| With the wide use of pulp molded products in logistics packaging and transportation packaging,they are often faced with transportation under different humidity conditions.At the same time,packaging is often in a complex transportation environment such as extrusion,drop impact and so on.In this paper,the Johnson cook constitutive model and the Johnson cook damage model of the pulp mold material were obtained by static tensile test.Based on the above model,the static compression simulation of the barrel structure of pulp mold is carried out.The load displacement curve of the simulation results is in good agreement with the test results,and the deformation nephogram is consistent with the test results.When the damage model is not added,the load displacement curve of the simulation results is far from the test results,and the deformation nephogram of the simulation results is far from the test results.It shows that the damage of pulp mold material and the decrease of mechanical properties must be considered in the simulation of large deformation of pulp mold under static condition.A Johnson-cook constitutive model with strain rate effect was obtained by tensile tests at different rates.Based on this constitutive model,the computer buffer structure of bamboo pulp model was simulated at 500mm,760mm,910mm heights,and the acceleration-time curve of the simulation results was compared with the test results.The results show that the maximum acceleration of the simulation results is larger than that of the experimental datas.Through the tensile tests of the same part of the pulp mold structure before and after the drop,the results show that the mechanical properties of the pulp mold materials decrease during the drop process.In order to improve the accuracy of the impact simulation of the pulp mold structure,the damage model must be added.Finally,Based on Johnson-cook damage model,the gap between simulation results and test data was reduced,which can provide reference value for actual detection and design.This shows that the accuracy of simulation results can be improved by considering the damage of pulp mold materials and the decrease of mechanical properties.The moisture constitutive equation of pulp mold material was obtained by tensile test under the same temperature and different humidity.The results show that the mechanical properties of pulp molding materials decrease exponentially with the increase of humidity at constant temperature. |
