Simulation of a clamping ring under high dynamic loading

Clamping rings are used in a wide range of mechanical applications in order to assemble two or more cylindrical parts, e.g. tubes and pipes, pressure vessels and tanks. Another application area of clamping rings is in turbo engines, where they connect compressor, bearing and turbine casings for example. For normal operating conditions, standard rules or simple static analyses are adequate to determine the relevant design parameters of this device. But these analyses are not sufficient for highly dynamic loading as in case of misuse or failure, e.g. shock waves, compressor surge and in particular the impeller burst. In these cases the loading of the clamping ring is no longer static nor linear. The impulse transmitted and the mass inertia of the parts connected play an essential role for the loading scenario. In addition the non-linear material behaviour, the high geometric deformation and plastification up to material failure as well as the complex contact situation have to be taken into account. For these extensive analyses explicit simulations using LS-DYNA have proven to be a highly efficient tool. This presentation gives an overview on how to use CAE simulation for designing a clamping ring for highly dynamic loading. As a first step in the process described, a quasi-static pullout test is used to achieve a high correlation between hardware testing and simulation. The paper also gives an idea of the influences of some typical design parameters of a clamping ring, e.g. wall thickness and numbers of segments of the v-shaped lower strap. A focus of the development needs to be on the balance of structural stiffness of the clamping ring for one thing and the flanges of the parts connected for another. The presentation concludes by showing a successful simulation using LS-DYNA Explicit for the highly loaded clamping ring due to an impeller burst.