Research On Design And Optimization Of Large Cross-Laminated Timber Press

Cross-laminated timber(CLT)is a new type of wood production for construction.Pressing is one of important processes in production of CLT.Special press is needed as breadth of the CLT is large and high pressure is required for the pressing.There are few studies related to the design of CLT press in China.As a result,a mature design method of CLT press is urgently needed with the increasingly broad market of CLT.Taking the cross-laminated timber press as the design and research object,this paper took a tentative step in the research of design method for cross-laminated timber press.In this paper,the body structure and the upper pressing plate of the cross-laminated timber press were designed.Then the finite element static analysis of the whole body and the key parts were carried out to find out weak links and optimization direction of the structure.Afterwards,based on Isight software,the optimal design of the upper pressing plate and the upper cross beam was carried out to improve the structure and reduce the weight.Finally,a special hydraulic system was designed for the press.The main contents of this paper are as follows:(1)The research background and significance of the cross-laminated timber press were summarized.Then the basic structure and the development status at home and abroad of hydraulic press were introduced.And the application and development status of structural design method as well as optimization design method of hydraulic press were introduced.(2)The overall structure of the cross-laminated timber press was determined,and the structures of upper beams,lower beam,columns and tie rods were designed respectively of which the shape and size were determined.The stress of each key component was calculated with method of material mechanics,and the strength and stiffness of each key component were checked.(3)The static analysis of the contact condition between the upper pressing plate and the wood was carried out by using the finite element analysis software ABAQUS,and the pressure distribution on the contact surface between the wood and the upper pressure plate was obtained.The three-dimensional models of the parts of the body are modeled by the modeling software CATIA,and the static analysis of the body under the nominal load was carried out by using the finite element analysis software ABAQUS.The results showed that the strength and stiffness of the key components met the design requirements.(4)The method of integrating three-dimensional modeling software CATIA and finite element analysis software ABAQUS with optimization design platform Isight was explored,where the functions of three-dimensional model reconstruction and finite element analysis,data reading and transmission,approximate model construction and optimization were realized.Multi-objective optimization design was carried out for the upper pressing plate and the result showed that the deviation of pressure distribution on the upper surface of wood was reduced from 17.9% to 7.0%,and the pressure distribution was more uniform.The optimization design of the upper cross beam was carried out,and the result showed that the weight of the optimized upper cross beam lost by 22.2%.(5)The main hydraulic system of the cross-laminated timber press was designed.In this system,the conversion of six working states,consisted of descending,pressurizing,holding,supplementing,relieving and rising,was realized by connecting three kinds of oil circuit,consisted of main pressure oil circuit,filling oil circuit and pressure relief control oil circuit.With the application of components,the holding pressure was stable,and the heating of the system was less.The hydraulic system had the advantages of rich functions,simple structure,high efficiency,energy saving and environmental protection.The large cross-laminated timber press designed in this paper met the needs of use,and had the advantages of simple structure,safety and reliability.In the research,an optimal design method taking the uniformity of surface pressure distribution as the optimization objective was proposed,and the method of integrating CATIA and ABAQUS with Isight was explored.The design and research in this paper lay a solid foundation for the follow-up research and development for this type of presses,provided a certain reference for the design of similar hydraulic presses,and provided a new method for structural optimization design.