| In recent years,the construction industry was driven into a period of vigorous development with the rapid urbanization and vigorously promoting demolition and transformation.However,the shortage of labor had also become an important factor restricting its development.Therefore,the trend of machinery substitute for manual construction has become popular.Plastering machine is a kind of construction machinery which can replace human to complete large area plastering operation,and the application of plastering machine can change the traditional manual operation mode,besides it improve the rendering efficiency and eliminate the disadvantages of big labor intensity and the long construction period.This paper will design a new plastering machine which can realize automatic positioning and adjustment function,in addition to a vibration device was designed that can be modulated to adapt to different plastering mortar materials;finally the finite element model of plastering plate-mortar was established,and the property of mortar is defined based on Drucker-Prager yield criterion.Then the vibration compaction process was simulated by Ls-Dyna,and analyzed the stress distribution and displacement characteristics of the mortar under the combination of different compaction parameters.The results provide reference for the practical application of the project.The specific research contents are as follows:(1)This paper introduced the research status,basic structure,working principle and working flow of the plastering machine.Besides,the research of the vibration compaction technology and the finite element simulation analysis about the vibration system were introduced;(2)The overall scheme of plastering machine was determined according to the functional requirements and the operation mode.An adjustment method with three degree of freedom was designed to ensure the absolute flatness and verticality of the mortar layer and realize the automatic positioning.The excitation device of the plastering machine is designed according to the requirement of the density of different plastering mortar.The basic structure size of parts was determined base on the technical parameters of plastering machine and the key components were calculated.Finally the three-dimensional model was established by Pro/E which laid the foundation for the subsequent analysis;(3)The key components of plastering machine were analyzed by ANSYS in order to verify the safety.The dynamic analysis of the gear rack dynamic contact of the main drive system was carried out to verify the reliability.Especially the dynamic characteristic of the plastering board was analyzed which laid the foundation for the dynamic analysis of vibration system;(4)The dynamics model of plaster board-mortar was established,and mortar elastic-plastic matrix expression was calculated based on the elastic-plastic theory.The Drucker-Prager mortar elastic-plastic material was defined and the simulation of the vibration system was carried out with the help of LS-Dyna.Then the correctness of the finite element model was verified by comparing the vibration acceleration and the experiment data of the plaster board;(5)The multi parameter simulations were carried out by taking the amplitude,vibration frequency and moving speed as the main control parameters of compaction.Then optimal scheme which is suitable for thin layer of mortar was determined by drawing factor trends which expresses the influence of three factors on the dynamic response of mortar.Finally,it is found that the value of the dynamic stress in the depth direction of mortar layer is attenuated by exponential function by using MATLAB.The results provide a theoretical basis for the rational selection of the compaction parameters and the prediction of the compaction effect. |
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