A New Stress-Based Formulation for Modeling Notched Fiber-Reinforced Laminates

Area of Science:

• Materials Science
• Mechanical Engineering
• Composite Materials

Background:

• Traditional models for laminated plates use infinite dimensions, limiting accuracy for real-world structures.
• The Whitney-Nuismer (WN) stress criteria are foundational for predicting residual properties of open-hole structures.

Purpose of the Study:

• To derive a new finite-width stress formulation based on WN criteria for notched carbon-fiber-reinforced plastic (CFRP) laminates.
• To investigate the impact of notch shape and size on the applicability of the new formulae and the tensile properties of CFRP laminates.

Main Methods:

• Experimental analysis using tensile tests on CFRP laminates with various notches.
• Digital Image Correlation (DIC) technique to measure full-field surface strain.
• Development of Continuum Damage Mechanics (CDM)-based finite element models to predict stress concentrations and failure.

Main Results:

• The developed finite-width stress criterion effectively predicts the failure of notched CFRP laminates.
• Experimental results validated the accuracy of the new formulations.
• Notch size significantly affects strength prediction, while fiber direction influences the fracture mode.

Conclusions:

• The new formula offers an effective approach for implementing finite-width stress criteria in evaluating notched fiber-reinforced laminates.
• The study highlights the importance of considering finite width and notch geometry for accurate mechanical property prediction in CFRPs.