Numerical analysis of the failure mechanisms of continuous miner’s cutter sleeves for redesign and remanufacture

Traditional failure analysis approaches for continuous miner’s cutter (CMC) sleeves used for cutting coal from its seam during underground mining operations employ visual and microscopic examinations to identify modes, causative factors, and mechanisms of their damage. However, this approach is not able to: (i) determine the actual stresses and deformation which cause premature failure of the CMC sleeves, (ii) analyze the influence of sleeve geometry on its failure; nor (iii) assess the feasibility of the recommended remedial measures to mitigate the failure of CMC’s sleeves. To address these concerns, this study used ANSYS software for finite element analysis (FEA), analytical calculation for model verification and the simulation findings were validated via experimental microscopic observations. The results of the FEA static analysis revealed that the collar fracture resulted from a high stress concentration (above 200 MPa) along the transition fillet areas while plastic deformation was caused by stresses above 100 MPa. Interactions between the sleeve and the rock seam generated cyclic stresses between 17-25 MPa which caused collar wear. Geometric redesign and surface modification of the impact prone areas of the sleeve were implemented both singly and synergistically to mitigate the failure of the sleeves. Geometrical redesign of the sleeve collar by increasing fillet radius (1mm to 9mm) lowered the stress concentration factor, resulting in 65% stress reduction. Surface modification with TiC20%wt composite coating reduced stress by 28.06%. Hybrid composite C (TiC10%wt-WC10%wt) exhibited best wear-resistance by achieving 86.33% stress reduction. This was experimentally confirmed through comparative analysis with existing preceding studies on wear-resistance of the three variants of composites. It is concluded that multi-faceted failure analysis not only uncovers the failure modes, causes and mechanisms of premature failure of rotary sleeves, but also ascertains the causative stresses and remedial measures to mitigate the failure of CMC’s sleeves.