Diagnostics of Multilayered Composite Structures with the Help of a Fiber-Optic System for Strain Measurements

Abstract

The paper considers a built-in fiber-optic array system for technical diagnostic of composite structures measuring local strains in hazardous cross sections of these structures. The effect of repeated microscopic bends of optical fibers on the transmitted flux in structures strained by a tensile force of up to 1 kN over a temperature range of 20 to 100°C has been investigated. The increase in the tensile stress in components of a composite structure leads to a growth in the optical losses of up to 20–23% of the initial optical flux. The loss function \(\tilde W\)(F) is linear in the region of mechanical forces of up to 1 kN and temperatures up to 40°C. An explanation has been suggested for the nonlinearity of \(\tilde W\)(F) at temperatures above 40°C. The conclusion is that the developed system enables one to estimate the strength of multilayered composite structures and detect their prefracture states using singular points on opto-mechanical characteristics of optical fibers.