Uncertainty in fiber optic strain measurements for blade bending moments
report
Recently, fiber optic strain measurements are being used for blade bending moment measurements to larger extents. Hence, this report describes a general mathematical model for fiber optic strain and blade bending moments. It allows for a complete overview and relation between all relevant uncertainties specified for the two presented fiber optics measurement principles: (temperature calibrated) pad mounted and stud mounted. The latter is referred to as the fiber optic blade monitoring FOBM sensor. The way in which the sensors are mounted to the blades plays an important role as there is some response attenuation between the strain transfer from the specimen to the strain sensor. We believe that because of the glue layer, the response attenuation for pad mounted sensors is higher than for stud mounted sensors. That means that, if we ignore uncertainty, the FOBM is better able to represent the strain in blades than (temperature calibrated) pad mounted fiber optic sensors. Typically, we estimate this effect to be 2%.
TNO Identifier
885102
Publisher
TNO
Collation
18 p. (incl. bijlagen)
Place of publication
Petten