This work was designed to determine the mechanical properties and static cushioning performance of polyvinyl alcohol (PVA)/bagasse fibre foam composites with a multiple-factor experiment. Scanning electron microscopy (SEM) analysis and static cushioning tests were performed on the foamed composites and the results were compared with those of commonly used expanded polystyrene (EPS). The results were as follows: the materials had a mainly open cell structure, and bagasse fibre had good compatibility with PVA foam. With increasing PVA content, the mechanical properties of the system improved. The mechanical properties and static cushioning properties of the foam composite almost approached those of EPS. In addition, a small amount of sodium tetraborate obviously regulated the foaming ratio of foamed composites. With increasing sodium tetraborate content, the mechanical properties of foamed composites were enhanced. The yield strength and Young’s modulus of the material prepared by reducing the water content to 80.19 wt% were too high and not suitable for cushioned packaging of light and fragile products.

为改善气凝胶复合材料的承压能力,设计了一种纸蜂窝作为夹层,两侧复合气凝胶复合材料的夹层板,并探究该夹层板能否取代聚氨酯泡沫,应用于冷库墙体保温夹层.利用导热系数仪测得的试验数据,对纸蜂窝、气凝胶复合材料、气凝胶纸蜂窝夹层板的隔热性能进行了分析,讨论材料厚度对气凝胶蜂窝夹层板导热性能的影响.结果表明:纸蜂窝的厚度较小时,气凝胶纸蜂窝夹层板的导热系数均低于聚氨酯泡沫板;当纸蜂窝厚度为10 mm、孔径为6 mm,气凝胶复合材料厚度为10 mm或15 mm时,气凝胶纸蜂窝夹层板的导热系数低于0.03 W/(m·K),满足我国保温隔热行业材料的使用要求.

目的 以明胶和预胶化淀粉为原料制备具有缓冲效果的生物质可降解泡沫材料,为缓冲包装用生物质泡沫提供一种新的选择.方法 通过对不同明胶-淀粉质量比、固含量、十二烷基硫酸钠(SDS)用量进行实验研究,并进行结构表征及静态压缩性能测定对泡沫材料进行综合评价.结果 得到了明胶-淀粉缓冲泡沫材料的最优条件,固含量(用质量分数表示)为20％,表面活性剂质量分数为0.75％,明胶-淀粉质量比为70:30.在此最优条件下的明胶-淀粉缓冲泡沫材料发泡倍率为5.14倍,表观密度为0.064 g/cm3,弹性模量为36.64 kPa,50％抗压强度为2.49 kPa.结论 以明胶和预胶化淀粉为原料制备的复合泡沫材料具有表观密度低、缓冲性能较好的特点.单因素实验结果表明,预胶化淀粉对泡沫的力学性能有增强作用.

Paper honeycomb sandwich plate is often used as transport packaging for the good cushioning and vibration isolation properties. However, the change of relative humidity has a great influence on the vibration performance of paper honeycomb sandwich plate because of its strong water vapor absorbing characteristics. In order to avoid the system resonance and reduce the product vibration damage, the main resonance frequencies for the paper honeycomb packaging system were evaluated by the sinusoidal vibration tests, further the effects of relative humidity, static compression stress, and the geometric parameters of honeycomb core on the main resonance frequencies were investigated. The results show that the main resonance frequency decreases with the increase of relative humidity, static compression stress, honeycomb cell length, and plate thickness.

The vibration transmissibility of paper honeycomb sandwich plate was tested and the vibration transmissibility curve was simplified and characterized. Based on the basic principle of vibration mechanics, the equation for calculating the energy dissipated by damping of paper honeycomb sandwich plate-block system during vibration was deduced. Furthermore, the effects of honeycomb structural parameters (cell length, sandwich plate thickness) and block mass on the damping energy dissipation were analyzed. The results showed that the curves of vibration transmissibility for paper honeycomb sandwich plate can be divided into three regions: plateau region, amplification region, and attenuation region. The vibration transmissibility ratio in different regions can be expressed as functions of frequency. The energy dissipated by damping of paper honeycomb sandwich plate-block system depends on its vibration transmissibility. If the vibration transmissibility ratio–frequency curve is obtained, the damping energy dissipation of the system can be calculated. The total energy dissipation of paper honeycomb sandwich plate-block system during vibration is about equal to that of plateau region, and the energy dissipated in amplification and attenuation region can be neglected. Different honeycomb structural parameters have the same effect on the damping energy dissipation of the system. Block mass has little effect on the damping energy dissipation in plateau region and the total energy dissipation during vibration but has a greater impact on the energy dissipation in the amplification and attenuation regions. The purpose of this paper is to provide a basic method for calculation of energy dissipated by damping and evaluation of anti-vibration property for packaging material.

Honeycomb paperboard has been widely used in transportation and packaging of electronic instruments and furniture owing to the advantages of light weight, good compression resistance, environmental friendliness, and easy degradation. As a common cushioning material in transportation, it is worth studying the damping characteristic and vibration reduction mechanism of honeycomb paperboard. Based on the basic principles of vibration mechanics, the damping of honeycomb paperboard was proposed. Then the influences of cell length, paperboard thickness, grammage of core paper, and the honeycomb structures with face sheet or without face sheet on the damping characteristic of honeycomb paperboard were analyzed. Finally, the vibration reduction mechanism of packaging system with honeycomb paperboard and block was discussed briefly. The results show that the damping value of honeycomb paperboard decreases with the increase of cell length and paperboard thickness. The honeycomb paperboard with large grammage of core paper has high damping value, and yet paper honeycomb core structure without face sheet has poor damping capacity. What's more, the vibration reduction capacity of packaging system is influenced by the deformation and damping characteristic of honeycomb paperboard, among which material damping and structural damping contribute more, honeycomb deformation and air damping contribute less. The weight of block does not affect the damping characteristic of honeycomb paperboard, but affects the vibration reduction capacity of the whole system.

The maximum vibration transmissibility of paper honeycomb sandwich structures with different sizes of honeycomb core under various static stresses was investigated using the sine frequency sweep test. The effects of the cell length of the honeycomb, the thickness of the sandwich structure, and the static stress on the maximum vibration transmissibility were evaluated and a linear polynomial equation for evaluating the maximum vibration transmissibility was obtained. The results show that the maximum vibration transmissibility increases steadily with the increase in the cell length of the honeycomb, the thickness of the sandwich structure, and the static stress. The proposed equation for the maximum vibration transmissibility is suitable for predicting the maximum vibration transmissibility of paper honeycomb sandwich structures. In addition, the fitted three-dimensional diagrams of the effects of the factors on the maximum vibration transmissibility derived from the evaluation equation were shown to be in good agreement with the experimental results.

Vibration transmissibility is an important factor to characterize the vibration absorption performance of cushioning packaging materials during transportation. Reasonable prediction of vibration transmissibility can guide antivibration design and reduce packaging cost. As a kind of green cushioning material, paper honeycomb sandwich structure is widely used in transport packaging because of its good machinability. But at the same time, it also has strong water absorption capacity. To a great extent, the vibration transmissibility of paper honeycomb sandwich structure may be affected by ambient humidity. In this research, the vibration transmissibility of paper honeycomb sandwich structures with various structure sizes under different humidity was tested by sine frequency sweep experiments. The rule of maximal vibration transmissibility with moisture content, cell length of honeycomb, and thickness of sandwich structure was analyzed. The results show that the maximal vibration transmissibility of paper honeycomb sandwich structure increases with the increase of moisture content, cell length of honeycomb, and thickness of sandwich structure. In order to construct the relationship between maximal vibration transmissibility and various factors, the moisture content was standardized. Finally, the maximal vibration transmissibility evaluation equation of paper honeycomb sandwich structure containing standardized moisture content and size of sandwich structure was obtained, which is of some reference value for vibration prediction of paper honeycomb sandwich structures.

目的 针对蜂窝纸板的振动防护性能,研究不同结构和材料参数的蜂窝纸板振动传递特性的有限元仿真分析方法.方法 利用有限元软件Abaqus/Standard建立蜂窝纸板-质量系统模型,设定2种蜂窝纸板,分别具有不同的面纸材料参数和蜂窝胞元边长.仿真分析蜂窝纸板的振动传递特性,并对其进行实验验证.结果 通过仿真和实验得到了蜂窝纸板的振动传递率-频率曲线,共振频率的仿真结果与实验值误差小于3.43％,共振时振动传递率的仿真结果与实验值误差小于11.31％.结论 利用该有限元仿真方法,能够获得不同结构和材料参数的蜂窝纸板的振动传递特性.仿真分析结果表明,面纸定量对蜂窝纸板振动传递特性的影响不大,而蜂窝胞元边长较大的蜂窝纸板,其系统共振频率较小,振动传递率变化不明显.

The finite element model for paper honeycomb was constructed, and the finite element method of out-of-plane compression for the paper honeycomb was studied. Then four kinds of paper honeycomb with different structural parameters were simulated and analyzed using finite element software ABAQUS. Moreover, the results obtained from finite element method were verified based on the existing theoretical research results and experimental results, respectively. The results show that stress–strain curves obtained from finite element method clearly show the four deformation stages of the paper honeycomb under out-of-plane compression, which is basically consistent with the trend of the typical curve. The values of initial peak stress, plateau stress and densification strain are close to the theoretical results. The stress–strain curves and deformation contours coincide with experiments well. The differences of initial peak stress σpk, plateau stress σpl and densification strain εD between theoretical, finite element method and experimental results are less than 15%. Therefore, the finite element method can be used to analyze the stress–strain curves and deformation characteristics of paper honeycomb. In addition, the results also show that the thickness of specimen has little effect on the stress and strain. However, people often prefer to use the thicker paper honeycomb to get better cushioning effect in practical applications, which was explained.

目的研究芯层结构因素和静应力因素对纸蜂窝夹层板-质量系统主共振频率的影响。方法采用正弦振动试验测试纸蜂窝夹层板-质量系统的振动传递特性,分析不同静应力作用下不同蜂窝芯的纸蜂窝夹层板-质量系统的主共振频率变化规律。结果纸蜂窝夹层板-质量系统的主共振频率在150～350Hz之间;蜂窝芯结构及芯层材料影响纸蜂窝夹层板的刚性,从而影响系统的主共振频率;载荷质量变化引起静应力的变化,也会影响系统的主共振频率。主共振频率均随蜂窝胞元边长、纸板厚度、芯纸定量及静应力的增大而降低。结论可为纸蜂窝夹层板的振动传递特性研究提供基础,有助于不同材质蜂窝夹层板的优化设计。

通过构建保温箱基本模型,运用有限元法及Fluent进行热流耦合分析,得到保温箱内温度场,并通过实验进行验证.选取3种常见保温材料[挤塑聚苯乙烯(XPS)、发泡聚氨酯(EPU)与真空隔热板(VIP)],通过模拟仿真研究不同材质保温箱内温度场分布规律.结果表明:保温箱使用的保温材料不同,内部温度场有较大的差异性,其中VIP保温箱内温度最接近蓄冷剂相变温度值,且温度场分布最均匀;3种材料都具有较好的阻热性能,其中VIP的阻热性能最好,在保温箱内相同位置的温度比EPU和XPS要低.

目的 探讨蓄冷剂摆放位置不同时,保温箱保温过程中内部温度场的分布情况和变化规律.方法 应用有限元法,以ICEMCFD建立保温箱基本模型,并通过改变模型内部蓄冷剂的摆放位置建立侧面摆放(2种)、顶部摆放和边缘摆放共4种摆放方式.将内部空气的对流换热与箱体的热传导过程统一成一个整体,通过Fluent进行热流耦合分析.结果 得到了保温箱内部温度场分布一般规律,蓄冷剂摆放位置不同时温度场分布情况有很大差异,其中边缘摆差异性最大,侧摆次之,顶摆温度场分布最均匀.结论 针对可利用体积、温度场均匀程度、箱内平均温度来说,顶摆方式无疑是最佳的蓄冷剂摆放位置.

Paper honeycomb sandwich panel is an environment-sensitive material. Its cushioning property is closely related to its structural factors, the temperature and humidity, random shocks, and vibration events in the logistics environment. In order to visually characterize the cushioning property of paper honeycomb sandwich panel in different logistics conditions, the energy absorption equation of per unit volume of paper honeycomb sandwich panel was constructed by piecewise function. The three-dimensional (3D) energy absorption diagram of paper honeycomb sandwich panel was constructed by connecting the inflexion of energy absorption curve. It takes into account the temperature, humidity, strain rate, and characteristics of the honeycomb structure. On the one hand, this diagram breaks through the limitation of the static compression curve of paper honeycomb sandwich panel, which depends on the test specimen and is applicable only to the standard condition. On the other hand, it breaks through the limitation of the conventional 2D energy absorption diagram which has less information. Elastic modulus was used to normalize the plateau stress and energy absorption per unit volume. This makes the 3D energy absorption diagram universal for different material sandwich panels. It provides a new theoretical basis for packaging optimized design.

The influence of the temperature and relative humidity on the moisture content of corrugating medium was studied by experiments. The ideal three-dimensional diagram between the moisture content and the temperature and relative humidity was constructed by the GAB model. The prediction equation of the moisture content and the relative elastic modulus was fitted after analyzing the test results by MATLAB software. The results show GAB model can predict the moisture content of corrugating medium in different temperature and humidity conditions, and the fitting equation can describe the relation between the elastic modulus of corrugating medium and the moisture content. The predicted elastic modulus can be used to evaluate the cushioning properties of corrugated sandwich paperboard.

温度敏感型产品在流通中外界环境温度变化无常,高温或者低温对保温箱保温性能产生不同的影响规律.试验模拟三种不同外界环境温度(30℃,0℃,-30℃),分析环境温度对保温箱保温性能的影响规律,进一步结合蓄冷剂相变传热过程,探讨保温箱内部各测点温度分布情况,得出保温箱内外温差越大,有效保温时间越短,保温箱内各测点温度分布均匀性越差的结论.因此采用同一种保温包装形式无法满足不同外界环境温度下对产品2℃～8℃的温控要求,针对不同的季节和地区,保温箱的保温方式不能一成不变,必须制定符合实际情况的保温方案来应对外界环境温度的变化,以保证温度敏感型产品的流通安全.

综述了蜂窝纸板振动传递特性的研究进展,从实验研究、振动传递特性模型构建和有限元分析方法3个方面总结了国内外研究成果.重点讨论了当前研究中结构参数对蜂窝纸板共振频率和振动传递率的影响规律,指出蜂窝纸板振动传递特性的下一步研究可从以下方面开展:分析蜂窝结构参数对包装系统振动传递特性及减振特性的影响规律,从理论和仿真两方面分别建立与蜂窝结构参数相关的振动传递特性数学模型和有限元模型,进一步揭示蜂窝纸板材料振动传递规律,阐明蜂窝纸板振动变形机理.

Considering the slight deformation of the paper honeycomb sandwich plate in the vibration, the stiffness coefficient of the paper honeycomb sandwich plate was equivalent to the elasticity. The analytical model of natural frequency related to the structural and material parameters of the paper honeycomb sandwich plate and mass of block was derived. Subsequently, 5 different paper honeycomb sandwich plates and 3 different blocks were chosen to modify the analytical model by finite element method and verify it by experiment. The results show that the modifying factorl is 0.606 and the error between analytical and experimental results is less than 10%. In the future, the analytical model can be used to predict the natural frequency of paper honeycomb sandwich plate with different structural parameters under different blocks. Therefore, it provides the necessary theoretical reference for the optimization design of paper honeycomb sandwich plate.

研制了一种适用于食品冷链运输的复合相变蓄冷剂.通过差示扫描量热仪(DSC)对硝酸钾、碳酸钠的筛选,确定了以相变潜热较高的硝酸钾水溶液为基础,再与甘露醇、乳酸钙进行复配,最终确定蓄冷剂方案为硝酸钾和乳酸钙复配,并通过添加羧甲基纤维素钠(CMC)作为增稠剂,使其保持溶胶态降低了流动性.获得蓄冷剂最优配方为:3％(wt,质量分数,下同)硝酸钾,1％乳酸钙,3％ CMC,其余为水.该相变蓄冷剂的相变潜热为308.2J/g,起始融化温度(Onset温度)为-3.79℃.往复融冻实验表明,该蓄冷剂具有较好的稳定性,无明显的过冷及相分离,能长期反复使用,可应用于食品冷链运输领域.