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Electromechanical Actuator Cooling Fan Reliability Analysis and Safety Improvement
ISSN: 0148-7191, e-ISSN: 2688-3627
Published September 20, 2016 by SAE International in United States
Annotation ability available
The aircraft electromechanical actuator (EMA) cooling fan is a critical component because an EMA failure caused by overheating could lead to a catastrophic failure in aircraft. Fault tree analysis (FTA) is used to access the failure probability of EMA fans with the goal of improving their mean time to failure (MTTF) from ∼O(5×104) to ∼ O(2.5×109) hours without incurring heavy weight penalty and high cost. The dual-winding and dual-bearing approaches are analyzed and a contra rotating dual-fan design is proposed. Fan motors are assumed to be brushless direct current (BLDC) motors. To have a full understanding of fan reliability, all possible failure mechanisms and failure modes are taken into account. After summarizing the possible failure causes and failure modes of BLDC fans by focusing on each failure mechanism, the life expectancy of fan ball bearings based on a major failure mechanism of lubricant deterioration is calculated and compared to that provided in the literature. The advantages and disadvantages of the three fault-tolerant cases are discussed. Finally, measures to quantify a fan's reliability are recommended and the method to estimate MTTF by Weibull distribution is provided.
CitationWu, W., Lin, Y., Chow, L., Gyasi, E. et al., "Electromechanical Actuator Cooling Fan Reliability Analysis and Safety Improvement," SAE Technical Paper 2016-01-1997, 2016, https://doi.org/10.4271/2016-01-1997.
- Bennett J.W. et al Safety-critical design of electromechanical actuation systems in commercial aircraft IET Electric Power Applications 5 1 37 47 2011
- Blanke M. and Thomsen J. S. Electrical steering of vehicles - fault-tolerant analysis and design Microelectronics Reliability 46 1415 1420 2006
- ISO 281 Rolling Bearings-Dynamic Load Ratings and Rating Life 2nd International Organization for Standardization 2007
- NSK Technical report 30 43 NSK Ltd 2009 http://www.nskamericas.com/cps/rde/xbcr/na_en/Technical_Report_NSK_CAT_E728g.pdf
- ISO 10302 Acoustics-Method for the Measurement of Airborne Noise Emitted by Small Air Moving Devices 1st International Organization for Standardization 1996
- Ball bearing life calculation http://www.spb-usa.com/info-life-load-rating.php
- McCluskey F. P. , Kweon Y. D. , Lee H. J. and Kim J. W. et al. Method for Assessing Remaining Life in Electronic Assemblies Microelectronics Reliability 40 2 293 306 2000
- Shek J.K.H. Reducing bearing wear in induction generators for wave and tidal current energy devices IET Conference on Renewable Power Generation, no. 1 1 6 2011
- Papoulis A. and Pillai. S. U. Probability, Random Variables, and Stochastic Processes 4th Boston McGraw-Hill 0-07-366011-6 2002
- Kim S. , Vallarino C. and Claassen A. Review of Fan Life Evaluation Procedures International Journal of Reliability, Quality, and Safety Engineering 1996 10.1142/S0218539396000077