共查询到17条相似文献,搜索用时 156 毫秒
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考虑相邻叶冠之间的接触摩擦作用,将扭形带冠叶片简化为自由端带有集中质量的悬臂梁,冠间接触采用带有迟滞特性的宏观滑移模型模拟,基于Timoshenko梁理论和库仑摩擦定理,提出了一种干摩擦扭形带冠叶片动力学响应的数值求解方法。基于所提方法,分析了叶片安装角和扭角对干摩擦叶片动力学特性的影响,并通过有限元方法验证了求解结果。研究结果表明:随着安装角和扭角的增加,会削弱冠间接触表面的减振效果,但并不会对最优法向接触压力产生影响;并且,相比于有限元方法,所提方法在保证求解精度的情况,具有较高的求解效率。此研究结果能够为旋转扭形叶片冠间阻尼结构的设计和优化提供理论指导。 相似文献
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为了考虑钢板屈曲对双钢板-混凝土组合(DSCC)剪力墙的轴压承载力的影响,该文首先以4个组合墙的轴压试验为基础,采用ABAQUS建立DSCC剪力墙的有限元模型。模型中混凝土采用实体单元,钢板采用壳单元,剪力连接件采用非线性弹簧单元SpringA,并考虑了材料非线性和钢板初始缺陷。在验证有限元模型后,研究了不同参数对钢板屈曲的影响,得到了钢板屈曲应力的计算公式。分析结果表明:当钢板出现局部横向贯通屈曲时,破坏模式为屈曲位置的混凝土压碎;当钢板未发生屈曲时,破坏模式为钢板屈服;墙侧面钢板宽度较小时,侧面钢板不会发生屈曲。最后,基于钢板屈曲分析以及构件极限状态下的应力状态分析,提出了新的DSCC剪力墙的轴压承载力计算方法,引入了钢板屈曲的影响。结构表明:对比规范JGJ/T 380―2015采用的计算公式,该文提出的计算方法具有更高的精度和稳定性,可用于DSCC剪力墙的深入研究以及工程设计。 相似文献
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航空发动机自带冠叶片减振特性研究 总被引:1,自引:0,他引:1
摘 要:将自带冠叶片模化为质量弹簧模型。自带冠叶片减振主要是由于冠间碰撞和摩擦的组合运动来实现的,因此本文将冠间的接触简化为带对称间隙的弹簧阻尼模型,摩擦模型采用Sgn模型,从而建立该系统的动力学方程,进而采用Runge-Kutta数值方法求解系统的动力学方程。本文主要探讨了冠间间隙、刚度比、接触角度、摩擦系数等多种参数对减振效果的影响。结果表明:叶片的振动能量与冠间间隙、刚度比、接触角度、摩擦系数等参数有关,参数选取要考虑工作转速的范围。冠间的碰摩组合运动为硬式分段线性的非线性振动,因此本文同时采用Poincaré映射图和频谱图等方法对系统的非线性特性进行了一定的研究。
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发展了一种描述复杂运动状态下界面约束力的三维干摩擦接触数值模型,该模型通过在接触界面建立多个摩擦接触点对得到多点分布的界面约束力,可以描述界面的粘滞-滑动共存状态和法向接触正压力不均匀分布。在该模型中还考虑了界面动静摩擦系数的不同和界面的各向异性。采用三维干摩擦接触数值模型和高阶谐波平衡法,计算了某真实围带阻尼结构汽轮机叶片在复杂激励下的非线性振动响应。计算出叶片振动响应在一个运动周期出现多个局部极值,呈含多谐波的周期函数。 相似文献
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Amir R. Khoei S. O. R. Biabanaki S. M. Taheri-Mousavi A. R. Vafa S. M. Parvaneh 《International Journal of Material Forming》2012,5(2):163-173
In this paper, the three-dimensional large frictional contact deformation of powder forming process is modeled using a node-to-surface contact algorithm based on the penalty and augmented-Lagrange approaches. The technique is applied by imposing the normal and tangential contact constraints and modifying the contact properties of frictional slip. The Coulomb friction law is employed to simulate the friction between the rigid punch and the work piece. It is shown that the augmented-Lagrange technique significantly improves imposing of the constraints on contact surfaces. In order to predict the non-uniform relative density and stress distributions during the large deformation of powder die-pressing, the nonlinear contact friction algorithm is employed within the framework of large finite element deformation, in which a double-surface cap plasticity model is used for highly nonlinear behavior of powder. Finally, the numerical schemes are examined for accuracy and efficiency in modeling of a set of powder components. 相似文献
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重卡钢板弹簧断裂失效分析 总被引:1,自引:0,他引:1
通过宏观检查、化学成分分析、硬度测试以及金相检验等结果分析。确定了重型卡车用钢板弹簧的断裂原因。结果表明:因超载使钢板弹簧出现过度反弓,造成板簧卡中的螺栓杆与钢板弹簧动态接触.发生磨损腐蚀,形成凹坑.成为应力集中点;在过大的交变应力作用下.应力集中点萌生裂纹并不断扩展.最终造成钢板弹簧疲劳断裂。最后提出了防止其发生断裂失效的预防措施。 相似文献
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建立了一个稳态滚动轮胎的有限元分析模型,考虑了轮胎变形的几何非线性、轮胎与地面和轮胎与轮辋的大变形非线性接触、轮胎材料的非均匀性、橡胶材料的不可压缩性和物理非线性、橡胶基复合材料的各向异性及轮胎与地面接触滑动摩擦。结果表明,该模型是较为合理的。 相似文献
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合理的颗粒接触摩擦模型是从微观角度研究各类结构面强度的基础,然而受制于岩土体颗粒在微观高应力环境中表现出的复杂接触特征,该问题一直未能很好解决。Fujimoto 在2000 年给出了受切向荷载作用的微凸体在理想弹性或完全塑性接触状态下的微观位移特性,但却缺少对塑性强化接触状态下的摩擦进行解析,难被用于分析微观高应力状态下岩土颗粒的接触摩擦。为此,以Fujimoto模型为基础,结合作者曾经提出的塑性强化接触变形理论,在构建塑性强化接触状态下颗粒微观位移模型的基础上,系统的研究了切向荷载作用下塑性强化材料颗粒的接触摩擦机理,阐明了不同接触状态下塑性强化材料颗粒的切向微观位移特征。最后通过算例分析显示了模型的合理性。结果表明:颗粒摩擦本质上是不同法向荷载不同接触状态区域按照不同摩擦类型提供摩擦的综合,而摩擦失稳就是接触面上微滑区扩大、粘着区缩小并消失的过程。 相似文献
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《Materials Science & Technology》2013,29(7):864-873
AbstractThe paper investigates the effects of friction on the heterogeneity of deformation during rolling through studies using plane strain (2D) and three-dimensional (3D) finite element models designed to simulate the deformation of the embedded pin inserts during rolling. Redundant work due to friction is defined as a path function along the arc of contact. Since deformation during rolling is profoundly influenced by the amount of redundant work, which depends on friction as a path function along the arc of contact, the study has focused especially on methods of representing these frictional effects. The friction studied has been in one of two classes: the coefficient of friction being constant or varying parabolically along the arc of contact. The results show that the values of shear stress and normal pressure along the arc of contact depend upon the friction profile. The magnitude of these frictional effects is revealed by the through thickness variation of the relative pin insert displacement. This displacement changes in the 3D model because transverse spread reduces the amount of displacement along the axial direction. Comparison of the simulations with experimental pin insert shapes shows close agreement between the predicted and experimental results, while revealing the direction of further work needed to provide suitable mechanics models to interpret experimental pin insert data. 相似文献
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M. Hamedi 《国际生产研究杂志》2013,51(13):2775-2788
In the past two decades, simulating workpiece–fixture interactions has remarkably drawn the attention of academia. However, many aspects of the workpiece–fixture system, specifically workpiece–fixture contact condition, still enjoy research effort. For the efficient use of Automated Fixture Design (AFD) systems, verification of their outputs is required. This paper presents a workholding simulation approach that considers assessment of AFD system outputs regarding different workholding parameters. The effect of friction forces on workholding and part rigid body stability is considered. Besides, determining deformation and stress in the workpiece, locators and clamps are modelled and their elastic deformation and stress distribution are computed. A procedure based on the application of contact elements in finite-element method is developed to quantify the status of contact between the workholding elements and the workpiece. Clamping tightness is modelled and its effect on the workpiece–fixture system performance is quantified. The central component of the verification tool is the use of nonlinear finite-element analysis to model the frictional interactions in workpiece–fixture system. 相似文献