# Influence of Interface Inclination Angle and Connection Method on the Failure Mechanisms of CFRP Joints

## TL;DR

This study explores how the design of carbon fiber joints affects their strength and failure under bending, offering insights for aerospace and wind power applications.

## Contribution

The study introduces a novel analysis of bonding interface inclination and hybrid connection methods to optimize CFRP joint performance.

## Key findings

- Bonded connections showed increased bending load with interface slope, improving by 21.87% and 39.75%.
- Hybrid bonding–bolting connections achieved the highest peak load, improving by 38.38% and 43.91%.
- Stress concentration from sharp geometric discontinuities was identified as a key failure mechanism.

## Abstract

Carbon fiber reinforced polymers (CFRPs) are widely used in aerospace and wind power applications, but the complex failure mechanisms of their connection structures pose challenges for connection design. This study aims to investigate the influence of bonding interface inclination angle and connection method on the failure mechanisms of CFRP joints under bending loads. The study investigated two design parameters: the joint geometry of the bonding interface (single-slope, transition-slope, and single-step) and the connection methods (bonding, bolting, and hybrid bonding–bolting). Finite element simulations analyzed the mechanical performance and failure modes under different design parameters. Bending tests validated the mechanical properties of the joint interface, validating the effectiveness of the numerical simulation. The study found that under bonded connections, the bending load increased with the slope of the connection interface, with improvements of 21.87% and 39.75%, respectively. The main reason is stress concentration caused by sharp geometric discontinuities. The hybrid connection had the highest peak load, with improvements of 38.38% and 43.91% compared to the other connection methods. Hybrid bonding–bolting connections further optimized structural performance and damage tolerance. This study reveals the damage mechanisms of the bonding interface and provides a reliable prediction method for aerospace and wind turbine blade applications.