Carton Clamp Test Methodologies and the Effects on Load Containment and Retention

A carton clamp is an alternative material handling device for moving packages and material. The need for changing the clamping force for variations in size, shape and weight of the load creates the potential for underclamping (slippage) and overclamping (compressive damage). Currently, there are two test standards that provide lab‐based forklift/clamp testing guidance – ISTA 3B and ASTM 6055. While ISTA provides a stationary simulation of carton clamp handling, ASTM offers a more mobile approach. The ISTA recommended testing equipment tends to be fairly expensive and is not easily accessible in North American test facilities. The ASTM standard proposes the use of a carton clamp truck in industry but does not specify any specific parameters making repeatability between laboratories and practitioners ambiguous. This study examined the implementation a carton clamp lift truck as found in industry allowing for mobile (hazard course) testing. A modified version of ISTA 3B was paired off against ASTM 6055 for evaluating both column and cross stack pallet patterns with a variety of treatments. This study attempted to determine if carton clamps as found in industry are capable and repeatable enough to provide consistent data. This study also examined the test methodologies' effect on load containment via stretch film force, load retention via unitized load slippage and the effects of ride height and driver interaction. The study sought to understand if these effects are uniform across the unitized load or if particular layers of the load are more affected than others. Copyright © 2014 John Wiley & Sons, Ltd.     

滑板托盘集装单元货载搬运稳定性研究

目的为了规避托盘单元货载在叉车装卸搬运过程中因散垛、塌垛导致的货物事故。文中基于ADAMS仿真定量分析叉车装卸搬运过程中托盘单元货载稳定性。方法瓦楞纸箱货物分别采用重叠堆码和交错堆码,在牛卡纸滑板托盘上堆码达到2200mm的极限高度,形成滑板托盘集装单元货载,不施加裹膜、捆扎等固定措施。以这2种堆码方式形成的滑板托盘集装单元货载为研究对象,建立叉车搬运作业ADAMS动力学仿真模型,并进行货载稳定性分析。结果从仿真结果中可以得到,当货物质量为14 kg时,货物偏移和振动加速度最大,此时对比叉车车身速度曲线和实验要求曲线,验证了仿真数据设置的合理性;提取货物与托盘间位置偏移曲线,得到重叠堆码时,货物沿着叉尖方向的偏移量达到了最大值123.4 mm;提取货物振动加速度曲线,对货物脆值进行评价,得到货物若脆值需在60以上才不会因振动损坏。结论在不施加裹膜、捆扎等固定措施的情况下,采用这2种堆码方式形成的滑板托盘集装单元货载在叉车装卸搬运过程中虽未出现塌垛现象,但堆码在高层的货物发生了较大位置偏移和颠簸振动而存在散垛及损伤货物的危险。建议施加外部约束如裹膜、捆扎等必要措施。     

The effect of pallet connection stiffness,deck stiffness and static load level on the resonant response of pallet decks to vibration frequencies occurring in the distribution environment

This paper summarizes the results of a preliminary study of the relationship between pallet design and the resonant response of pallet decks to sinusoidal vibration. Sine sweep frequency vibration tests between 3 Hz and 50 Hz were conducted to determine the effect of pallet deckboard stiffness, joint stiffness and the static load level on the resonant response of pallet decks. As the stiffness of the pallet joints and deckboards increases, the resonant frequency of the unit load increases and transmissibility decreases. As the static load on the pallet increases the resonant frequency of the unit load decreases and the transmissibility increases. The survivability of a unitized product, sensitive to vibration, during shipping and distribution is affected by the pallet design. Pallets designed using rigid connections and stiffer decks will reduce damage to vibration‐sensitive products. Copyright © 1999 John Wiley & Sons, Ltd.     

美军弹药的托盘化集装现状及发展趋势

介绍了美军弹药托盘化集合包装的现状,分析了新时期美军集装托盘包装的发展趋势,并就开展我军弹药托盘化集合包装提出了初步设想.     

基于荷载时程分析法的商用飞机撞击钢板混凝土结构安全壳的有限元分析

由于钢板混凝土墙背部钢板能够有效地约束混凝土在撞击方向上的运动以及限制混凝土碎片的飞溅,为了抵御商用飞机撞击,新型核电机组的核岛厂房外墙通常设计为钢板混凝土结构(SC)。本文基于荷载时程分析法,运用经典的显式非线性动力分析软件ANSYS/LS-DYNA,进行了波音707-320型号商用飞机撞击某钢板混凝土结构安全壳的响应分析。计算结果表明,即使在安全壳筒身最不利撞击部位冲击作用下,像波音707-320型号的商用飞机对该安全壳的影响是较小的,且增大钢板的厚度能够有效的减小冲击作用下结构的响应。     

标签裹包折标机构设计

目的设计一套标签裹包折标机构。方法基于机构设计理论与方法,将解析法与Auto CAD辅助作图法相结合,对裹包折标执行机构进行参数设计;利用Solid Works软件的建模工具,对裹包折标机构进行局部结构建模设计。结果针对矩形纸板标签及特定裹包要求,设计提出了标签裹包折标的系统机构原理,以最小传动角理论对关键折标机构完成了参数化设计,并设计了结构模型,理论上验证了设计的标签裹包折标机构的可行性。结论设计的标签裹包折标机构适用于刚性或柔性物体包装,为标签裹包系统设计及技术应用提供了理论参考。     

Evaluation of an innovative system for improving readability of passive UHF RFID tags attached to reusable plastic containers

Radio frequency identification (RFID) is a contactless identification technology that has proven to work well in conjunction with reusable plastic containers (RPCs). The impact of this technology on returnable containers has been explored by several past studies. This study evaluates an innovative system for improving readability of passive UHF RFID tags in conjunction with RPCs. The system involves an energy transfer device (ETD), which when attached to the RPCs, passively transfers radio frequency signals to interior regions of a unitized load thereby improving the readability of all RFID tags attached to the RPCs. This study included an evaluation of the improvement in readability of tagged RPCs in a unitized load with forklift truck speed, product type and pallet pattern as the variables and with readability as the main control variable. It was observed that ETDs vastly improve the readability rates by nearly 97%. Results are also included in this paper describing the effects of the product type, pallet patterns and forklift truck speeds on the readability of tagged RPCs in a unitized load. Copyright © 2011 John Wiley & Sons, Ltd.     

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.     

Measurement and analysis of low-acceleration and long-duration longitudinal events using delivery van

This study investigates longitudinal acceleration events during freight transportation characterized as low-acceleration and long-duration using delivery van type vehicles. In the past several decades, there has been an increase in shipments requiring only single or small pallet load quantities and mixed palletized unit loads comprised of different goods. These loads are often transported in delivery vans without load securing devices, increasing the risk of product loss and damage due to load failures resulting from unit loads shifting. A field data acquisition system was used to observe and record the random acceleration events from five vehicles for 5 days, explicitly targeting the vehicles' braking and acceleration manoeuvres. The study aimed to understand the physical phenomenon and provide new information that can be used during preshipment tests to prevent damage to goods and ensure unit load integrity is maintained throughout the supply chain. The events were statistically analysed to understand their probability of occurrence, severity level, and quantify critical parameters such as event rise and hold times. For the braking manoeuvre, the statistical mean of average deceleration was 0.25 g with a corresponding rise and hold duration of 0.83 and 1.27 s, respectively. During the vehicle's acceleration manoeuvre, the statistical mean of average acceleration was 0.29 g with a rise and hold time of 1.29 and 1.39 s, respectively. Utilizing the field data, composite profiles were developed, and these profiles were compared to the currently available test procedures and previous results of other studies.     

蓄电池塑料箱自动缠膜包装机设计

目的 针对蓄电池外壳塑料箱贮存、物流运输过程中出现的粉尘污染、破损等问题,在注塑成型后,需经覆膜处理。由于蓄电池外壳较薄,热缩工艺防护手段变形严重,对产品质量产生较大影响,迫切需要设计一种高效、便捷的蓄电池外壳防护包装工艺。方法 依据功能模块化设计理念提出托盘式塑料箱缠膜的解决方法,针对缠膜包装制定了集整形、缠膜、物料输送为一体的塑料箱自动缠膜工艺和各功能模块机械系统设计,并通过数字化手段验证工艺的合理性。结果 该设备实现了对多种规格的蓄电池外壳塑料箱的整形、缠膜、物料输送一体化生产,效率达到42s/件,相较于人工方式的效率提升了1.4倍。结论 该设备结构合理,在保证缠膜包装质量的前提下,提高了缠膜包装效率,推动了企业自动化进程,为塑料箱自动缠膜包装提供了解决方案。     

地震作用下钢筋混凝土安全壳的SCA可靠性分析

以秦山核电站的钢筋混凝土安全壳为工程背景，分析了结构在地震作用下的可靠度并给出其年破坏概率。安全壳结构模型为壳体有限单元组成的结构系统，系统可靠度分析的稳定构形法（简称ＳＣＡ）被用来求结构系统的破坏概率。通过随机振动分析，将结构所受地震作用等效为沿壳体分布的静态力。单元极限状态分别考虑混凝土压碎和钢筋屈服两种情况。最后的数值结果证明秦山核电站安全壳具有足够的抗震安全性。     

Structural integrity assessment of nuclear containment through fracture characterization

The paper deals with the study of structural response of partially cracked nuclear containment model structure in over pressurized condition with the simulated experiments conducted under severe accidents analysis program for Indian nuclear containment structures. In this research, the fracture characterization of concrete containment structure is also investigated through the over pressure experiments on the BARC Containment (BARCOM) test model structure, which represents 1:4 scale of the prototype 540 MWe Tarapur pre‐stressed nuclear containment structure. In addition to the surface‐type electrical resistance, strain gauges conventionally and commonly deployed for containment proof‐test and ultimate load capacity evaluation of containment models, embedded vibratory wire strain gauges (VWSGs), the digital image correlation (DIC) technique, and soap bubble tests are employed in this study. For fracture characterization, an optical crack profile (OCP) technique is developed through DIC full‐field experiment conducted at the identified critical locations with conventional strain gauges to evaluate the fracture energy and the characteristics of the fracture process zone of concrete containment model structure subjected to the over‐pressure condition for its performance assessment in the case of the beyond design basis accidents. The combination of conventional sensors and full‐field DIC deployed for the first time on the largest scale containment model along with the associated analysis is shown to be effective in fracture characterization and improved structural integrity assessment of the containment model.     

Study of lateral shocks observed during fork truck and pallet jack operations for the handling of palletized loads

This study measured the lateral impact levels that occur when fork trucks are used to handle palletized loads. The existing ASTM-D4003 standard on pallet marshalling recommends a 40 G, 10 ms shock or a 10G. 50ms shock to simulate impacts on pallet loads due to fork truck equipment. This study investigated the validity of these levels since no previous studies documenting these levels is provided in the ASTM standards.⁵ A set of ten impacts were conducted in the two different scenarios using boxes, bins and drums. These scenarios represent a palletized load on a fork truck impacting a similar stationary pallet load and an empty fork truck impacting a pallet load. Results are presented for each category of impacts performed in terms of average and maximum levels measured. The average peak acceleration for the data collected was 36 G and the average duration of impact was 4.3 ms. An analysis describing the limiting conditions for the shock acceleration G and the duration T as a function of the fork truck weight, impact speed, pallet weight and impact condition was determined. This showed that the impacts should have the product of maximum shock (in G) and duration (T) mms lying between 37.2 and 368 for half-sine shocks.     

卷簧式紧膜包装机械设计

目的设计一种利用卷簧对包装薄膜实现紧膜的裹包类机械。方法利用卷簧回旋力来实现裹卷运动而实现变力的输出,然后利用轴与齿轮之间的相互传动来实现力的赋予。卷簧的运动相当于给予薄膜一定的张力,而这种可实现张力也成为卷簧裹包的施力部分,通过该机械各根轴间与相对应齿轮的相互配合实现该紧膜机械的传动。结果针对薄膜张力的不同施加相对张力的要求,得出同一种膜在不同横向张力下的紧膜张力不同。结论卷簧式紧膜包装机械设计对于薄膜包装材料在不同的张力下对于物品的包裹及膜材包装件缓冲特性实践有重要意义。     

Development of a 3-component Load Cell for Structural Impact Testing

This paper describes the development of a 3-component load cell for structural impact testing. The test specimen is mounted directly on the load cell, which measures the axial force as well as two orthogonal bending moments. Basically, the load cell is a stocky cylinder with thick end flanges machined in one piece of high-strength steel. The load measurement system is based upon four strain gauges glued to the central shaft. The signal from each strain gauge is sampled separately. Afterwards, this data is used to compute the axial force and the bending moments. The load cell was originally developed for testing of automotive components.     

Preventing failure in spent nuclear fuel canisters

A spent nuclear fuel canister has been developed with the goal of no containment failure even during accidental drop conditions. This canister was designed to be loaded with U.S. Department of Energy spent nuclear fuel and then used for interim storage, transportation to the nation’s repository, and final disposal at the repository. The design required a high degree of confidence against failure if the canister were subjected to loads (e.g., accidental drop events) resulting in large plastic deformations and high strains. Significant testing of the canister clearly demonstrates that it can safely achieve the intended design goals without failure. The canister skirt and its attachment to the containment boundary are the key engineered elements of the design that allow significant impact damage without failure of the containment. A combination of analytical techniques and physical testing was used to develop and demonstrate the viability of the design. Finite element modeling coupled with scaled drop tests established the design prototype. To validate the design concept, nine full-scale test canisters were fabricated and dropped from various heights and orientations. The nine test canisters experienced varying degrees of damage to their skirts, lifting rings, and containment boundary components. However, all of the tested canisters maintained the containment boundary as evidenced through the results of pressure and selective helium leak testing. Pre- and post-drop finite element analyses were also performed. The analytical results provide accurate predictions of canister responses to the drop tests. The results achieved for the canister can also be applicable to other well-designed containers (canisters, casks, cans, vessels, etc.) subjected to similar loads. Properly designed containers can maintain containment after experiencing dynamically induced high strains, and computer analyses can accurately predict the response of these containers to dynamic loads.     

Regulation of the membrane wrapping transition of a cylindrical target by cytoskeleton adhesion

The adsorption of external objects to the cell membrane often triggers cellular responses involving large deformations. In phagocytosis, upon contact with the target, the cell creates large extensions that wrap around the target and ultimately lead to its engulfment. Although active force generation, in particular by actin polymerization, is required for completion of this process, the elastic deformation of the cell membrane upon adhesion to an external object might play an important part in its initiation. In this paper, the elastic deformation of a bilayer owing to the binding of a cylindrical object is studied, taking into account the membrane bending rigidity and the surface tension, the membrane adhesion to both the external target and inner cytoskeleton. The problem is studied within the framework of the Helfrich–Hamiltonian and using force balance relations and the proper boundary conditions that are related to the adhesion energy coefficients. It is shown that membrane wrapping around the target may be a continuous or abrupt transition upon increasing the target binding energy, depending on the value of the parameter. The degree of wrapping and the shape of the membrane in the vicinity of the object are computed numerically, and analytical expressions are given for the boundaries separating the different wrapping regimes in the parameter space.     

Effectiveness of advanced composites in repairing heat-damaged RC columns

Thirteen rectangular RC column specimens, constructed at 1/3 scale, were tested under axial loading to investigate the use of advanced composites in repairing heat-induced damage. Eleven of the column specimens were subjected to elevated temperatures of 500 °C for 3 h. Nine heat-damaged columns were repaired using carbon fiber reinforced polymer (CFRP) sheets and plates. The effects of wrapping configuration, thickness of wrapping sheets, inclusion of plates as externally-bonded longitudinal reinforcement and the area of plates were examined using seven repair schemes. Test results confirmed that elevated temperatures adversely affect the axial load resistance and axial stiffness of the columns while increasing their toughness. Buckling under pure compressive loads was evident in heat-damaged columns except in those repaired using longitudinal CFRP plates. Partial wrapping with unidirectional CFRP sheets was found ineffective in augmenting the axial load capacity and stiffness of the damaged columns whereas full wrapping increased their axial load resistance and toughness. Using externally-bonded longitudinal CFRP plates, confined with circumferential wraps, significantly enhanced the initial axial stiffness and axial load resistance of the damaged columns. However, none of the seven repair schemes investigated in this study managed to regain the original axial stiffness and load resistance of the undamaged columns.     

Reliability assessment and design load factors for reinforced concrete containment structures

The current ASME code for reinforced concrete containment structures is not based on probability concepts. This paper develops reliability assessment and probability-based design load factors for reinforced concrete containment structures. The purpose of constructing reinforced concrete containment structures is to protect against radioactive release, and so the use of a serviceability limit state related to cracking that can cause the emission of radioactive materials is suggested as a critical limit state for reinforced concrete containment structures. Load factors for the design of reinforced concrete containment structures are proposed. The proposed load factors are also examined in terms of a set of code performance objectives and consistency in limit state probability.     

Mechanical properties of coated paper: Influence of coating properties and pigment Blends

The effect of percentage solids content, coating film thickness and plastic pigment on mechanical properties of coated paper was studied. The results showed that the tensile strength, TEA, stretch and tensile stiffness were improved as the percentage solids content and the coating film thickness were increased. Bending stiffness slightly increased when solids content was increased and showed higher values on increasing the coating film thickness. The addition of plastic pigment to both clay based and GCC based coating mixtures improved the mechanical properties considered in this study. Although tensile strength and tensile stiffness increased with the addition of plastic pigment of smaller particle size, stretch and TEA showed a reverse trend.