Composite additive manufacturing (AM) can form complex shapes that are impossible to achieve by conventional machining methods, and thus it is expected to contribute to the fabrication of value-added products. However, AM has disadvantages such as long cycling time in manufacturing, high material cost, and low material strength. Therefore, we developed a manufacturing method that combines AM and injection molding, which are extensively used as rapid and inexpensive manufacturing processes. In this study, after designing the structure and molding conditions to prevent AM insert breakage, injection molding and quality confirmation tests were performed to verify the feasibility of this manufacturing process.

This study experimentally and numerically investigates the crystallization behavior of polyphenylene sulfide (PPS) resin and carbon-fiber-reinforced PPS (CF/PPS). Differential scanning calorimetry and polarized optical microscopy were performed under various solidification conditions. Subsequently, a numerical model using the framework of the phase-field method was developed based on the experimental results. Both experimental and numerical results indicated that the crystallization of thermoplastic resin strongly depends on the solidification conditions and the presence of impurities. The developed numerical model could qualitatively predict the crystallization behavior. Therefore, the developed model is useful for material design considering that the microstructure depends on the manufacturing conditions.

Chopped carbon fiber tape reinforced thermoplastics (CTT) have recently attracted attention owing to their excellent moldability. However, internal fiber waviness may occur depending on the molding conditions, such as the material charging pattern. Large out-of-plane waviness is known to be a strength reduction factor, and method for non-destructive observation of the out-of-plane waviness is necessary. Herein, a method was developed to detect the location and degree of fiber out-of-plane waviness using scattering Computed Tomography (CT) images acquired via X-ray Talbot-Lau interferometry. X-ray Talbot-Lau interferometer is equipped with diffraction gratings for detecting small-angle X-ray scattering, and hence, fiber information can be acquired with a wider field of view than that via conventional X-ray CT. Out-of-plane waviness was extracted from the evaluation samples; tensile testing and cross-sectional observation confirmed that fracture occurred at the location with large out-of-plane waviness. These results suggest that out-of-plane waviness can be used as a parameter to improve the accuracy of predicting the strength reduction location.