共查询到20条相似文献，搜索用时 31 毫秒
1.
采用强度折减有限元法,分析软黏土地基中坑中坑式基坑的内坑开挖对外坑抗隆起稳定性的影响。随着基坑开挖,塑性应变区出现在外坑墙脚和内坑坑底,逐渐扩张至贯通,在内坑距离外坑挡墙较近的一侧形成近似圆弧状的剪切破坏面。坑外土沿着破坏面发生塑性流动,最终导致隆起破坏。研究内外坑的间距和内坑的尺寸对坑中坑式基坑的抗隆起稳定性的影响,发现增大内外坑的间距,内坑的深度以及内坑的宽度会改变破坏面的形式以及坑中坑式基坑的抗隆起稳定安全系数的大小。归纳得出在3种参数影响下总共存在3种不同的破坏面形式。 相似文献
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CUI Xiao-long CHEN Guang-ming 《浙江大学学报(A卷英文版)》2007,8(2):210-215
INTRODUCTION Cryogenic high-pressure vessels are used to store liquid hydrogen and liquid oxygen, and are necessary equipments in the fields of chemical engineering, astronautic engineering and nuclear power plant, and so on. Safe operation of the vessel is always a concern of environmental protection. The inner pressure of the vessel can reach 40 MPa at temperature of 20 K; Therefore, the vessel requires high-performance wall material excellent in mechanical strength, plastic property,… 相似文献
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火力发电厂使用的筒式钢球磨煤机的进出料口 ,各有一个倾斜 4 5°的椭圆形溜槽 ,在以往的设计制造过程中 ,其椭圆均用椭圆近似画法完成 ,用解析方法推导出筒式钢球磨煤机进出料口椭圆的计算公式 ,并经过计算 ,得出进出料口椭圆计算的 4组数据。用这 4组数据设计过近 30 0种不同规格的磨煤机进出料口衬板 ,衬板的外壁和外壳的内壁均能很好地贴合 ,有效防止衬板的松脱、变形 相似文献
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超长钢筋混凝土结构温度应力分析一直是设计人员所关注的课题。文章结合工程实例对超长结构温度应力进行分析，提出了温差的取值方法，并采用PMSAP有限元软件对超长结构进行计算，分析其变形和内力特点，总结出了设计中减小温度应力的措施。 相似文献
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针对薄壳等截面销状碰击开关不能承受高速火箭橇试验过程中的高过载问题,提出薄壳变截面销状碰击开关的设计.该设计在原碰击开关的基础上将极筒由等截面改为变截面,增加了根部厚度,内极延长到底,定位方式由细定位销改为与外极等外圆的法兰盘,内、外极形状由圆柱改为圆锥,并将极筒与法兰盘间的过渡由清角改为圆角,增加了绝缘座轴向厚度.仿真分析和试验结果表明:该设计有效提高了碰击开关的抗高过载能力,具有一定的工程指导意义. 相似文献
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An analytical solution is obtained for a rotating multiferroic composite hollow cylinder made of radially polarized piezoelectric and piezomagnetic materials. Both the number of layers and the stacking sequence of the composite cylinder can be arbitrary. General mechanical, electric and magnetic boundary conditions can be applied at both the inner and outer cylindrical surfaces. The state space method is employed so that only a 2×2 matrix is involved in the whole solving procedure. In the numerical experiments, the distributions of elastic, electric as well as magnetic fields in an internally pressurized rotating BaTiO3/CoFe2O4 composite hollow cylinder subjected to different boundary conditions are presented graphically. The results clearly show that the stress fields in a multiferroic composite cylinder are controllable. 相似文献
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在传统理论计算的基础上,借助abaqus软件进行数值模拟分析,主要讨论在不同板料厚度下成形带凸缘圆筒件的应力分布和变化情况,以及壁厚的变化情况,找出其应力和壁厚随板料厚度变化的规律。验证理论计算的科学性和合理性,同时也反应数值模拟的参数比理论计算更精细化,为该类零件的成形工艺提供借鉴和参考。 相似文献
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厚壁圆筒热冲击作用下的温度场 总被引：4，自引：0，他引：4
贠英伟 《洛阳工业高等专科学校学报》2005,15(2):25-28
针对冲击的瞬时特性，在热冲击问题的边界条件中引入6函数，运用Laplace变换的方法求解了厚壁圆筒内部受热冲击作用时的温度场．探讨了温度场随时间和圆筒内外径比的变化．为研究管式反应器热冲击应力场奠定基础． 相似文献
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THE CONTROL VALUE OF THE DEFLECTION OF THE EMBEDDED CYLINDRICAL STRUCTURE, WHICH IS THE MAXIMUM DEFLECTION ALLOWED FOR STABILITY OF THE CYLINDER, IS A VITAL QUANTITY OF STABILITY CALCULATION. THE DEFLECTION AND THE SOIL PRESSURE ON THE EMBEDDED CYLINDER WERE INVESTIGATED BY MODEL EXPERIMENT. WHEN THE INCLINED ANGLE OF CYLINDER IS LESS THAN OR EQUAL TO 0. 25°, THE EFFECTIVE ANTI-OVERTURNING RATIO INCREASES GRADUALLY AND REACHES THE MAXIMUM. WHEN THE INCLINED ANGLE OF CYLINDER IS MORE THAN 0.25°, THE EFFECTIVE ANTI-OVERTURNING RATIO DECREASES GRADUALLY. THE CONTROL VALUE OF INSTABILITY OF THE CYLINDRICAL STRUCTURE APPROXIMATES 0. 2°, AND THE BEARING STRESS AT THE BACK EDGE OF THE CYLINDER IS EQUAL TO ZERO. 相似文献
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一钢框架结构分别以普通砌块和泡沫混凝土为填充墙材料,据此建立有限元模型来研究其对结构抗震性能的影响。根据数据分析,砌块填充墙和泡沫混凝土填充墙对结构的动力特性有不同程度的影响,结构的位移反应也有不同的表现。 相似文献
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Finite element models were established to analyze the influence of soft filler on stress concentration for a rectangular plate with an elliptic hole in the center. The influence was quantified by means of stress concentration factor (SCF). Seven shape factors of the elliptic hole and three levels of elasticity modulus of the soft filler were considered. The reduction coefficient and sensitivity index of SCF are the two indicators in evaluating the influence of soft filler. It was found that the reduction coefficient of SCF increases significantly as the shape factor and the elasticity modulus of the filler increase, indicating that soft filler can reduce the concentrated stress effectively, especially when the shape factor is great. Analysis for the sensitivity index of SCF indicates that SCF is more sensitive to materials with small elasticity modulus than to materials with large one. 相似文献
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钮教礼 《楚雄师范学院学报》2009,24(1)
底层书写是上世纪90年代文学界兴起的一个热点现象,它主要关注的是何谓底层以及底层如何表述的问题.郑小琼的诗歌通过"铁"的意象,从底层打工者生存的三个方面--生存环境、生存状况、话语缺失展现了底层生活的状态以及她对底层生活的见证和反思,体现了明显的底层书写特征. 相似文献
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以北海穗丰金湾小区1#楼为例,针对85m相对悬空高度、3.8m大悬挑砼圆形构件施工过程中模板及支撑系统的设计和施工,介绍高空大悬挑砼构件模板与支撑系统的施工方案。该支模承重体系主要利用下部结构为剪力墙的受力支撑点搭设出一个钢桁架承重平台,以此来支撑上部结构施工过程中的荷载。该体系具有较高的安全性和较强的可操作性,设计思路可供建筑工程技术人员参考和借鉴。 相似文献
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An analysis of the instability in the Taylor-Couette flow of fiber suspensions with respect to the non-axisymmetric disturbances was performed. The constitutive model proposed by Ericksen was used to represent the role of fiber additives on the stress tensor. The generalized eigenvalue equation governing the hydrodynamic stability of the system was solved using a direct numerical procedure. The results showed that the fiber additives can suppress the instability of the flow. At the same time, the non-axisymmetric disturbance is the preferred mode that makes the fiber suspensions unstable when the ratio of the angular velocity of the outer cylinder to that of the inner cylinder is a large negative number. 相似文献
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在实际情况下,薄壁四点轴承与轴承座、轴的配合对薄壁轴承载荷分布、承载能力、轴承刚度有着很大影响。建立腕关节薄壁四点接触球轴承—基座—空心轴构成的轴承系统有限元模型以模拟轴承配合,从而选择最佳配合模型,对实际情况下的轴承配合具有指导意义。基于 ANSYS 有限元软件建立薄壁四点接触轴承不同配合的有限元模型,通过对不同配合模型接触特性进行有限元分析,得出薄壁四点接触球轴承较为精确的椭圆接触区域形状和四点接触状态。对于轴承配合模型 H7 在内外套圈与空心轴及基座接触时有明显应力集中现象,由于轴承滚珠并非在侧面对称,导致轴承与基座及空心轴在靠近滚珠的一边出现应力集中情况。对不同配合的有限元模型进行静态接触特性分析,发现各轴承配合整体等效应力最大值、外圈等效应力最大值、接触应力最大值、基座等效应力最大值区别不大,选择 K7/j7 的轴承配合模型才能使轴承内圈与空心轴的最大等效应力最小。计算结果较为精确地模拟了薄壁四点接触球轴承的接触特性和载荷分布规律,对于实际情况下轴承装配具有一定指导意义。 相似文献
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运用类比法对挡土墙及类似结构传统的抗倾覆稳定验算方法提出质疑.推荐一种直接计算挡土墙基宽的方法,并附以简要图表,不需另行专门验算抗倾覆稳定性.这是将验算地基承载力、抗倾覆一起核算的方法. 相似文献
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为了研究移动荷载下路面结构内部细观结构的响应,采用离散元方法进行了多尺度路面结构移动荷载响应的分析．建立了柔性基层沥青路面典型结构的离散元模型,并计算了移动荷载作用下沥青层底的应力和应变,通过与已有经典计算程序荷栽响应计算结果的比较,验证了所建立的离散元模型．以该离散元模型为基础,在沥青混凝土结构层的底部,采用尺度较小的离散单元描述粗集料的体积含量、分布特征以及空隙大小等细观结构,以此建立路面结构的多尺度模型．对路面结构宏观响应与细观结构的荷载响应进行了比较分析,并分析了沥青砂浆劲度对细观结构处荷载响应的影响．结果表明：粗集料与沥青砂浆界面位置的拉应力均值和离散系数均大于沥青砂浆内部;荷载引起的应力和应变在沥青砂浆内部和界面内部均存在不均匀分布;沥青砂浆的劲度越大,沥青混凝土内部的荷载响应分布越趋于均匀． 相似文献
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The response of dynamic wave pressures on structures would be more complicated and bring about new phenomena under the dynamic interaction between soil asnd structure.In order to better understand the response characteristics on deeply embedded large cylindrical structures under random waves,and accordingly to offer valuable findings for engineering ,the authors designed wave flume experiments to investigate comparatively dynamic wave pressures on a single and on continuous cylinders with two different cembedment depths in response to two wave spectra ,The time histories of the water surface elevation and the corresponding dynamic wave pressures exerted on the cylinder were analyzed in the frequency domain,By calculating the transfer function and spectral density for dynamic wave pressures along the height and around the circumference of the cylinder,experimental results of the single cylinder were compared with the theoretical results based on the linear diffraction theory ,and detailed comparisons were also carried out between the single and continuous cylinders ,Some new findings and the corresponding analysis are reported in present paoer,The investigation on continuous cylinders will be used in particular for reference in engineering applications becaus information is scarce on studying such kind of problem both analytically and experimentally. 相似文献
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湿式旋风脱硫除尘器是一种高效脱硫除尘装置 ,本文对其短期内出现破损机理进行了分析 ,其原因是高速含尘气流对除尘器锥体内壁的冲刷磨损和不锈钢应力共同作用的结果 ;并提出防腐耐磨综合措施。实践证实这种措施是可行的。 相似文献