Session: 13-12-01: Modeling of the Fracture, Failure, and Fatigue in Solids I

Paper Number: 166552

Fatigue Crack Growth Analysis: Evaluating a High-Fidelity Simulation Model Against Experimental Observations 

Analyzing fatigue crack growth presents several challenges. The process is highly complex and influenced by various factors, including material properties, crack geometry, environmental conditions, and cyclic loading patterns. Currently, most engineers still rely on extensive physical tests under controlled conditions to understand the problem and validate their product design, which can be time-consuming and costly. To address these challenges, simulations are increasingly being adopted as a more cost-effective and efficient approach to complement physical tests in studying fatigue crack growth. Additionally, with the recent advancements in machine learning and artificial intelligence technologies, simulation has become essential for providing high-quality training data to AI/ML models, which is often challenging to obtain solely from testing. The AI/ML model could then be used for the creation of virtual representation of the real structure, and thus enhance predictive accuracy and enable real-time monitoring of the structural integrity, reducing the risk of sudden failures and extending the lifespan of critical assets such as aircraft, bridges, and offshore platforms

Regarding simulation-based fatigue crack growth analysis, there are also several challenges: 1. Capturing the complex crack shape in three-dimensional and properly re-meshing the extended crack. 2. Accounting for the fatigue loading pattern that might not be of constant amplitude. 3. The manual nature of the simulation process for each crack increment, and its computational intensity.

In this study, we conducted a direct comparison of subsequent fatigue crack growth from an existing crack between a three-dimensional finite element (FE) model and open-sourced experimental measurement provided by the ERSI working group for two T7050-T7451 specimens. The developed FE model leverages Ansys SMART crack growth framework, which autonomously manages crack extensions and remeshing without imposing any degree of freedom constraints on the crack front. This capability facilitates the modeling of more complex crack shapes, which is a significant challenge in simulation-based fatigue crack analysis. To improve computational efficiency, the mesh coarsening away from newly created crack tip for each simulation step was also adopted. The FE model also incorporated a representative tabular fatigue crack growth law and loading patterns consisting of various sub-load cycles with differing magnitudes and R-ratios observed during the experiments. Additionally, the current paper investigates and discusses the potential effects of plasticity-induced crack closure when the crack grows closer to the specimen's free surface. The simulated crack propagation shows good agreement with experimental measurements in terms of crack size and pattern at various loading cycles, showcasing a promising, high-fidelity simulation-based approach to analyze fatigue crack growth.

Presenting Author: Linqi Zhuang Synopsys

Presenting Author Biography: Linqi Zhuang is currently a lead application engineer in Ansys, part of Synopsys. He is leading the application solution developments for composites and durability analysis inside Ansys. Prior to joining Ansys, he worked as wind turbine blade structural designer in major wind turbine OMEs. Linqi Zhuang received a Ph.D. degree in Polymeric Composites from Luleå University of Technology, Sweden, and another Ph.D. degree in Aerospace Engineering from Texas A&M University, US.

Authors:

Linqi Zhuang Synopsys
Ali Najafi Synopsys
Kaan Ozenc Synopsys
James Zuo Synopsys
Guoyu Lin Synopsys