arrow_back_ios

Main Menu

See All Software See All Instruments See All Transducers See All Vibration Testing Equipment See All Electroacoustics See All Acoustic End-of-Line Test Systems See All Academy See All Resource Center See All Applications See All Industries See All Services See All Support See All Our Business See All Our History See All Global Presence
arrow_back_ios

Main Menu

See All nCode - Durability and Fatigue Analysis See All ReliaSoft - Reliability Analysis and Management See All Test Data Management See All DAQ Software See All Drivers & API See All Utility See All Vibration Control See All High Precision and Calibration Systems See All DAQ Systems See All S&V Hand-held Devices See All Industrial Electronics See All Power Analyzer See All S&V Signal Conditioner See All Acoustic Transducers See All Current and Voltage Sensors See All Displacement Sensors See All Force sensors See All Load Cells See All Multi Component Sensors See All Pressure See All Strain Sensors See All Strain Gauges See All Temperature Sensors See All Tilt Sensors See All Torque Sensors See All Vibration See All Accessories for Vibration Testing Equipment See All Vibration Controllers See All Measurement Exciters See All Modal Exciters See All Power Amplifiers See All LDS Shaker Systems See All Test Solutions See All Actuators See All Combustion Engines See All Durability See All eDrive See All Production Testing Sensors See All Transmission & Gearboxes See All Turbo Charger See All Training Courses See All Acoustics See All Asset & Process Monitoring See All Custom Sensors See All Data Acquisition & Analysis See All Durability & Fatigue See All Electric Power Testing See All NVH See All Reliability See All Vibration See All Weighing See All Automotive & Ground Transportation See All Calibration See All Installation, Maintenance & Repair See All Support Brüel & Kjær See All Release Notes See All Compliance See All BKSV Worldwide Contacts
arrow_back_ios

Main Menu

See All API See All Experimental Testing See All Piezoelectric Charge Accelerometers See All Piezoelectric CCLD (IEPE) accelerometers See All Electroacoustics See All Noise Source Identification See All Environmental Noise See All Sound Power and Sound Pressure See All Noise Certification See All Industrial Process Control See All Structural Health Monitoring See All Electrical Devices Testing See All Electrical Systems Testing See All Grid Testing See All High-Voltage Testing See All Vibration Testing with Electrodynamic Shakers See All Structural Dynamics See All Machine Analysis and Diagnostics See All Dynamic Weighing See All Vehicle Electrification See All Calibration Services for Transducers See All Calibration Services for Handheld Instruments See All Calibration Services for Instruments & DAQ See All On-Site Calibration See All Resources See All Software License Management

List of Terms related to Strain Measurement with Optical Sensors

λ Wavelength

Wavelength is the measured peak wavelength of a fiber Bragg grating sensor. It is normally expressed in nanometers (nm).

λ0 Reference wavelength

The reference wavelength is the peak wavelength of a fiber Bragg grating sensor at a reference condition (zero strain, at reference temperature, and so forth.. It is normally expressed in nanometers (nm).

Δλ Wavelength variation

The wavelength variation (also commonly referred to as shift or as change) is the difference between the wavelength and the reference wavelength (reference value): Δλ= λ- λ0. It is normally expressed in nanometers (nm).

k k-factor The gauge factor k (also referred to as k-factor) of an optical strain gauge is the proportional change in the Bragg wavelength (Δλ/λ0) and the strain variation Δε. Is is being measured as: Δλ/λ0 = k.Δε. This value is a dimensionless number and depends on the characteristically used optical fiber and sensor encapsulation. In the case of HBM optical strain sensors, the k-factor is identified on the data- and calibration sheets that are individually delivered with each sensor.
ε Strain

Strain is a dimensionless value that represents the relative change in the length of a material to its initial length. It is normally of a very small value, and hence is represented by µm/m, ppm or 10-6.

S Sensitivity

The sensitivity of an optical strain sensor is the direct ratio between the measured strain and the change in the Bragg wavelength: Δε/Δλ= S. It is normally stated as value in micro-strain per nanometer [(µm/m)/nm)] and is different for every sensor, as it depends on its initial base wavelength, that is: S=1/(k. λ0).

 TCS Temperature cross-sensitivity

The temperature cross-sensitivity is a sensor measurement drift caused by temperature variation. It is the strain that is wrongly measured when there is a change of 1ºC (or 1ºK) in temperature. The value is given in (µm/m)/ºC [or (µm/m)/ºK] and can be used to compensate the effect of temperature on the optical strain sensor (not considering the compensation for the thermal expansion of the specimen).

σ Stress

Mechanical stress is expressed by the quotient of the force F and the cross-sectional area A of the stressed material, σ=F/A. It is normally represented in KPa.

E Elastic modulus

The modulus of elasticity, or Young’s modulus, is the ratio between stress and strain in a linear elastic material. It is given by Hooke’s Law (σ=E.ε). It is normally represented in GPa (109 Pa) to correlate strain in µm/m (10-6) with stress in KPa (103 Pa).

v Poisson's ratio

Poisson's ratio is defined by the division of the transverse strain εt and the longitudinal strain εl. For aluminum alloys, ν = 0.33, for example.


null

Support Content