Numerical Simulation Of Deformations Resulting From The External Turning Of Thin Spherical Shells

This project is sponsored by the CAEP Science Development Funds. In CAEP's weapons research and manufacture, the processing of thin-spherical-parts occupies an important place. The minimization of the deformation occurring in processing is a determining factor in improving precision work. In actual processing, technological measures based on qualitative analysis and rules of thumb are often taken to reduce deformation, which usually involves plenty of time and experimentation and suffers from a certain degree of uncertainty. The present study proposes to describe by numerical computation the major physical factors bearing on the deformation in processing and establish a relatively accurate model for predicting the degree of deformation and the possible effects of technological ameliorations. This may help to cut down on the time and experimentation involved in the processing and raise the processing standards of some spare parts.In this paper, we first elaborate on the basic finite element theory and its application to the processing with a particular view to the processing of thin spherical shells. Secondly, we set up a technological model of the processing by drawing from actual engineering experience. Thirdly, we make an analysis of the mechanical factors involved in the deformation resulting from the processing, thereby establishing a mechanical model and a finite element model of the deformation for the processing of thin spherical shells. Finally, on the basis of detailed analysis and research, we have used MARC, a powerful simulation software, to carry out numerical simulation of the deformation that occurs in the processing of thin spherical shells due to the effect of the turning force and the clamping force. The numerical model has been confirmed byexperiments as a fairly close reflection and prediction of the actual deformation.This project has reached its goals and is significant in offering guidance in doing related weapons research and development. Following is a summary of the major innovative points in this paper:1. This paper proposes to set up numerical models for the prediction of the possible deformations resulting from the processing of thin spherical shells by turning. This offers an effective means to compare and analyze major physical factors involved in deformation-related deformations, predict the effects of various technological ameliorations, reduce the experimental costs, and improve the technological standards of processed spare parts.2. This paper investigates the effects of such deformation-related factors as the turning force, the clamping force, the turning energy, and the machine tool, on deformation. Based on this investigation, this paper has simplified the processing of thin spherical shells and establishes the mechanical models of their deformation.3. By adopting the spring finite-element theory and computer simulation technology, this paper has studied the numerical models of the deformation of thin spherical shells in processing. The data achieved by using MARC, a simulation software, generally agree with those achieved from the experiments, with an error reasonably acceptable, showing that the mechanical model and the finite-element model we establish are convincingly correct.4. The computation methods by numerical simulation as proposed in this paper are capable of making a relatively accurate prediction of the effects that technological ameliorations may have on the processing of thin spherical shells, and thereby setting up a data bank for simulation results. This is highly significant in offering guidance to engineering practice, improving the processing standards of spare parts, raise the rate of processing, and reduce the productive costs.