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Date of Publication:2008-01-01

Journal:机械强度

Affiliation of Author(s):运载工程与力学学部

Volume:30

Issue:5

Page Number:848-853

ISSN No.:1001-9669

Abstract:An experimental method for measuring surface crack depth of plate structures under tension using polyvinylidene fluoride (PVDF) films is developed. First, the relationship between the surface crack opening displacement and the crack depth of the plate structure was deduced, based on the analytical solution of the displacement jumps across a crack surface embedded into the infinite three-dimensional homogeneous elastic solid. Finite element analysis for some cracked models was also performed to check the relationship, in which the numerical solution of the crack opening displacement was used to estimate the crack depth. Then, an experimental method for measuring the surface crack opening displacement by the use of PVDF films and an electrostatic voltmeter of non-contact type is proposed. In this method, a piece of PVDF film is adhered onto the surface crack directly. The surface crack opening displacement can be calculated by the measured electric potential on the polarized PVDF film, when the film has deformation caused by the opening displacement. Experiments were carried out on a plate specimen with a surface semi-elliptical crack in order to verify the feasibility and accuracy of the proposed experimental method. The proposed method is suitable for only the surface crack depth measurement of plate structures under tension, because it originates from the analytical solution of the displacement jumps across a crack surface under uniform tension and considers only boundary effect coefficients for the plate structure.

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