Research On The Vibration Mechanisim And Characteristic Of Packaging System With Air Cushion

Air cushion is a new packaging materials used in field of transport packaging in recent years,and It is a great value things for engineering applications to research this materials on load-bearing characteristics and cushion property.Based on the geometric compression model,the subject establish the theoretical stiffness model of the cylindrical air cushion.The quasi-static compression test and dynamic compression test were dong on cylinder air cushion,which is to analysis load-bearing characteristics,stiffness property and prove the feasibility of theoretical stiffness models.Moreover, the influences of load-bearing characteristic and response of packaging system was discussed connecting with the initial internal pressure, external boundary conditions and structural parameters. The main contents include:(1) Based on thermodynamics changes and geometry model of air cushion ,the topics established theoretical characterization of load characteriistics and stiffness of cylindrical air ,also to further explore the feasibility of theoretical characterization.The results of the study showed that columnar air cushion and rigidity of load is obviously nonlinear characteristics.(2)Testing on cylindrical air cushion for quasi-static compression , the load characteristic curves were obtained which measured in different specifications and different initial relative pressure conditions. Using difference method to get the stiffness characteristics , and the curves of displacement-stiffness were getted through matlab. It is necessary to prove the feasibility of theoretical stiffness models comparing to the curves of the static rigidity. The results of the study showed that the static stiffness of the theoretical value and the tested value were the same trend under different specifications.The theoretical stiffness models deviation from experiments largely along with the increase of deformation. Results from calculation and experiments are in good agreement when deformation decrease.(3)Study on air cylindrical cushion for impact test to disscuss dynamic compression characteristic and to obtain the acceleration response signals. The curves of displacement-time were gained through double integral. air cushion dynamic stiffness-displacement curve were gained through the Matlab programming conversions,based on the relationship between the force and the acceleration.To discuss the feasibility of the theoretical model of dynamic stiffness calculation and experiments should be compared Thus,The results show that the static stiffness of the theoretical value and tested value were the same trend under the conditions of different specifications air cushion. The theoretical dynamicstiffness models deviation from experiments largely along with the increase of deformation. Results from calculation and experiments are in good agreement when deformation decrease.(4) The single degree of freedom mechanical model of air cushion system was established, subject also get the free vibration equation of packaging system, the forced vibration equation of harmonic excitation and kinetic equation under impact of a rectangular pulseexcitation.Using the fourth-order Runge-Kutta method and Matlab calculations, the numerical solution was acquired. The response of the foundation, the shock spectra and damage boundary law were also discussed. With the system para- meters, cushioning material damping,excitation conditions based on the product response, shock spectrum and the influence of the damage boundary.The results show that: with the initial pressure , the incentive frequency and incentive amplitude increasing ,the system vibration, impact acceleration and displacement response increase; The natural vibration frequency with the increase of the initial pressure, present the tendency of decreasing first and then increasing; Impact state, material of damping can effectively reduce the system acceleration response, increases the safety area.The bigger initial pressure, the larger acceleration response change, decreasing the damaged security area change and the rectangular pulse .Acceleration fluctuates significantly when the system amplitude became large.