Multiaxial Fatigue Damage Parameter and Life Prediction without Any Additional Material Constants

Area of Science:

• Materials Science
• Mechanical Engineering
• Fatigue Analysis

Background:

• Predicting fatigue life in critical aerospace alloys like TC4 and GH4169 under complex loading is challenging.
• Existing multiaxial fatigue models often require numerous material-specific constants and may lack accuracy across different loading regimes.

Purpose of the Study:

• To propose a simple, efficient, and accurate multiaxial fatigue damage parameter for titanium alloy TC4 and nickel-based superalloy GH4169.
• To evaluate the proposed parameter against modified Ince-Glinka and Fatemi-Socie models under various proportional and non-proportional loading conditions.
• To demonstrate the superiority of the new parameter through model comparison and prediction error analysis.

Main Methods:

• Utilizing the critical plane approach to develop a novel multiaxial fatigue damage parameter.
• Evaluating generalized strain amplitude and strain energy models, alongside the Fatemi-Socie model with a variable parameter k.
• Conducting comparative analysis and prediction error assessments for different loading scenarios.

Main Results:

• The proposed damage parameter demonstrates superior accuracy in multiaxial fatigue life prediction for TC4 and GH4169 alloys compared to existing models.
• Generalized strain amplitude models are more suited for low cycle fatigue, while generalized strain energy models are better for high cycle fatigue.
• The Fatemi-Socie model's parameter k is not constant, necessitating careful consideration for its application.

Conclusions:

• The developed multiaxial fatigue damage parameter offers a robust and efficient solution for life prediction in aviation alloys.
• The new parameter eliminates the need for additional material constants, simplifying its practical application.
• This research provides a superior tool for ensuring the structural integrity of components subjected to complex fatigue loading.