COBEM99

S21 Vibrações e Análise Modal

Title:

IMPLEMENTATION OF A POLARIMETRIC OPTICAL FIBER SENSOR FOR MEASUREMENT OF STRAIN IN STRUCTURES

Summary :

THIS WORK DESCRIBES THE IMPLEMENTATION OF A POLARIMETRIC FIBER OPTIC SENSOR FOR MEASUREMENT OF STRAIN IN STRUCTURES. THE SENSOR IS BASED ON THE EFFECT OF RELATIVE PHASE SHIFT BETWEEN TWO ORTHOGONALLY POLARIZED EIGENMODES OF A HIGHLY BIREFRINGENT (HB) POLARIZATION-MAINTAINING OPTICAL FIBER WHICH SERVES AS THE SENSING ELEMENT. THE INSTRUMENTATION OF THE SENSOR CONSISTS OF A HE-NE LASER, POLARIZERS, OBJECTIVES, A SILICON PHOTODETECTOR AND A LOCK-IN AMPLIFIER. THE SENSING ELEMENT WAS EMBEDDED IN ACRYLIC CYLINDERS. THE PROTOTYPE WAS COMPENSATED AGAINST UNDESIRABLE EXTERNAL PARAMETERS, SUCH AS THE TEMPERATURE, USING THE SPLICE TECHNIQUE PROPOSED BY DAKIN AND WADE (1984). IT WAS CONSTRUCTED USING A 5 MM SENSING LENGTH AND WAS ABLE TO MEASURE STRAIN IN THE RANGE OF 0 TO 500 UE. THIS STRAIN RANGE IS USEFUL FOR STUDYING CONCRETE STRUCTURES. THE SENSOR CAN BE ADJUSTED TO A SPECIFIED STRAIN RANGE THROUGH AN APPROPRIATE CHOICE OF THE SENSING LENGTH AND WAVELENGHT OF THE INCIDENT LIGHT. KEYWORDS: FIBER OPTIC SENSOR, STRAIN SENSOR, POLARIMETRIC SENSOR, STRAIN MEASUREMENT, STRUCTURE STRAIN

Author :

de Carvalho, Aparecido Augusto
Ferreira, Wagner Peron
Kitano, Cláudio 0

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