# Numerical Simulation of Fatigue Damage in Cross-Ply CFRP Laminates: Exploring Frequency Dependence and Internal Heat Generation Effects

## TL;DR

This study uses simulations to show how different loading frequencies affect fatigue damage and heat generation in carbon fiber composites.

## Contribution

The study introduces an enhanced degradable Hashin failure model to simulate frequency-dependent fatigue damage and internal heat effects in CFRPs.

## Key findings

- Transverse crack formation occurs faster at 10 Hz compared to lower frequencies.
- High-frequency loading increases internal heat, accelerating damage progression.
- Damage accumulation rate initially increases with frequency but then decreases.

## Abstract

A numerical simulation investigating the frequency dependence of fatigue damage progression in carbon fiber-reinforced plastics (CFRPs) is conducted in this study. The initiation and propagation of transverse cracks under varying fatigue test frequencies are successfully simulated, consistent with experiments, using an enhanced degradable Hashin failure model that was originally developed by the authors in 2022. The results obtained from the numerical simulation in the present study, which employs adjusted numerical values for the purpose of damage acceleration, indicate that the number of cycles required for the formation of three transverse cracks was 174 cycles at 0.1 Hz, 209 cycles at 1 Hz, and 165 cycles at 10 Hz. Based on these results, it is demonstrated that under high-frequency cyclic loading, internal heat generation caused by dissipated energy from mechanical deformation, attributed to the viscoelastic and/or plastic behavior of the material, exceeds thermal dissipation to the environment, leading to an increase in specimen temperature. Consequently, damage progression accelerates under high-frequency fatigue. In contrast, under low-frequency fatigue, viscoelastic dissipation becomes more pronounced, reducing the number of cycles required to reach a similar damage state. The rate of damage accumulation initially increases with test frequency but subsequently decreases. This observation underscores the importance of incorporating these findings into discussions on the fatigue damage of real structural components.