Accession Number : ADA315223

Title :   An Axial-Torsional, Thermomechanical Fatigue Testing Technique.

Descriptive Note : Technical memo,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s) : Kalluri, Sreeramesh ; Bonacuse, Peter J.

PDF Url : ADA315223

Report Date : MAY 1995

Pagination or Media Count : 27

Abstract : A technique for conducting strain-controlled, thermomechanical, axial-torsional fatigue tests on thin-walled tubular specimens was developed. Three waveforms of loading, namely, the axial strain waveform, the engineering shear strain waveform, and the temperature waveform were required in these tests. The phasing relationships between the mechanical strain waveforms and the temperature and axial strain waveforms were used to define a set of four axial-torsional, thermomechanical fatigue (AT-TMF) tests. Real-time test control (3 channels) and data acquisition (a minimum of 7 channels) were performed with a software program written in C language and executed on a personal computer. The AT-TMF testing technique was used to investigate the axial-torsional thermomechanical fatigue behavior of a cobalt-base superalloy, Haynes 188. The maximum and minimum temperatures selected for the AT-TMF tests were 760 and 3l6 dec C, respectively. Details of the testing system, calibration of the dynamic temperature profile of the thin-walled tubular specimen, thermal strain compensation technique, and test control and data acquisition schemes, are reported. The isothermal, axial, torsional, and in- and out-of-phase axial-torsional fatigue behaviors of Haynes 188 at 316 and 760 deg C were characterized in previous investigations. The cyclic deformation and fatigue behaviors of Haynes 188 in AT-TMF tests are compared to the previously reported isothermal axial-torsional behavior of this superalloy at the maximum and minimum temperatures.

Descriptors :   *THERMOMECHANICS, *TORSION, *FATIGUE TESTS(MECHANICS), *AXIAL FLOW, TEST AND EVALUATION, COMPUTER PROGRAMS, REPRINTS, TEMPERATURE, REAL TIME, DYNAMICS, DEFORMATION, PROGRAMMING LANGUAGES, WAVEFORMS, STRAIN(MECHANICS), PROFILES, ENGINEERING, DATA ACQUISITION, TUBULAR STRUCTURES, FATIGUE(MECHANICS), THERMAL FATIGUE, CALIBRATION, MICROCOMPUTERS, COMPENSATION, THERMAL STRESSES, SUPERALLOYS, COBALT, SHEAR STRENGTH, THIN WALLS.

Subject Categories : Mechanics
      Fluid Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE