Fatigue Life Forecast On Excavator Boom Aim At Engineering Machinery's Remanufacturing

In order to remanufacture recycled excavator booms appropriately, it's required to forecast remaining fatigue life of them. Fatigue life forecasting by combining CAE simulation with fatigue analysis software such as FE/SAFE, MSC.Fatigue is the common method, which is however mostly applied to optimization during the phase of new product design. And the result of this method is so ideal and virtual, that it's not suitable to use it for remanufacturing of recycled excavator booms obviously. Therefore, in this article a new method has been presented, hoping to improve the accuracy of remaining fatigue life forecast aimed at remanufacturing.In general, an excavator boom is made up of 12 pieces Q345(16Mn) steel plates by means of welding. In the reality, almost every crack initiates in the position of welding. Currently,the remanufacturing of booms is only replacing these welding-having steel plates with new ones, but that's not enough because it's also necessary to remanufacture those welding-not-having-but-with-fatigue steel plates. Because of the complex working conditions' history the excavator has and the unreliability by using method of “CAE+fatigue analysis software”, in this article a new research approach was proposed. Firstly, 3 typical working conditions were selected based on “cluster analysis” and “equivalent transformation” after conducting analysis on the excavator's working conditions. secondly, before calculating the fatigue ratio of an excavator boom's 12 steel plate, it was still needed to do simulation on that3 typical conditions by CAE, so that the places where the cracks mostly initiate can be located by means of FEM. Thirdly, it was very important to gather the actual working condition's history samples of excavator boom, to design BPNN of boom's remaining fatigue life forecasting combined with Palmgren-Miner theory. Finally, based on the research mentioned above and the building of expert system, a software named “recycled excavator boom management & remaining fatigue life forecasting system” was developed, which realizes better management of booms, remaining fatigue life forecasting of booms and providing corresponding remanufacturing-advice, and performed well in functional test.