Weight Optimization of Design Structural Parameters of Sandwich Composite Shells

The paper deals with the main aspects of the technique for weight optimization of design parameters of sandwich shell-type composite structures with a honeycomb filler. This technique was implemented in the framework of the comprehensive approach proposed earlier for the integrated designing of assembly units of the equipment class considered. Multi-parameter problem of optimization of the parameters of sandwich shell-type composite structures was solved. The optimization process was divided into several stages in accordance with the reasonable levels of significance of the parameters included in the objective function, i.e., minimum weight. The results allow us to achieve a deep level of simultaneous optimization of the reinforcement pattern and structure of load-bearing skins, the height of the honeycomb filler, and the geometric parameters of its cell, as well as parameters of the additional structural frame in the regular zone and local reinforcement zones for almost all spectrum of external actions. At the same time, the load-bearing capacity of the structure was provided in all critical areas taking into account the deterioration of the physicomechanical characteristics of materials employed due to thermal effect and fulfilment of additional functional and technological constraints. Using an example of the interstage compartment of a launch rocket, implementation of the technique proposed for synthesis of its rational design and technology parameters was shown. Results of ground-based strength tests of the interstage compartment at this stage of development confirmed the reliability of the results obtained. The results taken as a whole form are the scientific basis for the rational design of sandwich shell-type systems with the honeycomb filler under simultaneous strength and thermal loadings, taking into account of technological constraints and can be used in designing of the other load-bearing shell-type units for aviation, space, and conversion applications.