| "Cooling tower" can save investment and operation cost as an advanced environmental protection technology,and it effectively enhances the spreading height of flue gas after desulfurization,so it reduces air pollution.The design of FRP flue is a important content of technology of "cooling tower".History of FRP flue is short,engineering cases and design standards are lacked,at present the main technical problem: material of flue is anisotropic,effective methods of predicting the mechanical properties of the flue are not enough.Therefore,this paper mainly predicts mechanical properties of FRP flue from strength,stiffness,thermal expansion coefficient,and provides the basis for the design of flue,what’s more,visual design program of FRP flue is exploited.Firstly,this paper established a model of strength prediction for progressive failure analysis of laminate.The improved Hashin failure criterion and material degradation criterion was integrated into the finite element analysis,restarting technology could complete each step loading,and the model migth effectively simulate laminates from the initial failure to the ultimate destruction of the gradual process.The ultimate strength of laminates with different plies structure were predicted by using this model,the results of the finite element method were in good agreement with the experimental results,and the errors were less than 7%,which verified the validity of the proposed failure model.This mode provided the basis for predicting the ultimate strength of flue structure.Secondly,unidirectional composite RVE model was built up.Based on micromechanics,the relationship between mesoscopic and macroscopic was created in the finite element.The numbers of predicting the macro elastic modulus and thermal expansion coefficient agreed with the test results.So based on this model,the influences of mesoscopic parameters were studied on the flue macro elastic modulus and thermal expansion coefficient of unidirectional composite material.It could provide the basis for the design and optimization of flue of unidirectional composites,and reduce test iterations.Thirdly,laminated RVE was proposed.This paper considered the relationship between the lamina mechanical properties and the lamanite equivalent mechancial properties.The nine equivalent elastic modulus of the laminate and three equivalent coefficient of thermal expansion were predicted based on the finite element method,the errors were within 2% compared with the literature values,which validated the laminated RVE,the parameters were provided for calculation of flue structure.Using the model predicted the laminate stiffness and thermal expansion coefficient of the four kinds of flue plies,and the effects of the roving content on them were analyzed.Fourthly,the progressive failure model was used to predict the hoop and axial strength of the four kinds of flue plies,furthermore,the damage location and damage form of a fabric a roving ply structure were analyzed,the value of hoop tensile strength was compared with the experimental results,and the errors were 8.6% within the acceptable range.With the increase of the roving,hoop strength was increased,and axial strength was decreased.This paper innovatively put forward a fabric three roving,which axial strength still met the design requirements,moreover the construction was easy to produce,a new ply solution was provided for the design of FRP flue.Finally,based on the prediction of the mechanical properties of FRP flue,the design procedure of the flue based on ANSYS was developed.Flue laminate was considered as the equivalent anisotropic plate in the program,besides the overall stress of the flue structure was thought about,the prediction parameters of flue mechanical and parameters of geometry,load and others were simply input,then ANSYS software could be called to calculate in the background.The program had a good interactive interface,and it reduced the personal workload design and improved the efficiency of the analysis.The influences of different plies of FRP flue in a coal-fired power plant were analyzed based on the program.The calculations showed: the ply of a fabric three roving met the design requirements,and it was more economical and reasonable.This design had a certain theoretical and practical significance for engineering design and application of FRP flue. |
