L-shaped structures made from ultrathin chopped carbon fiber tape reinforced thermoplastics: delamination behavior and optimization

Abstract

We examined L-shaped structures prepared from ultrathin chopped carbon fiber tape reinforced thermoplastics (UT-CTT), attempting to mitigate their delamination and minimize interlaminar out-of-plane tensile stress using four-point bending tests and finite element modeling. The reasonable agreement between experimental and simulated results was achieved, and interlaminar tensile strength was obtained by finite element modeling and analytical methods. Additionally, free-shape optimization was utilized. The structural optimization problem was formulated using interlaminar tensile stress as the objective function (with constraints placed on structural stiffness and weight), and thickness variations of the inner parts of the L-shaped structure were used as design variables. Optimization reduced the interlaminar tensile stress of the L-shaped structure from 53.77 to 37.29 MPa while maintaining its original stiffness and weight, suggesting that the described approach is generally applicable to determining the interlaminar tensile strength of UT-CTT and can be used to increase the delamination initiation load.

Keywords:

• ultrathin chopped carbon fiber tape reinforced thermoplastics (UT-CTT)
• L-shaped structure
• interlaminar tensile strength
• free-shape optimization

Acknowledgments

Part of this study was conducted as Japanese METI project ‘the Future Pioneering Projects/Innovative Structural Materials Project’ since 2013. Authors would like to express sincerely appreciation to the project members who have provided valuable information and useful discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.