Influence Of Relative Humidity And Perforating On Compressive Strength Of Paper Honeycomb Core Layer

The paper material has hygroscopicity.The environment with medium and high humidity will lead to warpage,deformation,mildew and strength reduction of honeycomb paperboard,which can affect the drying process,production efficiency and packaging protection performance of honeycomb paperboard.In view of the practical engineering problems,the design of double-layer cell walls with perforation of paper honeycomb core layer is put forward,and the influences of relative humidity,diameter and number of circular hole on compressive strength of paper honeycomb core layer are studied.The main researches are as follows:First of all,taking the honeycomb core paper strip and paper honeycomb core layer without and with hole as the research object,the effects of relative humidity and perforation(the diameter and number of circular hole)on ring crush resistance of honeycomb core paper strip and out-of-plane compressive strength of paper honeycomb core layer are studied by ring crush and static compression test.The results show that the ring crush resistance and out-of-plane compressive strength decrease with the increase of relative humidity,diameter and number of circular hole.Then the influences of relative humidity and pore diameter on ring crush resistance are evaluated by multiple linear regression analysis and SPSS.The empirical relationship between the length defect rate and the coefficient of ring crush resistance can be used to predict the ring crush resistance of honeycomb core paper strip with perforation.Secondly,taking honeycomb core paper as the research object,the effects of relative humidity,the relationship between fiber and tensile direction,the number of cell wall layers and adhesive on physical properties of honeycomb core paper are analyzed by tensile experiment,and the average values of elastic modulus,yield strength,breaking force and tensile strength of honeycomb core paper under different relative humidity conditions are obtained,which provide the material parameters for theoretical calculation and finite element analysisThirdly,taking the paper honeycomb core layer without and with hole as the research object,based on its symmetry characteristics,two element models are employed to deal with the honeycomb cell walls loaded along the out-of-plane direction as simply-supported elastic plate without and with hole.The prediction formulas of critical stress of elastic buckling and plastic plateau stress are derived.The calculated critical stresses and plateau stresses are in good agreement with the static compressive test resultsFinally,considering the orthotropic properties of the paper sheet,the finite element models without and with perforation of honeycomb core paper strip,paper honeycomb core layer and paper honeycomb cell are established,and the elastic-plastic buckling analysis is carried out The influences of the pore diameter on the instability of honeycomb core paper strip and the bending-folding deformation of paper honeycomb cell wall are simulated to verify the rationality of the analysis model.