Improved Formulation for Predicting the Load Capacity of Marman Clamps

Abstract

Marman clamps are the most commonly used attachments for spacecraft to expendable launch vehicles. Accurate prediction of the load capacity of the marman clamps is required for spacecraft programs. The currently used empirical formulation underestimates the load capacity of marman clamps and lacks the capability of predicting the influence of the structural parameters on the load capacity. In this paper, the reason for the conservatism of the empirical formulation is examined by primarily using a three-dimensional finite element model, of which the modeling techniques are validated by quasi-static tests. Then, the empirical formulation is improved by taking into account the deformation of the interface ring under external loads. Finally, comparisons of the improved and conventional formulations and the finite element simulation results are conducted. It is revealed that the improved formulation is capable of predicting the load capacity of marman clamps with sound accuracy and is beneficial for understanding the influence of most of the design parameters on the clamp load capacity.