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.     

Tensile strength and bonding in compacts: a comparison of diametral compression and three-point bending for plastically deforming materials

The tensile strength of tablets is frequently used as a measure of the bonding achieved during compaction. Tablets from two plastically deforming materials and one brittle material have been subjected to tensile strength testing using diametral compression and three-point bending. The plastically deforming materials exhibited marked inhomogeneities, with the surfaces of the tablets considerably more compact than the inner material. The results from the two tests were different, with the three-point bending test giving higher results for tensile strength. The rate of change of tensile strength with overall tablet porosity was, however, the same for the two tests. Diametral compression would thus appear to give a reasonable estimate of bonding despite the non-homogenous nature of tablets prepared from plastically deforming materials.     

水泥抗折强度测量结果不确定度评定

本文就水泥胶砂抗折强度依据GB/T17671-1999《水泥胶砂强度检验方法》(ISO法)进行测试,按JJF1059-1999《测量不确定度评定与表示》对水泥胶砂抗折强度的测量结果不确定度的评定方法。     

Numerical and experimental investigation of the strength of corrugated board packages

The buckling behaviour of corrugated paper packages was studied by means of an experimental and theoretical analysis. Mechanical behaviour of paperboard was first evaluated experimentally, then a local geometry FEM model, able to reproduce with a very good accuracy buckling loads obtained experimentally in the standard edge compression test, was developed. In order to investigate the buckling of a complete package, a finite element ‘corrugated board’ was introduced by means of a dedicated homogenization procedure. The FEM model of the package, assembled with this new element, can accurately predict the experimental data of incipient buckling observed during the standard box compression test, despite the few degrees of freedom and the minimal computational effort. Copyright © 2003 John Wiley & Sons, Ltd.     

瓦楞纸箱抗压强度的计算方法及计算机辅助设计

论述了抗压强度的计算方法 ,其中 Kellicutt公式和 Makee公式为最主要的计算方法 ,并对一个实例进行计算 ,比较两种数学模型得到的结果 ,由此得到一些有用结论 ,并提出了相应的计算机程序 ,使计算准确合理     

先进高强度钢板弯曲类回弹特性的试验研究

随着先进高强钢板在汽车及航天航空领域的广泛应用,回弹导致的成形精度问题日益突出.为了获取先进高强钢的弯曲回弹特性,通过采用U形件回弹模型,针对600MPa级别的3种典型高强钢(DP钢、TRIP钢、HSLA钢)进行了回弹试验研究.实验结果表明:在相同变形条件下,TRIP钢弯曲回弹最大,DP钢次之,HSLA的弯曲回弹最小;不同工艺条件、不同材料性能参数对弯曲回弹呈单调的影响规律,而润滑条件对弯曲回弹的影响趋势并未出现一致性规律.     

An analysis of the influence of hand hole and ventilation hole design on compressive strength of corrugated fiberboard boxes by an artificial neural network model

This research aimed at developing a high-performing corrugated fiberboard box compression strength prediction model and to analyze the influences of ventilation and hand hole designs for these containers on the box compression test (BCT) by applying artificial neural network (ANN) modeling. The input variables considered in this study are composed of nine parameters including box dimension as well as shapes, sizes, positions, and locations of ventilations and hand holes of a regular slotted container (RSC, FEFCO 0201). Back propagation algorithms (BPNs) of ANN models were developed from 970 BCT testing data points (single wall boards, C flute, 205/112/205 g/m²). Tested data was randomly broken into three groups for the model development as 80:10:10 for the training set, testing set, and validating set. According to the analysis performed, a BPN 9-13-1 model reflected the highest prediction performance with R² = 0.97. According to the analysis, BCT was significantly affected by the hand hole location followed by the geometrical dimensions of the box (height, length, and width) and the ventilation factors (shape, number, and location) in that order. Hand holes at the top flaps caused a lower BCT reduction compared with those at the vertical locations of the box. Slight changes to the eliminated board area for both hand holes and ventilation (±5%) contributed to less BCT reduction compared with its locations and shapes. Interestingly, increasing the box height significantly increased the BCT, and this was found to be limited only to shorter boxes fabricated from a high stiffness corrugated board.     

Finite element analysis of vent/hand hole designs for corrugated fibreboard boxes

Corrugated fibreboard is an economical and efficient material for fabricating shipping containers that are widely used for the distribution, transportation and storage of goods. Corrugated fibreboard is usually considered to be an orthotropic material because the principal fibre directions, machine direction (MD) and cross‐machine direction (CD), are identical to the fibres in paperboard, which has apparent directional property differences. The purpose of this study is to investigate the principal design parameters of ventilation holes and hand holes in the faces of the shipping container, (corrugated fibreboard boxes), using finite element analysis (FEA). Various designs of ventilation holes were studied with respect to stress distribution and stress level. It was found that the appropriate pattern and location of the ventilation holes were vertical oblong‐shaped and symmetrically positioned within a certain extent of distance to the right and left from the centre of the front and rear faces of the boxes. On the other hand, the appropriate location and pattern of the hand holes were a short distance from the centre to the top of the boxes on both side faces. The appropriate pattern was a modified shape, such as the radius of curvature of both sides in horizontal oblong. The pattern and location of both the ventilation holes and the hand holes determined by the FEA simulation generally agreed well with laboratory experimental results. The decrease in compression strength of the box could be minimized with identical area of the ventilation holes if the length of the major axis of the ventilation hole is less than 1/4 of the depth of the box and the ratio of the minor axis to the major axis is 1/3.5–1/2.5, provided that even‐numbered holes are located symmetrically. Copyright © 2006 John Wiley & son, Ltd.     

Estimation of the compression strength of corrugated fibreboard boxes and its application to box design using a personal computer

Many papers have been published on the compression strength of corrugated fibreboard boxes, using such formulae as Kellicut's equation and McKee's equation for the calculation. These equations, however, require known values of the strength of linerboard or corrugated fibreboard, they do not include the influence of moisture content and they are inadequate in the case of wrap-around boxes. The present author measured the mechanical properties of a large number of fibreboard boxes, and has derived a statistical formula useful for estimating the compression strength of a box based on its specifications — grade of corrugated fibreboard, size of box, type of box, printed area and moisture content. The calculation gives fairly good agreement with experimental results. The estimation technique has further been converted into a personal computer program, which renders the design of corrugated fibreboard boxes an easier task.     

超高强度硼钢板热弯曲数值模拟

为研究热自由弯曲和热接触弯曲方法的淬火效果和成形精度,应用ABAQUS软件,对超高强度硼钢板U形件的热弯曲过程进行了数值模拟研究.研究表明:热接触弯曲改善了热弯曲零件底部的淬火效果,且热接触弯曲可获得比热自由弯曲更好的成形精度;不同压边力下热接触弯曲回弹均随着压边力的增加而逐渐减小;数值模拟结果与实验结果吻合较好,验证了有限元模型的可靠性.     

Influence of core hardness on bending strength of tooth in cylindrical gears under quasistatic loading conditions

Dynamically loaded mechanical components can withstand overloading if they are designed by considering sufficient safety of margin for the static strength. In this study, the influence of core hardness on bending static strength of the tooth in cylindrical hardened gears is investigated experimentally. For this purpose, shot peened and unpeened gears having different core hardness and comparable surface hardness are tested on a pulsator test rig, which provides a quasi‐static loading condition by means of a servomotor. All test gears are made of 20MnCr5 steel and have the same geometry (module m = 5 mm). Average static load for fracture is measured. The relationship between the applied load and bending stress is known. Hardness profiles from the surface to the core of the test gears were measured. Strength is assumed to be a function of depth depending hardness to justify fracture initiation on the surface under bending static load conditions. Tooth root failures originating from the surface were observed experimentally. It is found that the shot peening treatment and core hardness have no considerable influence on the bending strength of the tooth under static loading conditions.     

Device for determining the ultimate strength in bending for refractories at elevated temperature

A device is developed and prepared for determining the ultimate strength in bending of refractories at elevated temperature according to GOST R 50523-93 and ISO 5013-85, that in functional possibilities, metrological characteristics, accuracy of determining physicomechanical and thermomechanical properties of test objects and other parameters surpasses existing Russian analogs. Translated from Izmeritel’naya Tekhnika, No. 2, pp. 34–37, February, 2009.     

Three-point bending of sandwich beams with aluminum foam-filled corrugated cores

Sandwich panels having metallic corrugated cores had distinctly different attributes from those having metal foam cores, the former with high specific stiffness/strength and the latter with superior specific energy absorption capacity. To explore the attribute diversity, all-metallic hybrid-cored sandwich constructions with aluminum foam blocks inserted into the interstices of steel corrugated plates were fabricated and tested under three-point bending. Analytical predictions of the bending stiffness, initial failure load, peak load, and failure modes were obtained and compared with those measured. Good agreement between analysis and experiment was achieved. Failure maps were also constructed to reveal the mechanisms of initial failure. Foam insertions altered not only the failure mode of the corrugated sandwich but also increased dramatically its bending resistance. All-metallic sandwich constructions with foam-filled corrugated cores hold great potential as novel lightweight structural materials for a wide range of structural and crushing/impulsive loading applications.     

Quasi-isotropic bending responses of metallic sandwich plates with bi-directionally corrugated cores

In order to reduce anisotropic behaviors of sandwich plates with open channel cores under the bending load, bi-directionally corrugated cores were introduced. Bi-directionally corrugated core has two additional design parameters related with a corrugation pass than uni-directionally corrugated core, so that its properties with respect to core orientations can be controlled. Sandwich plate with bi-directionally corrugated core is designed optimally so that beam buckling of face sheets is reduced drastically and anisotropic buckling behavior in the face sheets is minimized. The cores fabricated by a sectional forming process were bonded with face sheets by adhesive bonding. Three-point bending experiments were carried out with respect to core orientations. It has been shown from the experiments that sandwich plates with bi-directionally corrugated cores exhibit quasi-isotopic bending behaviors and structural performances in sandwich plates.     

制备工艺对SiCf/Si-O-C复合材料弯曲强度的影响

以聚硅氧烷为先驱体，采用先驱体转化法制备SiCf／Si-O-C复合材料。研究制备工艺参数模压压力、裂解时升温制度、裂解温度、保温时间对材料的力学性能的影响。通过对复合材料微观结构的分析研究，发现界面结构与致密度是影响SiCf／Si-O-C复合材料性能的主要因素。     

Effect of load history on the performance of corrugated fibreboard boxes

This paper investigates the effect of load histories (static and dynamic) on the compression strength and shock absorption properties of corrugated fibreboard boxes. Experiments were set up in the laboratory to simulate compressive forces and drops that occur during normal transportation of packaged products. The results show that static compression forces (not to failure) do not have significant influence on the compressive strength or shock absorption of corrugated boxes, and that dynamic compression forces do have a significant influence on these performance factors. This study was limited to one box size and style and suggests that more extensive research be undertaken to determine the effects of previous loading histories on a broad range of box configurations.     

Industrial experiences of bending fatigue strength in table liner for cement mill

A table liner for the vertical roller mill has been used to grind natural limestone. Unexpected fatigue failure accidents have occurred during portland cement manufacturing process. The design life of a table liner is 4 × 10⁷ cycles, but the actual fatigue life of a table liner is 2 × 10⁶ to 8 × 10⁶ cycles. The fatigue crack of a table liner initiates from the outside edge of the grinding path of the limestone. When such a crack occurs, the table liner has to be replaced, and this requires 30% of the total maintenance cost of the vertical roller mill. Therefore, this study examines the fatigue failure of a table liner by plane‐bending fatigue test, stress measurement test, finite element analysis and fatigue fracture analysis.     

陶瓷纤维长度对复合精铸型壳抗弯强度与透气性的影响及增强行为

为了分析纤维长度对陶瓷纤维增强硅溶胶型壳抗弯强度与透气性的影响及增强行为,采用1~6mm六种不同长度陶瓷纤维制备硅溶胶型壳试样。研究结果表明,陶瓷纤维长度对硅溶胶型壳强度和透气性的影响显著,随着陶瓷纤维长度的增加,型壳的抗弯强度先增大后减少,型壳的透气率先增大后减小再增大。当陶瓷纤维长度为4mm时,型壳的常温及焙烧后抗弯强度达到最大值,分别为2.97 MPa和6.84 MPa;型壳的透气率达到最大值2.90。当陶瓷纤维长度大于4mm时,纤维在型壳中分散性变差,纤维的桥联作用得不到有效发挥,型壳孔隙率减少,导致型壳强度和透气性变小。