Investigation On Accelerated Random Vibration Test Of Product Transportation Packaging System

The rise of e-commerce promotes the development of modern logistics industry,which has the characteristics of long journey,long duration and broad geographical distribution.During transportation phase,products frequently suffer from hazards of random vibration due to rough road,uneven vehicle speed,and so on.Packaged products will damage under this effect and fatigue failure will occur once the accumulated damage reaches to a certain value,which will result in the discount of use value and business value.Therefore,it is very important to evaluate the safety performance of transportation packaging system.Real transportation test and laboratory simulated test are two common methods to evaluate the mechanical property of transportation packaging system.However,method of real transportation test is less used because it is time-consuming and highcost.The laboratory simulated test time is reduced by enhancing random vibration intensity.This is the accelerated random vibration test,which can improve work efficiency and reduce development and design cycle of products and packagingThe structure and materials of transportation packaging system are complex,so vibration fatigue mode and damage mechanism of the system are not identical.The current theory and method of accelerated random vibration test is not complete and it deserves deep investigation.Based on present study,this paper makes comprehensive exploration and research.The studies are from four aspects as following:（1）The accelerated random vibration test method of the products under multiaxis excitation was developed.Based on the linear elastic hypothesis,the relationship of the response of products’components and external excitation was obtained through finite element method and lumped mass method.S—N curve can be replaced by G_rms-N curve to be used as the life curves of products’components.According to the principle of damage equivalence,the general time scale and method of accelerated random vibration test based on Power Spectral Density function（PSD）and G_rms-N curves of products’ components was developed.The simplification time scale was derived in the two cases that G_rms-N curves conform to Basquin type and exponent function type.The developed method was verified by experiments and finite element analysis（2）The accelerated random vibration test method of transportation packaging system under uniaxis external excitation was established.Transportation packaging system was considered as multi-degree-of freedom system composed of the main part and many key components.Then,the relationship of the response of products’components and external excitation was obtained According to the principle of damage equivalence,the general time scale and method of transportation packaging system’s accelerated random vibration test under vertical vibration excitation was developed.The accelerated random vibration test procedures were given under the guidance of the developed theory.Finally,the developed theory and method was confirmed by the experiments of desktop computer packaging system（3）The vibration fatigue behavior and G_rms-N curve of corrugated paperboard box was studied.The overall stiffness of corrugated paperboard box was used as the index to trace and monitor the damage of corrugated paperboard box.Corrugated paperboard box was regarded as fatigue failure when the stiffness decreased by 20%,30%and 40%.The G_rms-N curve was plotted under these fatigue failure standards.The results indicate that the fatigue mode of corrugated paperboard box conform to both Basquin type and exponent function type.The value of index b in Basquin type is 8.16-11.01,in exponent function type is 21.19-26.84（4）The vibration scuffing behavior and G_rms-N curve of printing ink scuffing was studied The scuffing device was designed and made in this paper,which can be used to simulate the scuffing behavior of packaging during logistics.The ink scuffing process was obtained by random vibration experiments.A new calculation method of printing scuffing was proposed in this paper.By applying scuffing value 6%and 8%as scuffing failure standards,G_rms-N curve was developed from the points of excitation acceleration G_rms,e and relative acceleration G_rms,re.The results show that the scuffing failure conforms to Basquin type and exponent function type.In addition,the effect of excitation frequency range on the response of product packaging system was discussed in the endThis paper develops the accelerated random vibration test theory and method of product packaging system based on PSD and G_rms-N curve of components.This is suitable for any products packaging system and it is more practical.This study promotes the development of accelerated random vibration test investigation.Under this guidance,the accelerated random vibration test of transportation packaging system will be carried on more scientifically.The research has significant value in engineering.The vibration damage of the typical container and common scuffing mode in transportation are explored and G_rms-N curve is plotted,which can provide reference for accelerated random vibration test in laboratory.