Evaluation of product dropping damage based on key component

This paper analyses the packaging system of a product as a two‐degrees‐of‐freedom system, one degree for the key component and the other for the main part of the product. The dropping damage boundary curve was developed based on the key component for linear and non‐linear packaging systems to predict product damage as a result of drop impacts. The dynamic models of two‐degrees‐of‐freedom dropping shock were obtained. For a linear packaging system, the dropping response of the key component was determined by the dimensionless dropping shock velocity, the frequency parameter ratio, the mass ratio and the damping parameters; for a non‐linear system, the system parameter was also used. The frequency parameter ratio of the packaging system and the dimensionless dropping shock velocity were selected as the basic evaluation quantities for the dropping damage of the key component. As an example, the dropping damage boundary curves based on the key component were given for linear and tangent packaging systems. The influence of related parameters such as the mass ratio, the system parameter and the damping parameters on the dropping damage boundary curve was investigated. To verify the theory, experiments were designed and completed. Experiment results for both linear and tangent packaging systems were consistent with the theory suggested in this paper. These results have important value not only for the design of cushioning packaging but also for the improvement of products. Copyright © 2010 John Wiley & Sons, Ltd.     

On evaluation of product dropping damage

As an extension of the classical damage boundary curve in the case of product dropping shock, the concept of a dropping damage boundary curve for linear and non‐linear packaging system to evaluate the dropping damage of product is developed in this paper. The dropping damage boundary curves are given for linear and hyperbolic tangent packaging systems with different damping. For a linear packaging system the dropping damage of a product is determined only by the natural frequency of the corresponding packaging system without damping and the dropping shock velocity of package except the system damping, and they compose the basic evaluation quantities of product dropping damage. For a non‐linear hyperbolic tangent packaging system, the system parameter and the dimensionless dropping shock velocity are two basic quantities in the evaluation of product dropping damage. It should be emphasized that the dimensionless dropping shock velocity is related not only to the dropping height of package box but also to the system parameter integration. This is the important feature differentiating a non‐linear packaging system from a linear one. The influence of system damping on the dropping damage boundary curves is also discussed. This concept and the results have important value in the design of cushioning packaging. Copyright © 2002 John Wiley & Sons, Ltd.     

Shock spectra and damage boundary curves for non‐linear package cushioning systems

This paper suggests a general approach for obtaining shock spectra and damage boundary curves for cushioning packaging systems. This approach can treat both linear and non‐linear cushioning systems such as cubic, tangent and hyperbolic tangent systems. Corresponding software has been developed for analysing different cushioning systems, and the shock spectra and the damage boundary curves are given for a tangent non‐linear cushioning system under the action of a rectangular, half‐sine, terminal‐peak saw‐tooth and initial‐peak saw‐tooth pulse, respectively. It is worth noting that the shock spectrum is affected not only by the damping parameter but also by the dimensionless pulse peak, and that both the damping parameter and the dimensionless fragility also influence the damage boundary curve. These are important features of non‐linear cushioning system. Copyright © 1999 John Wiley & Sons, Ltd.     

Shock spectra and damage boundary curves for hyperbolic tangent cushioning system and their important features

By applying the method suggested in the author's previous paper, shock spectra and damage boundary curves are investigated for a hyperbolic tangent cushioning system under the action of rectangular, half‐sine, terminal‐peak saw‐tooth and initial‐peak saw‐tooth acceleration pulses, respectively. The shock spectrum is affected not only by the damping parameter but also by the dimensionless pulse peak, and both the damping parameter and the dimensionless fragility influence the damage boundary curve for this cushioning system. Some important features of a hyperbolic tangent cushioning system that differs from a tangent cushioning system are discussed in detail. Copyright © 2001 John Wiley & Sons, Ltd.     

缓冲包装系统跌落破损边界曲线研究

建立了线性和非线性缓冲包装系统的无量纲跌落冲击方程,得到了产品最大加速度响应,提出了评价线性和非线性包装系统产品安全与否的跌落破损边界曲线概念。对于线性包装系统,固有频率和跌落冲击速度是产品跌落破损的评价量;对于非线性包装系统,系统参数和无量纲跌落冲击速度是产品跌落破损的评价量。     

功能型双拱瓦楞纸板缓冲动力学模型及跌落失效评价

基于功能型双拱瓦楞纸板压缩力学变形特征,建立其压缩非线性模型.在此基础上建立其缓冲包装系统跌落动力学方程,进行无量纲化并求解,分析系统动力学响应特征,找到系统响应的关键控制变量,据此提出描述瓦楞包装系统跌落失效的评定方法,并分析了产品脆值与材料阻尼对系统跌落破损边界的影响.研究结论对指导功能型双拱瓦楞包装系统设计具有一...     

基于变分迭代法的悬挂式弹簧系统的跌落破损评价

以悬挂式弹簧系统为研究对象,应用变分迭代法求解系统跌落冲击无量纲动力学方程,得到了系统无量纲位移、加速度响应一阶近似解析解,无量刚位移响应峰值,无量纲加速度响应峰值和无量刚跌落冲击持续时间表达式,与龙格-库塔数值分析结果进行了比较。 结果表明,无量纲加速度响应曲线吻合程度较好,无量纲加速度响应峰值和无量刚跌落冲击持续时间相对误差小于 4% 和 2% 。 建立了包含系统参数、产品脆值、无量纲跌落冲击速度、系统悬挂角等多变量的跌落冲击破损评价方程。 以无量纲跌落冲击速度和系统参数为基本评价量,获得了系统跌落破损边界曲线;以无量纲跌落冲击速度、系统参数和初始悬挂角为基本评价量,获得了系统跌落破损边界曲面。 结果表明,随着系统初始悬挂角减小,系统安全性能提高,悬挂系统几何非线性特性对产品保护性能优于线性系统。 为悬挂式系统缓冲设计提供了理论依据。     

缓冲包装设计中构建破损边界曲线的新途径

多年的运输包装实践说明,根据传统破损边界曲线(DBC)得到的产品脆值应用到缓冲包装设计时,常会产生保守性,导致过度包装及包装材料的浪费等。根据瞬态振动理论中冲击响应谱(SRS)的基本特性,采用Biot模型代表一个产品的结构系统模型,则该结构系统是由一系列单自由度(SDOF)质量-弹簧振子所组成,再获得其SRS。通过现代的实验装置及先进测头可以获得结构系统中易损元件的SRS。然后根据工程力学中动荷系数的概念,在上述易损元件SRS基础上,设定易损元件危险点处最大应力达到弹性极限时,SRS表示的最大响应加速度值即达到了临界值,在此基础上绘制新的DBC,据此可求得基于响应加速度的新脆值。此新脆值使用在缓冲包装设计时,将会避免上述传统脆值可能带来的保守性。     

跌落损伤脆值及损伤边界

提出了跌落损伤脆值与跌落损伤边界的新概念,并提出了测定获取跌落冲击损伤脆值与跌落损伤边界曲线的技术过程与方法.以嘎拉苹果为研究对象,设计多组高度对嘎拉苹果进行自由跌落刚性冲击试验.在测试获得冲击力-时间数据的基础上,通过理论分析计算,得到加速度-时间、变形量-时间等动态关系曲线,获得了嘎拉苹果跌落损伤脆值;构造了嘎拉苹果跌落损伤边界曲线.结果表明,跌落损伤边界曲线与传统产品跌落破损边界曲线存在较大差异.对应果品类产品,即使速度很小,只要产品瞬时加速度达到一定值,也将产生冲击损伤;对应不同的损伤率,可构造相应的多条损伤边界曲线.提出的概念及研究结果为控制果品类产品的跌落损伤、合理地进行缓冲包装设计提供了新的理论基础.     

物品包装临界跌落高度与缓冲衬垫特性参数关系初探

运用经典的加速度损坏边界和新提出的位移损坏边界理论，研究了线性包装系统临界跌落高度与缓冲衬垫特性参数（缓冲初垫刚度、最大可压缩量）间的关系，并给出了数值解，为包装动力学理论在工程缓冲设计中的简化应用提供了一种途径和方法。     

斜支承系统包装物体的跌落破损边界研究

以斜支承系统为研究对象,建立系统无量纲跌落冲击动力学方程。应用龙格-库塔数值分析方法,以系统特征参数、无量纲跌落冲击速度以及支承角或阻尼比为基本评价量,构建系统的二维跌落破损边界曲线和三维跌落破损边界曲面,讨论系统阻尼比、系统支承角以及系统特征参数等对跌落破损边界的影响。研究表明,系统特征参数、无量纲跌落冲击速度以及系统阻尼比对破损边界影响显著,系统存在最佳阻尼匹配,当系统阻尼比接近最佳匹配值时,系统对产品具有良好的保护性能,降低系统的特征参数或减小系统支承角可改善对产品保护性能。研究结论可为斜支承系统设计提供理论依据。     

现代包装力学

包装工业现代化提出了许多与力学各分支学科相关的问题。从缓冲包装理论、产品脆值和破损边界理论、包装材料、包装容器和缓冲包装设计方法等方面，阐述了有关的力学问题和目前的研究工作进展，初步构划出现代包装力学的学科体系。     

面向电脑SRS要求的缓冲包装设计

电脑的缓冲垫要求按冲击响应谱的破损边界曲线进行设计.全面介绍了冲击响应谱的基本原理、测试及其在电脑缓冲垫设计中的应用.该研究完善了当前冲击脆值理论,使缓冲包装设计更精确,更符合实际.     

物品包装系统位移损坏边界

Ｒ．Ｅ．Ｎｅｗｔｏｎ提出的基于物品易损度的加速度损坏边界概念及其表达式仅反映了为保护物品安全，对其加速度响应的限制，未考虑缓冲衬垫压缩变形范围有限的制约条件。本文对物品的相位位移响应引入约束条件，首次定义了物品包装位移易损度及位移损坏边界，与加速度损坏边界相结合，用以确定物品包装系统的安全区，讨论了两类损坏边界的关系。并推导了后峰锯齿脉冲及矩形脉冲作用下，双线性及线性包装系统损坏边界的表达式。     

半正弦激励下烤箱脆值及破损边界曲线试验分析

目的为了获取烤箱产品在半正弦激励下的破损边界曲线和机械冲击脆值,解决因脆值选取不合理而造成的过包装问题。方法参考ASTM D 3332及相关理论,并通过预试验确定试验的相关参数,根据预试验参数,分别进行产品临界速度变化量测定试验,以及临界加速度测定试验,从而确定产品的破损边界曲线和脆值。结果该产品的临界速度变化值Δvc=2.27 m/s,第1次和第2次临界加速度测量值分别为Gm1=72.93g,Gm2=65.06g,脆值G=52g,并得到了破损边界曲线。结论试验结果为缓冲包装设计提供了可靠的脆值数据,为包装结构设计的合理性提供依据;试验中运用的产品破损边界曲线及产品本身的机械冲击脆值的测定方法对同类试验具有一定参考意义。     

悬挂系统易损件跌落破损评价

以考虑易损件的悬挂系统为研究对象,建立跌落冲击下系统无量纲动力学方程。利用四阶龙格库塔数值分析方法求解动力学方程,以系统参数、无量纲跌落冲击速度、频率比、阻尼比或悬挂角为基本评价量,构建易损件跌落破损边界曲面,讨论系统悬挂角、频率比及阻尼比等对易损件的跌落破损边界的影响。数值分析表明:高频率比有利于系统对产品的保护;小阻尼条件下,阻尼匹配满足一定的范围对产品具有较好的保护作用;较小的系统悬挂角时,系统的安全区域较大;系统设计中应综合考虑各参数的影响,提高系统抗冲击性能,达到保护产品的目的。     

高硼硅玻璃沙拉碗缓冲包装跌落仿真分析

目的 研究高硼硅玻璃沙拉碗跌落冲击时的应力和变形情况,为沙拉碗安全包装提供参考。方法 运用Pro/E软件和Ansys软件建立沙拉碗及其缓冲包装三维有限元模型,对有无缓冲包装以及不同跌落高度和跌落姿态分别进行跌落仿真模拟,获取沙拉碗跌落冲击过程的应力、变形和加速度分布及变化规律。结果 沙拉碗跌落冲击时,最易损坏的部位在上部边缘、底部缓冲包装棱边及角的冲击部位;无缓冲包装时最大应力和脆值分别为76 MPa和1.84×105g,有缓冲包装时的最大应力和脆值分别为0.139 MPa和73.5g。结论 对沙拉碗进行包装设计时,应加强对上部碗口边缘部位和缓冲垫边角的保护;缓冲包装结构对沙拉碗起到了明显的保护作用,该研究为高硼硅沙拉碗缓冲包装的理论研究和结构优化设计提供了参考。     

单自由度模型苹果脆值的预测

目的 以苹果为研究对象,建立一种易操作的脆值测定方案对苹果进行缓冲包装设计和分析。 方法 通过静态压缩试验测得苹果的线刚度,通过跌落试验测出破损临界跌落高度,进而基于单自由度理论模型计算出苹果脆值。根据苹果的脆值和缓冲材料的静态缓冲系数设计出最优包装方案。最后,模拟公路随机振动和跌落试验评价上述缓冲方案的可行性。结果 无泡沫网苹果的破损临界跌落高度为 5 cm,线刚度为106.59 kN/m,固有频率为109.79 Hz;带泡沫网苹果破损临界跌落高度为10 cm,线刚度为104.48 kN/m,固有频率为106.58 Hz,临界脆值Gc约为96.28。据此,按照80 cm的搬运跌落高度设计时,缓冲材料EPE厚度需要达到1.98 cm。结论 建立的脆值测定方案具有精准度高,且较传统脆值测定方法对仪器依赖度低,具有操作简便易行、普适性强等优点,易于推广到其他类型包装件脆值的测定。     

Packaging performance comparison for distribution and export of papaya fruit

This paper presents the development and testing procedures for new packaging systems for papaya fruit. Papaya is a nutritious tropical fruit, consumed both in its fresh form and as a processed product worldwide. Thailand is a major exporter of fresh and processed papayas from Asia. Major quality indices for papayas include colour, size, firmness and freedom from defects and decay. A high percentage of post‐harvest losses of papaya fruits have been reported as exports have increased. Mechanical damage is one of the major causes of the quality loss of papaya fruits, therefore, proper packaging is demanded for better protection. In addition, other criteria are important to meet consumer acceptance. New packaging systems for papayas were compared with the existing systems currently used for local markets. The packaging systems were evaluated in terms of physical protection, heat transfer characteristics for rapid cooling and maintaining optimum temperature and relative humidity during post‐harvest, quality maintenance, and marketing issues. Two cushioning systems, foam nets and paper‐based wrap materials, were also compared. Actual shipment and vibration tests were performed and the effect on quality was determined. The new packaging systems tested showed better protective performance and improved quality parameters, as compared to existing systems. Minimized mechanical injuries resulted in a decreased susceptibility to decay and bruising. Paper‐based cushions showed similar protection to plastic foam nets materials but offered a better ripening response for papayas. The data were compared to seek an optimum packaging system for papayas based on the various criteria. Copyright © 2005 John Wiley & Sons, Ltd.