STP964

    Nondestructive Evaluation of Fiber FP Reinforced Metal Matrix Composites

    Published: Jan 1988


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    Abstract

    Fiber FP is a continuous polycrystalline alumina fiber suited for reinforcement of metals, plastics, and ceramics. Fiber FP/metal composites are very attractive for weight and stiffness critical applications. In order for these materials to be accepted in the marketplace, quality control methods needed to be developed. In this study, we developed methods based on computed tomography (CT) and ultrasonic scanning to identify porosity, delamination, and other discontinuities in Fiber FP reinforced composites.

    Prior to this work, Fiber FP/metal plates and coupons were inspected using a combination of X-ray and ultrasonic methods—both with significant limitations. The ultrasonic evaluation utilized a defect threshold technique with inherent sensitivity uncertainties of defects close to the threshold level. This study demonstrated that defect intensity level scanning was superior to threshold scanning for Fiber FP reinforced composites. We developed color indicators for the various intensity levels to facilitate data interpretation.

    The ultrasonic technology was also limited to simple flat shapes. Fiber FP development programs have recently shifted to fabrication of more complex prototype components such as connecting rods and helicopter transmission housings. CT offers several advantages over traditional radiographic techniques. Standard radiography creates an obscure 2-D image of a 3-D body by superimposing defect indications. A CT scanner has the ability to look at 2-D slices of a 3-D component. A series of 2-D images can be taken, and then interfaced with a computer to show the 3-D nature of the object. This technique has been demonstrated for prototype connecting rods and confirmed via destructive testing.

    Keywords:

    nondestructive tests, ultrasonic scanning system, through-transmission, FP/magnesium, FP/aluminum, computed tomography, composite materials, attenuation


    Author Information:

    Widrig, JE
    Section engineer, section engineer, and research technician, Experimental Station, Du Pont Company, Wilmington, DE

    McCabe, DD
    Section engineer, section engineer, and research technician, Experimental Station, Du Pont Company, Wilmington, DE

    Conner, RL
    Section engineer, section engineer, and research technician, Experimental Station, Du Pont Company, Wilmington, DE


    Paper ID: STP25956S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP25956S


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