Cable shovels are used in the primary excavation of in situ and/or prefragmented formations in surface mining operations. Poorly fragmented hard rock formations and the random occurrence of hard boulders in soft formations cause extreme variability of material dig ability, resulting in varying shovel stress loading. High static and the repeated dynamic impact loading of a shovel's front-end assembly could exceed component yield strength, resulting in component failure. The conventional design process, which uses physical shovel simulation studies, is very costly and time consuming for achieving statistically significant results. In this paper, rigid and flexible multi-body dynamic theories are used to develop component stress loading models of the cable shovel assembly. The models are solved in the ADAMS/NASTRAN/FLEX simulation environments. A virtual prototype simulator, based on the geometry of the P&H 4100A cable shovel, is developed to capture a three-dimensional interactive surface mining environment. Detailed simulation of this virtual shovel simulator is carried out to find the front-end driving loads and torques, component stress distributions and nodal stresses under varying formation conditions. The simulated results are validated using existing test data. The results show that, under the given simulation environment, the highly stressed fields occur in the boom, crowd arm, boom-point sheave and hoist rope. During the simulated digging cycle, the stresses vary from a minimum of 205.47 MPa (29,800 psi) in the boom to 313.31 MPa (45,440 psi) in the rope attachment to the dipper. This study is significant in the areas of machine reliability, performance efficiency and production economics. It provides a solid foundation for further studies into machine fatigue failure for optimizing shovel-operating performance and minimizing maintenance costs.
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