GUIDED WAVE ULTRASONIC CHARACTERIZATION OF ADVANCED COMPOSITES

摘要

Safe use of composite materials in critical structural applications demands independent structural integrity verification. Traditional ultrasonic non-destructive methods are inappropriate and often misleading when applied to anisotropic and complex composite materials. Complexity of the advanced composite materials structures represents challenges in developing optimized ultrasonic tests that can directly characterize mechanical properties of the material. In advanced technology applications such as aerospace and with industrial emphasis on economics and safety, it is critical to develop and apply new robust and practical ultrasonic nondestructive test (NDT) methods. New guided wave laser ultrasonic sources and small aperture receiving sensors configurations enable testing of advanced composites far beyond conventional ultrasonic capabilities. In contrast to pseudo-imaging methodology such as ultrasonic C-scan, guide wave response to in plane mechanical state of the composite is analyzed and this emerging technology explores the ability of the inhomogeneous, anisotropic composite material to propagate ultrasonic guided waves over a range of distances and part configurations. Appropriate customizing of ultrasonic transduction process enables measurements of material properties and estimate of defect conditions along in-plane sound propagation path. From guided wave acoustic response, one can develop meaningful estimate of material modulus, fatigue damage, thermal damage and sense mechanical defect conditions without need to point-vise scan the complete structure.