Fatigue Behavior of a Box-Type Welded Structure of Hydraulic Support Used in Coal Mine
Hydraulic support is the main supporting equipment of the coal mining systems, and they are usually subjected to fatigue failure under the high dynamic load. The fracture positions are generally at welded joints where there is a serious stress concentration. In order to investigate and further improve the fatigue strength of hydraulic support, the present work first located the possible position where fatigue failure occurs through finite element analysis, and then fatigue tests were carried out on the different forms of welded joints for the dangerous parts. Finally, Fatigue strength-life (S-N) curves and fracture mechanism were studied. This research will provide a theoretical reference for the fatigue design of welded structures for hydraulic support.
Force Transmission Analysis of Sliding Block-Type Hydraulic Support under Impact Loads
In thin coal seams mining, the structure and support performances of traditional hydraulic support are strictly limited by the working environment. The new type sliding block-type hydraulic support is dedicated for thin coal seams mining. In order to comprehensively evaluate the load-bearing performance of this support, this study investigated the force state of key parts under the effect of impact loads. First, the numerical analysis model of the support was built in ADAMS software. Then, under the pressure action of the top plate, six key points on the top surface of the top beam were selected and applied with impact loads. Linear slippage pairs between sliding block and base in the model were set as different friction coefficients. Force changes at different hinge joints under various impact loads were obtained, and the influence of different friction coefficients of the sliding block on force transmission was explored. Results indicate that hinge joints are sensitive to impact loads in different degrees and thus exert dissimilar influences on the friction coefficient of the sliding block. This study is helpful for structural optimization and strength design of sliding block-type support. paper
Hot-Spot Stress Design Curves For Fatigue Assessment of Welded Structures
Fatigue design rules for welded structures have not kept pace with computing developments in design, notably the increasing use of finite element stress analysis (FEA). In this respect, a design approach based on the hot-spot stress is expected to be the most suitable for treating welded joints in which weld toe cracking is the likely mode of failure. As part of a recent JIP addressing the fatigue design of FPSOs, available hot-spot S-N data obtained from structural weld details, including results obtained as part of the JIP, were evaluated as the basis for hot-spot stress design S-N curves.