N25B-T032 TITLE: Advanced Fretting Fatigue Life Prediction Method for Naval Aerospace Applications

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Computing and Software; Advanced Materials; Sustainment

OBJECTIVE: Develop innovative tools for advancing the science, physics-based modeling & simulation (M&S), and mitigation techniques for fretting fatigue damage to improve durability, reliability, and performance in naval aero-structural applications.

DESCRIPTION: Fretting fatigue occurs across various naval aero-structural applications such as bolted and screw joints, engine mounts, and rotor hub assemblies. The intricate interplay between frictional wear and cyclic stress often leads to premature material failure and reduced fretting fatigue life of critical components. As aircraft and aerospace systems are exposed to maneuvers, vibrations, thermal variations, and fluctuating loads, the potential for fretting fatigue damage increases, particularly in high-performance aircraft, which operate under more extreme conditions.

While existing mitigation strategies primarily focus on surface treatments, coatings, and material modifications, there exists a significant gap in the understanding of fretting fatigue mechanisms and reliable life-estimation techniques. Moreover, the lack of a universal approach for fretting fatigue estimation or prediction exacerbates the complexity of the problem, necessitating innovative solutions tailored to the specific requirements in naval aero-structural applications.

Current approaches to fretting fatigue management predominantly revolve around empirical methods and standardized tests to assess the performance. These methods often involve cyclic loading tests combined with surface inspections to detect early signs of wear and crack initiation. However, these empirical methods are limited in their ability to fully capture the complex interactions at play in different fretting fatigue scenarios.

Advanced materials and surface treatments, such as shot peening, laser shock peening, and various coating technologies, have shown promise in extending the life of components by enhancing surface hardness and reducing stress concentrations. Despite these advancements, challenges persist in accurately predicting fretting fatigue, particularly in complex aerospace systems subjected to diverse operational environments and loading conditions.

Existing models often oversimplify the phenomena or fail to account for variable factors such as temperature fluctuations, varying coefficient of friction or cyclic frequency, and in-service operational stresses. Lack of comprehensive modeling frameworks also limit the ability to develop effective mitigation strategies that address the root causes of fretting fatigue. There is a need for integrated approaches that combine advanced modeling, real-time monitoring, and innovative materials science to provide more accurate and reliable solutions to fretting fatigue.

The Navy seeks innovative solutions to address key challenges in understanding the science, modeling and mitigation of fretting fatigue damage, aiming to advance the state of the art in each of these areas. This includes developing advanced M&S techniques to elucidate fretting fatigue mechanisms, devising accurate prediction models for estimating component life in the presence of multiaxial stresses, and exploring novel mitigation strategies that go beyond traditional approaches. There is currently no universal approach for fretting fatigue estimation/prediction or testing, underlining the need for innovative solutions tailored to specific naval aero-structural applications.

The Navy needs to explore innovative methods for detecting and monitoring fretting cracks to enable proactive maintenance and repair to prevent failure. Understanding the effect of varying coefficient of friction due to factors such as temperature fluctuations, humidity, and surface treatments is essential for developing accurate predictive models and effective mitigation strategies tailored to specific operational conditions. Furthermore, exploring novel coating technologies that enhance durability and performance under fretting conditions are important considerations for fretting fatigue mitigation.

PHASE I: Design, develop, and demonstrate feasibility of the innovative approach(es) in advancing understanding of the science, mitigation, and modeling of fretting fatigue for naval aero-structural applications. The emphasis will be on conceptualizing advanced models for material behavior under fretting conditions. Participants will investigate developing predictive models and the design of innovative mitigation techniques. The Phase I effort will include prototype plans to be developed under Phase II.

PHASE II: Refine the design(s) and model(s) based on Phase I results and optimize for performance, reliability, and scalability. Comprehensive testing and evaluation will be conducted to demonstrate the effectiveness of the durability and performance of the prototype. This should ensure that the solutions are robust and effective in different application scenarios. The final prototype will be showcased, providing detailed performance data and demonstrating its potential for widespread adoption in aero-structural applications.

PHASE III DUAL USE APPLICATIONS: Transition validated full fretting fatigue modeling tool to acquisition program and integrate with existing engineering analysis tools.

Complex fretting damage resulting in fractures is a risk for commercial producers in aerospace, automotive, trucking, heavy equipment companies, medical reconstruction, and any other private sector that utilizes assemblies of parts subjected to motion. The benefits to the private sector would be lower failure rates/warranty costs and mitigated damages.

REFERENCES:

1. D. Croccolo, M. De Agostinis, S. Fini, G. Olmi, F. Robusto, C. Scapecchi, "Fretting Fatigue in Mechanical Joints: A Literature Review", Lubricants 10.4 (2022): 53. https://doi.org/10.3390/lubricants10040053
2. Lykins, Christopher D., Shankar Mall, and Vinod Jain. "An evaluation of parameters for predicting fretting fatigue crack initiation." International journal of fatigue 22, no. 8 (2000): 703-716. https://doi.org/10.1016/S0142-1123(00)00036-0
3. Namjoshi, Shantanu A., S. Mall, V. K. Jain, and O. Jin. "Fretting fatigue crack initiation mechanism in Ti–6Al–4V." Fatigue & Fracture of Engineering Materials & Structures 25, no. 10 (2002): 955-964. https://doi.org/10.1046/j.1460-2695.2002.00549.x
4. Khan, Thawhid, Andrey Voevodin, Aleksey Yerokhin, and Allan Matthews. "Materials aspects in fretting." In Fretting Wear and Fretting Fatigue, pp. 173-199. Elsevier, 2023. https://doi.org/10.1016/B978-0-12-824096-0.00009-3
5. David, W. Hoeppner. "Fretting fatigue considerations in holistic structural integrity based design processes (HOLSIP)—A continuing evolution." Tribology international 44, no. 11 (2011): 1364-1370. https://doi.org/10.1016/j.triboint.2011.01.001
6. Hattori, Toshio. "The Mechanisms and Mechanics Analyses of Fretting Wear and Fretting Fatigue." In Fretting Wear, Fretting Fatigue and Damping of Structures: Design Engineering Hand Book Learned from Failure Cases, pp. 71-175. Cham: Springer Nature Switzerland, 2023. https://link.springer.com/chapter/10.1007/978-3-031-46498-0_3
7. Abbasi, F., and G. H. Majzoobi. "Effect of out-of-phase loading on fretting fatigue response of Al7075-T6 under cyclic normal loading using a new testing apparatus." Engineering Fracture Mechanics 188 (2018): 93-111. https://doi.org/10.1016/j.engfracmech.2017.08.010
8. Croccolo, D., M. De Agostinis, S. Fini, G. Olmi, L. Paiardini, F. Robusto, and C. Scapecchi. "Fretting fatigue of interference fitted joints: development of a novel specimen for four-point rotating-bending tests and experimental results." Engineering Failure Analysis 144 (2023): 106994. https://doi.org/10.1016/j.engfailanal.2022.106994
9. Neu, R. W. "Progress in standardization of fretting fatigue terminology and testing." Tribology International 44, no. 11 (2011): 1371-1377. https://doi.org/10.1016/j.triboint.2010.12.001

KEYWORDS: Fretting fatigue; Coatings; Crack initiations; Debris; Tribology; Friction

TPOC 1: Alan Timmons
(301) 342-6925
[email protected]

TPOC 2: Nam Phan
(301) 342-9359
[email protected]

TPOC 3: John Hamel
(240) 427-7924
[email protected]

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