A Semi-combustible Cartridge Artillery Sealing Structure Multi-Objective Optimization

The sealing technology of the swing chamber is one of the CTA gun's key Technologies. Semi-combustible cartridge structure was used in a new-type CTA gun to seal the swing chamber. While achieving the goal of sealing, the extracting problems was brought. Based on the background of Defense Pre-research project, finite element method, elastic-plastic mechanics, and optimal design theory were used to research the principle of the sealing and extracting problems, which can not only provide theoretical foundation and design decision for engineering practice of such weapon systems, but a new way of thinking for solving the engineering-related problems. The main research content is as follows:(1) The principle of a new-type swing chamber gun was analyzed, the key sealing area was found. The reliable criterion of the semi-combustible cartridge, the sealing time of the channel B, was established to judge the effect of the whole sealing system.(2) The large-scale nonlinear FEA software ABAQUS was further developed with Python language, the design variables which had great impact on the extracting force were parameterized and the parametrical finite element model for the seal structure was created to achieve the automation of the optimization process.(3) By studying the physical process of extracting ammunition, the main reason leading to the extracting problem was found. Meanwhile, the basic assumptions for the structure's material properties were proposed. The interaction between the cartridge and the chamber during the 3 stages, paste chamber, from paste chamber to maximum chamber pressure and unloading, was analyzed. The calculation model for the new-type gun was derived based on the static elastic-plastic theory. By comparing the finite element results, the model was verified reasonable. Through further discussion of the model, the two important ways, optimal materials and optimize design parameters, were found to reduce the extracting force.(4) Based on the parametrical finite element model mentioned before, the mathematic model for the sealing structure was created, with the length, the thickness and the initial seal clearance as design variables, the reliable seal as restriction, the residual contact stress, the time for establishing a reliable seal and the mass of the sealing structure as objective. Meanwhile, the range of the 3 parameters and the "step" were determined from the engineering point of view. Finally, based on the multidisciplinary design optimization software mode-FRONTIER, the seal structure was optimized via combining multi-objective genetic algorithm and the response surface method. Check the effect of the optimal parameter compounding during the entire time domain, showing it satisfied the requirement.(5) Taking the characteristic which nonlinear finite element requires a lot of time into account, the respond surface methodology was used in the optimization.3 plans were proposed based on RSM. Comparing the design of experiment (DOE), establishment and validation of response surface of the 3 plans, finally the programming orthogonal polynomial fitting method was selected as the only RSM in the paper. It is suggested that, the optimize method used in this paper guarantees balance between accuracy and efficiency, it is a promising design method for solving related engineering problem.