The effect of pallet top deck stiffness on the compression strength of asymmetrically supported corrugated boxes

During unitized shipment, the components of unit loads are interacting with each other. During floor stacking of unit loads, the load on the top of the pallet causes the top deck of the pallet to bend, which creates an uneven top deck surface resulting in uneven or asymmetrical support of the corrugated boxes. This asymmetrical support could significantly affect the strength of the corrugated boxes, and it depends on the top deck stiffness of the pallet. This study is aimed at investigating how the variations of pallet top deck stiffness and the resulting asymmetric support affect corrugated box compression strength. The study used a scaled-down unit load compression test on quarter-scale pallet designs with different deckboard thicknesses using four different corrugated box designs. Pallet top deck stiffness was determined to have a significant effect on box compression strength. There was a 27%–37% increase in box compression strength for boxes supported by high-stiffness pallets in comparison with low-stiffness pallets. The fact that boxes were weaker on low-stiffness pallets could be explained by the uneven pressure distribution between the pallet deck and bottom layer of boxes. Pressure data showed that a higher percentage of total pressure was located under the box sidewalls that were supported on the outside stringers of low-stiffness pallets in comparison with high-stiffness pallets. This was disproportionately loading one side of the box. Utilizing the effects of pallet top deck stiffness on box compression performance, a unit load cost analysis is presented showing that a stiffer pallet can be used to carry boxes with less board material; hence, it can reduce the total unit load packaging cost.     

基于快递纸箱二次利用理念的纸家具设计

目的 将快递纸箱进行纸家具设计,实现资源的再次利用.方法 从可持续发展的角度出发,对瓦楞纸家具的国内外发展情况进行了对比分析,并且研究分析了快递瓦楞纸箱的类型、尺寸和特点以及瓦楞纸家具所适用的人群特点,确立了用快递纸箱进行家具设计的可行性,结合理论条件以及相关技术工艺条件,设计出一系列以快递纸箱为原材料的成本可控的瓦楞纸家具.结论 将快递纸箱二次利用直接进行纸家具设计,在给环境带来益处的同时,也是再次实现了其自身的一个使用价值,更是给有需求的群体节省资本带去便利.快递纸箱作为生活中随处可见的材料,在进行家具设计时可以跟随DIY家具的潮流,让使用者自身也参与到瓦楞纸家具的制作中,使其感受到纸家具的可靠性.     

A technique to quantify morphological damage of the flute profile in the midplane of corrugated fibreboard

This research presents a technique to quantify morphological damage to flutes in corrugated fibreboard (CFB). The method involves laser cutting thin samples and analysing digital images of the flute profiles. The surface profiles of creased CFB before and after laser cutting were measured using fringe projection and showed that the sample preparation does not significantly affect the flute profile. After imaging the laser cut samples, skeleton analysis was used to derive a digitised profile of the flute shape. To characterise the level of damage to the flute profile, a similarity factor (SF) was introduced to quantify the relative difference between test sample and reference flute profiles. Validation of this analysis technique was done by generating known images of flute profile with variations that include distortions that could occur to CFB. These images were then fed into the skeleton analysis, and the results were compared with the original profile. This comparison showed good agreement between the initial and skeleton‐analysed flutes. A demonstration of the skeleton analysis on purposefully damaged actual CFB flute profiles shows that the SF reduces as the level of crushing increases, showing that the technique could be used to enumerate morphological damage to CFB during manufacture, conversion, and use.     

Preparation and Properties of Carbon/Zeolite Composites with Corrugated Structure

Composites of carbon/zeolite with corrugated structures were prepared by carbonization, steam activation and/or hydrothermal treatment of corrugated paper. No zeolite formation resulted from conventional hydrothermal treatment of the carbonized and activated samples in NaOH solution but zeolite Na P1 was formed by addition of silica to the solution. By contrast, zeolites Na P1 and Na A were formed by the in-situ crystallization method (hydrothermal treatment of solid samples impregnated with NaOH solution). With higher impregnating NaOH concentrations, longer reaction times and higher reaction temperatures, the products changed to sodalite- and cancrinite-type compounds. Hydrothermal treatment was effective in increasing the specific surface area of the products by the formation of zeolite from amorphous calcium aluminosilicate, and also increased the mechanical strength by gluing together the carbon fibers in the samples. The resulting samples showed enhanced adsorption for polar molecules such as ammonia, water vapor and methanol due to the formation of composites of activated carbon with hydrophilic zeolites.     

马蹄形断面波形钢腹板支架稳定承载性能研究

为了研究波形钢腹板支架结构在围岩压力作用下的平面内稳定性能,设计了马蹄形断面波形钢腹板支架的模型试验,分析了支架的稳定承载力、位移与应变发展规律。试验结果表明：支架的最终破坏形态为整体非对称失稳,支架两侧向外变形产生水平位移,右侧水平位移明显大于左侧水平位移;极限荷载时,仅拱顶翼缘和角部腹板进入了塑性阶段。支架的试验结果与有限元分析结果吻合良好,验证了有限元模型的正确性。在此基础上,对波形钢腹板支架的弹塑性屈曲性能进行了有限元参数分析,表明波形钢腹板支架对初始缺陷并不敏感,而腹板高度、腹板厚度及翼缘厚度是弹塑性稳定承载力的敏感参数,影响较大。长细比较小时,对称失稳和反对称失稳均可能发生;长细比较大时,支架会发展反对称失稳;支架的弹塑性屈曲荷载随长细比的增大而降低。有限元计算结果表明,相同边界条件和荷载情况下,波形钢腹板支架的极限稳定承载力是用钢量相同的矿用工字钢支架的2倍以上。     

混凝土肋式转向装置力学性能研究

针对波纹钢腹板体外预应力箱梁结构的力学和构造特点,采用有限元分析与实验研究相结合的方法,研究用于波纹钢腹板体外预应力箱梁的混凝土肋式转向装置的承载机理、受力特点、破坏形态、极限承载力等力学特性。采用非线性有限元方法对结构从加载开始直至破坏的受力全过程进行了模拟分析,并用实验对有限元分析的结果进行了验证,二者吻合良好。研究结果表明,转向装置对混凝土翼缘板的局部影响集中在转向装置与混凝土翼板连接的部分及附近区域内。转向装置破坏时,受拉区混凝土受拉开裂、环向钢筋受拉屈服,而受压区混凝土受压劈裂破坏。转向装置受压区混凝土的受力表现出明显的偏心受压构件的受力特点。研究结果可供工程设计人员在设计波纹钢腹板体外预应力箱梁转向装置时参考。     

混凝土肋式转向装置力学性能

针对波纹钢腹板体外预应力箱梁结构的力学和构造特点,采用有限元分析与实验研究相结合的方法,研究用于波纹钢腹板体外预应力箱梁的混凝土肋式转向装置的承载机理、受力特点、破坏形态、极限承载力等力学特性．采用非线性有限元方法对结构从加载开始直至破坏的受力全过程进行了模拟分析,并用实验对有限元分析的结果进行验证,二者吻合良好．结果...     

波纹管对纳米复合相变材料蓄放热性能影响的试验研究

以纳米复合材料作为相变蓄热材料,加工制作了相变蓄热装置,并搭建了蓄热器热性能实验台,对传热元件分别为光管和波纹管的蓄热容器进行了相变蓄热实验,测量了相变材料的温度并通过数据采集仪进行数据采集,整理绘制了在不同条件下的温度时间曲线并进行了分析讨论。结果表明波纹管能够加快热媒体在波纹管中的流动,缩短蓄热所需时间,并且提高放热速率。     

英峪沟桥结构力学特性有限元分析

河南英峪沟桥是我国第1座变截面波形钢腹板PC组合连续箱梁公路桥。通过空间有限元计算,分析结构的受力性能,为该类型桥的研究提供经验。     

波纹管层流传热与流动的三维数值模拟

应用计算流体力学软件FLUENT对波纹管在层流情况下的传热与流动问题进行了三维数值模拟。所模拟的波纹管的母线由多段凹凸圆弧组成(半径分别为R1和R2),其公称直径为20mm,长度为2m。模拟了几何参数R1、R2对其传热与流动性能的影响。在模拟过程中压力-速度耦合选用SIMPLEC格式,压力方程的离散选用Standard格式,其他方程的离散均选用QUICK格式。结果表明:与光管相比,层流情况下波纹管能显著强化传热,在雷诺数(Re)相等情况下,波纹管的R1越大、R2越小时的强化传热效果越好;在几何参数相同情况下,Re越大,强化传热效果越好,在所研究的范围内,Nu最大增加了199.5%。同时,波纹管还具有良好的流动性能,大部分Re的范围内流动阻力系数小于光管的情况,并且随着Re的增大而逐渐接近于光管的摩擦系数。