a high compressive strength and a relatively low tensile strength is evaluated. The test loading is by impact from an air-fired projectile. The loading device utilizes a 250-gram projectile, and can produce an impact momentum varying from zero to over three pound-seconds. The rise time of the stressing pulse or shock wave produced in the test pieces is in the order to 20 to 30 microseconds, and the pulse length about 10 inches. The test method considered is based on the measurement of the velocity imparted to a pellet lightly attached to the distal end of a cylindrical test specimen subjected to the impact of an air-fired projectile. This velocity measurement provides the basis for computing the maximum longitudinal stress or strain created in the test specimen by the impact loading. The validity of this test method, which is designated as the 'Pellet Technique', is evaluated by attaching strain gages to the test specimens and comparing this direct measurement of maximum longitudinal strain with that indicated by the pellet technique. Comparative measurements of this type were made on cylindrical test specimens of aluminum, quartz monzonite rock, plain concrete, and fibrous-reinforced concrete. There was good correlation between the strains measured directly and those obtained by means of the pellet technique. It is concluded, within certain limitations, that the pellet technique can be used to obtain quantitative values of the dynamic tensile strength for materials that have high compressive strength and relatively low tensile strength.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1966
- Accession Number
- AD0480990
Entities
People
- Donald L. Birkimer
- Frank M. Mellinger