Issue 42

J.-f. He et alii, Frattura ed Integrità Strutturale, 42 (2017) 263-271; DOI: 10.3221/IGF-ESIS.42.28 267 Materials (slider/External cylinder) Applied load (MPa) Friction coefficient (m/s) Temperature ( ℃ ) 35CrMo/PTFE 50 ～ 70 0.01 ～ 0.03 -180 ～ 250 35CrMo/POM 50 ～ 70 0.15 ～ 0.35 -180 ～ 260 35CrMo/P-Ni 0 ～ 715 0.1 -180 ～ 200 Table 1 : Property of numerical models of hydraulic hammers with horizontal oriented sliders. There are totally 42318 elements in each of numerical model, and the meshed grids are hexahedrons, which are obtained by sweep meshing of ANSYS. All of the meshed grids are volume grids with a maximum diameter of 3mm, and the grid coordination is excellent. The maximum grid deviation is 5%, which guarantees the accuracy of simulation results. The meshed elements of a horizontal oriented slider are shown as Fig. 3. Boundary Conditions and Solver Settings In order to reduce the computational time, the numerical model was simplified with horizontal friction force, and other extra loads were ignored, such as hydraulic pressure, fluids resistance and buoyance of drilling mud. Moreover, the boundary condition of contact region between horizontal oriented slider and external cylinder is simplified as wetting boundary conditions. In addition, the initial load on oriented sliders was applied with 1kN, and friction coefficient between oriented slider and external cylinder is denoted as 0.02. Once all numerical models were finishing computing, the abrasion rate of hydraulic hammer has been obtained, which is helpful to optimize the structure design of hydraulic DTH hammers with horizontal oriented sliders. Figure 4 : Contact cells between horizontal oriented slider and external cylinder. With regard to the solver settings of numerical simulation with horizontal oriented sliders, there are totally 1000 time steps were set. The details of solver settings are as shown in Tab. 2. Thus the abrasion property of hydraulic hammers with horizontal oriented sliders can be obtained with various material models and boundary conditions. R ESULTS AND DISCUSSIONS he abrasion property of a hydraulic hammer with horizontal oriented sliders has been numerically modeled by FEA simulation. Especially the moving velocity of the anvil, the mass of anvil or applied load, and the friction coefficient of horizontal oriented sliders have been separately analyzed with various numerical models. Meanwhile, T