共查询到20条相似文献，搜索用时 31 毫秒
1.
This paper proposes a theoretical method using finite element analysis （FEA） to calculate the plastic collapse loads of pressure vessels under internal pressure, and compares the analytical methods according to three criteria stated in the ASME Boiler Pressure Vessel Code. First, a finite element technique using the arc-length algorithm and the restart analysis is developed to conduct the plastic collapse analysis of vessels, which includes the material and geometry non-linear properties of vessels. Second, as the mechanical properties of vessels are assumed to be elastic-perfectly plastic, the limit load analysis is performed by employing the Newton-Raphson algorithm, while the limit pressure of vessels is obtained by the twice-elastic-slope method and the tangent intersection method respectively to avoid excessive deformation. Finally, the elastic stress analysis under working pressure is conducted and the stress strength of vessels is checked by sorting the stress results. The results are compared with those obtained by experiments and other existing models. This work provides a reference for the selection of the failure criteria and the calculation of the plastic collapse load. 相似文献
2.
This paper discusses stress intensity factor (SIF) calculations for surface cracks in round bars subjected to combined torsion
and bending loadings. Different crack aspect ratios, a/b, ranging from 0.0 to 1.2 and relative crack depths, a/D, ranging from 0.1 to 0.6 were considered. Since the loading was non-symmetrical for torsion loadings, a whole finite element
model was constructed. Then, the individual and combined bending and torsion loadings were remotely applied to the model.
The equivalent SIF method, F*EQ, was then used explicitly to combine the individual SIFs from the bending and torsion loadings. A comparison was then carried
out with the combined SIF, F*FE, obtained using the finite element analysis (FEA) under similar loadings. It was found that the equivalent SIF method successfully
predicted the combined SIF for Mode I. However, discrepancies between the results determined from the different approaches
occurred when F
III was involved. It was also noted that the predicted F*FE using FEA was higher than the F*EQ predicted through the equivalent SIF method due to the difference in crack face interactions. 相似文献
3.
苗德华 《天津工程师范学院学报》2011,21(3)
应用疲劳试验机对退火后15号和45号碳钢及其各自3种塑性变形材料进行了回转弯曲及扭转疲劳实验,讨论了在相同塑性变量的条件下,两种钢材的扭转疲劳极限与回转弯曲疲劳极限之间的关系。实验结果表明：15号和45号钢的扭转与弯曲疲劳极限的比,分别为0．53～0．57和0．57～0．58,即塑性变量相同的情况下,含碳量高的材料其疲劳极限比也较高;相同含碳量的情况下,塑性变形量较小时其疲劳极限比较低。 相似文献
4.
INTRODUCTION Reinforced concrete elements with box section are commonly used in horizontal subsystems and in vertical support of bridge structures. The horizontal structural members normally have box section and top flange. The vertical supports of the bridge usually have a box section also. To simplify the deduction of such structural member under combined forces, the box sections without top flange are discussed here. Fig.1 shows the typical section types of reinforced concrete members.… 相似文献
5.
The buckle and collapse of offshore pipeline subjected to combined actions of tension, bending, and external pressure during
deepwater installation has drawn a great deal of attention. Extended from the model initially proposed by Kyriakides and his
co-workers, a 2D theoretical model which can successfully account for the case of simultaneous tension, bending, and external
pressure is further developed. To confirm the accuracy of this theoretical method, numerical simulations are conducted using
a 3D finite element model within the framework of ABAQUS. Excellent agreement between the results validates the effectiveness
of this theoretical method. The model is then used to study the effects of several important factors such as load path, material
properties, and diameter-to-thickness ratio, etc., on buckling behaviors of the pipes. Based upon parametric studies, a few
significant conclusions are drawn, which aims to provide the design guidelines for deepwater pipeline with solid theoretical
basis. 相似文献
6.
Thetechnologyofcoldpressureweldingiswidelyusedtoachievethejoiningofthesameordifferentmetalswithdif ferentthermal physicspropertiesandotherconditions ,foritsparesenergysources ,simplifiestheweldingequipment,anditdoesnotneedtobeheatedanddoesnotcausethemeltingandtheheateffectzone ,brittlecompounds .Accordinglythetechnologymaybesatisfyingwithdemandforcomprehensivepropertiesinindustry ,andwillsettletheconflictbetweentheincreasingdeficienciesandgrowingdemands .Onthesideofmetallurgicability[1] ,thewe… 相似文献
7.
以汽车裙边塑件为例,分析了大规格弯曲薄壁塑件的结构和成型性能特点,然后将浇注系统设定为圆柱体内的塑料熔体流动,其它非圆截面浇注系统采用形状因子等效,并通过数值模拟,获得熔接痕位王及锁模力、进浇口压力的变化曲线.在此基础上,对浇注系统进行改进,有效控制了熔接痕的大小和位置. 相似文献
8.
M assimiliano FRALDI Antonio GESUALDO Federico GUARRACINO 《浙江大学学报(A卷英文版)》2014,15(7):482-495
研究目的：研究方法：通过有限元分析和极限分析,研究了在纵向和横向载荷下钢框架的最大负荷和坍塌模式,并考虑了塑性铰链住轴向力和弯曲力矩的作用下住实际旋转时的运动学。在垂直和水平方向载荷共存的情况下,基于轴向力和弯曲力矩的交互作用,研究延性框架的极限载荷和坍塌模式对产生于塑性铰链的真实运动学的敏感性。通过两个基本的案例和通过成功地评估非线性有限元分析和直接实施的极限分析步骤,并利用MATHEMATICA,揭示了其敏感性。
在标准规程的框架下,即使在最简单的案例中,极限分析的主要结果也会考虑在坍塌时的运动学,这与设计和加固的目的都是相关的。如果没有对所有的结构元件的轴向力和弯曲力矩的交互作用进行合理的计算,塑性铰链的定位计算可能得出不正确的坍塌机理和误导性的安全系数。就具体方面而言,本文清楚地表明,在设计新的结构或者为现有结构进行加固时,即使是使用看起来已经非常完备的经典步骤,也必须非常小心。本文的模型可以为处理规程设计的执业工程师和标准化委员会提供参考。 相似文献
9.
A study of the interference simulation based on robot welding of the radar pedestal was carried out by using the
KUKA Sim Pro simulation software and off-line program technology. Compared with the actual robot welding process, it was
found that the trajectory of the simulated robot welding process in line with that recorded in the actual welding process, and the
actual limit and interference appeared at the same place as the simulation process. There was no interference phenomenon on the
outside weld-seam; on the internal weld-seam, especially on the weld-joint of support plate connected to the cylinder, a
phenomenon of interference appeared. It was helpful to use the simulation method to guide the actual robot welding so as to
protect robot from impacting and reduce the weld defects. 相似文献
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11.
怎样快速绘制剪力图和弯矩图 总被引：2，自引：0，他引：2
毛和业 《黔南民族师范学院学报》2005,25(3):81-83
在工程构件中，最常见的变形形式是弯曲变形和弯扭组合变形。它们的强度计算必须以剪力图和弯矩图的绘制来找到危截面为前提，而这一绘制过程复杂，计算量大。根据各种载荷的剪力图和弯矩图规律对这一过程进行简化，可找到一种学生易于掌握，且准确率高的方法。 相似文献
12.
The soil-structure interaction (SSI) decoupling is applied to simplify buried structure against internal blast load as spring effect. Shear failure, bending failure and combined failure modes are considered based on five transverse velocity profiles for the rigid-plastic structural element. The critical equations for shear and bending failure are derived respectively. Pressureimpulse diagrams are accordingly developed to assess damage of the buried structures against internal blast load. Comparison is done to show influences of soil-structure interaction and shear-to-bending strength ratio of a structural element. A case study is conducted to show the application of damage assessment to a reinforced concrete beam element of buried structure. 相似文献
13.
Pipes, especially buried pipes, in cold regions generally experience a rash of failures during cold weather snaps. However, the existing heuristic models are unable to explain the basic processes involving frost actions. This is because the frost action is not a direct load but one that causes variations in pipe-soil interactions resulting from the coupled thermohydro-mechanical process in soils. This paper developed and implemented a holistic multiphysics simulation model for freezing soils and extended it to the analysis of pipe-soil systems. The theoretical framework was implemented to analyze both static and dynamic responses of buried pipes subjected to frost actions. The multiphysics simulations reproduced phenomena commonly observed during frost actions, e.g., ice fringe advancement and an increase in the internal stress of pipes. The influences of important design factors, i.e., buried depth and overburden pressure, on pipe responses were simulated. A fatigue cracking criterion was utilized to predict the crack initialization under the joint effects of frost and dynamic traffic loads. The frost effects were found to have detrimental effects for accelerating fatigue crack initialization in pipes. 相似文献
14.
朱甫星 《淮南职业技术学院学报》2009,9(1):17-19,44
不锈钢光纤束管的焊接质量影响光缆的使用性能,利用涡流擦伤法检测不锈钢光纤束管焊接质量,可以有效的检测、监控不锈钢光纤束管;介绍了涡流法在线检测不锈钢光纤束管时几个重要参数的确定以及确定这些参数所采用的一般方法。 相似文献
15.
某汽车配件公司生产汽车油管发生折弯开裂现象,采用金相显微镜和扫描电镜等对油管进行观察并分析开裂原因。结果表明:原双层卷焊管表面存在细小裂纹,在折弯过程中,裂纹在外力作用下发生了扩展,最终导致开裂。 相似文献
16.
《天津大学学报(英文版)》2017,(5)
The composite bucket foundation(CBF) is a new kind of foundation which has been applied in the offshore wind industry. A reasonable connection pattern between the tower and the CBF top cover is crucial for load transmissions from the superstructure. Therefore, it is essential to choose an optimum structure type for the transition section. The line type and the arc transition section models were established by ABAQUS, and the internal forces of cross section were extracted along the height direction. Specifically, the force transfer mechanism for different types of the transition sections was investigated comparatively with monotonic as well as composite loadings. The results show that the curved transition structure exhibits the better mechanical characteristics under the monotonic and composite loadings, and the reason can be illustrated that its specific arc-shape structure can effectively convert the tremendous bending moment from the turbine tower into the limited tensile and compressive stresses downwards, without the occurrence of force concentration. 相似文献
17.
轴对称压力容器弹塑性与强度分析 总被引：1，自引：0，他引：1
本文应用第一、第三强度理论对轴对称压力容器圆筒和半圆球部分进行弹塑性力学分析,得到各自弹性和塑性极限应力,将其与压力容器规范中径分析结果作对比分析。此外,本文还分析了径比对压力容器结构设计和强度的影响。 相似文献
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19.
Water distribution networks are essential components of water supply systems. The combination of pipe structural deterioration and mechanics leads to the failure of pipelines. A physical model for estimating the pipe failure must include both the pipe deterioration model and mechanics model. Winkler pipe-soil interaction （WPSI）, an analytical mechanics model developed by Rajani and Tesfamariam （2004）, takes external and internal loads, temperature changes, loss of bedding support, and the elastoplastic effect of soil into consideration. Based on the WPSI model, a method to evaluate the elastic and plastic areas was proposed in the present study. An FEM model based on pipe-soil interaction （PSI） element was used to verify the analytical model. Sensitivity analyses indicate that the soft soil, long pipe and high temperature induced the axial plastic deformation more likely, which, however, may not occur in normal scenarios. The soft soil, pipes in small diameters, long unsupported bedding are prone to form flexural plastic area. The results show that the pipes subjected to the same loads have smaller stresses in the elastoplastic analysis than elastic analysis. The difference, however, is slight. 相似文献
20.
根据荷载集度与剪力、弯矩之间的导数关系,找出了绘制内力图的规律,应用此规律画剪力图和弯矩图不必列内力方程,只需依据梁在不同荷载作用下剪力图及弯矩图的图形特征计算出控制截面的内力值,即能简便、快捷地画出内力图。 相似文献