铝合金及复合材料板开孔损伤分析

分析计算了中心开孔损伤对铝合金板和不同铺层方式的复合材料板承载能力的影响。结果表明：在开孔尺寸一定的情况下，随着板宽的增大，开孔损伤板的应力集中因数减小；随着材料各向异性程度的提高，开孔损伤对板件的应力集中因数和承载能力的影响增大。这一结果在试验中得到证实。     

复合材料修复飞机损伤孔有限元分析

目前,复合材料不仅在飞机结构中得到了大量的应用,而且还应用到飞机受损结构的维修中。本文主要研究复合材料在飞机结构修理中的设计应用。基于有限元方法,在有限元分析软件ANSYS Workbench下,建立飞机复合材料铝合金板胶结修理三维有限元模型,利用复合材料专用模块ANSYS Composite Prep/Post,对复合材料修复的含损伤孔洞的铝合金板的强度、刚度进行数值分析,分析补片长度和厚度对飞机损伤结构修复效果的影响,进而设计出合理的复合材料补片尺寸,使其确保飞机结构安全性的前提下,同时保证了维修的经济性。     

复合材料开孔薄板受力有限元分析

对复合材料开孔层合板应力集中情况进行了深入探讨,给出理论上分析计算复合材料开孔应力集中的一般方法,得出了影响应力集中问题的主要因素.并通过有限元分析软件NASTRAN对一典型开孔复合材料层合板进行有限元分析,得出开孔复合材料板应力集中较金属材料严重的结论,具有一定的工程指导意义.     

含双向布复合材料开孔薄板拉伸性能研究

对含有双向布的三种不同铺层厚度的中心开孔复合材料薄板拉伸性能进行研究,分别得到三种复合材料带孔板的孔边应变分布规律以及试件的损伤演化和失效行为,并得到其断裂强度值。试验结果表明,试件的铺层对试件的刚度和强度影响较大,相对于[45/0/45]的铺层,[45/(0)/0/(0)/45]增加了两个0°单向布层,其刚度及强度得到大幅改善;[45/90/0/0/0/90]s增加了多个0°双向布层,使得其刚度最大,强度也有明显提升。用Abaqus软件对三种薄板的拉伸行为进行渐进损伤模拟分析,分析中采用Hashin准则作为材料的失效准则获得薄板的断裂载荷、应力分布及渐进损伤失效过程,得到的模拟结果与试验结果吻合较好。     

碳纤维复合材料小孔加工难点与研究现状

碳纤维增强环氧树脂基复合材料在高新技术领域产品轻量化、小型化的发展趋势下具有广阔的应用前景和使用价值。微小零器件的连接装配需要进行大量的小孔加工,而碳纤维复合材料的难加工性以及小孔径加工时散热条件差、微小刀具刚度低等特点,使复合材料小孔加工比常规尺寸的孔加工更容易产生加工损伤,制孔形状、位置精度难以保证。列举了碳纤维复合材料常见的制孔损伤形式,分析了复合材料小孔加工的技术难点,综述了国内外在复合材料小孔加工机理、制孔刀具、制孔工艺等方面的研究现状。     

3D打印复合材料开孔板力学性能影响规律

为了改善3D打印技术制备的连续碳纤维增强复合材料样件的拉伸力学性能，研究了不同填充路径对复合材料开孔板拉伸性能的影响。采用主应力轨迹路径的规划方法制备了主应力轨迹路径填充开孔板测试样件，并将其与栅格路径填充开孔板和机械加工开孔板进行了拉伸性能对比。结果表明：主应力轨迹路径填充开孔板与机械加工开孔板相比，拉伸强度高9.73%，弹性模量高25.58%；主应力轨迹路径填充开孔板在断裂前圆孔周围的应变分布更均匀，应变更小。     

Hashin准则的应力应变形式在复合材料渐进损伤计算中的对比

Hashin准则在复合材料渐进损伤分析中得到广泛应用,它的原始形式用应力表达,而在渐进损伤实际计算中用到了应变形式。推导了这两种形式下渐进损伤计算中需要的复合材料非线性本构关系及对应的切线刚度矩阵,对比分析了它们之间的不等价性。将这两种Hashin准则形式与不同损伤演化模型相结合,应用于开孔板的渐进损伤数值模拟,并与试验数据相对比。将Linde损伤演化模型分别与Hashin准则变形式和应力形式组合,前者的计算结果与试验值符合更好;将Sleight损伤演化模型与Hashin准则应力形式相结合,选取不同的衰减控制参数进行数值模拟,控制参数取0.8时比取其他值与试验结果符合更好。理论推导和数值模拟结果对复合材料渐进损伤实际应用中合理选取损伤准则形式和损伤演化模型有指导意义。     

开孔泡沫金属的结构特性及流体透过性能的研究

依据渗流铸造法制得的开孔泡沫铝合金制品，用灌注石蜡的办法，测试分析了开孔泡沫金属的结构特性，分别计算了各被测试样的孔隙率和通孔率；用自行设计的试验装置，测试研究了泡沫金属的流体透过性能。结果表明：开孔泡沫铝合金具有较高的孔隙率、通孔率和流体透过性能。因此，适合应用在工业中的许多领域。     

机床支承件合理化设计初探

本文用有限元法计算了十种形状相同，壁厚不同的车床床身模型受力后的变形情况，并分析了合理壁厚和开孔位置对刚度的影响。     

液体垫片对复材-铝单搭接接头拉伸性能的影响

由于复合材料受本身性质以及成型工艺方法复杂性的限制,其构件的制造精度偏低,与铝合金构件装配时配合面间会产生装配间隙,而液体垫片可以很好地起到补偿效果。以复合材料-铝合金单搭接接头为研究对象,利用3D-DIC技术测量接头拉伸的实验过程,通过有限元分析与实验对比来研究强迫装配与液体垫片补偿对复合材料-铝合金单搭接接头拉伸刚度与峰值载荷的影响。研究表明:强迫装配时,接头拉伸载荷与刚度随着间隙的增大均减小;液体垫片补偿后,随着垫片厚度的增加,接头峰值载荷增大,拉伸刚度减小,但是与强迫装配时比较都增大。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.