The Fatigue Life Of Identify Of Box Type Pump Truck Boom

Boom is a key carrying parts of concrete pump truck, its structure is a typical thin arm box welding beam structure which is under the cyclic loading and easy to fatigue failure in the process of work. Especially with the large-scale development of construction machinery, yield strength of 700 to 900 Mpa and higher strength steel material is widely used in pump truck arm shelf structure. Compared with the ordinary steel, high strength steel are more sensitive for defects, less fatigue resistance, fatigue has become a key problems that affect the pump truck boom security. Therefore, at the beginning of the design, it is very important to get the understanding for fatigue characteristics of pump truck boom and accurately estimate the fatigue life of beam.In this paper, the research object on the fatigue life is based on the high strength steel pump truck boom, apply the theoretical research results in the actual production effectively for solving the practical problems in engineering.(1) In order to get the high strength steel material S-N curve, the identity of the mother material experiment with welded joint fatigue properties can be taken.Combining with Miner damage rule, using the nominal stress method to boom shrink more than the model forecast, and doing bench experiment of boom shrink ratio model, introducing the correcting coefficient for pump truck boom S-N curve.(2) The experiment of fatigue crack propagation rate based on High strength steel should be carried out for getting the the Paris formula of high strength steel material. Using the method of fracture mechanics to forecast the boom shrinkage model life, and carrying out the bench experiment on the boom shrinkage model,according to the experimental results to correct the Paris formula for the pump truck arm C、m, with a shelf life of forecast values.(3) For verifying the accuracy of the above methods and finding the experience formula of the forecast of high strength steel pump truck arm shelf life through the boom of bench experiment, nominal stress method and fracture mechanics method is used to pump truck arm forecasts for the whole life cycle in the first quarter. In addition, virtual fatigue analysis was also carried out on the pump truck boom, through fatigue bench test, the accuracy the virtual fatigue of the finite element analysis was verified.This paper obtained the identity of the pump truck arm shelf life forecast empirical formula, and the experiment and the actual test and verify. This methodcan not only be used on the estimate the service life of the pump truck at the early and applied to the current evaluation in the pump truck arm shelf life, but also has the reference function for other forms of pump truck boom and the service life of the whole machine forecast work evaluation.