NEW METHOD OF MEASURING TEMPERATURE AND STRAIN IN HIGH TEMPERATURE LOW CYCLE FATIGUE AND THERMO-MECHANICAL FATIGUE TESTING

摘要

A new method of measuring both temperature and strain in the parallel length of the gauge section in HTLCF and TMF tests is investigated. The temperature is measured by a type-K-bar-thermocouple that is situated directly in the inside of the testing cross section of the specimen with an in lying drilled hole. The strain is even measured directly in the testing cross section by a special high temperature extensometer. The advantage of this method measuring both temperature and strain in the parallel length of the gauge section is to minimize possible inaccuracies with conditional transfer functions. In this study the effects of the in lying drilled hole on Low Cycle Fatigue results should be determined by means of two aluminium wrought alloys (two batches with a heavyset difference in there static property) with its specific shear fracture behaviour and an aluminium cast alloy with its specific brittle fracture behaviour. Moreover the influence of the dwell time at the maximum temperature in TMF tests, an important influence factor for thermal-mechanical fatigue is investigated. Out-of-phase TMF tests are performed for three different dwell times at the particular maximum temperatures to investigate the deformation and fatigue response.