How does TMF meet the testing requirements of high-end indus
Thermomechanical fatigue (TMF) test is a difficult and challenging test, which is very important for the development of advanced turbines. In the testing process, the material needs to endure the double periodic test of mechanical strain and temperature change. At first, this test was only an unconventional test used by a few professionals in highly specialized industry research, but now it has become an important characteristic parameter and a set of standardized test methods, which are increasingly favored by users.
This test comes from the high temperature low cycle fatigue (LCF) test, which better simulates the synchronous changes of strain and temperature of materials under the actual working conditions of turbines and power generation equipment. Different testing schemes will produce different phases, so synchronization is very important. For example, strain and temperature can increase or decrease synchronously, or one can increase first and then the other can also increase, which will have a significant impact on damage accumulation and performance of any material. In addition, during the performance test of materials, due to the change of temperature, it is necessary to analyze and compensate the thermal expansion and cold contraction of materials, otherwise the strain applied to the samples may be quite different from the expected level. In addition, because the required cycle time is only within tens of seconds to hundreds of seconds, the traditional high-temperature furnace technology is gradually eliminated by induction heating and air jet cooling. The induction heating system not only has remarkable heating effect, but also has high sensitivity to the geometric structure and material of the sample. Finally, although we have well established the low cycle fatigue (LCF) test procedure, we should not mistakenly think that it is an easy test. Accurate alignment, machine rigidity, high precision and strain control are all important considerations. Moreover, because the samples yield in each cycle, operators need to be careful.
This test comes from the high temperature low cycle fatigue (LCF) test, which better simulates the synchronous changes of strain and temperature of materials under the actual working conditions of turbines and power generation equipment. Different testing schemes will produce different phases, so synchronization is very important. For example, strain and temperature can increase or decrease synchronously, or one can increase first and then the other can also increase, which will have a significant impact on damage accumulation and performance of any material. In addition, during the performance test of materials, due to the change of temperature, it is necessary to analyze and compensate the thermal expansion and cold contraction of materials, otherwise the strain applied to the samples may be quite different from the expected level. In addition, because the required cycle time is only within tens of seconds to hundreds of seconds, the traditional high-temperature furnace technology is gradually eliminated by induction heating and air jet cooling. The induction heating system not only has remarkable heating effect, but also has high sensitivity to the geometric structure and material of the sample. Finally, although we have well established the low cycle fatigue (LCF) test procedure, we should not mistakenly think that it is an easy test. Accurate alignment, machine rigidity, high precision and strain control are all important considerations. Moreover, because the samples yield in each cycle, operators need to be careful.