含复杂孔形复合材料板孔边应力场的数值分析

孔的存在对于结构强度有相当大的影响。对于复杂孔形孔边边界条件的描述在数学上有一定的难度。边界条件建立的不够准确会给后续的计算带来很大误差。本文通过复变函数理论建立复杂孔形精确的边界条件,提高有限元建模的精度。对含机翼检修孔的正交各向异性板在外荷载作用下进行计算,得到孔边应力场的数值解。给出孔边应力分布和板的变形。     

一种失效准则在面外载荷下含孔层合板的应用

开孔和面外弯曲会引起层合板局部应力过高,导致局部基体开裂、纤维断裂以及层间分层等失效模式。本文采用解析法和有限元法相结合的方法,对开孔无限大层合板的孔边应力进行研究。基于经典层合板理论和复变函数理论对复合材料平板在面外载荷作用下进行孔边应力分析,通过保角变换,解决应力函数在复杂孔形边界上的问题;引入Puck和Yamada-Sun混合强度失效准则,对层合板刚度进行迭代,研究了带孔复合材料平板孔边真实应力应变分布,并与有限元结果进行了对比,吻合较好。本文工作以期能对开孔层合板的失效预测提供指导。     

复合材料板孔边应力场的有限元分析

根据复变函数理论引入保角变换,得到描述所研究孔形的参数方程。由此建立精确的边界条件。并在ANSYS中选择相适应的单元建立有限元计算模型,对含圆孔的复合材料板进行分析,得到了孔边应力场的数值解,给出孔边应力分布和板的变形。计算结果表明,板的变形是沿力的方向均匀伸长,且孔口形状在外力作用下由圆变成了类似椭圆的形状。在板的应力结果中,x方向应力集中现象明显,最大拉应力出现在0°和180°的地方,最大压应力出现在90°和270°的地方;y方向应力分布中,孔边有比较明显的应力集中现象,在受载过程中存在危险点;在xy方向应力分布中,孔边偏离轴心处应力集中现象比较明显。为了检验有限元计算结果的正确性,本文用解析方法对上述问题进行比较。     

基于数值计算方法的换热器管板等效方法研究

换热器管板等效方法影响到管板受力变形计算的准确性。以管壳式换热器为例,分别建立了开孔管板结构、共用节点的实心管板结构和主从节点绑定的实心管板结构有限元模型。采用数值计算方法,对管板的应力和变形进行了分析。有限元计算结果表明:采用主从节点绑定的实心管板结构与开孔管板结构变形最大相对误差为8.4%、孔边应力相对误差超过60%,说明主从节点绑定的实心管板结构仅可准确描述管板的变形。通过对比分析主从节点绑定的实心管板结构与开孔管板结构开孔区域应力分布,得到开孔边缘的应力集中系数为约3,开孔中部的应力集中系数约为2。     

膜孔形态结构图象分析研究——Ⅱ.膜孔结构定量表征

本文通过对多种微孔滤膜和超滤膜进行电镜照像及计算机图象分析,定义和得出了下列定量表征膜孔形态结构的参数:几何孔径分布、有效孔径分布、孔形不圆度、孔隙率以及孔形的分形(Fractal)维数。这些参数有利于成膜条件—膜孔结构—膜分离性能三者之间关系的研究,有利于膜成孔机理的研究,从而促进研制性能更好的膜。     

预埋件对碳纤维复合材料铆接应力变形消除的仿真研究

铆钉连接广泛应用于航空航天和车辆领域.在CFRP层压板的连接过程中,铆接过程中形成的干涉量是保证连接性能的关键因素.为了研究铆杆膨胀对层合板应力和变形的影响,借助有限元方法分析铆接过程中孔壁的应力和变形值.仿真结果表明,钉杆过度膨胀导致层合板孔壁附近产生损伤并且产生翘曲变形.为了减少应力和变形,设计了一种嵌入在层压板中...     

压力容器开孔接管区有限元应力分析

通过Ansys分析与探讨压力容器开孔接管区有限元应力,找出压力容器开孔接管区应力分布规律与受力特性,并系统性对压力容器开孔接管区有限元应力强度进行分析与探讨。     

橡胶止水带受力状态下的有限元分析

应用大型有限元分析软件ANSYS,建立了橡胶止水带于混凝土中在不同受力形式下的有限元模型,分析了在各种不同工况下止水带变形及应力的分布,描述了其可能出现裂纹的位置。通过分析计算得出,当止水带在混凝土中受力而产生应力时,对止水带伸缩性起主要作用的是中心孔的横梁结构,此部位承受了较大的应力。与此同时,计算得出在各种工况下止水带所受最大应力以及止水带中心孔横梁结构中心节点的最大反力。分析了各种工况下最大应力与位移的关系,以及止水带中心孔横梁结构中心节点反力与位移的关系。为止水带的设计、生产、安装及模型优化提供了依据。     

一种新型轻质高强应急路面器材的优化设计

利用有限元软件ANSYS建立路面结构的分析模型,根据加强杆及路面整体的受力分析结果,对复合材料轻质高强路面进行了优化设计。结果表明:3种多孔加强杆应力分布和变形趋势基本一致,仅在前后车轮位置附近产生应力和变形。最大应力出现在前轮作用处,最大应力均为291.667 k Pa;最大位移出现在后轮作用处,其中3孔结构位移最小,但位置基本一致。经综合分析比较,优化设计方案为应急路面器材加强杆件应采用60×30 mm 3孔箱体结构,路面杆件间距为60 mm。     

加热器矩形大开孔应力分析及评定

采用应力分析方法,基于有限元分析软件ANSYS,对一加热器矩形大开孔的应力进行了分析,并将应力在危险路径上分类开展强度评估。结果表明,。一次总体薄膜应力强度、一次局部薄膜应力强度、一次薄膜加一次弯曲应力强度、一次应力强度加二次应力强度均满足要求,说明该加热器矩形大开孔应力强度满足要求。     

鸡冠嘴金铜矿中深孔凿岩爆破参数的优化试验

通过爆破漏斗、斜面台阶、不等孔距爆破试验以及多排同段起爆试验,在综合统计并分析计算各种试验数据的基础上,对鸡冠嘴金铜矿的中深孔凿岩爆破孔底距、最小抵抗线、单位炸药消耗量等参数进行了优化,并在实际生产中推广应用,取得了较好的技术经济效果.     

针对大宝山矿北部采区爆破施工的探讨

对大宝山矿北部采区的环境出现的复杂情况及施工要求进行分析,包括地质环境复杂、采空区、高温孔、矿石与岩石的粒径要求等,并提出解决方法,合理安排施工方法,优化爆破参数。     

PDC钻头井底水力参数理论与数值模拟研究

为了精确计算模拟钻井过程井底水力参数,以Solidworks制图软件建立了三维模型,利用流体力学软件Fluent的k-ε模型对井底PDC钻头进行了三维流场数值模拟,从理论计算和数值模拟对喷嘴流量,冲击力和水功率两方面分析了PDC钻头水力参数,分析结果证明数值模拟能够较为精确地描述井底不同方位影响的水力参数,为优化PDC钻头水力参数与井底流场理论研究提供了重要依据,具有良好的参考价值。     

Reinforcement of proton-exchange membrane fuel cell performance through a novel flow field design with auxiliary channels and a hole array

A novel flow field was designed by deploying auxiliary channels inside the partially hollow ribs and drilling a series of arrayed holes on the auxiliary channels. This novel design rationally utilizes the ribs of the current collector and improves the volumetric efficiency of the parallel channels, leading to improved cell performance and homogeneity of current distribution. A three-dimensional, two-phase flow model was developed to analyze the influence of a variety of parameters on the oxygen and water saturation profiles, cell performance, and current uniformity. It was found that the combination of auxiliary channels and hole array provides an extra pathway for reactant transport and water removal. A reasonable optimization of the flow field geometry, for example, the hole size, the area ratio of arrayed holes and auxiliary channels, nonuniform distribution of arrayed holes, could further improve the cell performance and current uniformity at an extremely low pressure drop.     

Strength degradation and fractographic analysis of carbon fiber reinforced polymer composite laminates with square / circular hole using scanning electron microscope micrographs

In this article, experimental study has been carried out to obtain comparative information intended for designing and assembly of structural components made of carbon fiber reinforced polymer (CFRP) composite. Investigation on tensile strength has been done on unidirectional CFRP composite laminates with hole. Effect of stacking sequence, hole size, and hole shape on tensile strength has been examined independently by open hole tensile (OHT) test. Reduction in OHT strength is observed when stacking sequence is changed from [0]₈ to [0/90]_2s and when the hole size is increased. However, OHT strength is noticed to get increased when hole shape is changed from circular to square. Laminates containing square shaped hole demonstrate less sensitiveness towards tensile strength and show negligible effect of stacking sequences on the normalized strength than the circular hole. Fractographic analysis figures out the failure mechanism of tested specimens by correlating their mechanical properties. SEM micrographs and data analysis reveal that axial splits and local delamination effectively blunt the stress concentration around the hole resulting in higher OHT strength and less notch sensitiveness towards tensile strength.     

Effects of guide holes on the performance of a vertical turbo air classifier

The wide usage of guide parts makes it one of the most interesting research hot spots in the field of fluid machinery. To improve the flow field distribution of the vertical turbo air classifier, the guide holes in the air intake region are designed. The flow fields of the classifiers with and without guide holes are simulated using ANSYS-FLUENT. The gas-phase simulation results show that the guide holes have a ‘diversion’ effect on the airflow, decreasing the tangential velocity and increasing the radial velocity of the airflow. After the airflow passes through the guide holes, the small guide hole sizes cause the large radial velocity and the strong ‘diversion’ effect, which can improve the flow field distribution. The well-distributed flow field of the elutriation region and annular region are obtained when the guide hole size is 7 mm × 7 mm. The discrete phase simulation results show that the cut size of the classifier without the guide holes is 9.1 μm. The cut size is 13.4 μm when the guide hole size is 7 mm × 7 mm. With the increase in the guide hole size, the cut size increases. However, when the guide hole size is larger than 10.5 mm × 10.5 mm, the cut size is almost kept unchanged, which is 22.9 μm.     

PVC塑料门窗设置排水孔和气压平衡孔的重要性

排水孔和气压平衡孔的作用在于提高PVC塑料门窗的密封性能。本文通过排水孔和气压平衡孔的重要性、尺寸及其数量分布等的论述,指出了合理设置排水孔和气压平衡孔是提高PVC塑料门窗密封性能的主要措施。     

基于DeformS9厚钢板小孔冲裁过程模拟及参数优化

利用计算机数值模拟软件DEFORM2D,对厚钢小孔冲裁（t〉4,d／t≤1）过程进行模拟与分析,得出了其断裂与变形机理。通过DEFORM3D进一步优化成形参数,得出了间隙对厚钢板小孔冲裁力的影响规律,为提高厚钢板小孔冲裁模的寿命提供了理论依据。     

幕墙玻璃肋连接孔承载力试验与仿真研究

全玻幕墙具有较好的通透性,被广泛应用于现代建筑。对于大尺寸玻璃肋通常采用拼接的方式制作,拼接连接孔的承载能力对玻璃肋整体承载力影响很大,本文通过有限元软件ANSYS Workbench对连接孔接触进行分析,并与试验破坏荷载进行对比,比较玻璃孔内采用弹性介质尼龙1010套环与喜利得RE-500植筋胶两种连接孔构造对玻璃孔承载力的影响,然后分析玻璃孔尺寸对连接孔承载力的影响。结果表明：满足玻璃连接孔构造前提下,采用喜利得RE-500植筋胶的构造形式比采用弹性介质尼龙1010套环构造形式具有更高的承载能力;连接孔承载力随着开孔尺寸增大而提高,采用喜利得RE-500植筋胶构造形式下玻璃孔直径在?54～56 mm最合适;工程实际中需严格控制玻璃肋的精加工,避免因玻璃表面缺陷影响玻璃肋的整体承载能力。     

Improving quality and machining efficiency of hole during AlN trepanning with nanosecond pulse laser

Aluminum nitride (AlN) is essential material to electronics industry. Compared to traditional machining methods, laser trepanning has become one of the most popular options for hole machining on AlN. Due to involvement of multiple parameters, such as scanning number, laser beam jump direction, scanning mode, and filling circle interval, the optimization of hole quality is complex. To tackle this problem, this paper systematically studied hole trepanning on AlN using nanosecond pulse laser in order to examine the relationship among trepanning parameters and hole dimensions, quality, and machining efficiency. Thereby, the optimized combination of parameters could be obtained to improve the quality and efficiency of hole machining. Moreover, possible effect mechanisms like effect of laser fluence on hole diameters, effects of jump directions and scanning modes on hole machining quality were discussed. Most importantly, it is the first time that the relationship among trepanning parameters, hole quality, and machining efficiency is presented.