Accession Number : AD0815020

Title :   FATIGUE DAMAGE DURING TWO-LEVEL BIAXIAL-STRESS TESTS.

Descriptive Note : Summary rept. 1 Jan 63-31 Dec 65,

Corporate Author : MINNESOTA UNIV MINNEAPOLIS DEPT OF AERONAUTICS AND ENGINEERING MECHANICS

Personal Author(s) : Blatherwick, Allan A. ; Viste, Norman D.

Report Date : FEB 1967

Pagination or Media Count : 37

Abstract : Two-level cumulative damage fatigue tests were conducted under biaxial stress conditions for a selected ratio of principal stresses. The tests were conducted in a machine imposing alternating torque and axial force on tubular specimens of mild steel. It was observed that when the lower stress levels were followed by the high stress levels the cycle-ratio sums were greater than unity. When the higher level stresses were applied first, the sums were less than one, as has been observed in the case of uniaxial fatigue. The Miner and the Henry criteria for predicting damage under uniaxial stress were applied to these biaxial stress conditions. The Henry criterion was observed to be more accurate. A modified Henry criterion is proposed for biaxial-stress fatigue, and a concept of negative damage is introduced. (Author)

Descriptors :   (*FATIGUE(MECHANICS), STRESSES), (*MATHEMATICAL MODELS, FATIGUE(MECHANICS)), TORQUE, TENSILE PROPERTIES, ENERGY, NUMERICAL INTEGRATION, STEEL, RODS, EXPERIMENTAL DATA.

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE