基于有限元法的果蔬保鲜包装箱通风孔设计

通过建立不同通风孔设计的果蔬保鲜包装箱有限元模型,模拟分析了其应力分布云图,探讨了果蔬保鲜包装箱通风孔设计的主要参数。分析结果表明,长圆形、靠近纸箱中部且对称分布的偶数个通风孔设计,能有效减少应力集中,避免纸箱压缩强度的大幅下降。为实际应用中果蔬保鲜包装箱通风孔结构设计提供参考。     

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.     

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.     

Application of beam on elastic foundation to the interaction between a corrugated box and pallet deckboard

Corrugated boxes are ubiquitous in shipping and warehousing logistics. In physical distribution, corrugated boxes are often shipped in a unit load form where the interaction between the components determines the effectiveness and safety of the overall system. When lower stiffness pallets are used to support the corrugated boxes, the compression strength of boxes is reduced due to the uneven support conditions caused by the deforming top deckboards of the pallet. In this study, a modification of the principle of beam on elastic foundation was used to predict the effect of pallet deck stiffness on the performance of a corrugated box. In the model, the corrugated box acts as the elastic foundation, and the deckboard is represented as the beam. Pallet deck stiffness, pallet connection stiffness, and package stiffness are required model inputs. The resulting model was capable of predicting the normalized distribution of forces along the boxes' length sidewall but was not capable of predicting the compression strength of the box at failure.     

Flexural stiffness of selected corrugated structures

Top‐to‐bottom compression strength of a corrugated fibreboard box is partly dependent on the load‐carrying ability of central panel areas of the box. The ability of these central panel areas to resist a bending force from loading may increase the stacking strength of the box. The difference in the compression strengths of boxes that have identical dimensions and were fabricated with identical components but different flute types, is primarily caused by flexural stiffness of the box panels. Top‐to‐bottom compression strength of boxes can be accurately predicted by flexural stiffness measurements and edge crush test (ECT) of the combined boards. This study was carried out to analyse the flexural stiffness, to measure bending force and bending deflection by a four‐point bending test for various corrugated fibreboards, and to provide the major constructional factors which play a role in improving the compression strength of the box. Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of Pallet Deckboard Stiffness on Corrugated Box Compression Strength

The packaging industry has long considered pallets to be rigid structures. However, in a unit load, the weight of the product produces compressive forces that are distributed across the pallet causing the top deckboards to deflect. Corrugated paperboard boxes are highly susceptible to changing support conditions; therefore, the deckboard deflection directly impacts the vertical compression strength of the box. Therefore, the objective of this study is to evaluate the effect of pallet deckboard stiffness on the vertical compression strength and deflection of corrugated paperboard boxes. Additional treatments included gaps between the deckboards and location of the box relative to the pallet stringers. Copyright © 2016 John Wiley & Sons, Ltd.     

Finite element analysis (FEA) applied to polyethylene foam cushions in package drop tests

Two designs of polyethylene (PE) foam cushions were compared, using a rigid ‘product’ of mass 5.6 kg, and an outer corrugated fibreboard box. The acceleration–time history for the product was measured when the box was dropped flat from 1 m onto a rigid floor. The data was processed to calculate the impact force as a function of the packaging deformation. Finite element analysis (FEA) predictions of the impact force vs. package deflection were accurate for end‐cap designs using Ethafoam, but underestimated the slope of the experimental force vs. deflection relation for corner‐cap designs. The corner‐cap design is more efficient in reducing the peak product acceleration for multiple impacts. The contribution of the corrugated board box to the impact response appears to be small. The FEA results were compared with those from the cushion curve design method and were found to better predict the performance of complex shaped cushions. Copyright © 2004 John Wiley & Sons, Ltd.     

冷冻食品包装用瓦楞纸箱强度研究

针对冷冻食品包装用瓦楞纸箱在冷库贮存过程中的塌箱现象,指出了塌箱主要是由于纸箱力学性能降低引起的。通过对纸箱的低温贮存试验,分析了纸箱力学性能下降的原因。试验数据分析得出,纸箱中所含水分状态的变化是纸箱力学性能下降的主要原因,此外纸箱在冷库贮存过程中水分含量的增加与粘合剂使用性能的降低也是引起纸箱强度下降的因素。     

瓦楞纸箱强度的静态仿真分析及试验研究

选用某B型单瓦楞纸箱,将其切割成3段,对各段分别进行抗压试验,以探讨各段对整个纸箱强度的贡献度。考虑瓦楞纸箱的材料非线性和几何非线性,采用ANSYS有限元分析软件对纸箱上段和中段以及整个纸箱进行抗压试验仿真分析,以得到纸箱各段和整个纸箱的压缩变形结果、压溃力和压溃位移。结果表明:仿真分析结果与抗压试验结果基本一致,从而验证了所建模型的可行性,且纸箱的强度基本上取决于横向皱褶。     

冷冻食品包装用瓦楞纸箱结构设计研究

根据冷冻食品用瓦楞纸箱在冷库中易出现的塌箱现象,介绍了塌箱原因。从瓦楞纸箱结构设计的角度,研究了提高瓦楞纸箱抗压强度的方法。实验数据分析表明:按照纸板理论边压强度的1.25倍进行配纸,所得到的瓦楞纸板抗压强度可满足储运环境要求;此外,将常用02型箱型改为套合型箱型,也可明显提高纸箱的抗压强度。     

Measurement and analysis of shocks to products packaged in pails in single parcel ground shipments

The objective of this study was to measure and analyse the shocks and impacts experienced by pails in the single parcel distribution environment, with and without a secondary corrugated shipper. The study was conducted in the FedEx Ground shipping environment in the USA. Instrumented 5 gal pails were shipped with and without an outer corrugated box, and with and without handling (precautionary warning) labels, from East Lansing, Michigan to destinations in California and New York. Data recorders were used to collect and analyse shock distribution data (drop heights, drop orientations and number of drops). The results showed that the precautionary labels had no effect in improving the handling or reducing the drop height levels for both corrugated boxes and pails in this environment. Pails without boxes experienced 10 drops per one‐way trip with an average drop height of 0.23 m (9 in). Pails with boxes experienced 18 drops per one‐way trip with a higher average drop height of 0.30 m (12 in), which amounted to 80% more drops at a 25% higher drop height level than pails without boxes. Impact orientations of pails without boxes showed that 60% of the drops occurred on the sides, and 40% on the bottom. Pails shipped in corrugated boxes showed 22% of the drops occurred on the bottoms, 34% on the side faces, 28% on edges and remaining 16% on the corners. The data collected was analysed to develop pre‐shipment package performance tests that can be conducted in a lab environment. Copyright © 2009 John Wiley & Sons, Ltd.     

Modelling and Thermal Analysis of Tray‐layered Fruits inside Ventilated Packages during Forced‐air Precooling

Ventilated packaging is widely used in the forced‐air precooling practice for horticultural produce. Fresh fruits are living organisms which are sensitive to temperature in turn related to airflow and heat transfer inside package. In this study, a transient mathematical model considering heat of respiration and evaporation is developed to predict the thermal response of tray‐layered fruits in ventilated packages during forced‐air precooling. Specifically, the heat source is combined with the energy conservation equation and loaded into numerical solution by User Defined Function (UDF). Temperature profiles of three variously distributed circular and oblong vents in three different patterns (spaced, paralleled and crossed stacking) are simulated, separately. The results show that the heat source affects fruit cooling process, and the layered fruit in paralleled stacking pattern tends to be cooled better than others. Furthermore, the results indicate that vertical oblong vent could improve the longitudinal and lateral airflow, while non‐central vent design could greatly improve the overall cooling performance. Definitely a triangular distribution of three circular vents was superior to laterally distributed centre vents with 66.5% higher uniformity and 2.5°C lower of the highest temperature. Compared with the three identical vertical oblong vent conditions, vent design with one hand hole and two side vertical oblong vents can be cooled more uniformly with an increase of 6.5%. It is revealed that vents with large major‐to‐minor axis ratio could be applied to balance airflow and ease cooling differences for a rapid but uniform cooling. Experimental validations were performed for Sim2, Sim4 and Sim6, Sim8, Sim9, and good agreement was obtained considering the five vent conditions with the error less than 3.5°C but coordinated later (within the limits of the experimental uncertainty).Thus the numerical model can be used to predict and optimize temperature distribution within precooling packages. Copyright © 2016 John Wiley & Sons, Ltd.     

Assessment of technical and environmental performances of wheat‐based foams in thermal packaging applications

This paper presents an assessment of the technical and environmental performance of a wheat‐based foam (WBF) and bio‐composite for shipping chilled products. The thermal conductivity of the WBF was found to be higher than that of polyurethane foams commonly used in high‐value insulation packaging, but close to that of low‐density (expanded polystyrene) EPS foams and significantly lower than that of polyethylene (PE) foams, which are typically used in thermal packaging of foods. The insulation performance of a simple cool box constructed from both the WBF and EPS sandwich panels without the use of any refrigerant was studied experimentally. The comparison demonstrated that the performance of the WBF cool box was comparable to that of the EPS counterpart. Two industrial case studies were conducted on WBF cool boxes with refrigerants in comparison with PE or EPS counterparts. The WBF cool boxes had comparable thermal performance to the EPS and PE counterparts on the basis of identical foam thickness. The performance of the WBF cool boxes was also simulated with finite element (FE) modelling. Good agreement was achieved between experimental data and the FE prediction. The model was then used to assist cool box design. WBF cool boxes made from renewable raw materials are inherently biodegradable and may be used as an alternative to those based on polymer foams in thermal packaging applications. Life‐cycle assessment (LCA) was used to investigate environmental profiles of cool boxes made with WBF, EPS and PE foams. The WBF cool boxes offer substantially lower global warming and abiotic depletion potentials than equivalent cool boxes made from petrochemical foams. Copyright © 2010 John Wiley & Sons, Ltd.     

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.     

Corrugated fibreboard in modified atmospheres: Moisture sorption/desorption and shock cushioning

Corrugated fibreboard, the most used material for transport packaging, is moisture sensitive and therefore its performance is highly influenced by the moisture content. This paper examines the shock absorption under a range of humidity and temperature conditions and the appropriateness of a model for moisture sorption/desorption isotherms for corrugated fibreboard. A range of corrugated fibreboard materials was investigated by first conditioning samples using proximity cells, testing samples for impact absorption using a small scale cushion tester and modelling moisture sorption/desorption isotherms. Results show that the shock absorption is directly influenced by static loading, humidity and temperature and that isotherms can easily fit a widely accepted model.     

人机工程学在搬运手孔设计中的运用

从人机工程学的角度出发,对瓦楞纸板箱上搬运手孔位置的选择合理性进行了讨论.认为应该根据被包装物品的重量、高度及对称性等特点,结合人工搬运作业及人机工程学的特点来综合分析,不能简单地采用同一的开孔位置.对于高度不足1m又较重的物品,可以在侧下方开孔;对于高于1.2m又较重的物品,可以在侧下方开设斜置的手孔,并在对侧的上方开出辅助的指孔;对于不对称的物品,应使物品的重心处在两侧手孔中心线所形成的平面内.     

Moisture content of polyethylene coated solid fibreboard after industrial lamination

Solid fibreboard is used mainly in highly demanding packaging applications. One solid fibreboard quality having six paper and paperboard layers, a thickness of 1.7 mm and polyethylene coating was studied. Several material tests on liquid water and water vapour penetration were done to assess the environmental moisture sources that change the material moisture content after the lamination process. The in‐plane diffusion coefficient of the combined board was determined based on an integrated unsteady state moisture transport equation and moisture sorption measurements. The transverse diffusion coefficient of the polyethylene coated kraft paper and the solid fibreboard medium were based on water vapour transmission rate measurements. The original moisture content of the solid fibreboard sheet was measured gravimetrically 2 days after the lamination at the mill. The results show that high relative humidity (RH) conditions during the transportation (4°C/90% RH) change the moisture content of the transportation box made from a solid fibreboard sheet very little in 8 days. Local moister (or drier) areas are created near the sheet edges due to in‐plane moisture transport through open material edges. The in‐plane diffusivity for the solid fibreboard grade in question was 5.87 × 10^?10 m²/s. Copyright © 2011 John Wiley & Sons, Ltd.     

波形钢腹板(钢腹杆)-混凝土组合箱抗扭承载力试验与计算

为研究波形钢腹板（钢腹杆）-混凝土组合箱抗扭特性,进行了构件的抗扭承载力试验,结果表明:混凝土底板首先出现斜向裂缝,裂缝与混凝土主拉应变垂直,顶底板裂缝呈螺旋状开展,裂缝方向与主梁纵轴线约成45°;底板出现宽度较大的主斜裂缝,钢筋受拉屈服,组合箱受扭破坏。采用有限元软件ANSYS对扭转试验构件进行了非线性有限元分析,有限元分析结果与试验结果吻合良好。参照混凝土箱梁的开裂扭矩计算公式,建立了组合箱开裂扭矩的计算公式;应用混凝土箱梁变角度空间桁架理论,根据波形钢腹板（钢腹杆）-混凝土组合箱达到极限扭矩时可能出现三种破坏形式,建立了组合箱极限扭矩的计算公式。通过与试验结果和实桥截面有限元分析结果的比较表明,建立的波形钢腹板（钢腹杆）-混凝土组合箱抗扭承载力简化计算公式具较高精度,最大误差不超过10%,可运用于实桥计算。     

Elastostatics of a cubic box subjected to concentrated loads

This paper deals with the experimental strain, stress and deflection analysis of a cubic box subjected to concentrated loads applied at the centre of two opposite faces. The ratio between the inside span and the wall thickness varied between approximately 5 and 14. All corners had circular fillets. The experimental analysis was conducted using mechanical and electrical strain gauges and brittle coatings. Results, given parametrically by means of a family of curves representing normalized stresses, are applicable to boxes of any size, made of any elastic materials, provided the wall thickness falls within the investigated range. Some results obtained using the theory of structures approach are included for comparison purposes and presented in a form useful to designers.     

瓦楞纸箱运输包装系统设计

瓦楞纸箱是一种薄壁结构的绿色包装容器，广泛应用于商品包装。瓦楞纸箱运输包装系统的优化设计是一个多目标函数、多变量的优化问题，以仓储空间利用率最大为优化目标函数，瓦楞纸箱强度为约束条件，优化瓦楞纸箱结构、配料方案及装载模式，能够较全面进行纸箱优化设计，较好实现瓦楞纸箱对产品的安全保护、方便储运功能。