Study On The Forming Process Of Composite Kagome Grid With Combined Hard Die

Composite Kagome grid is a lightweight structure with excellent mechanical properties,and it has excellent performance in terms of stiffness,strength,and stability.At the same time,Kagome grid has the characteristics of periodic order and multi-functional design,so it has a broad application prospect in the fields of aviation,aerospace,ship and transportation.However,due to the special geometric shape of the Kagome grid,composite Kagome grid forming process is complex,and the finished product quality is low,failing to achieve the expected mechanical properties.And the bonding ability between the panel and the core is weak,which can easily cause the core debonding.These factors have become a major constraint on the wide application of composite Kagome grid.In this paper,the related manufacturing of composite Kagome grid was studied,on this basis,a combined hard die forming process of composite Kagome grid was proposed,and a modular hard core die was designed and manufactured.The process parameters such as pressure,temperature and fiber placement method were studied.A panel mold was designed,which was strengthened by the card slot on the panel and core to enhance the core bonding ability.The equivalent stiffness mechanical properties of the Kagome core were analyzed,and the Kagome grid compression and three-point bending mechanical properties were tested to verify the feasibility and effectiveness of the process.The main research content of this paper are as follows:1 The equivalent stiffness of the composite Kagome grid core was studied.The representative volume element method(RVE)was adopted to homogenize the Kagome core in this paper,the periodic boundary conditions of each stiffness coefficient and the corresponding formula of the stiffness coefficient were also given,and the results were compared with other literature method.The numerical simulation analysis of the discrete model and the equivalent model under different working conditions were completed,and the deformation results of the two models are compared.The effect of the number of core units was considered on the composite Kagome grid core equivalent model,it was found that the more the number of unit cells is,the more accurate the calculation result of equivalent stiffness is.2.A combined hard molding process of composite Kagome grid was proposed.The modular movable metal blocks were used in the process as the core mold,and the designed mold can achieve integral forming of Kagome core through vacuum assistance.Meanwhile,the movable blocks can be positioned and assembled according to the different arrangement and combination of the prepared Kagome grid core,which expands the use efficiency of the mold.The process parameters such as temperature,pressure and fiber placement method in the forming process were also studied.The composite Kagome core prepared with different process parameters were tested to determine the appropriate process parameters.3 An enhancement scheme between face and core was proposed.In this paper,a panel mold with a card slot was designed,through the function of the card slot and core,the bonding area between the panel and core is increased,so the bonding ability of these was improved,and the debonding of core and face can be reduced.The effectiveness of the scheme was verified by relevant compression and three-point bending mechanics tests.