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1.
The effect of axial shallow groove on the nonlinear dynamic response and buckling of laminated cylindrical shells subjected to radial compression loading was investigated. Based on the first-order shear deformation theory （FSDT）, the nonlinear dynamic equations involving the transverse shear deformation and initial geometric imperfections were derived with the Hamilton philosophy. The axial shallow groove of the laminated composite cylindrical shell was treated as the initial geometric imperfections in the dynamic equations. A semi-analytical method of expanding displacements and loads along the circumferential direction and employing the finite difference method along the axial direction and in the time domain is used to solve the governing equations and obtain the dynamic response of the laminated shell. The B-R criterion was employed to determine the critical loads of dynamic buckling of the shell. The effects of the parameters of the shallow groove on the dynamic response and buckling were discussed in this paper and the results show that the axial shallow grooves greatly affect the dynamic response and buckling. 相似文献
2.
利用有限元分析软件ANSYS Workbench对某内压筒体沿周向开设矩形排孔的结构进行有限元分析,得到该结构的应力分布状况和最高应力水平,并据标准对此结构进行了强度评定。分析结果表明,沿筒体轴向因开孔致应力集中的影响范围较小,而周向各接管开孔应力集中的影响互相叠加,其范围遍布筒体的整个周向,最大应力分布在各接管拐角和各接管与筒体的角焊缝处,故矩形接管的焊缝应全焊透且需进行表面渗透检测,以满足JB4730I级合格标准,并避免安排在拐角处。 相似文献
3.
Buckling design of large steel silos with various slendernesses 总被引：1，自引：0，他引：1
Large steel silos are typical kinds of thin-walled structure which are widely used for storing huge quantities of granular solids in industry and agriculture. In the present analyses, the buckling design of large steel silos subject to Eurocode-specified solid pressure is demonstrated. The finite element model is established using the commercial general purpose computer package ANSYS. Six types of buckling analyses are carried out for the geometrically perfect and imperfect models with and without consideration of material plasticity. The load cases of concentric discharge, discharge patch load, large eccentricity discharge, and large eccentricity filling are considered. The buckling behavior of six example steel silos with capacities of 30 000–60 000 m3 is investigated. The silos’ slenderness ranges from 4.77 to 0.35, comprising very slender, slender, intermediate slender, squat, and retaining silos. The index called the ratio of capacity to steel consumption (RCS) is initially defined in the paper, which provides an effective measure for the economical design of steel silos. It is validated that the RCS index increases rapidly with the decrease of silo slenderness, and the storage efficiency of steel silo improved greatly as the slenderness changes from slender silo to retaining silo. The effects of patch load reveal that the buckling modes in the case of discharge patch load are very different from those of silos under concentric solid pressure, and the effect is unfavorable for buckling resistance of all levels of slenderness of the example silos, but contributes a small decrease to the RCS index (less than 10%). The buckling deformations from both the linear and nonlinear buckling analyses in large eccentric discharge are strongly asymmetrical arising from the circumferential and meridional non-uniform distribution of the solid pressures. The buckling is mainly governed by the non-uniform distribution of the solid pressure other than other influential factors such as the weld imperfection, geometrical and material nonlinearity, compared with the load case of concentric discharge. The RCS index of example silos under large eccentric discharge is reduced substantially, and is approximately half that of silos under concentric discharge. The linear and nonlinear buckling deformations in large eccentric filling are also asymmetrical, deviating from the center to the side where the most friction locates to the highest wall contact. The RCS index of example silos under large eccentric filling is also reduced substantially, and is approximately 70% that of silos under concentric discharge. This reveals that the large eccentricity both in discharging and filling could result in a strong decrease of storage efficiency of steel silos. 相似文献
4.
Ten slender steel reinforced cencrete (SRC) composite columns are tested under eccentric loading conditions.Effects of concrete strength, slenderness of columns and eccentricity of the axial load are studied. The load-carrying capacity is reduced with increased slenderness ratio and eccentricity. Concrete strength has no obvious influence on eccentrically loaded columns. Then, a nonlinear numerical method of pin-ended slender columns is also presented. This method is applicable for determining the material failure load or buckling failure load of a slender steel reinforced concrete composite column. In this method both material and geometric nonlinearities are taken into account. The results of numerical analysis accord well with the test results. The test results are also compared with the results predicted by ACI318-05 and the China Specifications. 相似文献
5.
INTRODUCTION Vibrations of cylindrical shells are of consider-able importance as they are extensively used in in-dustry,flight structures and marine crafts.The naturalfrequencies and mode shapes are important sources ofinformation for understanding and controlling thevibration of these structures,so many papers on theprediction of the natural frequencies of cylindricalshells have been published over the past years.Many shell theories have been developed andvarious solution methods have bee… 相似文献
6.
针对内、外焊缝余高过大导致焊缝处应力集中,抵抗动载荷能力下降等影响焊管力学性能的问题,在充分分析焊缝滚压冷轧处理工作流程的基础上,以西门子S7—200PLC为系统核心,EasyView触摸屏为人机界面,提出能够自行调节滚压行程、滚压速度、回程速度、加减速和比例阀控制死区等设置的一整套电气控制方案,完成对小口径不锈钢焊管的内、外焊缝的滚压冷轧处理,解决了以往设备需要依赖进口或调试困难、故障率高、维修难的问题,提高了产品成材率和品质,满足了生产大型电站、锅炉换热器用小口径不锈钢焊接管的生产工艺要求。 相似文献
7.
"露露"易拉罐是一种薄壁圆筒,但由于存在纵向连接缝,破坏了结构的轴对称性.利用有限元法对有纵向连接缝的圆筒进行了特征值屈曲分析,计算结果与实验值能较好地吻合.对有、无纵向连接缝圆筒临界压力的有限元计算结果进行了比较,发现当主要考虑筒体的侧向失稳时,该连接缝对其失稳性能影响很小,可用做外压圆筒稳定性实验的试件. 相似文献
8.
SUNG Wen-pei SHIH Ming-hsiang LIN Cheng-I GO Cheer Germ 《浙江大学学报(A卷英文版)》2005,6(8):878-885
INTRODUCTION The conventional design of rails uses steel clipboards and bolts to link rails, and avoids bucklingcaused by thermal expansion effect by mountingexpansion joints to solve axial restraint generated byseasonal or day-and-night temperature changes. Butthe discontinuity at the rail joints brings discomfortand noise to passengers when the train has suddenlystops or starts, during which train speed cannot beeffectively increased, rails are more easily damaged,and the cost of mainte… 相似文献
9.
基于仿真模拟软件SYSWELD,建立了P91钢材料属性数据库,设计开发了考虑马氏体相变的“热-冶金-力学”耦合计算方法,采用热循环曲线法对P91钢平板对接接头残余应力场进行数值模拟仿真分析。参照原始焊接工艺方案进行上下0.5mm/s焊接速度的调整,并进行残余应力仿真计算。结果表明,马氏体相变能抵消焊缝热收缩时产生的拉应力。后道焊缝焊接过程中施加的热载荷对前道焊缝应力变化和平板角变形有着显著的影响。考虑后道焊缝焊接过程中施加的热载荷对前道焊缝组织变化的影响时,焊接接头整体的拉应力大幅度下降,热影响区的拉应力上升,角变形起缓和作用。焊接速度越大,Von Mises残余应力和横向残余应力越大,纵向残余压应力越小。 相似文献
10.
建立了T形配钢型钢混凝土偏压构件力学性能分析的有限元模型,计算结果得到以往实验结果的验证。在此基础上,分析了不同阶段材料应力状态和各参数对偏压构件力学性能的影响。结果表明:T形配钢型钢混凝土构件在不同加载角下的性能有所不同,加载角为180°时极限承载力大于其他角度情况;混凝土抗压强度、型钢含钢率、配筋率、荷载偏心率、长细比对构件荷载-变形曲线的影响较大,随着混凝土强度、型钢含钢率、配筋率的增加,极限承载力和刚度增加;随着荷载偏心率的增加,极限承载力和刚度下降;随着构件长细比的增加,构件承载力总体呈现线性下降趋势,刚度下降明显。 相似文献
11.
Seismic behavior of steel reinforced ultra high strength concrete column and reinforced concrete beam connection 总被引：1，自引：1，他引：0
To investigate the seismic behavior of connections composed of steel reinforced ultra high strength concrete （SRUHSC） column and reinforced concrete （RC） beam, six interior strong-column-weak-beam connection specimens were tested subjected to reversal cyclic load. Effects of applied axial load ratio and volumetric stirrup ratio on ductility, energy dissipation capacity, strength degradation and rigidity degradation were discussed. It was found that all connection specimens failed in bending in a ductile manner with a beam plastic hinge. The ductility and energy dissipation capacity increased with the decrease of applied axial load ratio or increase of volumetric stirrup ratio. The displacement ductility coefficient and equivalent damping coefficient lay between those of steel reinforced ordinary concrete connection and those of reinforced concrete connection. The applied axial load ratio and volumetric stirrup ratio had less influence on the strength degradation and more influence on the stiffness degradation. The stiffness degraded sharply with the decrease of volumetric stirrup ratio or increase of applied axial load ratio. The experimental results indicate that SRUHSC column and RC beam connection exhibited better seismic performance and can provide reference for engineering application. 相似文献
12.
To investigate the mechanical behavior of segmental lining,a three-dimensional numerical analysis and test using three actual segments were used to analyze the effects of axial force and reinforcement ratio on the failure mechanism and ultimate bearing capacity of segmental lining.Both numerical and test results confirmed that the cracking load,yield and ultimate load were strongly influenced by axial force,and it was also proved that the yield and ultimate load would increase with the increase of reinforcement ratio,but the cracking load was almost not affected.The cracking load,yield and ultimate load are about 28.7%,500% and 460% larger due to the effect of axial force respectively.The comparison between numerical calculation and test results showed that the finite element analysis results were in good agreement with the test results. 相似文献
13.
The creep-induced deformation of the arch rib of concrete-filled steel tubular （CFST） arches under a sustained load can increase the bending moment, which may lead to earlier stability failure called creep buckling. To investigate the influences of concrete creep on the buckling strength of arches, a theoretical analysis for the creep buckling of CFST circular arches under distributed radial load is performed. The simplified Arutyunyan-Maslov （AM） creep law is used to model the creep behavior of concrete core, and the creep integral operator is introduced. The analytical solutions of the time-dependent buckling strength under the sustained load are achieved and compared with the existing formula based on the age-adjusted effective modulus method （AEMM）. Then the solutions are used to determine the influences of the steel ratio and the first loading age on the creep buckling of CFST arches. The results show that the analytical solutions are of good accuracy and applicability. For CFST arches, the steel ratio and the first loading age have significant influences on creep buckling. An approximate log-linear relationship between the decreased degrees of the creep buckling strength and the first loading age is found. For the commonly used parameters, the maximum loss of the buckling strength induced bv concrete creen is close to 40% 相似文献
14.
讨论弹性有限长度杆端部受冲击载荷作用，在轴向应为波传播和反射过程中的动态屈曲问题．利用扰动方程的解、端部支承条件和应力波反射前后波阵面相容条件得到了动态屈曲的分叉条件，临界载荷和屈曲模态．数值结果表明：临界载荷有多个分支且随时间增加而降低；由于应力波在端部的反射，使临界载荷进一步下降．这个结果就解释了实验中的一些现象． 相似文献
15.
Zhou Cheng-ti 《大连大学学报》1991,(1)
本文论述了复合材料的强度和稳定性理论中的三个近代问题:复合材料迭层板的强度准则,多层复合材料圆柱壳的非线性稳定性理论,以及复合材料板的动力稳定性理论。关于迭层板的强度准则,论述了目前以张量多项式形式所表述的唯象性破坏准则,着重讨论和比较了各种近代理论在确定耦合系数方面的特点和差别。提出了近代理论中所存在的困难和发展趋势。在多层复合材料圆柱壳的非线性稳定性理论分析中,主要的问题在于如何研究和考虑那些非线性因素,诸如由材料的剪切模量所引起的物理非线性,横向剪切变形的影响,壳体结构的初始缺陷和几何非线性,以及前屈曲变形和边界支承条件的影响等。本文指出了考虑这些因素的方法以及它们的影响程度。复合材料板的动力屈曲性能研究是一个重要的近代研究方向。本文提出了关于复合材料本身的阻尼系数,纵向和转动惯性力影响,横向剪切效应,迭层板的初始几何缺陷,以及增强纤维的铺设方向等因素对于动力屈曲性能的影响。同时提出了计算这些影响的方法,指出这些因素在复合材料板的动力稳定性分析中有着重要作用。 相似文献
16.
Brittle cracks were observed in the welded beam-to-column connections of steel frames during an earthquake. The crack propagation and accumulated damage to the connections can lead to fractures at much lower ductility ratios. Understanding the connections’ damage behavior during an earthquake is crucial for the design of steel moment frames in seismic areas. Nine full scale beam-to-column connections were tested under constant amplitude and variable amplitude cyclic loading. The effects of loading amplitude, loading history, and peak load on the connection damage were analyzed. The damage characters were studied and three damage evolution models were calibrated and validated based on test results. The damage mechanism was investigated and an effective plastic strain index was developed to evaluate connection damage based on a ductile fracture mechanism. A fatigue fracture mechanics-based model, for evaluating the damage process of beam-to-column connections under cyclic loading, was proposed. 相似文献
17.
A numerical investigation of thin-walled complex section steel columns with intermediate stiffeners was performed using finite
element analysis. An accurate and reliable finite element model was developed and verified against test results. Verification
indicates that the model could predict the ultimate strengths and failure modes of the tested columns with reasonable accuracy.
Therefore, the developed model was used for the parametric study. In addition, the effect of geometric imperfection on column
ultimate strength and the effect of boundary conditions on the elastic distortional buckling of complex section columns were
investigated. An equation for the elastic distortional buckling load of fixed-ended columns having different column lengths
was proposed. The elastic distortional buckling load obtained from the proposed equation was used in the direct strength method
to calculate the column ultimate strength. Generally, it is shown that the proposed design equation conservatively predicted
the ultimate strengths of complex section columns with different column lengths. 相似文献
18.
Zhou Chengti 《大连大学学报》1992,(1)
本文运用柯依脱理论(Koiter'sTheory)对于复合材料圆柱壳屈曲性能的初始缺陷影响进行了一般性分析,为复合材料壳体的初始缺陷敏感度分析建立了基本控制方程;壳体的初始缺陷被设定为具有某些固定形式的或者是随机形式的,为了讨论和比较各种复合材料叠层壳体的缺陷敏感度的影响,用数值算例计算了由玻璃/环氧,硼/环氧,和炭/环氧等复合材料所组成的圆柱壳体的届曲性能。 相似文献
19.
To investigate the bilateral shear strength of rectangular frame column subjected to oblique horizontal load, we presented a simplified space truss-arch model developed from unilateral truss-arch model. Main parameters in the new model were the cross-sectional area, transverse reinforcement raito, axial load, and material strength of the column. The reduction coefficient of concrete sterength owing to the severe cracking of column was also introduced in the model. Finally, 14 specimens under oblique horizontal load were tested to verified the feasibility and applicability of the space truss-arch model. 相似文献
20.
研究了变形速率对低合金结构钢 3 5CrMo磨擦焊接头组织与力学性能的影响 .结果表明 ,增加变形速率可改善焊缝韧性 .焊缝韧性改善的机理为近缝区晶粒细化和硬度降低 .采用金相法、TEM法对近缝区粒状组织精细结构进行了观察 ,粒状组织小岛由M -A组成 .指出增加变形速率使近缝区金属强化机制为位错强化、一定数量的岛状第二相强化和细晶粒强化 .通过测试异种金属焊缝界面近区碳浓度的分布 ,探讨变形速率对磨擦焊最高加热温度的影响 ,增加变形速率可使磨擦焊界面的最高加热温度下降 相似文献