重型夹芯纸板侧压强度数值仿真分析

目的对典型重型夹芯纸板结构的侧向抗压强度进行精确的对比分析,为合理应用夹芯纸板提供依据。方法利用有限元软件Ansys分别建立蜂窝纸板及AAB型重型瓦楞纸板大尺寸规格试样的数值模型,并基于屈曲分析准则对重型瓦楞纸板纵向及蜂窝纸板2个侧向抗压强度进行研究。结果在选材、用纸量及试样尺寸规格大小相同的情况下,蜂窝纸板2个方向的侧压强度均高于AAB型重型瓦楞纸板的边压强度。结论仿真分析对蜂窝纸板和AAB型重型瓦楞纸板的选材、材料用量及尺寸规格进行了严格控制,消除了重型瓦楞纸板和蜂窝纸板的材质、耗纸量、试样尺寸规格、试样加工工艺及环境条件等因素的变化对分析结果产生的影响。     

瓦楞／蜂窝复合结构纸板强度性能的试验研究

比较分析了瓦楞/蜂窝复合结构纸板的平压强度、边压强度、耐破度、戳穿强度等力学性能.结果表明,这种复合结构纸板的平压强度变化比较复杂,而它的边压强度、耐破度、戳穿强度均大于蜂窝纸板.     

纸蜂窝结构平压性能的实验研究

通过对蜂窝纸芯和纸板平压强度的测试，分析孔径比、犀度对蜂窝纸芯平压强度的影响以及纸芯和纸板平压强度的差异，探讨了生产工艺对蜂窝纸板平压强度的影响。     

蜂窝纸板与瓦楞纸板边压强度有限元分析

将结构对纸板边压强度的影响从众多影响因素中解耦,建立了蜂窝纸板和典型瓦楞纸板的有限元模型并进行了屈曲分析,得到蜂窝纸板两个方向的边压强度和典型瓦楞纸板的边压强度.提出了利用克重材料抗压效率评价纸板抗压能力的方法,利用边压强度和纸板的定量计算了每种纸板克重材料抗压效率.分析结果表明:蜂窝纸板在两个侧向上的克重材料抗压效率均大于瓦楞纸板;蜂窝纸板不仅具有优良的平压强度,而且具有优良的边压强度.     

新型环保包装“瓦楞蜂窝复合纸板生产线”问世

近日,浙江瑞安市红旗轻工设备厂开发的"瓦楞蜂窝复合纸板生产线",通过省级技术成果鉴定.自动式瓦楞蜂窝复合纸板的生产线是利用企业自主专利技术而开发的.采用瓦楞、蜂窝复合结构,显著提高了纸板的强度,其力学性能明显优于单蜂窝或单瓦楞结构的纸板.其主要功能是将再生纸全自动制成瓦楞蜂窝复合纸板,具有强度高、防震性能好、成本低、重量轻,以及再生纸可循环利用符合环保要求     

蜂窝-瓦楞复合纸板的面外承载及静态缓冲性能研究

通过静态压缩试验,测定了蜂窝纸板、蜂窝-瓦楞复合纸板的静态缓冲特性曲线,讨论了蜂窝-瓦楞双面复合纸板的静态压缩变形过程,并分析了复合层数和瓦楞楞型对蜂窝-瓦楞复合纸板的面外承载性能和静态缓冲性能的影响。结果表明,蜂窝-瓦楞复合纸板的面外承载能力明显低于未经复合的蜂窝纸板;蜂窝-瓦楞复合纸板在低应力阶段的缓冲性能明显优于蜂窝纸板,但在高应力阶段与蜂窝纸板的缓冲性能基本一致。     

材质对蜂窝纸板缓冲性能的影响

对两种不同材质的蜂窝纸板静态应力应变性能和动态缓冲结果进行了比较分析。讨论了蜂窝纸板力学性能对应变速度的敏感性及两种纸板的缓冲性能差异。缓冲试验结果表明。在不同的冲击应变率下蜂窝纸板的材质影响蜂窝纸板缓冲性能。     

高强瓦楞复合纸板侧压性能实验研究

为了了解高强瓦楞复合纸板侧压性能,采用夹层结构材料侧压性能的测试方法对其进行了实验测试。实验选用了10,15,20和30 mm 4种厚度的高强瓦楞复合纸板样品,分别按照横向和纵向进行了测试。结果表明:相同厚度纸板纵向的侧压强度大于横向;不同厚度纸板随着纸板厚度的增加,横向和纵向侧压强度都呈降低趋势。研究结果对于提高高强瓦楞复合纸板托箱的堆码承载能力,具有很强的实践应用价值。     

叠置蜂窝纸板衬垫的平压性能研究

对叠置蜂窝纸板衬垫的平压性能和平压性能进行了研究.结果表明,双层叠置纸板的压溃过程可分为7个阶段;叠置蜂窝纸板与单层蜂窝纸板的压溃强度基本相同,且错对与正对两种叠置衬垫的抗压性能基本相同.试验结果说明利用蜂窝纸板厂的生产性蜂窝纸板废弃物制作运输包装用叠置缓冲衬垫可行.     

蜂窝/E形瓦楞复合纸板的缓冲特性的研究

探讨蜂窝/E形瓦楞复合纸板的G's-T、F-S、σ-ε、C-ε,分析蜂窝/E形瓦楞复合纸板的力学性能.指出蜂窝/E形瓦楞复合纸板做缓冲材料设计的价值,提供未来的实际应用的理论数据.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。