共查询到19条相似文献,搜索用时 703 毫秒
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《现代制造技术与装备》2021,(5)
基于一阶剪切变形圆板理论,应用最小势能原理,推导了梯度多孔材料圆板在径向载荷与横向载荷共同作用时的控制微分方程及边界条件,并将其退化为经典板理论下的结果。利用打靶法求解圆板非线性力学行为的数值解,并根据结果分析了梯度多孔材料的性质、机械载荷及边界条件等因素对圆板非线性力学行为的影响。 相似文献
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线性分布载荷作用下双模量圆板的计算分析 总被引:1,自引:0,他引:1
双模量圆板在线性载荷作用下,会形成各向同性的拉伸区和压缩区.可将双模量圆板看成两种各向同性材料组成的层合板,采用弹性理论建立双模量圆板在外载荷作用下的静力平衡方程,利用此静力平衡方程即可确定双模量圆板的中性面位置.建立双模量圆板在外载荷作用下的弯曲微分方程,求得双模量圆板在线性分布载荷作用下的挠度方程.通过算例讨论分析双模量对圆板弯曲变形的影响,得到圆板材料拉压弹性模量相差较大时,其挠度计算不宜采用相同弹性模量经典薄板理论,而应该采用双模量薄板理论的结论. 相似文献
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作为一个封装托卡马克的真空压力容器,杜瓦将为冷屏和磁体系统提供真空环境,同时传递来自于自身和线圈系统的载荷,在正常和非正常运行的过程中杜瓦将会遭受地震载荷、电磁力、测试压力、自身净重等载荷的冲击,其中净重和压力载荷是影响杜瓦结构安全性的关键因素,该研究首先基于无力矩理论计算了杜瓦在压力载荷、自身净重以及两者联合作用下的应力状态,获得了杜瓦的危险区域,在此基础上通过应力线性化,提取了危险区域的薄膜、弯曲和峰值应力,最后基于ASME的分析设计对各种不同的应力进行了评定,并分析了局部应力集中的原因,这对于杜瓦的设计优化以及中国聚变工程实验堆杜瓦的设计制造都具有一定的指导作用. 相似文献
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接管外载荷作用下补强圈结构的应力分析 总被引:7,自引:2,他引:7
本文对接管外载荷在具有补强圈补强的圆筒压力容器中引起的局部应力进行了试验研究及有限元分析。三台具有不同d/D比的模型容器的研究结果表明,无论在接管轴向推力还是在接管纵向弯矩及横向弯矩的作用下,补强圈的补强效果是明显的。它使接管区容器上的应力明显降低。研究结果同时表明,由接管横向弯矩在容器横向截面内产生的应力比同样大小的接管纵向弯矩在容器纵向截面内产生的应力大得多。 相似文献
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带接管内压圆柱形容器通常受到内压与接管弯矩的组合作用,接管弯矩会影响内压圆柱壳开孔接管结构的强度性能。在内压与接管弯矩组合作用下,对4台具有不同开孔率的带径向接管圆柱壳容器开孔接管结构强度性能进行试验研究和有限元分析,考察内压与接管纵向弯矩、内压与接管横向弯矩组合作用下容器开孔接管区弹性应力分布、应力集中、开孔接管结构的变形规律及塑性极限载荷等。结果表明,载荷大小相同时,横向弯矩作用产生应力增量较纵向弯矩作用产生应力增量大,横向弯矩对内压容器开孔接管结构强度较危险。内压作用在开孔接管区纵向截面产生应力增量较横向截面应力增量显著。较小值的内压作用可减缓开孔接管结构弯矩作用下的变形,内压能降低开孔接管结构的纵向极限弯矩,较小内压能增加开孔接管结构的横向极限弯矩。 相似文献
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外真空杜瓦是国际热核聚变实验反应堆ITER(International Thermonuclear ExperimentaReactor)上的重要装置,是ITER托卡马克的最外侧部件,主要功能是提供真空环境,避免过多的热载荷传递到磁体系统和冷屏等结构;为了在氦气泄露,以及等离子体破裂等极端情况下保证主机的安全,外真空杜瓦必须具有足够的强度。ITER杜瓦上环体是杜瓦的重要组成部分,属于薄壁圆筒结构,由18部分组成(各部分焊接连接),取其1/9体模型和1/18壳模型分别运用大型有限元分析软件ANSYS,对其不同载荷状况进行了数值计算,分析结果表明,应力集中在矩形孔、轴向筋板和加强圈处,能够满足上环体强度要求,分析结果为其结构设计与优化提供了理论依据。 相似文献
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针对横向载荷作用下的螺栓连接松动过程开展研究,给出了面向螺栓松动仿真的建模方法,分析了循环往复载荷作用下接触状态与残余预紧力的变化规律,并研究了载荷作用位置、幅值和频率对螺栓连接松动的影响。分析结果表明:在横向循环载荷作用下,残余预紧力出现交替的上升与下降;螺纹接触面先于螺头承压面进入滑移状态;横向载荷作用在上板或下板对松动没有影响;载荷幅值是影响松动的主要因素,载荷幅值越大松动越容易发生,而加载频率对松动影响较小。本研究分析结果与Junker试验结果一致性良好,可推广到复杂载荷条件下的应用。 相似文献
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V.A. Eshwar 《International Journal of Mechanical Sciences》1978,20(8):477-484
The analysis of clearance fit joints falls within the realm of mixed boundary problems with moving boundaries. In this paper, this problem is solved by a simple continuum method of analysis applying an inverse technique; the region of contact is specified and the corresponding causative load is evaluated. Illustrations are given for a rigid clearance fit pin in a large elastic plate with smooth zero-shear interface between pin and plate, under biaxial plate stress at infinity and due to load transfer through pin. 相似文献
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在ITER装置正常运行时,杜瓦内外温度不均,有一定的温度分布。考虑热辐射对杜瓦温度分布的影响,建立了用于辐射换热分析的杜瓦数值模拟模型,运用CFD软件Fluent对其进行数值模拟计算,得到杜瓦的温度分布,为后续的热应力分析提供了依据和参考。 相似文献
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A new storage container for freeze-etch specimens is described which (1) dramatically reduces the loss of liquid nitrogen from the storage dewar, (2) which always sits on the bottom of the dewar and can be quickly identified and retrieved therefrom, (3) which cannot open accidentally during long term storage and (4) which can withstand continual exposure to temperature extremes. Using such containers over 300 different kinds of specimens can be readily stored in a 30 1 liquid nitrogen dewar. 相似文献
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A spectral element method (SEM) is introduced for the vibration analysis of rectangular plates under distributed dynamic loads.
In this paper, the spectral plate element matrix (often called the dynamic stiffness matrix) is formulated from the relation
between the forces and displacement along the opposite two parallel edges. The distributed dynamic load is discretized into
a sequence of equivalent line loads. The plate is then considered as a connection of two spectral plate element with the joint
node line along which the equivalent line load acts. The spatial coordinate dependence of each equivalent line load is then
removed through the spatial Fourier transformation so that the plate (2-D) problem becomes a simplified equivalent beam like
(1-D) problem. The remaining solution procedures is therefore the same as that used for beam problems. Numerical tests show
that the present SEM provides very accurate solutions when compared to finite element solutions. 相似文献
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以往对双轴断裂的研究多采用线弹性断裂力学参量且限于弹性材料,局部法理论提出了威布尔应力参量,威布尔应力作为度量脆性断裂概率的参量已广泛采用。为研究双向载荷对威布尔应力的影响,文中开发了威布尔应力计算程序并进行考核验证,以威布尔应力为参量,以ASTM A36钢中心裂纹板为研究对象,结合有限元分析方法,研究二维裂纹问题在不同双向载荷比下威布尔应力参量的变化规律,从而得到双向载荷对脆断概率的影响。计算结果表明,平面应力状态下,双向载荷对威布尔应力和脆断概率基本上没有影响;而在平面应变状态下,威布尔应力和脆性断裂概率随双向载荷比增大而增大。 相似文献
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以典型的基于Kirchhoff假设的匀速旋转弹性薄板为对象,研究其动载荷时域识别技术.首先,从结构动力学的正问题着手,建立弹性薄板在匀速旋转情况下受到分布动载荷时的受迫振动微分方程;然后,选取一种通用厚薄板单元并分析其有限元形式;最后,研究对应的基于广义正交多项式的匀速旋转薄板动载荷时域识别技术.数值算例表明,该时域识别技术精度较高,计算稳定性良好,方法简单有效,适合在工程中应用. 相似文献
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《Wear》2006,260(9-10):942-948
Surface mechanical attrition treatment (SMAT) was employed to fabricate a nanocrystalline surface layer on a pure copper plate. The grain size is about 10 nm in the top layer and increases with an increasing depth from the treated surface. The tribological behavior of the nanocrystalline surface layer was investigated under dry conditions. Experimental results show that the load-bearing ability is markedly enhanced with the nanocrystalline surface layer relative to the coarse-grained form. The friction coefficient of the nanocrystalline layer is lower than that of the coarse-grained copper when the applied load is below 20 N. With increase of the load, the difference in wear resistance between the SMAT and the conventional Cu decreases. When the load exceeds 40 N, for the SMAT Cu, there occurs a transition of wear regime from local damage to delamination of a mechanical mixed layer. There is an abrupt increase of the wear volume, which corresponds to the wearing away of the nanocrystalline layer. The enhanced wear properties of the nanocrystalline surface layer are correlated with the stability of the mechanical mixed layer and the high hardness of the nanocrystalline structure. 相似文献
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Osama K. Bedair 《International Journal of Mechanical Sciences》1997,39(1):33-49
The elastic behaviour of stiffened plates under non-uniform edge compression is investigated. As a first stage, an energy formulation, in which the structure is modelled as assembled plate and beam elements, is presented. A Sequential Quadratic Programming (SQP) algorithm is then used to evaluate the buckling load and the associated buckling mode for given plate/stiffener geometric properties. Results are presented showing the influence of the stiffener location on the stability of the structure under combined compression and bending. Then, a strategy is presented for optimum location of the stiffener. The proposed methodology can be used to develop an improved design procedure for efficient design of stiffened plates under this type of loading. 相似文献