Layup Configuration Effect on Notch Residual Strength in Composite Laminates

Area of Science:

• Materials Science and Engineering
• Mechanical Engineering
• Composite Materials

Background:

• Increasing demand for composites due to high stiffness-to-weight ratio and advancements in manufacturing.
• Challenges in joining thermoset composites with metals (steel, aluminum) using traditional circular holes.
• High stress concentration induced by circular holes in composite materials.

Purpose of the Study:

• To investigate the impact of laminate layup configuration on notch stress distribution in composites.
• To analyze how different layup designs affect stress concentration around holes used for joining.

Main Methods:

• Machining of circular holes using a 5 kW continuous wave (cw) CO2 laser for high-quality, uniform results.
• Evaluation and comparison of stress distribution using finite element analysis (FEA) and Lekhnitskii's equations.
• Analysis of notch strength and strain distribution using the digital image correlation (DIC) technique.

Main Results:

• Demonstrated significant influence of layup configuration on notch stress distribution.
• Validated FEA and Lekhnitskii's equations for predicting stress concentration in composite laminates.
• Provided insights into strain distribution patterns around machined holes.

Conclusions:

• Optimized layup configurations can effectively mitigate stress concentration in composite joints.
• This study offers a pathway to enhance the structural performance and reliability of composite-metal joints.
• Findings contribute to cost-effective and high-performance applications of advanced composite materials.