Based on the curing process of carbon fiber/epoxy prepreg with autoclave, two kinds of unidirectional carbon fiber laminates with in-plane and out-of-plane waviness were fabricated by rolling prefabricated out-of-plane waviness and inserting prepreg strip, respectively. Fiber waviness defects in composites were characterized by waviness ratio. The specimens containing fiber waviness were successfully prepared with almost the same fiber content and low porosity. The influences of fiber waviness with different waviness ratio on tensile, compressive, and charpy impact properties of unidirectional laminates were studied, and the corresponding failure modes were observed. The mechanism of the effects of fiber waviness on mechanical properties was discussed. The experimental results show that tensile property and compressive property decrease by in-plane buckling and out-of-plane wrinkling, especially with large waviness ratio. Reduction of 33.0% of compressive strength with out-of-plane wrinkling is seen in the case of 0.037 waviness ratio, while 25.4% reduction is obtained for in-plane buckling under 0.038 waviness ratio. Charpy impact strength decreases by in-plane buckling, whereas increases by out-of-plane wrinkling. Failure morphologies of various specimens are changed by fiber waviness, which are consistent with the mechanical degradation. In addition, there are some differences on the sensitivity of mechanical properties to different types of fiber waviness. Tensile strength is more sensitive to in-plane buckling in comparison with out-of-plane wrinkling, and compressive property is more sensitive to out-of-plane wrinkling.

This paper successfully developed a resistance heating method based on carbon fiber thin veil for molding continuous glass fiber reinforced polypropylene composite. Electrical resistance, temperature distribution, and heating response of carbon fiber veil were investigated to evaluate its resistance heating behavior. One layer of carbon fiber veil with about 0.1 mm thickness was sandwiched by prepreg stacks with about 2 mm thickness and composite plate was fabricated through resistance heating and forming process. Void content, glass fiber distribution, and thickness of composite plate were obtained to evaluate forming quality. Flexural test was employed for mechanical assessment. The results shows that carbon fiber veil coupled with copper foil is an effective heating element with uniform temperature distribution and quick heating response, and the processing quality of composite plate is comparable to that using oven heating process. The feasibility of secondary resistance heating of composite plate based on carbon fiber veil was also demonstrated and the results indicate that composite plate containing carbon fiber veil can be molded into composite product using resistance self-heating process.