Accession Number : ADA194402

Title :   Automated Measurement of Crack Length and Load Line Displacement at Elevated Temperature,

Corporate Author : ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRAN CE)

Personal Author(s) : VAN Leeuwen, H P ; Groep, F F ; Schra, L ; Dam, N

PDF Url : ADA194402

Report Date : Feb 1988

Pagination or Media Count : 13

Abstract : Test results in the literature show that, in creep cracking tests at elevated temperature under steady load, the crack growth rate correlates best with the contour integral C, also called J*, in comparison to other possible parameters. In the case of the fatigue at elevated temperature, the crack growth rate correlates best with C* if cracking is predominantly time dependent. If, however, cracking is predominantly cycle dependent the crack growth rate correlates best with the range delta J of the contour integral J. It is discussed that in such testing C* and J are fairly easily determined if, apart from load and crack length, the load line displacement is measured. A description is given of a test set-up developed for elevated temperature creep cracking tests in which crack length was measured with the electrical potential drop method and load line displacement was measured with two inductive transducers located inside the furnace. Measurement was automated with the aid of a personal compute which controlled the measurements and processed the results automatically. This set-up can be adapted for elevated temperature fatigue testing. Keywords: Creep tests; Crack propagation; High temperatures; Automatic control; Fatigue tests.

Descriptors :   *CRACK PROPAGATION, *CREEP TESTS, *DISPLACEMENT, *LOAD DISTRIBUTION, AUTOMATIC, AUTOMATION, CONTOURS, CRACKS, FATIGUE TESTS(MECHANICS), FURNACES, INTEGRALS, LENGTH, MEASUREMENT, STEADY STATE, THERMAL STRESSES

Subject Categories : Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE