ENGINEERING METHOD FOR CALCULATING ISOGRID COMPOSITE REINFORCEMENT IN COMBINED TOROIDAL TANKS

The article focuses on determining the parameters of isogrid reinforcement for a combined toroidal tank. It addresses the need to implement a simplified model for a method that can be used for preliminary tank design. This approach allows for analyzing the impact of geometric parameters of isogrid reinforcement and the effect of the mechanical characteristics of the composite reinforcement tape on the mass of the combined toroidal shell. The research is based on developing a simplified model in which the composite reinforcement operates under linear stress conditions, while the liner functions in the nonlinear deformation zone. Compatibility conditions for deformation between the liner and the composite are met, and the composite's performance is assessed using the strain-based strength theory. An algorithm for calculating of the proposed method has been developed. Using this algorithm, combined toroidal tanks with isogrid reinforcement were calculated. A comparison was made with existing metal tanks used in the first and second stages of the European Ariane launch vehicle and water tanks of the Indian GSLV Mk3 and PSLV launch vehicles. The results show that application of isogrid reinforcement can reduce tank mass by up to 50%. The proposed method was also compared with an existing one for assessing the mass of a combined tank with continuous longitudinal-transverse winding of composite tape. This research expands the set of engineering methods for designing combined toroidal tanks with isogrid composite reinforcement. The study is limited to analyzing the geometric parameters of isogrid reinforcement and does not address optimizing the tank's design parameters. The work aims to use the initial approximation results in creating a model for finite element analysis. Future studies may focus on application of the method for parametric modeling of the shell via the finite element method and conducting numerical experiments to determine a viable minimal-mass structure.