Establishment And Application Of Dynamic Constitutive Model For Expanded Polyethylene

During the circulation of the article,the pressure generated during stacking,the impact during loading and unloading,and the vibration during transportation may eause damage to the article.Whether the contents are damaged or not,are affected by the environment during transportation(such as ambient temperature,transportation means,drop height,static stress,etc.);they are also affected by the properties of the cushioning packaging material(such as material type,initial density,thickness,etc.);It is also related to the brittleness of the contents themselves.To this end,the dynamic model of buffer packaging materials in the logistics process is studied,the response law of articles in the transportation environment is revealed,and the principle of scientific packaging protection is sought,thereby optimizing the packaging structure and circulating for various mechanical and electrical products and household appliances.The protective packaging design in the process provides an important theoretical basis.In this paper,foamed polyethylene is used as the research object.Static compression test,dynamic compression test and vibration test(loads are applied in the thickness direction of the material),systematically explore the influence of environmental conditions and material properties on the mechanical properties of foamed polyethylene.Analyze and summarize the influence of various factors on the stress-strain curve of EPE,and establish a more complete dynamic constitutive model of foamed polyethylene including initial density and other factors.Using static compression experiments,the initial density of EPE(16 kg/m3,23 kg/m3,35 kg/m3,56 kg/m3),thickness(30 mm,40 mm,50 mm,60 mm,75 mm)was explored.Loading speed(9 mn/min,40 mm/min,100 mm/min,300 mm/min)and the effect of the number of compressions on its static compression performance.The results show that under static compression conditions,the mechanical properties of EPE are not affected by material thickness,loading speed and compression times,but are sensitive to the initial density of the material,and the density and strain coupling affect the stress,and the bearing capacity increases with the initial density.This characteristic is more pronounced in the large strain region.Based on this,a static compression constitutive model of foamed polyethylene was established.Using the drop impact test,the initial density,thickness,impact times,drop height(76 cm,66 cm,51 cm,46 cm)and static stress(7508 N/m2,9468 N/m2,11428 N/m2)of EPE were explored.The effect of its dynamic impact performance,and the use of laser displacement sensors to collect changes in material displacement during impact.The results show that the dynamic compression performance of EPE is closely related to material density,thickness and drop height.When the initial density and thickness increase,the load-carrying capacity of the material increases,and when the drop height increases,the degree of material damage increases.Combined with the static constitutive model,a more complete nonlinear dynamic constitutive model of foamed polyethylene including initial density is established.Provide an important basis for product protection during transportation.In the vibration experiment,the influence of EPE thickness and density on its vibration characteristics was explored.The results show that the larger the material thickness,the better the protection effect;the larger the initial density,the better the deformation resistance of the material,laying the foundation for the protective mechanism of cargo transportation packaging.