Computer Aided Study Of Modeling And Cutting Pattern Of Pneumatic Membrane Structure

Membrane structure is a new kind of space structure styles appeared in the middle period of the 20th century. It can create lots of colorful outer architecture shapes which are quite different from other structure styles. Therefore, since membrane structure has been acquainted and develops into a kind of structure style, it has been widely used by lots of architects and civil engineers in the space structure buildings such as large gymnasiums, stadiums, exhibition halls and etc.Air-supported structures is a nearlier arisen form of membrane structures.In 1970's and 1980's, it was well used in some countries such as Japan and America,but it was seldom used in our country.Although air-supported structures has some irevocable shortcomings, its advantage in certain field is obvious. Developing with the progress of the level of technology and successive improvement of inflation equipment, it is believed that air-supported structures will be rapidly developed in our country during the next few years.During the design of pneumatic membrane architecture, we not only should meet the demand of graceful and novel, but also should meet the demand of reasonable on mechanics.The shape of this kand of architecture is ususlly figured by mechanics analysis which composed by some discrete planes with no geometric or peremeter denotation. As a result, we can't carry out the shape modeling and drawing by traditional geometric modeling method. In this paper, according to the data format of surface in mechanics analysis software and based on computer aided geometric modeling, we present a novel intersection and trimming algorithm based on triangular discrete surface to realize the complex modeling of pneumatic membrane structure.The analysis of the cutting-pattern is another key step in the designing of the pneumatic membrane structure. The inaccurate cutting-pattern may incur that the shape of the membrane architecture can't meet the anticipated needs of the architects. What's more, it may also cause that it appears fold in the membrane surface. It is more serious that the there is some crack and even more destructive that the wholemembrane structure system collapses. It discusses the definite methods of cutting-pattern lines in the paper and also solves the problems to expansion of the membrane curved surface on the basis of modeling analysis. The paper combines two kinds of methods: the plane cutting method and the expansion method based on spring-mass system, to realize the cutting pattern analysis of the pneumatic membrane structure.This paper's contents are as follows. Firstly, the characteristic of pneumatic membrane structure is described in the paper together with some kinds of membrane materials and their performance. Then it emphasizes the analysis of modeling and cutting-pattern, which are the two key steps in membrane structure designs..At the end of the dissertation, some conclusions are summarized and the problems that should be studied further are put forward.The modeling and cutting pattern analysis programs of pneumatic membrane structures are worked out quite completely by Visual Basic.