Experimental Characterization and Numerical Simulation of Voids in CFRP Components Processed by HP-RTM

Area of Science:

• Materials Science
• Manufacturing Engineering
• Composite Materials

Background:

• Continuous carbon fiber-reinforced composites face manufacturing cycle time limitations for mass vehicle production.
• High-pressure resin transfer molding (HP-RTM) offers a faster (<5 min) manufacturing cycle using fast-reactive resins.

Purpose of the Study:

• Investigate the impact of HP-RTM process variables on void characteristics and flexural properties of CFRP components.
• Analyze the influence of fiber volume fraction and resin injection flow rate on defect formation and mechanical performance.

Main Methods:

• Utilized ultrasonic scanning and optical microscopy for defect analysis, focusing on void characteristics.
• Conducted quasi-static bending experiments on CFRP specimens with varying void contents.
• Employed numerical simulations alongside experimental validation.

Main Results:

• A strong correlation exists between void content and flexural strength; an increase of ~0.5% void content led to an ~8% decrease in flexural strength.
• Void sizes were predominantly smaller than 50 μm.
• Increased resin injection flow rate significantly increased void number, with a greater impact than fiber volume fraction.

Conclusions:

• Resin injection flow rate is a critical parameter influencing void content and mechanical properties in HP-RTM manufactured CFRP.
• Careful optimization of resin injection flow rate, potentially via simulations or preliminary experiments, is crucial for producing complex CFRP components with enhanced mechanical performance.