The present invention relates to a stress-strain testing system for a large-diameter steel pipe pile of an offshore wind turbine and a construction method, comprising a steel pipe pile, wherein copper belt type sensor cables are correspondingly welded on both sides of the steel pipe pile along an axis direction; each sensor cable is sequentially covered with an epoxy adhesive, gold foil paper and an angle steel welded on the steel pipe pile centering on the copper belt type sensor cable; a fiber core of each copper belt type sensor cable is transferred into a high-strength armored optical cable by a special fixture and then is led out; and the high-strength armored optical cable is connected with a Brillouin optical fiber demodulator. The present invention is applicable to the field of foundation engineering testing and detection technology.

A system for detecting forces on and measuring deformation of an anthropomorphic test device (ATD) includes a plurality of body parts and at least one optical fiber supported by and in contact with at least one of the body parts. The body parts form the ATD and simulate at least a part of a human body and the articulation of the human body. The optical fiber extends between a first end and a second end and comprises a plurality of sensors disposed between the ends. An emitter is in communication with the optical fiber for emitting a light having a predetermined band of wavelengths through the optical fiber that is reflected by the sensors and an interrogator is in communication with the optical fiber for detecting the reflected light from the sensor such that changes to the reflected light indicate a strain on the at least one body part.

Aspects of the present disclosure describe Rayleigh fading mitigation via short pulse coherent distributed acoustic sensing with multi-location beating-term combination. In illustrative configurations, systems, methods, and structures according to the present disclosure employ a two stage modulation arrangement providing short interrogator pulses resulting in a greater number of sensing data points and reduced effective sectional length. The increased number of data points are used to mitigate Rayleigh fading via a spatial combining process, multi-location-beating combining (MLBC) which uses weighted complex-valued DAS beating results from neighboring locations and aligns phase signals of each of the locations, before combining them to produce a final DAS phase measurement. Since Rayleigh scattering is a random statistic, the MLBC process allows capture of different statics from neighboring locations with correlated vibration/acoustic signal. The combined DAS results minimize a total Rayleigh fade, in both dynamic fading and static fading scenarios.

A high backscattering optical fiber comprising a perturbed segment in which the perturbed segment reflects a relative power such that the optical fiber has an effective index of n.sub.eff, a numerical aperture of NA, a scatter of R.sub.p.fwdarw.r.sup.(fiber) that varies axially along the optical fiber, a total transmission loss of α.sub.fiber, an in-band range greater than one nanometer (1 nm), and a figure of merit (FOM) in the in-band range. The FOM being defined as: $\mathrm{FOM}=\frac{R_{p.fwdarw.r}^{\left(\mathrm{fiber}\right)}}{{{\alpha }_{\mathrm{fiber}}\left(\frac{\mathrm{NA}}{2n_{\mathrm{eff}}}\right)}^2}.$

A fiber includes M primary cores and N redundant cores, where M an integer is greater than two and N is an integer greater than one. Interferometric circuitry detects interferometric pattern data associated with the M primary cores and the N redundant cores when the optical fiber is placed into a sensing position. Data processing circuitry calculates a primary core fiber bend value for the M primary cores and a redundant core fiber bend value for the N redundant cores based on a predetermined geometry of the M primary cores and the N redundant cores in the fiber and detected interferometric pattern data associated with the M primary cores and the N redundant cores. The primary core fiber bend value and the redundant core fiber bend value are compared in a comparison. The detected data for the M primary cores is determined reliable or unreliable based on the comparison. A signal is generated in response to an unreliable determination.

Systems, devices and methods enable generation and monitoring of support platform structural conditions in a manner that overcomes drawbacks associated with conventional approaches (e.g., load cells) for generating and monitoring similar operating condition information. In preferred embodiments, such systems, devices and methods utilize fiber optic strain gauges (i.e., fiber optic sensors) in place of (e.g., retrofit/data replacement) or in combination with conventional load cells. The fiber optic sensors are strategically placed at a plurality of locations on one or more support bodies of a support platform. In preferred embodiments, the fiber optic strain gauges are placed in positions within a hull and/or one or more pontoons of an offshore platform. Such positions are selected whereby resulting operating condition data generated by the fiber optic strain gauges suitably replaces data received by conventionally constructed and located load cells of an offshore platform (e.g., a TLP).

A method and a system for interrogating an optical fiber includes a probe signal that has a first frequency comb at a first repetition rate (Δf) injected into the optical fiber. A backscattering signal that includes the probe signal convolved with an impulse response of the optical fiber in reflection which is sensitive to at least one parameter being measured from the optical fiber is gathered. The backscattering signal is beaten with a local oscillator signal to generate a beating signal, the local oscillator signal including a second frequency comb at a second repetition rate that is offset from the first repetition rate (Δf+δf) and being mutually coherent with the first frequency comb. The resulting beating signal is analysed to thereby determine the at least one parameter being measured from the optical fiber.

A hub for an optical shape sensing reference includes a hub body (606) configured to receive an elongated flexible instrument (622) with a shape sensing system coupled to the flexible instrument within a path formed in the hub body. A profile (630) is formed in the hub body in the path to impart a hub template configured to distinguish a portion of the elongated flexible instrument within the hub in shape sensing data. An attachment mechanism (616) is formed on the hub body to detachably connect the hub body to a deployable instrument such that a change in a position of the hub body indicates a corresponding change in the deployable device.

Aspects of the subject technology relate to systems and methods for determining positions of cementing plugs during a cementing process. Systems and methods are provided for determining a length of an optical fiber line deployed into a wellbore for a cementing process, measuring signal intensity data as a function of distance from the optical fiber line, the optical fiber line being attached to a lower cementing plug and an upper cementing plug, the upper cementing plug being attached to the optical fiber line by an attenuation assembly, generating signal intensity profiles based on the signal intensity data as a function of a round trip delay of a light signal in the optical fiber line, and determining positions of the lower cementing plug and the upper cementing plug based on the signal intensity profiles of the optical fiber line.

An optical strain gauge system measures strain on the exterior surface of a pipe to identify areas of wear on the interior surface of the pipe. The optical strain gauge system comprises an optical sensing interrogator and at least one optical fiber. The optical sensing interrogator comprises a light source and a light sensor. The at least one optical fiber includes fiber Bragg gratings along the length of the optical fiber. The optical fiber is arranged on the exterior surface of the pipe with the fiber Bragg gratings forming a two-dimensional array of points at which strain measurements are obtained. The two-dimensional array of strain measurement points provides an accurate assessment of the strains on the exterior of the pipe which can be used to identify areas of wear on the interior surface of the pipe.