Predicting The Mechanical Behaviour Of Large Composite Rocket Motor Cases
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A method to develop finite element models of the rocket motor cases of a strategic missile is presented. Based on the use of multivariate analyses, this approach is made necessary given the impossibility to control all input data: difficult characterization of filament wound materials, influence of manufacturing and qualification processes, unknown fabrication parameters, etc. An initial reference model is built up using preliminary data and theoretical winding laws. Having compared the models predictions and available structural test results, a sensitivity analysis is carried out to discuss the individual influence of the input data on the accuracy of the predictions. The multivariate analysis finally enables a global assessment of the parametric analysis results. Keywords: rocket motor case, composite filament winding, finite element model, variable scattering, multivariate analysis, test prediction. 1 Introduction In addition to providing ground test facilities for the development of the future generation of French strategic missiles, the Centre d’Achèvement et d’Essais des Propulseurs et Engins (CAEPE) is responsible for evaluating the degree of performance, durability and security of the solid propellant rocket motors constituting the missiles. The mechanical expertise work is carried out using finite element models able to predict the stresses and strains of the mechanical parts throughout the fabrication and service life. Many difficulties arise when attempting to describe the mechanical behaviour of the rocket motor cases. The filament-wound composite structures have complex geometry and properties especially in the dome area. As the wound layers are added on a cylindrical mandrel, the curvilinear path leads to a
rocket motor case, composite filament winding, finite element model, variable scattering, multivariate analysis, test prediction.