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Proceedings Paper

Nondestructive evaluation of residual stress in short-fiber reinforced plastics by x-ray diffraction
Author(s): Keisuke Tanaka; Syouhei Tokoro; Yoshiaki Akiniwa; Noboru Egami
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Paper Abstract

The X-ray diffraction method is used to measure the residual stress in injection-molded plates of short-fiber reinforced plastics (SFRP) made of crystalline thermoplastics, polyphenylene sulphide (PPS), reinforced by carbon fibers with 30 mass%. Based on the orientation of carbon fibers, injection molded plates can be modeled as three-layered lamella where the core layer is sandwiched by skin layers. The stress in the matrix in the skin layer was measured using Cr-Kα radiation with the sin2Ψ method. Since the X-ray penetration depth is shallow, the state of stresses measured by X-rays in FRP can be assumed to be plane stress. The X-ray measurement of stress in carbon fibers was not possible because of high texture. A new method was proposed to evaluate the macrostress in SFRP from the measurement of the matrix stress. According to micromechanics analysis of SFRP, the matrix stresses in the fiber direction, σ1m, and perpendicular to the fiber direction, σ2m, and shear stress τ12m can be expressed as the functions of the applied (macro-) stresses, σ1A, σ2A , τ12A as follows: σ1m = α11σ1A12σ2A, σ2m = α21σ1A + α22σ2A, τ12m = α66τ12A, where α1112, α21, α22, α66 are stress-partitioning coefficients. Using skin-layer strips cut parallel, perpendicular and 45° to the molding direction, the stress in the matrix was measured under the uniaxial applied stress and the stress-partitioning coefficients of the above equations were determined. Once these relations are established, the macrostress in SFRP can be determined from the measurements of the matrix stresses by X-rays.

Paper Details

Date Published: 2 June 2014
PDF: 8 pages
Proc. SPIE 9234, International Conference on Experimental Mechanics 2013 and Twelfth Asian Conference on Experimental Mechanics, 92340U (2 June 2014); doi: 10.1117/12.2054128
Show Author Affiliations
Keisuke Tanaka, Meijo Univ. (Japan)
Syouhei Tokoro, Meijo Univ. (Japan)
Yoshiaki Akiniwa, Yokohama National Univ. (Japan)
Noboru Egami, Meijo Univ. (Japan)

Published in SPIE Proceedings Vol. 9234:
International Conference on Experimental Mechanics 2013 and Twelfth Asian Conference on Experimental Mechanics
Somnuk Sirisoonthorn, Editor(s)

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