Fracture analysis for ceramic ball in backflow valve
Fracture analysis for ceramic ball in backflow valve
复制标题
回流阀陶瓷球断裂分析
DOI：
10.1111/j.1460-2695.2011.01619.x
复制
发表时间：
2012
影响因子：
3.7
通讯作者：
R. Kanbayashi
中科院分区：
文献类型：
--
作者：
Manabu Takahashi;N. Okabe;Y. Abe;K. Fujiki;R. Kanbayashi
陶瓷球被用作设备的部件，例如汽车和工业机器的高压泵。例如，在回流阀中，一个陶瓷球与一个锥形表面接触。陶瓷球的断裂极为罕见。研究这些罕见断裂的原因对于保证回流阀的高可靠性至关重要。本文利用断裂力学的应力强度，讨论了接触区域下等效法向应力σeq和接触边界附近最大主应力σp的断裂机理和强度。陶瓷球的断裂面垂直于载荷方向形成。通过对三次高应力的有限元分析，假设断裂源（缺陷/裂纹）存在于线段上。发现陶瓷球的实际断裂是由接触区下的等效法向应力引起的，而不是由赫兹主应力引起的。阐明了应力强度因子（SIF）与压力、锥角、crn涂层厚度和阀孔内部摩擦系数有关。采用三维椭圆型缺陷和等效法向应力的SIF方法估计了破坏过程中存在的缺陷尺寸。因此，可以通过考虑三维椭圆缺陷和缺陷的威布尔分布来评估陶瓷球的实际断裂，这种情况很少发生。
Ceramic balls have been used as components of devices, such as those found in high-pressure pumps for automobiles and industrial machines. In the backflow valve, for example, a ceramic ball is in contact with a conical surface. Fractures of ceramic balls are extremely rare. It is important to investigate the cause of these rare fractures to guarantee higher reliability in the backflow valve. In this paper, the fracture mechanism and strength are discussed for an equivalent normal stress σeq beneath the contact region and the maximum principal stress σp near the contact boundary using stress intensity from fracture mechanics. The fracture surface of the ceramic ball was formed perpendicular to load direction. We assumed that fracture origins (defect/crack) existed on lines through three high stresses that analysed by finite element method. Actual fracture of a ceramic ball was found to be caused by the equivalent normal stress beneath contact region and not to be caused by the Hertz principal stress. Stress intensity factor (SIF) was clarified to depend on pressure, taper angle, CrN-coating thickness and the friction factor of the inside of the valve hole. A pre-existing defect size involved in failure was estimated by the SIF using three-dimensional elliptic defects and equivalent normal stress. Therefore, the actual fracture of a ceramic ball, which rarely occurs, could be evaluated by considering three-dimensional elliptic defects and the Weibull distribution of defects.