Shearographic and holographic assessment of defective laminates with bond-lines of different elasticities

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Journal of Engineering Materials and Technology

DOI:https://doi.org/10.1115/1.2804546· OSTI ID:94429

Shang, H M; Tham, L M; Chau, F S ^[1]

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1. National Univ. of Singapore (Singapore). Dept. of Mechanical and Production Engineering

While defects in laminated plates are readily revealed using double-exposure shearography and holography, when an incremental vacuum pressure is applied between the exposures, the apparent defect size, measured from the boundary of the perturbed fringes, may over-estimate the actual defect size depending on the elasticity of the bond-line. In this paper, the perturbated fringes were described by a mathematical model derived from the theory of thin plates supported by a Winkler type elastic foundation which takes into consideration the elasticity of the bond-line. An iterative technique is subsequently presented for estimating the size and depth of the defect from the fringe pattern without the need to pre-determine the current elasticity of the bond-line. Laminates with a thick and highly elastic bond-line, found in foam-adhesive bonded metal laminates, and those with a thin and brittle bond-line, found in multi-layered glassfiber reinforced plastic plates, were tested. Results have shown that the defects in these laminates were accurately assessed.

• Sponsoring Organization: USDOE
• OSTI ID: 94429
• Journal Information: Journal of Engineering Materials and Technology, Journal Name: Journal of Engineering Materials and Technology Journal Issue: 3 Vol. 117; ISSN 0094-4289; ISSN JEMTA8
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
COMPOSITE MATERIALS
DATA ANALYSIS
DEFECTS
EXPERIMENTAL DATA
INSPECTION
ITERATIVE METHODS
MATHEMATICAL MODELS
NONDESTRUCTIVE TESTING