Int J Performability Eng ›› 2019, Vol. 15 ›› Issue (1): 127-137.

### Fatigue Life Prediction for Throwing Impeller of an Impeller Blower

Zhiping Zhaia, Can Lia, Hongmei Cuib*(), Hongyu Lianga, and Haiying Chenga

1. a College of Mechanical Engineering,Inner Mongolia University of Technology, Hohhot,010051,China
b College of Mechanical and Electrical Engineering,Inner Mongolia Agricultural University, Hohhot, 010018, China
•  Revised on  ; Accepted on
• Contact: Cui Hongmei E-mail:chm123m@126.com

Abstract:

Impeller blowers are used to convey materials for various forage harvesters. As the main working component, the throwing impeller endures various static and dynamic loads while conveying the materials. This makes the throwing impeller prone to fatigue fracture,so it is very necessary to find a feasible model to estimate the fatigue life of the throwing impeller accurately. In order to obtain the accurate random cyclic load applied on the high-speed rotating impeller, the finite element analysis and the fluid-solid coupling method are adopted to calculate the stress distribution of the impeller under the combined action of the fluid-solid coupling flow field pressure, the centrifugal force, and the gravity. At the same time, the stress on the dangerous section of the impeller is measured by using the DH5909 wireless strain testing system and is compared with the calculated one. The contrast results show that the numerical calculation results are reliable. To accurately predict the fatigue life of the throwing impeller at the design stage, the two-parameter nominal stress model is deduced and combined with the linear cumulative damage model of Miner and the lognormal distribution model. Its two parameters of the average stress Sm and the stress amplitude Sa can be obtained through finite element analysis and do not have to be equivalent to a symmetrical cyclic load. Therefore, its precision of estimating the fatigue life is improved. By contrasting the rated and predicted fatigue lives of an impeller, it was found that the impeller’s actual rated lives are closer to the predicted lives of the Goodman and Gerber two-parameter nominal stress model than those of the conventional S-N curve. In particular,they are closer to the calculation results of the Gerber-type two-parameter nominal stress model. This shows that the Gerber-type two-parameter nominal stress model is more accurate and suitable to predict the fatigue life of the throwing impeller. These achievements will play a significant role in further optimizing the impeller and improving its reliability.