The dynamic analysis will be demonstrated on the example of a seat for a small 4-seater GA airplane. The airplane is designed according to JAR/FAR-23 regulations. The geometry was subsequently transferred to the MSC.PATRAN preprocessor. This allowed creation of the finite element (FEM) model of the seat. Model of the seat was created using MSC.PATRAN (pre/postprocessor) and analysed using MSC. DYTRAN (solver). The rest of the seat structure was modeled using 1D elements (BAR2) 2D elements (QUAD4, TRIA3 ) and 3D elements (HEX8, WED6). FEM model of the dummy (simulating a pilot) is integrated in MSC.PATRAN/DYTRAN package and the dummy is generated by GEBOD application. The dummy is composed of 2 main parts - ellipsoids and skin.First part is made from RIGID ellipsoids. Ellipsoids are connected together using linkages that simulate articulations. This part of the dummy is responsible for the behavior of the dummy. Second part is the dummy's skin, using 2D elements. Materials in the seat construction were defined using DMATEP. This material model defines properties of isotropic elasto-plastic material for shell and beam elements. This model enables inclusion of the yield stress, changes in hardening modulus and failure. Loads were applied in accordance with JAR/FAR 23.562 (b) (1) as the change in velocity in the attachment between the seat/restraint system and the test fixture. Velocities and accelerations in chosen points on the dummy were monitored during computation. Points were chosen where necessary with respect to monitoring of max. accelerations. Such points are in the CG of occupant's head, chest and pelvis. Results were compared with recommendations of regulations for max. accelerations imposed on the human body.
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