共查询到19条相似文献，搜索用时 203 毫秒
1.
用有限元计算方法研究了温度载荷作用下异质结构界面端部区域的应力分布以及端部几何构形的影响，分析了在既有材料性质突变又有端部几何构形突变时，由于材料和几何构形这两种因素所造成的应力集中问题．研究结果表明：由于温度的变化，在界面层端部存在着很高的应力集中；界面端部的影响区域很小，仅在γ＜０．４ｍｍ的区域内．研究还表明：改变界面端部的几何形状可以有效地缓解端部应力集中程度，特别是减小了界面层上剥离应力σｙ的峰值．本文还用实验方法测量了界面端部区域的热变形并对端部几何钝化问题以及减小应力集中的方法进行了讨论 相似文献
2.
受沿经向简单剪切的织物屈曲分析 总被引：5，自引：0，他引：5
分析了织物受沿经向简单剪切时的屈曲 ,得到确定织物屈曲方向 (屈曲波的方向 )的方程 ,该方程表明织物屈曲方向与临界剪切值有关 .还证明了织物受沿经向简单剪切时会发生离面屈曲 ,并且只存在一种屈曲模态——弯曲屈曲模态 ,得到了该屈曲模态的屈曲条件及屈曲条件曲线 . 相似文献
3.
第五部分.压杆稳定问题与疲劳强度问题一、检查题1.理论推导题(1)试建立欧拉临界应力公式,并说明该公式的应用条件。(2)图1所示细长压杆,两端固定,试建立其临界载荷公式。P为 相似文献
4.
杜月红 《河北工业大学成人教育学院学报》1999,(2)
本文用能量法求解了矩形悬臂板在均布载荷或集中载荷作用下侧向屈曲问题。选取不同于文献［2」的多项式挠度函数,得到的最小临界载荷更加准确和安全。 相似文献
5.
《浙江大学学报(A卷英文版)》2019,(6)
目的:通过深入的数值分析研究面内综合加载条件下钢板的临界屈曲荷载变化规律。创新点:1.提出一个确定钢梁在平面荷载作用下的临界屈曲系数的新公式;2.通过与有限元分析结果对比以修正参数并获得解析公式的高精度。方法:1.采用有限元分析软件Strand 7研究矩形钢板在节点荷载、弯矩和剪应力综合作用下的弹性稳定性;2.针对节点荷载长度、载荷大小、板长宽比和长径比等参数分析对综合加载条件下的钢板稳定性的影响;3.借助一个实际的例子验证解析公式的有效性。结论:1.通过与有限元结果的比较,解析公式均表现出较高的精度,误差均在有限范围内且不受板几何形状的影响;2.节点荷载、弯矩和剪应力的综合作用通过减小板临界抗屈曲性导致钢板的屈曲失效;3.综合加载会导致临界抗屈曲性减小一半。 相似文献
6.
冲击过程中能量匹配分析 总被引：1，自引：0，他引：1
颜祥山 《贵州教育学院学报》2001,12(2):16-17
简论了冲击过程中采用应力波方法分析能量匹配问题 ,得出 :冲击机械中入射应力波如满足理想波形时 ,从冲击对象反射回来的反射应力波能量达最小 ,冲击机械的能效达到最大值 相似文献
7.
通过对电磁波和弹性波在分层媒质中的传播过程的分析，研究了它们在分层媒质中的反射特性，给定了反射系数的表达式，同时对电磁波和弹性波在分层媒质中传播性质的差异进行了比较． 相似文献
8.
本文在三维无反射型标量势和矢量势相等的条件下，给出了Dirac方程和KleinGordon方程的S波散射态精确解． 相似文献
9.
《浙江大学学报(A卷英文版)》2017,(1)
目的:通过双矩管装配式防屈曲支撑的滞回试验研究,探讨防屈曲支撑可能存在的破坏模式及各设计参数对支撑耗能性能的影响,验证支撑端部构造细节的合理性,提出支撑设计建议。创新点:1.试验研究铰接双矩管装配式防屈曲支撑的滞回性能;2.获得4种支撑破坏模式。方法:通过对7根铰接双矩管装配式防屈曲支撑的滞回性能试验,研究支撑外围盖板厚度、内核加强翼板高度和外围槽钢翼缘高度等参数对防屈曲支撑破坏机理及耗能性能的影响。结论:1.外围盖板厚度太薄,支撑易发生端部折曲破坏;2.端部转动受限制的支撑,其滞回性能优于纯铰接防屈曲支撑,但支撑连接节点处的附加弯矩不容忽视;3.支撑均表现出优良的屈曲耗能性能,验证了试验试件端部构造细节的合理性。 相似文献
10.
由于引脚、印制电路板和焊接剂的热-机材料属性不同,在受到热载荷或机械载荷时,引脚焊接界面端会产生奇异性应力,有可能产生界面开裂。为了基于界面端奇异场来评价QFP结构引脚界面端力学行为,采用数值方法求解引脚焊缝任意角度尖劈界面端的应力强度系数。具体步骤为:首先,基于高次内插有限元特征分析法确定两相任意角度尖劈界面端的奇异性指数和应力角分布函数,并引入常数热应力项,获得热-机耦合奇异性应力场表达式;采用有限元分析技术和最小二乘拟合法来获得应力强度系数的数值解。考察了热-机材料属性对热载荷下焊接剂/印制电路板界面端应力强度系数的影响。结果表明:弹性模量、泊松比和材料热膨胀系数等均对应力强度系数有影响,适当的做出调整可以使界面端呈现良好的热应力状态。 相似文献
11.
The effect of weld reinforcement on axial plastic buckling of welded steel cylindrical shells is investigated through experimental
and numerical buckling analysis using six welded steel cylindrical shell specimens. The relationship between the amplitude
of weld reinforcement and the axial plastic buckling critical load is explored. The effect of the material yield strength
and the number of circumferential welds on the axial plastic buckling is studied. Results show that circumferential weld reinforcement
represents a severe imperfect form of axially compressed welded steel cylindrical shells and the axial plastic buckling critical
load decreases with the increment of the mean amplitude of circumferential weld reinforcement. The material yield strength
and the number of circumferential welds are found to have no significant effect on buckling waveforms; however, the axial
plastic buckling critical load can be decreased to some extent with the increase of the number of circumferential welds. 相似文献
12.
This study investigated characteristics of bifurcation and critical buckling load by shape imperfection of space truss,which were sensitive to initial conditions.The critical point and buckling load were computed by the analysis of the eigenvalues and determinants of the tangential stiffness matrix.The two-free-nodes example and star dome were selected for the case study in order to examine the nodal buckling and global buckling by the sensitivity to the eigen buckling mode and the analyses of the influence,and characteristics of the parameters as defined by the load ratio of the center node and surrounding node,as well as rise-span ratio were performed.The sensitivity to the imperfection of the initial shape of the two-free-nodes example,which occurs due to snapping at the critical point,resulted in bifurcation before the limit point due to the buckling mode,and the buckling load was reduced by the increase in the amount of imperfection.The two sensitive buckling patterns of the numerical model are established by investigating the displaced position of the free nodes,and the asymmetric eigenmode greatly influenced the behavior of the imperfection shape whether it was at limit point or bifurcation.Furthermore,the sensitive mode of the two-free-nodes example was similar to the in-extensional basis mechanism of a simplified model.The star dome,which was used to examine the influence among several nodes,indicated that the influence of nodal buckling was greater than that of global buckling as the rise-span ratio was higher.Besides,global buckling is occurred with reaching bifurcation point as the value of load ratio was higher,and the buckling load level was about 50%-70% of load level at limit point. 相似文献
13.
The surface acoustic wave (SAW) propagating in a sample of steel is simulated by using finite element method (FEM). The waves are excited by a load function with propagation properties such as phase velocity dispersion and wide bandwidth. A two-dimensional model consisting of surface defects loaded with a wideband 50-200 MHz and short time 0.1 μs displacement function is investigated in the time and frequency domains. By transient dynamic analysis, Fourier transform and dispersion calculation, snapshots of propagating wave and responses from sensing points are presented. It is indicated that this supervision approach is sensitive to the surface cracks and reflections. 相似文献
14.
:焊接箱形梁腹板存在较高的屈曲后强度 ,可供利用 .对箱形梁腹板在各种受力条件下的屈曲后性能进行了理论分析 ,同时在参考国内外钢结构设计规范的基础上 ,提出了相应的简化分析方法 ,供工程设计和修订规范时参考 .计算结果表明 ,本文提出的分析方法简单可行 相似文献
15.
通过理论研究和数值计算，详细分析了大跨径钢管混凝土双肋拱桥的侧倾稳定性和地震响应。首先，根据双肋拱桥结构在竖向均布荷栽作用下的侧倾稳定临界力的近似解析解，讨论了横撑设置、横撑刚度等因素对稳定性的影响。其次，基于多点激振理论和拟静力位移概念，介绍了拱桥结构的动力特点和地震动作用下的响应，并讨论了行波效应的影响。分析表明，地震行波作用对大跨度拱桥影响很大，横撑设置对稳定性敏感。 相似文献
16.
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
17.
INTRODUCTIONThetensegritystructurecomposedofcablesandbarsisoftwotypes.Oneistheflexibletensegritystructure.Thistypeofstructurehasnostiffnessandtheshapeofthestructureisnotde terminedwhennoprestressisapplied .Theform findingprocessfortheinitialequilibriumisa… 相似文献
18.
The nonlinear finite element method is used to analyze the geometrical nonlinear stability of cabletruss domes with different
cable distributions. The results indicate that the critical load increases evidently when cables, especially diagonal cables,
are distributed in the structure. The critical loads of the structure at different rise-span ratios are also discussed in
this paper. It was shown that the effect of the tensional cable is more evident at small rise-span ratio. The buckling of
the structure is characterized by a global collapse at small rise-span ratio; that the torsional buckling of the radial truss
occurs at big rise-span ratio; and that at proper rise-span ratio, the global collapse and the lateral buckling of the truss
occur nearly simultaneously.
Project (No. 50278086) supported by the National Natural Science Foundation of China 相似文献
19.
SUNGWen-pei LINCheng-I SHIHMing-hsiang GOCheer-germ 《浙江大学学报(A卷英文版)》2005,6(2):132-140
In view of the recent technological development, the pursuit of safe high-precision structural designs has been the goal of most structural designers. To bridge the gap between the construction theories and the actual construction techniques, safety factors are adopted for designing the strength loading of structural members. If safety factors are too conservative, the extra building materials necessary will result in high construction cost. Thus, there has been a tendency in the construction field to derive a precise buckling load analysis model of member in order to establish accurate safety factors. A numerical analysis model, using modal analysis to acquire the dynamic function calculated by dynamic parameter to get the buckling load of member, is proposed in this paper. The fixed and simple supports around the circular plate are analyzed by this proposed method. And then, the Monte Carlo method and the normal distribution method are used for random sampling and measuring errors of numerical simulati 相似文献