Issue 48

Y.H. Shao et alii, Frattura ed Integrità Strutturale, 48 (2019) 757-767; DOI: 10.3221/IGF-ESIS.48.69 757 Fatigue reliability assessment of small sample excavator working devices based on Bootstrap method Yuhong Shao, Pengmin Lu, Binhua Wang, Qingyi Xiang Key Laboratory of Road Construction Technology and Equipment, Ministry of Education, Chang’an University, Xi’an 710064, China Shaoyh@chd.edu.cn , lpmin@chd.edu.cn , wangbh@chd.edu.cn, 383393093@qq.com A BSTRACT . To evaluate the fatigue reliability of the excavator working device, the fatigue tests of 2 sets of moving arm and bucket rod of medium-sized excavators with self-weight of 26000 kgwere carried out. The virtual augmented sample method (VASM) combined with Bootstrap method was used to analyze the reliability of the excavator working device under extreme small samples, and the interval and point estimations of life parameters were obtained. Based on the lognormal distribution of the excavator working device, the reliability evaluation model of the excavator working device was established, and reliability indexes, such as reliability function, failure distribution function, inefficiency function, reliable life and so on, were obtained. And the results of fatigue safety life under different confidence and reliability were calculated. The evaluation results show that the average failure time of the excavator working device is 6124 hours under the confidence of 75%, which provides an important reference for the design, the safety inspection and maintenance decision of the excavator working device. K EYWORDS . Fatigue reliability; Small sample; Bootstrap; Excavator working device; F test. Citation: Shao Y.H., Lu P.M., Wang B.H., Xiang Q.Y., Fatigue reliability assessment of small sample excavator working devices based on Bootstrap method, Frattura ed Integrità Strutturale, 48 (2019) 757-767. Received: 24.01.2019 Accepted: 21.03.2019 Published: 01.04.2019 Copyright: © 2019 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION he working device of the excavator is the direct actuator of the excavator operation, and the reliability of the working device is one of the key indexes of the excavator's quality. Therefore, it is of great significance to study the reliability of the excavator's working device [1]. Due to the high cost of the excavator working device and the limitation of the test cost and time, the fatigue life test can only be carried out by using 2~3 test pieces rather than the large sample size test data to meet the statistical requirements. As a result, the fatigue reliability evaluation of excavator working device is a problem of very small sample. T