【作者】 郭振斌；

【导师】 陈安军；

【作者基本信息】 江南大学 ， 包装工程， 2012， 硕士

【摘要】 薄膜空气垫是近几年来应用于运输包装领域的新型包装缓冲材料,对薄膜空气垫的承载特性及缓冲性能进行研究,在工程应用中具有重要价值。本课题以柱状空气垫为研究对象,基于几何压缩模型,建立柱状空气垫刚度特性理论模型,对柱状空气垫进行准静态压缩试验、动态压缩试验研究,分析气垫的承载力、刚度特性,并与理论模型进行比较,研究理论模型的可行性,探讨结构参数、初始相对内压、外界条件对其载荷性能及缓冲包装系统响应的影响,为气垫的包装应用提供技术基础。主要研究内容包括:(1)以柱状空气垫为研究对象,基于空气热力学变化规律,研究柱状空气垫的几何压缩模型,建立了空气垫载荷特性理论模型并推导出空气垫刚度的理论表征。研究结果发现,柱状空气垫的载荷、刚度理论表征呈明显的非线性特点。(2)对柱状空气垫进行准静态压缩试验,得到不同规格、不同初始相对内压条件下,气垫的载荷力-位移特性曲线,利用差分法得到空气垫的刚度数据,通过Matlab编程绘制气垫刚度-位移关系曲线,并与静态刚度理论模型进行比较,讨论静态刚度理论模型的可行性,结果表明:不同规格的柱状空气垫,其静态刚度的理论值与试验值变化趋势相同,相同规格条件下,当变形量较大时,静态刚度的理论值较试验值偏大;变形量较小时与试验值接近程度较好。(3)对柱状空气垫进行冲击试验,研究其动态压缩特性,得到柱状空气垫的加速度响应信号,经过二次积分,得到位移-时间关系,并由力与加速度的关系,通过Matlab编程转换,得到空气垫的动态刚度-位移关系曲线,数据处理结果与动态刚度的理论表征进行比较,讨论动态刚度理论模型的可行性。结果表明:相近初始内压条件下,不同规格空气垫刚度的理论值与试验值趋势相同,变形量增加时,动态刚度的理论值与试验值偏离增加,在变形量较小时,动态刚度理论模型可较好的表征空气垫的动态压缩特性。(4)建立空气垫缓冲包装系统的单自由度力学模型,研究系统的自由振动、谐波激励下的受迫振动、脉冲激励下的冲击响应规律,利用四阶Runge-Kutta法数值分析,获得系统自振响应、受迫振动响应规律及冲击状态下的冲击谱,讨论了系统参数、系统阻尼、外界激励对系统振动响应、冲击谱响应的影响规律。结果表明:气垫初始相对内压、激励幅值、激励频率越大,系统的振动、冲击加速度及位移响应增大;自振频率随着初始内压的增大,呈现先减小后增大的趋势;冲击状态下,阻尼对降低系统的加速度响应起作用,可增大安全区域;初始相对内压增大,加速度响应变大,破损安全区域减小;矩形脉冲幅值越大,系统加速度波动越明显。更多还原

【Abstract】 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.更多还原