High axial compressive strength in 3D-printed continuous carbon fiber reinforced thermoplastics by controlling printing forces

Microdefects such as fiber waviness and voids are critical problems in the three-dimensional (3D) printing of continuous carbon fiber-reinforced thermoplastics (CFRTPs), degrading their mechanical properties. This work demonstrates that a regularized microstructure can be achieved by controlling printing forces, resulting in high axial compressive strength, nearing theoretical predictions. A proposed 3D-printing mechanism that measures and adjusts printing forces reduced the microdefects, as evidenced by X-ray computed tomography and structure tensor analysis. Compressive tests are performed to evaluate the improvement of microstructures and their mechanical properties because compressive strength is sensitive to microdefects.