Vulnerability of embedded EFPI-sensors to low-energy impacts

• Published in: Smart materials and structures Vol. 6; no. 3; pp. 369 - 382
• Main Authors: Levin, Klas, Jarlås, Rolf
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Bristol IOP Publishing 01.06.1997; Institute of Physics
• Subjects: Applied sciences; Composites; Exact sciences and technology; Forms of application and semi-finished materials; Fundamental areas of phenomenology (including applications); Measurement and testing methods; Measurement methods and techniques in continuum mechanics of solids; Physics; Polymer industry, paints, wood; Solid mechanics; Structural and continuum mechanics; Technology of polymers; Optical fibers; Finite element method; Carbon fibers; Composite materials; Measurement sensor; Numerical simulation; Embedded transducer; Damage; Experimental study; Intelligent system; Mechanical shock
• ISSN: 0964-1726; 1361-665X
• DOI: 10.1088/0964-1726/6/3/015

The purpose of this investigation was to evaluate the vulnerability to low-energy impacts of fibre optic sensors embedded in carbon fibre composites. The task was to determine the critical contact load which leads to a deterioration in the sensor function. A bending-dominated case, typically resulting from an impact far from any supporting boundary, was chosen in this investigation of impact vulnerability of a modified EFPI-sensor embedded at different depths in a composite plate. An important finding from the experiments is that the depth position of the sensor in the plate had a significant influence on the contact load at which the sensor function deteriorates. The best position is in the middle of the plate. When the sensor is embedded closer to the plate surfaces, the sensor function becomes vulnerable to impact. It was shown that the function of the sensor deteriorates as an effect of debonding. In the finite element analysis the effect of embedded fibre optic sensors on the local stress distribution was a subject of special interest. The analysis supported the findings from the experiments that debonding of the sensor is the most critical failure mode for the sensor function; it is however difficult to predict the load level for initiation of damage. A new debonding criterion is proposed to improve the agreement with the experimental data.