http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Combination algorithm for cracked rotor fault diagnosis based on NOFRFs and HHR
Yang Liu,Yulai Zhao,Jiyuan Han,Qingyu Meng,Hongliang Yao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4
In this paper, a combination algorithm for diagnosing rotor crack fault is presented. Firstly, the nonlinear output frequency response functions (NOFRFs) are used to analyze the severity of crack damage in the rotor system qualitatively. The NOFRFs are obtained by processing the vibration signal through the nonlinear output frequency response functions. Further analysis of the NOFRFs can determine the crack depth qualitatively. Secondly, the position of the crack is then located using the crack position index (CPI) l based on the higher harmonic response (HHR) and the dynamic compliance matrix. The simulation and experimental results show that the G 2 (j2w F ) in NOFRFs is very sensitive to crack depth, and the crack position index (CPI) l can determine the shaft segment effectively where the crack is located. The advantage of this combination algorithm is that it can detect the crack faults by measuring the vibration signal of the cracked rotor at two speeds, which makes the measurement process more simplified and reduces the measurement time for real-time monitoring. At each speed only the vibration response of the two nodes need to be measured, which greatly reduces the number of sensor used in the measurement process and reduces the cost of monitoring. The combination algorithm can diagnose cracked rotor faults effectively and has certain application value in the diagnosis of cracked rotor fault.
Shear bond strength of zirconia to resin: The effects of specimen preparation and loading procedure
Bingzhuo Chen,Lu Yang,Zhicen Lu,Hongliang Meng,Xinyi Wu,Chen Chen,Haifeng Xie 대한치과보철학회 2019 The Journal of Advanced Prosthodontics Vol.11 No.6
PURPOSE. Shear bond strength (SBS) test is the most commonly used method for evaluating resin bond strength of zirconia, but SBS results vary among different studies even when evaluating the same bonding strategy. The purpose of this study was to promote standardization of the SBS test in evaluating zirconia ceramic bonding and to investigate factors that may affect the SBS value of a zirconia/resin cement/composite resin bonding specimen. MATERIALS AND METHODS. The zirconia/resin cement/composite resin bonding specimens were used to simulate loading with a shear force by the three-dimensional finite element (3D FE) modeling, in which stress distribution under uniform/non-uniform load, and different resin cement thickness and different elastic modulus of resin composite were analyzed. In vitro SBS test was also performed to validate the results of 3D FE analysis. RESULTS. The loading flat width was an important affecting factor. 3D FE analysis also showed that differences in resin cement layer thickness and resin composite would lead to the variations of stress accumulation area. The SBS test result showed that the load for preparing a SBS specimen is negatively correlated with the resin cement thickness and positively correlated with SBS values. CONCLUSION. When preparing a SBS specimen for evaluating bond performance, the load flat width, the load applied during cementation, and the different composite resins used affect the SBS results and therefore should be standardized.