CN-120702365-B - Composite material strain testing system and method for self-calibration of propeller

CN120702365BCN 120702365 BCN120702365 BCN 120702365BCN-120702365-B

Abstract

The invention discloses a self-calibration strain testing system and method for a propeller composite material, which solve the problems of high-precision measurement and real-time calibration of dynamic strain in a complex flow field environment. The system core comprises a linear fiber bragg grating sensor array attached to the surface of a blade and an optical fiber demodulation instrument integrated on a hub, wherein the sensors are symmetrically arranged along the spanwise direction, the infrared emission/receiving devices in pairs are intersected with the center O of the hub when the positions are accurate to form a global reference, the single sensor is installed through a biaxial flexible hinge, and an integrated Shape Memory Alloy (SMA) wire driving mechanism can realize independent micro-alignment of the spanwise direction/the chord direction according to infrared intersection deviation. The sensor is internally provided with a failure alarm, gallium indium tin alloy is filled by hollow glass beads, an alarm is triggered only when more than or equal to 3 beads are broken to form a conductive path, false alarm is avoided, and the problem of dynamic strain monitoring of the large-deformation composite propeller in high-pressure, low-temperature and strong electromagnetic environments is solved by the anti-electromagnetic interference module.

Inventors

ZHAO WEI
Han Hanqiao
PAN ZHI
LIU JIMING
YU HAITING
LONG YUN
CHEN JING

Assignees

中国船舶集团有限公司第七一九研究所

Dates

Publication Date: 20260505
Application Date: 20250529

Claims (8)

1. A composite material strain testing system for propeller self-calibration comprises an optical fiber grating sensor array and an optical fiber demodulator, wherein the optical fiber grating sensor array senses strain and temperature and converts the change into the change of the central wavelength of an optical fiber grating; the optical fiber demodulation instrument is arranged in the propeller hub and can collect and demodulate spectrum signals, and analyze the wavelength of the optical fiber grating, so that the structural strain and the temperature change of the propeller are obtained; the fiber bragg grating sensor arrays are arranged in a line shape along the surface of each blade in a fitting way, more than 5 single fiber bragg grating sensors are arranged on each blade in a line shape in series to form the fiber bragg grating sensor arrays, the single fiber bragg grating sensors of the corresponding sequence on each blade are arranged in the same plane in a space symmetry way, and are paired in pairs, each pair is respectively provided with an infrared emitting device and an infrared receiving device, and when the positioning is accurate, each pair of infrared rays intersect at a point center O; each fiber grating sensor is provided with a micro-displacement automatic regulating mechanism, when the fiber grating sensor deflects, the automatic calibration is carried out according to the infrared intersection point of the displacement, each fiber grating sensor is provided with a failure alarm, each fiber grating in the fiber grating sensor array is a light reflection filter, a plurality of fiber grating sensors with different wavelengths are used in series, each sensor is distributed with a bandwidth, the wavelength drift of each sensor in the whole working range is within the bandwidth, the system also comprises an anti-interference demodulation system, the anti-interference demodulation system comprises a magnetic shielding spectrum module and an annular fiber network, the spectrum module adopts a double-layer permalloy shielding shell, each fiber grating sensor is arranged on the surface of a blade through a biaxial flexible hinge, the double-shaft flexible hinge allows the sensor to independently micro-move in the spanwise and chordwise directions, and the tail end of the sensor is integrated with a shape memory alloy wire for driving the flexible hinge to deform so as to realize displacement adjustment.
2. The composite strain testing system of claim 1, wherein the failure alarm comprises hollow glass beads, wherein the inner walls of the beads are coated with a metal conductive film and filled with liquid metal, and a conductive path is formed when the metal conductive film breaks, and the failure alarm is triggered and infrared emission or infrared reception is stopped.
3. The composite material strain test system according to claim 2, wherein the hollow glass beads with diameters of 50-100 μm and densities of 100-300 particles/mm < 3 > are arranged in the failure alarm, the liquid metal is gallium indium tin alloy, and at least 3 cracks are ensured to trigger the alarm.
4. The composite material strain testing system of claim 1, wherein the optical fiber demodulator comprises two parts, namely a photoelectric processing module and a power supply part, wherein the photoelectric processing module comprises a photoelectric component and a photoelectric circuit, and the power supply part provides stable power supply guarantee for the instrument.
5. The composite material strain testing system of claim 4, wherein the photoelectric processing module comprises a broadband light source, a driving and spectrum analysis module, an AD converter, an FPGA control unit, a DSP digital signal processing unit, a communication interface circuit and an optical switch array, wherein the broadband light source outputs broadband light, the wavelength range covers 1510-1590 nm, the light source driving realizes constant current driving and constant temperature control of the broadband light source, normal operation of the broadband light source is guaranteed, the output light intensity of the broadband light source is controlled in a digital mode through the DSP, the light output by the broadband light source enters the optical switch array through a circulator and is measured in a time-sharing mode through a time-division multiplexing mode, and the reflected light from the fiber bragg grating sensor enters the spectrum analysis module through the circulator.
6. The composite material strain test system of claim 5, wherein the spectrum analysis module converts an optical signal output by the sensor into an imaging element voltage signal, the optical signal enters the spectrum analysis module and irradiates on the bulk grating after passing through the collimating lens, the refraction angles of the light with different wavelengths are different after passing through the bulk grating, the light with different wavelengths is finally projected to different positions of the linear detector, the light with different wavelengths is received by pixels at different positions of the linear detector, the purpose of spectrum measurement is finally achieved, the temperature sensor is built in the CCD chip and used for carrying out temperature compensation on the wavelength signal measurement, the AD converter converts the voltage output by the spectrum analysis module into a digital quantity, the FPGA control unit is used for realizing driving control of the spectrum analysis module and controlling the AD converter to realize acquisition of the pixel voltage signal, the DSP digital signal processing unit acquires pixel information collected by the FPGA, a plurality of pixel voltage values corresponding to each sensor are intercepted, the spectrum center wavelength value corresponding to each sensor is calculated by fitting the pixel voltage values, the temperature value is calculated according to a calibration curve of the sensor, and the wireless communication module is used for finally outputting the measurement result to the data coding unit.
7. The composite strain testing system of claim 4, the power supply portion comprising an EMI filter and protection circuit, a DC/DC module, and an output filter circuit.
8. The self-calibration method of the composite material strain testing system comprises the steps of S1, initially positioning, enabling infrared rays to meet at one point through symmetrically arranging fiber bragg grating sensors when a propeller is static, S2, detecting deviation, namely detecting that the sensor is deviated when the intersection point deviates, S3, automatically adjusting, driving a shape memory alloy wire and a flexible hinge to finely adjust when the horizontal deviation exceeds the limit until the intersection point returns, S4, detecting damage, namely forming a conductive path when a built-in hollow glass bead of a failure alarm breaks, triggering damage alarm at the moment, and prompting that the sensor is damaged to be replaced.

Description

Composite material strain testing system and method for self-calibration of propeller Technical Field The invention relates to the field of propeller material strain detection, in particular to a composite material strain testing system for self-calibration of a propeller. Background The large-deformation composite propeller is used as a core component of marine engineering equipment and a ship propulsion system, and the dynamic strain performance of the large-deformation composite propeller has important significance for guaranteeing navigation efficiency, reducing energy consumption and improving structural safety. The accurate acquisition of dynamic strain data of the propeller in actual operation is a key premise for optimizing design, evaluating service life and ensuring reliable operation. However, the current testing technology faces a plurality of bottlenecks in practical application, and severely restricts the development of the related field. In a laboratory environment, the high-speed shooting and laser Doppler measurement technology can capture the deformation characteristics of the propeller more accurately by virtue of the advantages of high-precision and non-contact measurement. The techniques rely on stable environments and controllable conditions provided by specific facilities such as circulating water tanks and the like, and deformation measurement is realized through tracking characteristic points of the surface of a propeller or analysis of Doppler frequency shift. However, limitations of these methods are not revealed when the scene is switched to a lake test or a sea test. The openness and complexity of the field environment make the fixed measurement facilities difficult to deploy, and the factors such as natural water flow, unstable illumination conditions and the like lead to the image quality of high-speed shooting to be difficult to guarantee, and the signals of laser Doppler measurement are also easily disturbed and interrupted. Therefore, in lake test or sea test, these laboratory techniques cannot be effectively implemented, so that dynamic strain data of the propeller under real working conditions is almost blank, and accurate evaluation and optimal design of actual performances are seriously affected. When the strain gauge is adopted for testing, strain information can be obtained to a certain extent, but each strain gauge needs to be connected to data acquisition equipment through independent cables, so that the number of measuring points is limited physically (excessive cables can lead to complex installation and difficult maintenance, the risk of signal mutual interference is increased), and the requirement of the large-deformation composite material propeller on multi-point and high-density strain monitoring is more difficult to meet. In the deep sea environment, the sensor is easy to shift to influence the detection accuracy, the existing system depends on manual calibration, the installation deviation and the environmental disturbance cannot be compensated in real time, the efficiency is low, the sensor failure lacks effective early warning, global data distortion is often caused by single-point faults, and the maintenance cost is high. Disclosure of Invention The invention mainly aims to provide a self-calibration system and a self-calibration method for a laminated symmetrical linear FGB sensor for testing the strain of a propeller composite material, which are characterized in that the self-calibration system of the laminated symmetrical linear FGB sensor, the test equipment is arranged at the tail part of the propeller, and dynamic performance detection is carried out in the synchronous rotation process of the test equipment and the propeller in a mode that the surfaces of the test equipment are linearly arranged and the gratings are symmetrically attached in space. The propeller blade is made of composite materials, the sensor and the optical fiber are embedded on the blade, the accuracy of dynamic performance detection is guaranteed, and the method aims to provide an efficient, accurate and reliable technical means for dynamic strain testing of the large-deformation composite material propeller and promote technical progress and engineering application in the related fields. A composite material strain testing system for propellers comprises an optical fiber grating sensor array and an optical fiber demodulator, wherein the optical fiber grating sensor array can sense strain and temperature and convert the change into central wavelength change of the optical fiber grating, the optical fiber demodulator is arranged in a propeller hub and can collect and demodulate spectrum signals, the wavelength of the optical fiber grating is analyzed to obtain structural strain and temperature change of the propellers, the optical fiber grating sensor array is linearly arranged along the surface of each blade in a fitting way, more than 5 single optical fiber grating sensors on