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For metal-intermetallic laminated composites, various types of defects often occur during the preparation process. This paper studied the evolution and formation mechanism of defects,such as pores, tunnel cracks, and delamination cracks in Ti-Al3Ti laminated composites prepared by vacuum hot-pressing method. Moreover, quasi-static and dynamic compression tests were performed to study the effects of pores and delamination cracks on the compression properties of the composites. The resu... 相似文献
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Based on the complex variable method, the analytical solutions of stress functions and stress intensity factors(SIFs) are provided for the plane problem of two collinear edge cracks emanating from an elliptical hole in an infinite plate under shear. The stress distribution along the horizontal axis is given in graphical forms, which conforms to Saint-Venant's principle. The influences of crack length and ellipse shape on the stress intensity factors are evaluated. Comparing the analytical solutions with finite element method(FEM) results shows good coincidence. These numerical examples show that the present solutions are accurate. 相似文献
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By constructing a new numerical conformal mapping and using the Stroh-type for-mulism, an anti-plane problem of four edge cracks emanating from a square hole in piezoelectric solids is investigated. The explicit expressions of the complex potential function, field intensity fac-tors, energy release rates and mechanical strain energy release rate near the crack tip are obtained under the assumptions that the surfaces of the cracks and hole are electrically permeable and elec-trically impermeable. Numerical examples are presented to show the influences of the geometrical parameters of defects and applied mechanical/electrical loads on the energy release rate and mechanical strain energy release rate under two electrical boundary conditions. 相似文献
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《中国航空学报》2020,33(10):2620-2632
The gears in aero-engines perform energy and motion transfer between the High-Pressure Rotor (HPR) and accessories. Firstly, an occurred fault with radial cracks in the driven gear disk was diagnosed as High Cycle Fatigue (HCF) failure through necessary examinations. Analysis of fault tree and test signals indicated that the fracture was relevant to the swing vibration of the driven gear excited by the unbalance excitation on HPR. Secondly, a corresponding mechanism model was established, in which the gear meshing effect was considered, with lateral and swing vibration mode. The Governing Equations (GEs) and the Finite Element Model (FEM) were established and verified. Then, the modal shapes, harmonic response, and transient response were analyzed, indicating that the swing vibration of the driven gear could be significantly excited by the unbalance on HPR, which induced the cracks in the driven gear disk to extend radially. Furthermore, influences of factors on the unbalance response were obtained, in which the unbalance response appeared local minimum points and maximum points. Meanwhile, 1# and 2# bearing stiffness had rather significant influences on the response. Thus it is efficient to modify them to achieve vibration control. 相似文献
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叶片裂纹故障的多普勒在线监测技术仿真研究 总被引:1,自引:1,他引:0
本文研究了文献[1]介绍的叶片裂纹故障声学多普勒在线监测技术的监测原理;提出了一种新的基于裂纹叶片振动响应波形不对称性的监测方法;编制了这两种方法的计算及信号处理程序。仿真计算证明这些程序是可行的,同时表明,本文建立的新的监测方法在监测有效性、可靠性方面具有优势。 相似文献
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用非线性分析方法对航空发动机等高速旋转机械常见振动故障:突发不平衡、转子裂纹、静动部件碰摩进行研究。用三维边界元法, 分析含开闭裂纹的转子刚度随转角变化的关系。用作用力模型来模拟动、静部件的碰摩。采用传递矩阵和有限元结合的方法建立系统运动方程。用Wil-son-θ积分法数值求解非线性方程。经过分析, 得出了一些有助于故障诊断的振动特征。 相似文献