Deformation Calculation Theory And Application Research Of Rubber Water Seal

The work performance of water seal sealing up component directly decides the sealing up effectiveness of gates, thus water seal has an important position in large span and high pressure gate design.The article aims at the obiectivity of calculation of water seal, making effort to look for better arithmetic to enhance the accuracy of simulating calculation, striving to better reflect the characteristic rule while water seal is working and estimate the water sealing effect of water seal. It can not excessively require the accuracy for characteristic value of water seal calculation. Regarding a complex and fuzzy system which may be disturbed by many non-simulative factors, it is impossible to get an accurate calculation value. The obiectivity of calculation is mainly reflected in master degree of characteristic rule of water seal, correctness of water sealing effect evaluation of water seal, and whether the calculated method is improved. In order to improve the accuracy of the simulation calculation of water seal, on the one hand, we hope realize by to improve the calculation theory of water seal, on the other hand, we hope realize by improving calculation method.This article firstly has discussed the space description of large deformation of water seal, analyzed and researched the measurement method of geometric nonlinearity large strain, the stress measurement method and a strict relationship between strain tensor and stress tensor, and established a finite element equation through variational principle. Has described in detail the basic theory and nonlinear handling method of calculation of large deformation, and proposed a method of selecting water seal material strain energy function according to various working conditions and accuracy requirements through the contrast of simulating calculation and model experiment.The mathematical calculation theory of water seal before needs futher improvement, which is an opinion in this article. Although employ Green strain tensor to measure strain is a main trend in mechanics, this article proposes that employ Green strain tensor to measure strain will appear to a false strain value when deformation subject simultaneously has large strain and large twirl, which is not exact. While employ additive decomposition of deformation gradient from Cheng Zhida(+=RStF) to measure strain can avoid this deviation. The simulating calculation for large deformation subject was not accurate enough before, the writer thinks one of the reasons is the manner fault to measure deformation. People are used to employ Green strain tensor to measure strain for a long time, as for the deformation subject simultaneously having large strain and large twirl like water seal, however, strain measured by Green strain tensor is not enough accurate.Large deformation of water seal often is accompanied with large twirl. Based on “Additive Decomposition”, this article has demonstrated that large strain and large twirl of large deformation is a coupling relation, and not a superposition of strain and rigid rotation. If the measurement method is changed, the description of constitutive relationship is corresponding changed. This article has analyzed and discussed the affection of “Additive Decomposition” to constitutive relation presentation of water seal material(i.e. the affection to manifest to stress-strain relationship according strain-energy function), has educed tangent modulus( includes①strain energy function models which are represented by strain tensor invariant, tangent modulus formulas under “additive decomposition”: formula 4-13, formula 4-14, formula 4-15, formula 4-16; ②Mooney-Rivlin strain energy function model, tangent modulus formulas under “additive decomposition”:formula 4-17, formula 4-18, formula 4-19, formula 4-20, ③ Ogden strain energy function model, tangent modulus formulas under “additive decomposition”:formula 4-21, formula 4-22, formula 4-23, formula 4-24) of water seal material under “Additive Decomposition”, thus has established strict material stiffness matrix of finite element calculation of water seal under “Additive Decomposition”, amended balance equation expressed by variational principle under T.L. format of incremental method in finite element calculation, prepared the user material subroutine of finite element calculation of water seal based on “Additive Decomposition”, eliminated the water seal calculation error caused by using Green strain tensor to measure strain. The presentation of the more perfect nonlinear finite element calculation theory and method is the highlight of this paper.The practice shows that the simulating calculation cannot simulate all factors in an actual engineering completely in real and the inherent characteristics of nonlinear calculation, which results in a deviation between results figured out in any case and the actual situation. This article employs response surface method to constitute a numerical model of parameters modification of water seal simulation, the calculation result of simulation after modified to material parameters is further similar to the experiment result of model(the real result of engineering is elusive, although randomness exist in experiment, but people acknowledge the experiment result of model can replace engineering result). Has used response surface of quadratic function with a cross term to make an inversion to the material parameters, discussed the method to improve the accuracy of response surface; used response surface of five function to make an inversion again to the parameters, improved the accuracy of response surface based on the inversion of quadratic function, and verified its validity through experiments.Propose the idea that makes use of metric tensor and Christoffel sign to process a simulation correction based on accurate measuring technique.Based on the research of this article, has made a feature analysis for air pressure retractable sealing up water seal of working door of lock head under ship lift of the Three Gorges Dam. The water sealing performance of section type of gate water seal of ship lift of Three Gorges is optimal in all kinds of current water seals, the seal has typicalness.