Modelling the development of defects during composite reinforcements and prepreg forming

Area of Science:

• Materials Science
• Mechanical Engineering
• Computational Mechanics

Background:

• Manufacturing defects significantly impact composite material performance.
• Accurate process simulations are crucial for predicting and mitigating these defects.
• Existing models often fail to capture complex defect behaviors in composite forming.

Purpose of the Study:

• To analyze and model three key defects in textile composite reinforcement and prepreg forming: wrinkling, transition zones, and large slippages.
• To investigate the influence of material properties, such as textile rigidity and fiber bending stiffness, on defect formation.
• To present advanced modeling techniques capable of simulating defect onset and development.

Main Methods:

• Analysis of wrinkling, considering the influence of textile reinforcement rigidities and the 'locking angle' concept.
• Development and application of a second gradient continuum mechanics approach to model fiber bending stiffness-induced 'transition zones'.
• Simulation of large slippages during preform forming using meso finite-element models for macroscopic forming analysis.

Main Results:

• Wrinkling behavior is influenced by textile reinforcement rigidity, challenging the traditional 'locking angle' concept.
• A second gradient approach successfully models the onset and development of 'transition zones' caused by fiber bending stiffness.
• Meso finite-element models effectively simulate large slippages in preform forming.

Conclusions:

• Advanced modeling techniques, including second gradient mechanics, are necessary to accurately simulate defects in composite forming.
• Understanding and controlling defects like wrinkling and transition zones is vital for optimizing composite manufacturing processes.
• The presented models provide a pathway to achieve defect-free or controlled-defect composite structures.