Plastic deformation analysis in metal using absolute optical fiber strain sensor

摘要

An absolute displacement and strain measurement system has been used to characterize plastic deformation in metal specimens. Here, an absolute extrinsic Fabry-Perot interferometric (AEFPI) sensor system uses a modified EFPI sensor element head with support optical and electronic signal processing to give an output signal proportional to the instantaneous air gap length within the sensor element. This information may be used to determine the local axial strain if the gage length of the sensor is known. Because the system does not require a reference phase, the support electronics may be turned off and back on with no loss of optical fringe information or ambiguity in reference point. Applications in the long term monitoring of residual strain and creep are suggested.