Accession Number : AD0470068

Title :   ON SECOND ORDER STRAIN ACCUMULATION IN ALUMINUM IN REVERSED CYCLIC TORSION AT ELEVATED TEMPERATURES.

Descriptive Note : Technical rept.,

Corporate Author : COLUMBIA UNIV NEW YORK INST FOR THE STUDY OF FATIGUE AND RELIABILITY

Personal Author(s) : Ronay,Maria

Report Date : JUN 1965

Pagination or Media Count : 63

Abstract : Experiments on superpure aluminum in reversed cyclic torsion at elevated temperatures showed that the second order axial elongation of the specimen increases with increasing temperature in the 100 - 300 C. temperature range. The quadratic relation between the accumulated second order strain increments and the applied shear strain amplitude already found at room temperature holds at each elevated temperature investigated. The second order strain increment is a function of the applied shear strain amplitude, previous number of cycles and temperature. The cycle and temperature effects can be separated, the temperatures function being exponential. A fictitious activation energy was calculated for the second order extension of aluminum ('cyclic creep') and was found to be almost one order of magnitude smaller than the activation energy of static (high temperature) creep, showing that different material parameters are involved in the two phenomena. The relation between first order cyclic recovery and second order strain accumulation was established. (Author)

Descriptors :   (*ALUMINUM, STRAIN(MECHANICS)), (*STRAIN(MECHANICS), ALUMINUM), (*FATIGUE(MECHANICS), ALUMINUM), DEFORMATION, CREEP, HIGH TEMPERATURE, HEAT OF ACTIVATION, THERMAL STRESSES

Distribution Statement : APPROVED FOR PUBLIC RELEASE