Strain-controlled thermal mechanical fatigue performance test method

Abstract

The invention relates to a strain-controlled thermal mechanical fatigue performance test method. The method comprises the following steps: firstly, carrying out testing to obtain thermal deformation data in a pure thermal cycle period; dividing the thermal cycle period into four parts, a temperature range of the I part being T0-Tmax, a temperature range of the II part being Tmax-T0, a temperaturerange of the III part being T0-Tmin, and a temperature range of the IV part being Tmin-T0; carrying out segmenting at the moment positions at which the thermal deformation rates change in the parts I,II, III and IV, and then, respectively solving the thermal deformation rate vth of each segment through linear fitting; calculating and determining the total deformation rate vtot of each segment according to the equation vtot=vm+vth, wherein the vm is the mechanical deformation rate required by the test; and finally, controlling a thermo-mechanical fatigue test system to apply a constant mechanical deformation rate vm to the test sample according to the total deformation rate vtot of each segmented test sample. According to the method, the probability that the sample is snapped or bent in advance is reduced, and the fatigue characteristic of the sample under the combined action of temperature and mechanical load at different phase angles can be reflected more accurately.

Description

technical field [0001] The invention belongs to the field of material performance testing, and in particular relates to a strain-controlled thermomechanical fatigue performance testing method. Background technique [0002] The development of modern science and technology tends to require higher and higher service temperatures for engineering components, which has brought the severity of transient heating during work to many equipment in industries such as metallurgy, aviation and chemical industry, especially during startup- During stop or acceleration / deceleration. Various transient thermal stresses and mechanical stresses caused by rapid heating or cooling are superimposed together to form a serious compound stress cycle. Once the equipment fails under the thermal engine fatigue load for a long time, it will often be accompanied by catastrophic accidents such as fire, poisoning, and environmental pollution. . In order to optimize the material selection design and accurat...

AI Technical Summary

Problems solved by technology

When the temperature fluctuates greatly at a certain moment, especially during the cooling process, the existing test method obtains a large deviation between the mechanical deformation at this moment and the actual target value

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