纸蜂窝夹芯复合板材静态缓冲性能研究

目的为了新型纸蜂窝夹芯复合板材在运输包装中的推广应用,对新型泡状纸蜂窝夹芯复合板和纸蜂窝夹芯复合平板的缓冲性能和吸能特性进行研究。方法主要通过静态压缩实验,研究不同芯高的纸蜂窝结构类板材的应力-应变曲线、总能量吸收图、单位体积能量吸收图和缓冲系数-应变曲线,分析结构和芯高对板材静态压缩性能的影响。结果数据表明同种芯高的板材,纸蜂窝夹芯复合平板的应力峰值稍高;纸蜂窝夹芯复合平板的能量吸收、单位体积能量吸收最好;泡状纸蜂窝夹芯板由于泡结构的作用,缓冲性能大大增强。结论纸蜂窝夹芯复合平板的平压强度最好,而泡状纸蜂窝夹芯复合板的缓冲性能优于同等结构的蜂窝纸板,2种板材都有很好的应用前景。     

闭孔EVA泡沫类静态缓冲性能的研究

目的 研究密度与应变率对闭孔EVA泡沫材料类静态缓冲性能的影响规律。方法 基于包装用缓冲材料静态压缩试验法和能量吸收图法,对密度为80、95、106、124和180kg/m³的闭孔EVA泡沫试样在不同应变率下进行类静态压缩试验,得到应力-应变曲线,基于此进一步处理得到相应的单位体积能量吸收、能量吸收效率、缓冲系数和最大比吸能等曲线,同时绘制试样类静态压缩过程中的能量吸收图。结果 闭孔EVA泡沫材料的密度越高,密实化应变越小,最大单位体积能量吸收越大;在压缩应变相同时,应变率越大,应力、单位体积能量吸收、能量吸收效率、最大比吸能越大;得到了5种密度闭孔EVA泡沫材料的本构方程和闭孔EVA泡沫材料的能量吸收图及其斜率与应变率的关系式;通过分析密实化应变与相对密度的关系,得到相关拟合公式。结论 密度与应变率对闭孔EVA泡沫材料的缓冲性能有着非常大的影响,在一定的应力水平下会有一个最佳的密度使得刚好能吸收完能量,并保护产品不破损,该最佳密度受应变率的影响,因此可以通过能量吸收图进行相关的缓冲包装优化设计。     

蜂窝纸板静态缓冲性能的影响因素分析

分析了影响蜂窝纸板静态缓冲性能的3个因素:蜂窝纸板厚度、蜂窝孔径和蜂窝纸芯定量。根据静态压缩试验所得的应力-应变曲线,得出了3个影响因素对临界应力和临界应变的影响趋势,为缓冲包装中蜂窝纸板的选材提供一定的设计依据。     

不同规格蜂窝纸板缓冲性能的研究

通过静态压缩和动态压缩试验,研究蜂窝纸板的静态缓冲特性和动态缓冲特性与它的蜂窝芯柱、蜂窝孔径的关系.根据静态压缩试验所得的应力-应变曲线计算出蜂窝纸板的缓冲系数-应变曲线,根据动态压缩试验所得的最大加速度-时间曲线计算出缓冲系数-静应力曲线,为包装中蜂窝纸板的尺寸设计提供一定的参考.     

随机移除胞壁对纸蜂窝异面缓冲性能影响试验研究

目的研究随机缺陷对蜂窝纸板承载及缓冲性能的影响。方法通过预制不同胞壁移除比的蜂窝纸板,采用准静态压缩试验,得到其应力-应变曲线、胞壁移除比与蜂窝纸板缓冲系数之间的关系曲线和初始峰应力及能量吸收曲线,并依据试验结果,分析缺陷率对蜂窝纸板承载与缓冲性能的影响。结果随着胞壁移除比的不断增加,材料的缓冲系数不同程度增加,缺陷会显著降低初始峰值应力,能量吸收性能呈现下降趋势。结论为产品包装优化设计提供了依据。     

预压缩对蜂窝纸板能量吸收的影响

目的探究相同温湿度环境条件下,不同程度的预压缩对不同型号蜂窝纸板缓冲性能的影响。方法利用电子材料试验机对材料进行压缩,进而通过Matlab软件绘制出应力-应变曲线、静态缓冲系数曲线以及能量吸收曲线。结果预压缩限制在线弹性阶段,对蜂窝纸板各项性能无明显影响;当预压缩进入弹塑性阶段,蜂窝纸板的各项性能产生较为明显的下降;当预压缩进入塑性坍塌阶段,蜂窝纸板的各项性能显著下降,甚至丧失缓冲特性。结论随着预压缩程度的增加,蜂窝纸板静态压缩性能、静态缓冲性能及能量吸收性能都会降低。     

折叠型瓦楞纸蜂窝芯及其缓冲性能研究

折叠型瓦楞纸蜂窝芯的静态压缩应力应变曲线经历线弹性、屈曲平台和密实化三阶段,用同样材质同样重量的七层瓦楞纸板分别制作成折叠型瓦楞纸蜂窝芯和多层瓦楞纸板,对其进行准静态压缩实验,结果表明折叠型瓦楞纸蜂窝芯的承压性能远远高于多层瓦楞纸板,但其回弹性能比多层瓦楞纸板差一些,因此折叠型瓦楞纸蜂窝芯的缓冲效率高于多层瓦楞纸板的缓冲效率,它特别适合于大型机电产品的缓冲包装.     

内含气体对蜂窝纸板静态缓冲性能的影响

目的研究蜂窝纸板的内部气体对其静态缓冲性能的影响规律。方法通过静态压缩实验,研究在不同孔隙率的条件下蜂窝纸板的缓冲性能。结果通过静态压缩实验,得到了应力-应变曲线,对比不同孔隙率条件下的应力-应变曲线,可以观察到孔隙率越大,蜂窝纸板在压缩过程中的静态峰应力越小,蜂窝纸板越容易被压变形,并且形成的密实层越薄,其中孔隙率为0与孔隙率为100%时的应力-应变曲线变化明显,且气体泄漏不受厚长比和孔径尺寸的影响。结论在静态压缩过程中,蜂窝纸板内的气体使蜂窝纸板所能承受的应力明显增强,并且通过理论推导,得出了内含气体影响下蜂窝纸板在静态压缩过程中各个阶段的应力理论公式,为其缓冲性能的研究提供了一定的理论方法。     

静态载荷下丝瓜络的能量吸收性能研究

为了深入了解丝瓜络的力学性能、能量吸收特性及其规律,对丝瓜络进行了轴向静态压缩试验,再通过拟合试验数据得到丝瓜络的单位体积的吸能量与密度的关系式。试验结果表明:丝瓜络的应力-应变曲线有3个阶段,即弹性阶段、屈服平台阶段和密实化阶段,屈服平台阶段的平台应力在0.15~0.50 MPa之间,密实化应变在70%左右,且其平台区较长,是一种理想的吸能材料;丝瓜络是一种对密度敏感的材料,其屈服强度、平台应力和单位体积的吸能量均随密度的增加而增加,密实化应变随密度增加而减小;丝瓜络单位质量的吸能量可以与泡沫铝材料相媲美。研究结果可作为设计基于丝瓜络结构的新型超轻仿生材料结构的基础数据     

静态径向加载速率对樟子松吸能特性的影响

目的研究樟子松在不同静态径向加载速率作用下的能量吸收特性。方法采用横纹径向压缩实验。结果在不同加载速率的作用下,应力-应变曲线都呈现出3个阶段,即弹性阶段,应力平台阶段以及密实化阶段。樟子松存在明显的应变速率敏感性,随着加载速率的增加,应力-应变曲线的应力平台阶段不断上升。当应变为0.06,加载速率为1 mm/min时,应力为4.38 MPa;当加载速率为10和30mm/min时,对应的应力分别为4.71和6.56 MPa。樟子松具有优良的吸能能力,其能量吸收效率可以达到0.7~0.8。其缓冲系数曲线呈"L"型,随着应变的增加缓冲系数不断减小,但受加载速率的影响不大。结论不同加载速率对樟子松的能量吸收特性有一定的影响。     

Energy absorption diagrams of paper honeycomb sandwich structures

It is very important to evaluate the cushioning properties of paper honeycomb sandwich structures for optimizing pack design. The energy absorption diagram is one method to characterize the cushioning properties of materials. In this paper, we investigate energy absorption and develop energy absorption diagrams for paper honeycomb sandwich structures. Based on static compression experiments, the compressive stress–strain curve is simplified into three sections: linear elasticity, plateau and densification. By considering the factors associated with the structure of paper honeycombs, the energy absorption model is obtained and characterized by the thickness‐to‐length ratio of the honeycomb cell wall. Both theory and experiment show that the compression energy absorption capability increases with the increasing thickness‐to‐length ratio of the honeycomb cell wall, and a good agreement is achieved between the theoretical and experimental energy absorption curves. The proposed method to develop an energy absorption diagram for paper honeycomb sandwich structures can be used to characterize the cushioning properties and optimize the structures of paper honeycomb sandwiches. Copyright © 2008 John Wiley & Sons, Ltd.     

规则排列圆形蜂窝共面对角线方向缓冲性能的研究

目的 研究冲击速度和结构参数对规则排列圆形蜂窝共面对角线方向缓冲性能的影响规律。方法 使用有限元分析软件ANSYS/LS−DYNA建立规则排列圆形蜂窝共面对角线方向动态冲击有限元模型,基于此模型进行参数化仿真模拟,得到不同冲击速度和结构参数下规则排列圆形蜂窝共面对角线方向的变形模式、密实化应变、平台应力和能量吸收特征,并以图表的形式呈现。结果 在共面对角线方向的不同冲击速度下,规则排列圆形蜂窝表现出不同的变形模式。密实化应变在低速和高速冲击下,只与壁厚半径比有关;在中速冲击下,密实化应变同时受冲击速度和壁厚半径比的影响。在给定壁厚半径比下,共面平台应力(或最佳单位体积能量吸收)与冲击速度的平方呈线性关系;在给定冲击速度下,共面平台应力(或最佳单位体积能量吸收)与壁厚半径比呈幂指函数关系。结论 并基于有限元计算结果,得到了动态密实化应变、平台应力和单位体积能量吸收的经验表达式。     

构型对正多边形蜂窝异面缓冲性能的影响

目的 利用有限元法研究应变率不敏感的双线性各向同性应变硬化正多边形（等边三角形、正方形、正六边形和正八边形）蜂窝的异面缓冲性能。方法 建立基于正多边形蜂窝特征单元的异面冲击分析有限元模型，提出最佳应变这一缓冲性能评价新指标，基于此重新定义各能量吸收评价指标，形成新缓冲性能评价方法。结果 以此获取不同相对密度的各正多边形蜂窝在不同冲击速度下的变形模式和应力-应变曲线，以及平均平台应力、比能量吸收和冲击力效率等评价指标值，并进行了分析。结论 给定相对密度下，正八边形蜂窝具有最大的异面平均平台应力；正多边形蜂窝的比能量吸收与冲击速度成二次关系；定密度的正六和八边形蜂窝的冲击力效率优于等边三角形和正方形蜂窝。     

Mathematical modelling of energy absorption property for paper honeycomb in various ambient humidities

A mathematical model was developed to describe the relationship between the energy absorption properties of paper honeycombs and ambient humidity, as well as the structural parameters thereof. The model is a piecewise function modelling the energy absorption of four deformation stages of paper honeycomb (linear-elastic stage, yield stage, plateau stage and densification stage) separately. Function of each stage is a simple formula relating the energy absorption capacity to the thickness-to-length ratio of honeycomb cell, the mechanical property of a cell-wall material tested under a controlled atmosphere [23 °C and 50% relative humidity (RH)] and the RH. Energy absorption curves were thereby obtained for paper honeycombs with a wide range of thickness-to-length ratios in arbitrary humidity environments. The created model was then verified by comparing the predicted energy absorption curves with the experimental ones. A good accordance between the predictions and the observations was achieved, indicating that the energy absorption models developed here could be used to practical application for the designing optimisation and material selection of paper honeycombs.     

内凹-反手性蜂窝结构的面内动态压溃性能研究

通过内凹六边形蜂窝与反手性蜂窝的结合得到一种内凹-反手性蜂窝(re-entrant anti-trichiral honeycomb,RATH)结构。利用显式动力有限元软件LS-DYNA对不同冲击速度和不同相对密度下内凹-反手性蜂窝的变形模式、抗冲击性能及拉胀性能进行了研究。结果表明,引入内凹结构可以显著增强中低速冲击时反手性蜂窝的局部“颈缩”现象,且在靠近内凹-反手性蜂窝的冲击端呈现出明显的“V形”变形带。与三边反手性蜂窝及传统蜂窝相比,内凹-反手性蜂窝的能量吸收性能更强,负泊松比效应更明显。基于一维冲击波理论,推导了内凹-反手性蜂窝的临界冲击速度和平台应力的经验公式。此外,讨论了冲击速度和胞壁厚度对平台应力及平台应变的影响。该研究将为混合变形机制拉胀蜂窝结构的设计提供新的思路。     

Plateau stress of paper honeycomb as response to various relative humidities

A mathematical model was developed to predict the plateau stress of axially loaded paper honeycombs in various humidity environments. It is a simple formula relating the plateau stress to the thickness‐to‐length ratio of a honeycomb cell, the yielding stress of a cell‐wall material tested under a controlled atmosphere [23°C and 50% relative humidity (RH)] and the ambient RH. Paper honeycombs with various thickness‐to‐length ratios were researched under several levels of RH, and the plateau stress of each kind of paper honeycomb was obtained. The created model was then verified by comparing the predictions with observations. A good agreement between them corroborates the feasibility and accuracy of the model. Predictions by the present model and those by empirical relations were compared as well. A better prediction was obtained using the present model for a wide range of thickness‐to‐length ratios, suggesting that the present model can replace empirical formulas to provide more accurate and effective predictions of the plateau stress for paper honeycombs. The proposed method can be used to characterize the energy‐absorption properties of paper honeycombs in an actual logistic environment, and so can be used to optimize the structural design of paper honeycombs. Copyright © 2010 John Wiley & Sons, Ltd.     

Impact behavior and energy absorption of paper honeycomb sandwich panels

Dynamic cushioning tests were conducted by free drop and shock absorption principle. The effect of paper honeycomb structure factors on the impact behavior was analyzed. Results of many experiments show that the dynamic impact curve of paper honeycomb sandwich panel is concave and upward; the thickness and length of honeycomb cell-wall have a great effect on its cushioning properties; increasing the relative density of paper honeycomb can improve the energy absorption ability of the sandwich panels; the thickness of paper honeycomb core has an up and down fluctuant effect on the cushioning properties; with the increase of the thickness of paper honeycomb core, the effect dies down; flexible corrugated paperboard as liners can improve the compression resistance and cushioning properties of paper honeycombs. The research results can be used to optimize the structure design of paper honeycomb sandwich panel and material selection for packaging design.     

Energy‐Absorbing Properties of Paper Honeycombs under Low and Intermediate Strain Rates

The effect of the strain rate on the mechanical behaviour and energy absorption of paper honeycombs is investigated by experiments on an environmental condition designed to simulate the actual logistic environment in most of South China. The strain rate varies from 3.3 × 10^?4 to 1.1 × 10² s^?1. The experimental results show that the load‐carrying capacity and the energy absorption performance of paper honeycombs are insensitive to the loading speed in low strain rate range (10^?4–10^?2 s^?1). However, the initial peak stress, the plateau stress and the densification strain of paper honeycombs under intermediate strain rate impact (10^?2–10² s^?1) increase with impact velocity and are obviously higher than that under static compression, thus demonstrating a certain degree of strain rate sensitivity. The restoring force due to gas compression in a confined space of hexagonal cavity contributes to the increase in dynamic plateau stress. A model is developed for the prediction of dynamic plateau stress by considering this restoring force. A good agreement between observation and prediction is obtained, indicating that the model constructed here can be used to evaluate the dynamic plateau stress for paper honeycombs. Copyright © 2011 John Wiley & Sons, Ltd.     

The effects of foam filling on compressive response of hexagonal cell aluminum honeycombs under axial loading-experimental study

In this paper the effects of foam filling of honeycomb panels on their plastic behavior and mechanical properties are studied experimentally. Five types of Al 5052-H39 honeycombs in bare and foam filled conditions are subjected to quasi-static axial compressive loading. The panels are selected so that the effects of parameters such as the cell size, the cell walls thickness and the panel thickness on the mean crushing strength, energy absorption capacity and the wavelength of the folds could be investigated. Tests show that foam filling of panels increases their mean crushing strength and energy absorption capacity up to 300% and the less the honeycomb density the greater the effect of foam filling. Furthermore, mean crushing strength of foam filled panels is larger than the sum of the mean crushing strengths of bare honeycomb and foam alone. The wavelength of folds and densification strain in foam filled panels are smaller than those of bare honeycombs. These tests also showed that unlike the theoretic formula the panel thickness influences the mean crushing strength of honeycomb.     

粉煤灰聚氨酯复合泡沫静动态力学特性实验研究

以大尺寸粉煤灰漂珠为主要组分,以硬质聚氨酯泡沫为黏结剂制备了一种具有多尺度胞孔形态的复合泡沫,对其准静态压缩和动态冲击下的力学性能和变形机制进行研究。结果表明:①该复合泡沫应力应变曲线具有典型的线弹性、塑性平台和致密化三个特征阶段且具有相对稳定的平台应力;在密度0.45~0.6 g/cm^3,复合泡沫平台应力(6.5~18 MPa)和到压实应变处吸收的能量(3.42~8.9 MJ/m 3)随密度增大而提高,且平台应力与相对密度之间满足幂函数关系;②采用铝蜂窝为增强相可使同密度下复合泡沫抗压强度和平台应力分别提升约20%~45%和10%~25%,准静态下复合泡沫主要发生剪切失效,增强泡沫的主要失效形式则转变为轴向压缩失效。③在0.001~1500 s^-1应变率范围内,复合泡沫抗压强度有明显的应变率效应但平台应力并未随应变率的增大而提高。增强复合泡沫的强度和平台应力均呈现出明显的应变率效应,采用铝蜂窝不仅能提高复合泡沫力学性能,还能够改善其力学行为,使材料具有更优异的动力学特性;研究为工业固废粉煤灰的综合利用提供新思路。