Research And Numerical Simulation Analysis Of Deformable Plastic Building Formwork

In recent years, a growing number of curved buildings spring up in public, which needs new technology of building construction. The traditional formwork has a complex manufacturing process, which improve the construction cost of the building. Therefore, in order to solve the personalized production requirements of plastic template, a new way of deformable plastic building formwork is proposed. Using the secondary processing properties of thermoplastics, combined with multi-point forming technology, plastic formwork can be deformed flexibly, which can be reused and reduces manufacturing costs. And the new building formwork has applied for national patent.The main contents of this paper is to verify the feasibility of deformable formwork and to optimize the parameters and paths in the forming process of deformable plastic building formwork and finally to discuss the main defects and corresponding controlling methods. The main research of this paper are as follows:(1) Manufacture of deformable plastic building formwork. The carbon fiber heating wire is arranged equidistant inside the template and the plastic raw material heated to be molten is poured into the mold. After the accomplishment of making process, the samples of deformable plastic template will be heated through charged carbon fibers, subsequently followed by a cylindrical-curved verification test. The results shows that after bending the template it doesn t appear surface cracks and maintains high strength, which proofs the feasibility of deformable plastic building formwork.(2) According to the theory of plastic high temperature viscoelastic and super elastic rubber, the material model parameters of plastic and elastic cushion are determined and the finite element model is established. The element selection, the way of the load and the boundary conditions are discussed. Two typical surfaces are chosen, cylinder and saddle surface, to simulate and analyze the deformation of PC and PVC plastic formwork.(3) To discuss the main indentation defects of the plastic formwork during the deformation process. By simulating different forming pressure and body size on the forming surface quality of the parts, it is concluded that the different temperature under plastic template minimum forming pressure and the optimum deformation temperature. Elastic cushions are applied to inhibit the occurance of indentations while simulating and analyzing the effect of elastic cushion thickness on the quality and precision of forming parts, which are aimed at an optimal thickness of elastic cushion under a certain basic body size.(4) The significance of deformable plastic building formwork is that its deformation can be used repeatedly for its deformation. Simulate the transformation between the saddle and cylinder surfaces of different materials and then compare the thickness distribution of before and after the transformation and average thickness error; to improve the lifespan of plastic template, the thickness distribution of formed part should be closed to the original one. Optimize the deforming path and analyze the uniformity of thickness distribution under different forming paths.According to the above research, it is feasible to add the carbon fiber into the plastic formwork. The forming parts with high precision can be obtained by multi-point forming technology, which can realize the repeated use of deformable plastic formwork.