| The portal crane is widely used in many departments of national economy. But the abominable working environment and complex loads cause the mainly load-carrying components of the structure often occured fracture unexpected. And these accidents lead to the enormous economic loss and casualty incident.By analyzing a lot of metal structure accidents of portal crane, we can see: The crackle has been always produced before accident taking place, and the crackle is expanding constantly as time goes on. When the crackle expanding to a certain degree, it make metal structure take place fateful destroy. Accompany by the trouble of metal structure emergence we always can see the great influence of fatigue in this course. Is there corresponding relationship of a certain degree between the fatigue and crackle of metal structure? This text takes the metal structure of portal crane as an example to discuss this question.This text uses parameterized technology to modeling the operating process of the portal crane, and analysis the fatigue of whole structure; Draw the fatigue nephogram of the crane by using Visual C++ software, and compare the result of fatigue calculation with the investigation statistics of the crackle, find out the relationship between them. The main research contents and results of the dissertation are as fellows:1) To build a portal crane's FEM model by using ANSYS internal command—APDL. This is the most basic and important step of the text;2) Analysis the strength of structure;3) Confirm the loads and method of fatigue calculation;4) Study the fatigue calculation result of the crane structure. Draw the fatigue nephogram of the crane basic on the datum by calculating out; Compare the fatigue calculation result with the investigate date of the crackle, find out the relationship between them;5) Propose some suggestions and methods on the basis of the above, delay the speed of fatigue and the speed of the crackle expansion, extend the service life of the portal crane.
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