Published: Jan 1967
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Because of the increasing use of high-strength alloy steels in structural applications and the use of more precise design procedures, knowledge of more detailed and less conventional mechanical properties is required by designers. As part of the effort to obtain such information, a program was initiated to develop a reversed-axial-load test specimen for high-strength steels that would yield reliable information on such properties as the Bauschinger effect and low-cycle fatigue. The program consisted of a theoretical and experimental buckling analysis of the specimen, the design of end grips that were best suited to reversed axial-load testing of high-strength steels, and development of data on the Bauschinger effect for steels with yield strengths from 40 to 185 ksi.
The results of the test development indicated that reliable test data can be obtained from an 0.252-in. diameter specimen with a ⅝-in.-long test section, a larger diameter stiffening section, and threaded ends. Although theoretical analyses indicated that specimen grips rigidly fixed on both ends would result in the highest critical strain in the test specimen at compressive instability, experimental evaluation showed that grips with one end fixed and one end pinned were superior to fixed-fixed or the pinned-pinned end grips.
Tests using the reversed-axial-load specimen with the fixed-pinned grips indicated that the per cent reduction in yield strength attributed to the Bauschinger effect was generally independent of yield strength for steels having yield strengths in the range 40 to 185 ksi. The importance of Bauschinger-effect data in structural design is discussed along with a comparison of reversed-axial-load fatigue data and bend-test fatigue data.
test methods, compression members, steels, fatigue (materials), Bauschinger effect, buckling, yield strength
Boblenz, T. L.
Associate research engineer, Ordnance,
Fisher, J. M.
Research assistant, University of Illinois, Urbana, Ill.
Rolfe, S. T.
Gross, J. H.
Chief, Ordnance Products Div., United,