Infrared measuring technique for determination of the increase of temperature in tension tests

Contactless infrared measurement is a suitable technique for the determination of temperature distributions along specimens during dynamic materials tests, e.g. fast tension tests. On the basis of the temperature curve along the specimen, the highest temperature at the point of fracture can be accurately determined. The height of the temperature peaks during fracture and their time sequence have been determined in this accurate manner for the first time. The findings agree well with more complex point contact measurements and, until just before fracture, with a model calculation. Thermal and optical observation on a tension test piece, together with other non-destructive methods (e.g. acoustic analysis, conductivity measurements), offer experimental possibilities for further investigation of fracture processes. As fas as the practical importance of deformation and fracture temperatures during materials tests is concerned, for the time being it can only be stated that specimen temperature increase for temperature- and rate-dependent material parameters should be the basis for comparison. (orig.)