用于文物包装的无酸瓦楞纸盒性能测试

目的该研究依据国标规定的包装件试验方法及理论,对用于文物包装的无酸瓦楞纸盒进行各项性能测试,并确定最优方案。方法参考运输包装件基本试验标准,通过抗压、堆码、跌落和振动试验,对比分析5组试样的各项性能。结果抗压试验时,5组试样载荷-变形曲线形态基本相似,B楞折叠纸盒的抗压性能优于E楞折叠纸盒,天地盖式折叠纸盒的抗压性能优于摇盖式折叠纸盒,粘贴纸盒的抗压性能优于折叠纸盒;堆码和跌落试验时,确定了堆码高度为500 mm,堆码层数为9层;正弦变频振动试验时,确定了每组试样的共振频率。结论在博物馆存储、运输工作中,建议选用E楞天地盖式折叠纸盒作为古代钱币的最终包装方案。     

摆线钢球行星传动啮合副非线性力学性能研究

摆线钢球啮合副为空间曲面啮合结构,啮合副承载与变形之间的非线性关系以及啮合副接触区扩展均会对其力学性能产生较大的影响。该文首先利用超静定方法建立了啮合副非线性力学模型,根据啮合力与阻力矩作功相等的原理推导出时变的啮合力函数。然后将啮合力转换为啮合接触区上的椭球状分布载荷,利用叠加法对接触区微元在集中力作用下的变形与应力结果进行积分,给出了接触区变形挠曲面方程、接触表面下各应力函数,以及最大切应力的深度位置。最后根据钢球位置方程,建立了啮合副不同啮合位置的有限元模型,对钢球与摆线槽的啮合过程进行了数值模拟,分析了啮合副应力分布状态以及啮合点等效应力的变化规律。结果表明:采用啮合副非线性力学模型和接触区分布载荷减少了线弹性和集中力简化处理造成的误差,为啮合副承载状态提供了更符合实际的计算结果。     

异型折叠纸盒数学模型研究

对异型折叠纸盒各体板之间的关系建立了数学模型。建立了相应三维坐标,并用齐次坐标表示各点位置,利用各点坐标与转换矩阵相乘的方法推导出了其成型角与纸盒成型后体板折叠角度之间的关系式。该数学模型为计算折叠纸盒的容积、体积和相关缓冲结构及其相关软件开发奠定了基础。     

齿形与记录曲线对应关系的确定

在光栅式单面啮合检查仪上,可以很方便的测出截面整体误差曲线。在截面整体误差曲线上,可以确定出每一个齿的齿形误差。但是截面整体误差曲线是一条连续的曲线。它包括被测齿轮的顶刃啮合曲线,以及测量蜗杆的顶刃啮合曲线。由于顶刃啮合曲线与齿形误差记录曲线的分界点不明显,在确定齿形误差时,因起始点与终止点不能准确定出而产生较大的误差。特别是确定截面整体误差曲线上的误差     

齿廓修形斜齿轮副啮合刚度解析计算模型

斜齿轮的轮齿误差是一个三维空间问题,其齿廓修形后啮合刚度的解析计算方法不同于直齿轮。改进了斜齿轮三维空间啮合线长度及位置计算方法,实现了斜齿轮啮合线长度及啮合位置的快速计算;根据力、变形分解原理和刚度/误差耦合关系,提出了一种考虑轴向变形以及齿廓修缘的斜齿轮啮合刚度解析计算模型;以一组斜齿轮副为例,研究了斜齿轮啮合刚度与啮合线长度在一个啮合周期内的变化规律,分析了不同齿廓修形参数对斜齿轮啮合刚度的影响规律。研究结果表明:利用该模型不仅可以准确快速地计算斜齿轮副啮合刚度,而且还可以确定最佳齿廓修形量,为斜齿轮的齿廓修形提供理论指导。     

变速器啸叫声与下线台架振动的相关性试验研究

在汽车变速器下线台架上根据齿轮振动传递路径理论选择两个振动测量位置,同时测量两个位置20台变速器的啮合振动。在整车上测量各档位啮合阶次噪声及其振动,并进行啸叫声的主观评价。通过下线台架的振动、整车上变速器各档位齿轮啮合阶次的噪声和振动三者间的相关性分析,确定了台架上最佳的测量位置和啸叫声可接受时的振幅临界值。该研究可以正确、有效地识别变速器的啸叫及其振动特性。     

基于精确齿面建模的ZA蜗杆蜗轮有限元接触分析

为了研究不同情况下蜗杆蜗轮间的接触应力和蜗杆扭转角与驱动力矩之间的关系,根据齿面方程建立具有精确齿面的ZA蜗杆蜗轮实体模型,利用ANSYS对此模型在同一载荷不同啮合位置和同一啮合位置不同载荷条件下进行有限元接触分析,研究在一个轮齿啮合周期内,各啮合齿对的接触应力分布和载荷在不同齿对上的分配情况.分析结果表明:理论接触应...     

纸盒高度变化对开盒成型装置的影响

为提高全自动装盒机对不同尺寸纸盒的适应性,分析纸盒高度变化对盒坯料仓中盒坯位置和取盒机构中吸盘轨迹的影响,并推导出在吸盘吸取纸盒基准位置不变的前提下,盒坯料仓的位置调整规律。以常用的螺纹传动与位置指示器相结合的位置调整方式为例,给出了齿节和导程的选取方法,以及实际设计中可能存在的调整偏差的消除方法。理论分析和实际测试表明,较小的调整偏差不会显著影响成盒装置的正常工作,可不必采取措施将其完全消除。     

单螺杆压缩机瞬时啮合诸齿空间位置的确定

以单螺杆压缩机基本啮合齿，槽对的齿面方程为基础，根据螺杆，星轮啮合运动规律，推导出与基本齿，槽对同时参与啮合的其它诸齿，槽对在同一坐标系下的齿面方程，从而确定了瞬时各啮合齿，槽对的相应空间位置，并以“直线包络螺杆副”为例，计算了瞬时啮合诸齿的齿面方程。     

功能型折叠纸盒作业线的研究

在折叠纸盒结构设计中,作业线是一个关键环节.根据功能型折叠纸盒的结构特点,提出了针对纸盒间壁形式,涂胶位置、纸盒尺寸、印刷装饰效果设计作业线的方法.从而保证纸盒在自动糊盒机上成型过程最简单且方便糊盒机自动操作.     

扑动轨迹对扑翼气动特性影响的数值研究

国内外对扑翼飞行的气动性能进行了大量研究,这些研究大多针对特定运动轨迹下的扑翼,然而大量观察发现,昆虫在飞行时其翅膀会出现各种不同的运动形式,这些不同的翅膀运动方式必定对其气动性能产生重要影响。该文基于对昆虫的实验和数值模拟中常用的几种扑动轨迹模型分析,建立了三种具有相同准稳态气动力的扑翼扑动轨迹,并采用数值求解N-S 方程的方法,研究了前飞状态下不同扑动轨迹对扑翼气动特性产生的影响。结果显示扑动和转动均为简谐函数轨迹形式的扑翼具有较高的升举效率和推进效率。进一步通过对不同扑动轨迹扑翼流场分析得出,扑动轨迹不能改变扑翼产生的尾流性质,但可以影响涡的强度,从而使扑翼产生不同的气动性能。     

液晶电视瓦楞纸箱材料选择与强度计算研究

根据给定的瓦楞纸箱强度要求,确定纸箱的原纸构成;按瓦楞纸箱原纸构成校核其耐破强度及抗压强度.     

A dynamic mesh strategy applied to the simulation of flapping wings

A robust and efficient dynamic grid strategy based on an overset grid coupled with mesh deformation technique is proposed for simulating unsteady flow of flapping wings undergoing large geometrical displacement. The dynamic grid method was implemented using a hierarchical unstructured overset grid locally coupled with a fast radial basis function (RBF)‐based mapping approach. The hierarchically organized overset grid allows transferring the grid resolution for multiple blocks and overlapping/embedding the meshes. The RBF‐based mapping approach is particularly highlighted in this paper in view of its considerable computational efficiency compared with conventional RBF evaluation. The performance of the proposed dynamic mesh strategy is demonstrated by three typical unsteady cases, including a rotating rectangular block in a fixed domain, a relative movement between self‐propelled fishes and the X‐wing type flapping‐wing micro air vehicle DelFly, which displays the clap‐and‐fling wing‐interaction phenomenon on both sides of the fuselage. Results show that the proposed method can be applied to the simulation of flapping wings with satisfactory efficiency and robustness. Copyright © 2016 John Wiley & Sons, Ltd.     

Bruising of apples in four different packages using simulated truck vibration

This paper presents the effects of truck vibration and packaging systems on the bruising of apples. The study investigated four different types of interior packaging, the foam tray, the paper pulp tray, and two different paperboard partition/box combinations. Testing was done on a vibration table using a random controller driven by a power density spectrum simulating truck trailers with leaf-spring and air-cushion suspensions travelling on expressways. The results showed that the foam tray was the best type of interior packaging followed by the paperboard partitions. The paper pulp tray produced the highest levels of damage. The air-cushion truck suspension showed larger damage levels than the leaf-spring suspension for all package types.     

SP型水泥窑系统分析

目前硅酸盐工业所介绍的分析法一般为黑箱法，作者分析了黑箱法进行分析的不足，介绍了系统分析法，通过ＳＰ窑实例进行厂系统分析的计算，并引进控制环节的概念来找出ＳＰ窑节能的关键部位，为用能、节能提供正确的指导。     

Structural perfection of laterally overgrown GaN layers grown in polar- and non-polar directions

The structural quality of GaN overgrown layers was evaluated using Transmission Electron Microscopy methods. Growth on polar and non-polar substrates was compared. Independent from growth polarity much better structural quality of the overgrown areas compared to the seed areas was obtained, but overgrowth on non-polar substrates is more difficult. For the latest samples, two wings on the opposite sites of the seed area grow in two different polar directions with different growth rates. Wings grown with Ga polarity are much wider than wings grown with N-polarity making coalescence of these layers difficult. Defects formed in the overgrown wings were characterized and their density was compared. It is shown that two-step growth (using two different temperatures) lead to much smaller misorientation between the wings than one step growth     

基于等价关系模糊聚类在岩石爆破性分类中的应用

岩石破碎的好坏对矿山工程在经济上和生产效率上有极为重要的影响,为提高爆破效率,需对岩石的可爆性进行分类。基于等价关系的模糊聚类是聚类分析中的一种。本文采用这种方法对岩石进行爆破性分类,根据不同水平的截距将岩石分成不同的类别。该方法分类合理,对提高爆破效率具有一定的指导意义。     

A 3D numerical and experimental investigation of microstructural alterations around non-metallic inclusions in bearing steel

Non-metallic inclusions such as sulfides and oxides are byproducts of steel manufacturing process. When a component is subjected to repetitive loading, fatigue cracks can emanate from these inclusions due to stress concentrations that happen because of mismatch in elastic–plastic properties of inclusions and matrix. In certain applications such as gears and bearings, crack initiation from inclusions is accompanied with microstructural alteration. This paper employs a numerical as well an experimental approach to investigate these microstructural changes which are so-called “butterfly wings”. A 3D finite element model was developed to obtain the stress distribution in a domain subjected to Hertzian loading with an embedded non-metallic inclusion. A formerly introduced 2D model based on continuum damage mechanics (CDM) was developed to simulate the butterfly wing formation in 3D. Wingspan-to-inclusion ratios were observed at different cross sections following an analytical serial sectioning procedure. A closed form solution was suggested for the wingspan-to-observed-inclusion-diameter ratio and the results were corroborated with the data available in the open literature. On the experimental front, nonmetallic inclusions inside a sample made of bearing steel was detected using ultrasonic inspection method. Rolling contact fatigue (RCF) tests were run on the specimen and post-failure serial sectioning was conducted to understand the 3D shape of butterflies formed around an inclusion detected by ultrasound. Comparison of experimental and numerical serial sectioning of the wings showed a close correlation in the butterfly wings geometry.     

Coal Rock Condition Detection Model Using Acoustic Emission and Light Gradient Boosting Machine

Coal rock mass instability fracture may result in serious hazards to underground coal mining. Acoustic emissions (AE) stimulated by internal structure fracture should carry lots of favorable information about health condition of rock mass. AE as a sensitive non-destructive test method is gradually utilized to detect anomaly conditions of coal rock. This paper proposes an improved multi-resolution feature to extract AE waveform at different frequency resolutions using Coilflet Wavelet Transform method (CWT). It is further adopt an efficient Light Gradient Boosting Machine (LightGBM) by several cascaded sub weak classifier models to merge AE features at different views of frequency for coal rock anomaly damage recognition. The results denote that the proposed method achieves excellent recognition performance on anomaly damage levels of coal rock. It is an effective method to detect the critical stability further to predict the rock mass bursting in time.     

基于等价关系模糊聚类在岩石爆破性分类中的应用

岩石破碎的好坏对矿山工程在经济上和生产效率上有极为重要的影响,为提高爆破效率,需对岩石的可爆性进行分类。基于等价关系的模糊聚类是聚类分析中的一种。本文采用这种方法对岩石进行爆破性分类,根据不同水平的截距将岩石分成不同的类别。该方法分类合理,对提高爆破效率具有一定的指导意义。