Low-intensity Test Prediction Method For Dropping Response Of Nonlinear Packaging System

The main reason for the damage of products in the process of circulation and application is shock and vibration,shock makes the package suffer the non-repetitive excitation in an instant and suddenly change the state of the system.While optimizing and improving the structure of the product itself,designing a reliable cushioning packaging structure can effectively reduce the damage to the product caused by vibration and impact.However,samples of cushioned packaging products must undergo a drop test prior to their circulation.A typical cushioned packaging design follows the five-step principle and its final step is a cushioned package test of the prototype shipping package,usually by physical testing(drop test And vibration test)and finite element simulation to verify.The drop test of packaging is mainly used to evaluate the impact drop ability of product package during transportation and loading and unloading,so as to improve and perfect packaging design.However,the traditional drop test process is complicated and can not guarantee the safety of the test sample.In addition,Considering the complicated dynamic response process of drop impact and the complex constitutive model problem of cushioning material,it is very challenging to simulate their physical characteristics more accurately to meet the drop simulation requirements.The purpose of this project is to analyze the dynamic response of single-degree-of-freedom packaging system under drop impact conditions and consider its peak response acceleration value from the perspective of prediction.The response of the cushioning system not only depends on the external force,and also depends on the structural characteristics of the system itself,like stiffness,damping and mass.In this paper,the cushion packaging system composed of EPE-mass is used as an example.The four models of linear damping,linear damping,tangent without damping and tangent damping are used to continuously predict and validate the peak response acceleration of the system.First,using the simplest linear packaging system as an example,four different safe drop heights were selected to perform dynamic compression tests on EPE,obtained the required data through the experiment to predict the peak acceleration of the system under the target drop height.The results showed that the error between the prediction result and the experimental verification value is large.In order to reduce or eliminate the error,this paper replaced the linear system with the damping to re-predict the peak value.The results indicated that the relative error is significantly smaller than that of the nondamping system.However,with the increase of the drop height,the error value shows an increasing trend.which proved that although the linear system has good prediction accuracy,it is still difficult or even impossible to explain the nonlinear problem in actual situation.Therefore,after conducting stress-strain analysis on the EPE dynamic compression test data in the following study,it was learned that the EPEcushioning material exhibited a tangential nonlinearity.when different predictions are made for the tangent nondamping and damping models.Respectively.Although the principle of the solution method of the analytical solution is different,which leads to differences in the prediction results,it can also be proved that the peak response of the packaged product can be predicted through theoretical and safety drop tests.