To ensure the safety and reliability of aero engines, the probabilistic damage tolerance assessment is required by airworthiness regulations to address the rare but significant threats posed by undetected manufacturing anomalies in high energy rotating components. Advisory Circular 33.70-2 also provides guidance for the use of probabilistic damage tolerance method for hole features in aero engines. To meet the requirement of the airworthiness requirement, the Southwest Research Institute (SwRI) has developed the probabilistic method to conduct the probabilistic surface damage tolerance assessment.

Generally, the essence of probabilistic surface damage tolerance methodology is to evaluate the risk of fracture induced by low cycle failure problem. Thus, the stress intensity factor is the indispensable parameter for analyzing crack growth process, and various theoretical and numerical methods for determining stress intensity factors have been generated. However, the existing theoretical solutions are mostly for relatively simple load cases. Besides, though the detailed three-dimensional numerical approaches such as finite element methods, can help obtain the stress intensity factors accurately, it can hardly meet the requirements of high efficiency in damage tolerance assessment. In this case, the univariant weight function method is applied to calculate the stress intensity factors of cracks located in regions characterized by complex stress fields at surface features such as holes. The weight function formulation enables the evaluation of stress intensity factors by integrating over the crack surface a product of the applied stress in the uncracked body with the weight function for the cracked structure.

This paper gives an overview of conducting surface damage tolerance analysis based on the universal weight function method. The weight functions of three-dimensional finite plates with different surface profiles, including the rectangular plates and the rectangular plates with a hole feature are calculated by response surface method. The derived weight function shows that, the stress intensity factors are determined by the ratio of crack size to the parameters including length, width, thickness and radius of the hole, and there exists a positive relationship between the ratio and the stress intensity factor. In addition, the stress intensity factor in the rectangular plates is larger than that of the rectangular plates with a hole feature. It means that by using the weight function of the rectangular plate to substitute the plate with hole features, the conservative risk value of hole features can be obtained. The establishment and analysis of weight function database is aimed to improve the probabilistic surface damage tolerance methodology in order to ensure the safety of aero engine disks.


Universal Weight Function Method on the Probabilistic Surface Damage Tolerance Assessment of Aeroengine Rotors

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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