Registration of local damage based on the use of fiber-optic strain sensors and numerical simulation results

Abstract

The paper describes the method of registration and development of local damage (defects) in the material based on experimental data on the strain values recorded by a limited number of fiber-optic strain sensors. The technique is based on the following statements: for external influences, which are different from each other by a constant factor, there is a combination of constants, consisting of all variants of strain ratios, recorded by two sensors; the reason for the conclusion about the defect appearance is a change in some of these constants, due to the fact that the defect appearance leads to a local change in the strains that must be registered by one of the sensors; the numerical simulation results of the stress-strain state are used to select the zones for the strain sensors location. The technique was tested on a structurally similar angle shaped element made of glass fiber reinforced plastic, in which the lower part of the substantially larger shelf is fixed, and tensile forces are applied to the short shelf. For experimental recording of strain, fiber-optic strain sensors based on Bragg gratings glued to the sample surface are used. The results of numerical calculations and experiments are presented, demonstrating that when a certain level of tensile force is reached, a defect, associated with the local destruction of the material in the corner zone, is recorded.