Research On Dynamic Characteristic Of Suspension Cushioning Packaging System

There is a lot of product damage and function failure situation due to the improper packing in the existing logistic transportation system. The major factors causing the damage are the vibration and shock during the product transport process. The product can be affected by high frequency or low frequency vibration on the high way, railway, shipping and air transportation and the dropping impact in the loading and uploading process. Considering the role of the way of packing in the product protection, the suspension cushioning packaging system was taken as the research object. Combined with the features of the system structure and using the cushion packaging dynamics research methods, the dynamic characteristics of the suspension cushioning packaging system were studied. The results can provide theory references for the logistics transport package design.The suspension cushion packaging system is a geometric nonlinear system based on the structure characteristic. The theory model of the system was developed. The mathematical model was established and the dynamic equation was solved. The factors of the system vibration, shock, dropping characteristic were analyzed.Firstly, the dynamic model was established. And the standard dynamic equation was obtained according to the Newton's second law. The standard dynamic equation can be simplified, approximate equation was obtained and nondimensionalized.It can be seen from the form of the equation, the suspended angle and length of the spring and so on were the main parameters that affect the dynamic characteristics of the system.Secondly, the vibration characteristics of the suspension cushioning package system were analyzed. The dynamic performance of natural vibration and force vibration were both studied. The frequency, the circle and the effect factors were discussed and the accuracy of the approximate equation was calculated. The error between the standard equation and approximate equation was very small. The nonlinear differential equation under the force vibration was solved by the harmonic balance method and the amplitude frequency characteristic curves were obtained. Under the natural vibration condition, the results show that natural frequency reduced with the decrease of the suspension angle, the system will present the soft spring characteristic. The natural frequency decreased with the increasing amplitude when it is large amplitude, the system present soft spring characteristic. The frequency increased with the increasing amplitude when it is small amplitude, the system present soft spring characteristic. The response of system reduced when chooses the small angle and proper frequency ratio under the force vibration.The shock characteristics of the suspension cushioning package system were studied. The shock response spectrum and the damage boundary curve were obtained according to damage boundary theory. Combined the structure parameters, for instance, the angle, the length of the spring and the stiffness to the traditional theory, the three-dimensional shock response spectrum and the three-dimensional damage boundary curve were obtained. The results show that reduced the angle and shock duration and increase the dimensionless pulse amplitude and damping can reduce the system acceleration response. Therefore, the proper angle, length of the spring and stiffness coefficient can achieve the best cushioning effect.Finally, the dynamic characteristics of the dropping impact response of the suspension cushioning package system were studied. The dropping impact differential equation was solved by the variation iteration method and verified by the elliptic integral method. The maximum displacement and maximum acceleration response were obtained under the dropping conditions. It is important to the structure design of the product packaging through the analysis of the dropping shock response.