Dynamic operational loading can cause failure of flat-faced gasketed joints of gearbox casings. To design a gasketed joint for certain operating conditions, sufficient knowledge of the behavior of gasket materials is required. Composite gasket materials and formed-in-place gaskets by sealing compounds show a complex nonlinear load-extension and friction behavior. This behavior is mainly influenced by the loading frequency, the amplitude of shear strain, the surface pressure and the operational temperature To identify the material behavior, a standardized method of testing is proposed. The material behavior is described by a modular phenomenol. model that is inserted directly into a general purpose nonlinear finite element program. Consequently, a comprehensive anal. of the mounting and service behavior of arbitrarily designed gasketed joints can be carried out.