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????? ????? 《力学与实践》1997,19(4):35-36
本文根据应变模态分析原理,针对微型汽车驱动桥桥壳,通过应变模态试验,建立了结构的动态应变场模型并分析其动态应变响应特性. 相似文献
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应变疲劳强度概率分布 总被引:1,自引:0,他引:1
利用概率论方法建立了应变疲劳强度概率分布与应变疲劳寿命概率分布之间的数学关系式,并根据应变-寿命转换关系,由已知的给定应变水平下的疲劳寿命概率分布求出给定寿命下的应变疲劳强度分布函数,便于进行可靠性分析。 相似文献
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针对高应力岩体爆破开挖卸载问题,自制了一台轴向加、卸载实验测试平台,通过实验测试获得了爆破卸荷过程中岩杆的动态应变及应变率数据。实测数据表明:开挖面附近岩体的爆破加、卸载以及初始应力卸载应变率均在10?1 s?1量级以上,验证了高地应力区岩体爆破开挖卸荷是一动态过程。建立了初始应力卸载一维力学模型,揭示了卸载波的传播机制;通过分析爆破卸荷过程应变能密度的时空分布特征,建立了应变能密度与各阶段应变率变化规律的联系。结合实测数据,采用隐式-显式顺序求解方法,进一步分析了高应力区岩体爆破卸荷荷载各阶段应变率沿岩杆的变化规律。结果表明:爆破加载阶段的平均应变率沿杆件逐渐衰减,且衰减速度逐渐减小;爆破卸阶段平均应变率沿杆件也呈衰减趋势;而初始应力的应变能稳定释放,其平均应变率无衰减趋势。 相似文献
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本文阐述了应变模态分析的基本原理及相应的参数识别方法,讨论了应变传递函数与应变模态振型、应变传递函数的性质,模态参数的识别以及应变传递函数与激振力谱、应变响应谱之间的关系。 相似文献
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实心圆轴扭转测定本构关系的概念和方法 总被引:6,自引:0,他引:6
本文提出了实心圆轴扭转试验建立有限应变本构关系(τ—γ曲线)的概念,并在文[1]工作的基础上完成了通过实心圆轴扭转试验建立文献[6]形式的有限应变本构关系的方法,它比单向拉伸试验所得到的本构关系更为精确,因拉伸实验变形较大时试件伸长和变细对测量结果有影响,尤其在“颈缩”后,很难对有关力学量作有效测量和分析,扭转本构关系的描绘也更为完整,以低碳钢为例,扭转本构关系所描述的有效范围比拉伸本构关系大十余倍,本文方法将有利于探讨研究更大应变下的材料力学行为。 相似文献
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本文利用假设剪切应和薄膜应变场的新型退化壳单元,并考虑大应主影响对壳体结构弹塑性动态分析进行了研究,并编制了相应的程度,此程序采用修正的Lagrangian公式,它不仅考虑了大变形大应变的影响,还对单元的节点坐标和厚度在每个时间步后都给予修正,通过对一些算例计算表明,此程序数值精度很好,可用于壳体结构的工程分析,并得出结论,对于应变问题考虑和忽略大应变影响将有较大的不同。 相似文献
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相对于有限元法,边界单元法在求解断裂问题上有着独特的优势,现有的边界单元法中主要有子区域法和双边界积分方程法.采用一种改进的双边界积分方程法求解二维、三维断裂问题的应力强度因子,对非裂纹边界采用传统的位移边界积分方程,只需对裂纹面中的一面采用面力边界积分方程,并以裂纹间断位移为未知量直接用于计算应力强度因子.采用一种高阶奇异积分的直接法计算面力边界积分方程中的超强奇异积分;对于裂纹尖端单元,提供了三种不同形式的间断位移插值函数,采用两点公式计算应力强度因子.给出了多个具体的算例,与现存的精确解或参考解对比,可得到高精度的计算结果. 相似文献
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2008年5月12日,汶川M80地震在四川省绵竹市清平乡文家沟内诱发一巨型滑坡。通过现场调查得知,滑坡前后缘高差455m,厚度20~30m,滑面为基岩层面,初始方量2750×107m3。滑体在运动中转化为碎屑流。滑坡-碎屑流总的水平运动距离为4022m,垂直运动距离为1443m,遗留的堆积物体积达5×107m3。滑坡距映秀—北川断裂仅36km,位于其下盘,地震烈度达XI度。滑坡导致文家沟中48人遇害,并形成一条完整的地震次生地质灾害链。初步分析表明滑坡启动速度快,滑坡向碎屑流转化过程明显、地点明确。碎屑流运动过程复杂,伴有强烈的“气垫效应”和“前缘气浪冲击效应”。作者认为,文家沟滑坡的高启动速度是长持时强烈地震动作用的结果,与山体的猛烈碰撞是导致滑体解体并转化为碎屑流的原因。 相似文献
2008年5月12日,汶川M80地震在四川省绵竹市清平乡文家沟内诱发一巨型滑坡。通过现场调查得知,滑坡前后缘高差455m,厚度20~30m,滑面为基岩层面,初始方量2750×107m3。滑体在运动中转化为碎屑流。滑坡-碎屑流总的水平运动距离为4022m,垂直运动距离为1443m,遗留的堆积物体积达5×107m3。滑坡距映秀—北川断裂仅36km,位于其下盘,地震烈度达XI度。滑坡导致文家沟中48人遇害,并形成一条完整的地震次生地质灾害链。初步分析表明滑坡启动速度快,滑坡向碎屑流转化过程明显、地点明确。碎屑流运动过程复杂,伴有强烈的“气垫效应”和“前缘气浪冲击效应”。作者认为,文家沟滑坡的高启动速度是长持时强烈地震动作用的结果,与山体的猛烈碰撞是导致滑体解体并转化为碎屑流的原因。 相似文献
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Junfeng Li 《Acta Mechanica Sinica》2014,30(3):281-281
One of the core issues in modern celestial mechanics is the orbital dynamics in the near-regime gravitational field of as- teroids, which provides deep insights into the mathematical nature of a class of nonlinear systems, and plays as a critical basis for in situ explorations of different science goals. Lots of efforts have been made to reveal the characteristics of orbital motion in the vicinity of asteroids, and to improve the skills of asteroid research in methodology. 相似文献
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Maxime Sauzay 《Comptes Rendus Mecanique》2006,334(6):353-361
Experimental studies of the plasticity mechanisms of polycrystals are usually based on the Schmid factor distribution supposing crystalline elasticity isotropy. A numerical evaluation of the effect of crystalline elasticity anisotropy on the apparent Schmid factor distribution at the free surface of polycrystals is presented. Cubic elasticity is considered. Order II stresses (averaged on all grains with the same crystallographic orientation) as well as variations between averages computed on grains with the same crystallographic orientation but with different neighbour grains are computed. The Finite Element Method is used. Commonly studied metals presenting an increasing anisotropy degree are considered (aluminium, nickel, austenite, copper). Concerning order II stresses in strongly anisotropic metals, the apparent Schmid factor distribution is drifted towards small Schmid factor values (the maximum Schmid factor is equal to 0.43 instead of 0.5) and the slip activation order between characteristic orientations of the crystallographic standard triangle is modified. The computed square deviations of the stresses averaged on grains with the same crystallographic orientation but with different neighbour grains are a bit higher than the second order ones (inter-orientation scatter). Our numerical evaluations agree quantitatively with several observations and measures of the literature concerning stress and strain distribution in copper and austenite polycrystals submitted to low amplitude loadings. Hopefully, the given apparent Schmid factor distributions could help to better understand the observations of the plasticity mechanisms taking place at the free surface of polycrystals. To cite this article: M. Sauzay, C. R. Mecanique 334 (2006). 相似文献
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Tuan Hung Le Luc Dormieux Laurent Jeannin Nicolas Burlion Jean-Franois Barthlmy 《Comptes Rendus Mecanique》2008,336(8):670-676
This paper is devoted to a micromechanics-based simulation of the response of concrete to hydrostatic and oedometric compressions. Concrete is described as a composite made up of a cement matrix in which rigid inclusions are embedded. The focus is put on the role of the interface between matrix and inclusion which represent the interfacial transition zone (ITZ). A plastic behavior is considered for both the matrix and the interfaces. The effective response of the composite is derived from the modified secant method adapted to the situation of imperfect interfaces. To cite this article: T.H. Le et al., C. R. Mecanique 336 (2008). 相似文献
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A. N. Rozhkov 《Fluid Dynamics》2005,40(6):835-853
The phenomena of hydrodynamic breakup of liquid jets, drops, films, bridges, and filaments are reviewed for liquids with viscoelastic properties. The reasons for breakup are capillary instabilities, collisions with rigid obstacles, and other forms of dynamic action. The relationship between the properties of the liquids and the features of the breakup process is discussed. 相似文献
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Flow stability analysis and excitation using pulsating jets 总被引:1,自引:0,他引:1
Classical flow stability applied to transition from laminar to turbulent flow may also describe the behavior of vorticity fluctuations created by a pulsating jet placed along a solid boundary. A numerical laminar flow experiment involving a pulsating jet placed along the surface of a duct with flow separation downstream, resulted in eliminating most part of the separated flow region. Applying the same approach to a turbulent flow, it was possible to develop a turbulent stability flow formulation and apply successfully turbulent pulsating jet flow separation control. To cite this article: D. Skamnakis, K. Papailiou, C. R. Mecanique 333 (2005). 相似文献