Ultrasonic and micrograph-based quantification of material characteristics for in-situ AFP composite structures

Achieving the maximum potential of parts manufactured with in-situ consolidation thermoplastic Automated Fiber Placement without a final bulk consolidation is a challenging task. This is due partially to the continual development of the technology itself and partially due to material defects which are not fully removed during part manufacturing. In this paper, a methodology is presented for the evaluation of prepreg tape and laminate quality relevant to the manufacturing process. A novel approach is presented to quantify tape quality and the fiber volume content distribution, porosity, all of which are identified as significant influences on laminate quality. A new approach to ultrasonic testing is applied for quantitative porosity analysis promising advantages over conventional methods. Laminate porosity was successfully measured using the proposed pulse-echo ultrasonic attenuation method. The fiber content distribution from the tape used in testing shows characteristics interpreted as unfavorable for high quality in-situ AFP.