Experimental Study on Compression Failure of Composite Laminates with Prefabricated Surface Cracks

Area of Science:

• Materials Science
• Mechanical Engineering
• Composite Materials

Background:

• Composite laminates are crucial in aerospace and automotive industries.
• Understanding damage tolerance in composites with surface cracks is vital for structural integrity.
• Existing testing methods may not fully capture complex crack propagation under compression.

Purpose of the Study:

• To design and validate a new compression test fixture for studying damage tolerance of composite laminates with surface cracks.
• To experimentally investigate the compression failure behaviors of CCF300/5228A quasi-isotropic composite laminates with prefabricated surface cracks.
• To elucidate the influence of crack geometry on failure modes and mechanisms.

Main Methods:

• Design and implementation of a specialized compression test fixture.
• Preparation of CCF300/5228A quasi-isotropic composite laminates with precisely controlled surface cracks.
• Experimental testing to capture crack growth and failure modes under compressive loading.
• Analysis of failure modes in relation to crack angles and depths.

Main Results:

• The designed test fixture successfully captured complex crack growth processes.
• Compression failure modes were significantly influenced by crack angles and depths.
• Two primary failure modes were identified: local intra- and inter-laminar damage from crack tips, and delamination from the crack leading edge.
• The study validated the effectiveness of the test fixture and methodology.

Conclusions:

• The developed test fixture and method are valid for studying compression failure in cracked composite laminates.
• Crack geometry (angle and depth) dictates the dominant failure mechanisms.
• This research provides critical insights into the compression failure mechanisms of composite laminates with surface defects, aiding in the design of more damage-tolerant materials.