Hydraulic Actuator

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Gussoni Enrico 804089 Olivari Laura 876599 HYDRAULIC ACTUATOR OBJECTIVES Given the geometry of the hydraulic cylinder, it is requested to: 1) provide a schematization of the cylinder structure for FEM modelling, paying attention to the boundary conditions (decide which are the important aspects to be modelled). 2) Model the complete actuator to compare results (in terms of strains) with experimental data. In addition, compare both numerical and experimental results with Mariotte formulae. 3) Model the cylinder+hole to compare results with the analytical solution of plates with hole at some selected points. POINT 1 In order to schematize the actuator in the FEM model we have to provide some simplification s, in particular:  In the shell model we have to pay attention to whe re two cell surfaces intersect: the shell element does not allow to represent in detail the real geometry, thus it is not possible to have an accurate simulation. To avoid problems, we decide not to model the cap in the shell model.  Boundary conditions of joint are applied on the edge of the cylinder in the shell model, on the entire external surface of the cap in the solid model.  We apply the pressure on the internal surface up to where there is the piston. In order to get goods results it is not important to model the rod part and its hole. POINT2 In the following graphs the zero is in correspondence of the end of the cap ; to get a meaningful comparison, FEM results are evaluated in the same point of the real application of the strain gauge. EXPERIMENTAL RESULTS The cylinder is pressurized by means of hydraulic o il. Resistive strain gauges are applied on the vessel in order to meas ure the strain along a straight line in the axial dir ection (cylinder generatrix). Each strain gauge is bia…