Research On Representative Steel Fatigue Crack Growth At High Temperature And Computer Simulation

In practice, especially in aviation, spaceflight, nuclear power generation, chemical engineering and petroleum chemical engineering, a great deal of components or equipments work at elevated temperature condition, and undergo cyclic loadings. One of the main failure patterns is caused by fatigue crack growth, so it is necessary to research material fatigue crack growth rate .So for, it is still a difficult problem to measure crack length at elevated temperature. In international, electric potential is used widely. It is expensive to experiment with the method.According to the characters of SHIMADZU electro hydraulic servo controlled fatigue testing machine and CT specimen, put forward a method based on compliance of stroke displacement which reflects the displacement of loading point at first time. Through studying the relation between crack lengths and loading point compliance, we get the quantificational formula. The results of experiment proof that the method is available and effective.We conduct fatigue crack growth experiment with four kinds of materials through the method, and get complete date of four kinds of materials' fatigue crack growth at first time. And also gain the laws of these four kinds of materials' at between 25 and 550 separately, that is the coefficient and exponent of Paris's formula. Meanwhile finding out the laws of fatigue crack growth of these four kinds of materials with the temperature changing.Based on the above, the author use ANSYS software to simulate the path of fatigue crack growth for sub-model of arbitrary component subjected to combined Mode I , Mode II loading . The conclusion of simulation is very good..The result of research enriches the trial method, get the fatigue crack growth laws of four kinds of pressure vessel materials at high temperature. Provide a kind of numeric method.