In the relentless pursuit of stronger, lighter materials, the composite industry is constantly pushing boundaries. Researchers have recently shed light on a critical issue plaguing composite laminates: transverse cracking. This phenomenon, where cracks form perpendicular to the fibre direction, can significantly weaken structures, posing challenges for industries reliant on composite materials, including the energy sector.
Nicolas Carrère, a researcher at ENSTA Bretagne, CNRS, IRDL, UMR 6027 in France, has been at the forefront of this investigation. His latest study, published in ‘Comptes Rendus. Mécanique’ (English translation: Mechanics Proceedings of the French Academy of Sciences), delves into the intricate mechanisms of transverse cracking in composite laminates.
Carrère and his team focused on laminates containing θ-plies adjacent to 90° plies, a common configuration in composite structures. Their findings revealed that the sequence of damage mechanisms—such as transverse cracking in 90° plies, cracking in θ-plies, or debonding between adjacent misoriented plies—is heavily influenced by the stacking sequence.
One of the most compelling discoveries was the role of the mismatch angle between adjacent plies. “We found that for a sufficiently large orientation mismatch, θ-ply cracking occurs at a much higher strain level than the first transverse cracking in the 90° ply,” Carrère explains. This insight could be pivotal for designing more resilient composite structures.
The study also highlighted the potential for debonding between adjacent plies, a phenomenon that becomes more likely with larger mismatch angles. This debonding can lead to catastrophic failure if not properly mitigated. Carrère noted, “Debonding between adjacent plies may occur as it becomes more favorable than adjacent ply crack re-initiation for sufficiently large adjacent ply mismatch angle.”
The implications of this research are vast, particularly for the energy sector. Composite materials are increasingly used in wind turbine blades, oil and gas pipelines, and other critical infrastructure. Understanding and mitigating transverse cracking could lead to longer-lasting, more reliable components, reducing maintenance costs and enhancing safety.
Carrère’s work also opens up avenues for future research. By integrating experimental observations with numerical simulations, the study provides a robust framework for predicting damage mechanisms in composite laminates. This could pave the way for more sophisticated design tools, enabling engineers to optimize composite structures with greater precision.
As the energy sector continues to embrace composite materials, insights from Carrère’s research will be invaluable. By addressing the fundamental issues of transverse cracking, the industry can move closer to realizing the full potential of composite laminates, driving innovation and sustainability in energy production and distribution.