SUBSTANCE: photoelastic element in plan view has a crosswise shape the frontal surfaces of which, parallel to the direction of applied efforts, are optically flat, and lateral surfaces of the photoelastic element have the constant and/or variable curvature radius.
EFFECT: increase of voltages in the central part of the photoelastic element, improvement of sensitivity of piezoelectric sensors due to the use of these photoelastic elements.
Area of technology
The invention relates to test and measurement technology, in particular to measure the deformation (strain) in various designs by means of polarization-optical converters, and can be used in construction, transportation, industrial production, control and measuring equipment.
The level of technology
Photoelasticity effect (piezooptical effect) is used for precision measurement of strain (or stress). Anisotropic mechanical stresses in the material lead to anisotropic change of refractive index (birefringence). This changes the angle of polarization of the light passing through the material. There are devices called piezooptical converters, which convert the amount of change in polarization angle in the magnitude of an electrical signal proportional to the amount of deformation or strain. It is known that the strain sensors, based on piezoelectric converters, have the greatest sensitivity compared with others, such as sensors based on piezoresistive transducers (Slesinger I. Piezooptical transducers. Measurement technology, 1985, No. 11, pp. 45-48) ).
Piezooptical Converter is �W led optically coupled, polarizer, phase plate, a photoelastic element analyzer and a photodetector. The form of photoelastic element can be different: box, cylinder, truncated cone.
The closest in technical essence to the proposed photoelastic element is a photoelastic element proposed in the patent of Russian Federation №2422786 dated 23.04.2010 and No. 2454642 from 29.03.2011 [2, 3]. In these patents the photoelastic element is in the form of either a cylinder or a truncated cone. Photoelastic element is initially clamped in two mutually perpendicular directions, which makes it work, as in compression and in tension.
The disadvantage of these designs photoelastic element (PE) is that, as shown by calculations and experiments, the voltage in PV is concentrated near the areas of its contact with the load element piezo-optical strain sensor, which fixed the Feh, and fall to the center of the PV, while the light beam of the sensor passes through the Central portion of the FE, i.e. in the region of minimum stress. This leads to a reduction of the sensor sensitivity.
At the same time as a load element, which is fixed Feh, greatly exceeding the dimensions of PV, it is not possible to reduce the dimensions of the piezo-optical strain gauge and make it miniature.
Disclosure of the Fig�"
The task of the invention is to provide such a form of photoelastic element, which will provide the increase of stresses in the Central (working) part of the photoelastic element.
The technical result - improving the sensitivity of PV to the load.
In addition, the use of the proposed PV in piezooptical the strain gauges will improve the sensitivity and accuracy of measurements and reduce their dimensions.
The task is solved due to the fact that known photoelastic element according to the invention has in terms of cruciform shape, the front surface of which is parallel to the direction of the efforts, are optically flat, and the lateral surface of the photoelastic element have a constant and/or variable radius of curvature.
Description of photoelastic element and justification of new signs
Description of the proposed photoelastic element is illustrated by Fig.1, 2, 3.
Fig.1 shows an example of a photoelastic element (PE), which has a cruciform shape, the side surfaces of which have a constant radius of curvature. To determine the effectiveness of this form Feh carried out numerical simulation of elastic stresses arising in the Feh volume of work effort. Originally Feh was elastically compressed in the direction of axes X and Y by the efforts of the Px=Py=87.9 MPa. R�Boxee force was applied along the Y-axis and equal to ΔP y=19.5 MPa. In the simulation varied the value of the "tie" d (see Fig.1) 0 mm, for a circular element with a diameter of 12 mm, to 3.5 mm.
Fig.2(a, b, C, d, e) shows the simulation results for different forms of FE, with the same work force. In the figures 2A-2D shows contours of the magnitude of the voltage difference of Δσ=σx-σy, the magnitude of which is proportional to the electric signal output piezooptical Converter. Numerical values of Δσ are indicated on the figure numbers in MPa. The value of the "frame" in Fig.2A, 2B, 2C, 2G, 2D to 0 mm, 1.13 mm, 1.84 mm, 2.55 mm, 3.26 mm, respectively.
Fig.3 shows the dependence of Δσ on the depth "tie-d. From the figures it is seen that as the "tie-in" voltage (with the same working force) shifted from the periphery of the PE to its center, i.e. in the area where the light beam piezooptical Converter. For example, to form Feh, shown in Fig.2G (depth "tie" is 2.55 mm, the radius of a "tie" is 5 mm, the diameter of the whole PV 12 mm) increase in Δσ compared to round Feh is 32%. Thus confirmed the increase in voltage, and hence the output signal piezooptical Converter with cross Feh. The obtained simulation results are in good agreement with experimental data.
Maximum depth and forms� "frame" is determined by the strength characteristics of the material of photoelastic element.
When placing a Phillips Feh in piezooptical the Converter, the attachment elements can be placed in the spaces between the side surfaces of FE, not exceeding the dimensions of the outer diameter of the PE (the shaded region in Fig.1). Thus, the transverse dimension of the transducer will not exceed the diameter of the PE.
As the material of photoelastic element can be used, for example, fused quartz, having a high damage threshold in compression, which provides high dynamic range measurements of deformations and reliability. In addition, the technology of processing of fused quartz is well developed, which reduces the design strain of the Converter.
Description of the device
Photoelastic element operates as follows.
When the measured load to the photoelastic element along one of its axes, there is additional stress Δσxand Δσyin the Central part of the Feh. As a result there is an additional phase difference of ±Δ between orthogonal polarization components of the beam passed through the photoelastic element. The phase difference caused by birefringence loaded Feh. Phase change of the polarization leads to a change of an electrical signal at the output of the photodetector. In the case of NB�topicscape Converter, it is recorded and processed by the processing unit of the signal. The magnitude of the transducer output signal is proportional to the value of Δσ=Δσx-Δσythat is proportional to the magnitude of the measured voltage (deformation).
Photoelastic element, characterized in that it has in terms of cruciform shape, the front surface of which is parallel to the direction of the efforts, are optically flat, and the lateral surface of the photoelastic element have a constant and/or variable radius of curvature.
SUBSTANCE: invention relates to aircraft engineering, particularly, to aircraft condition field monitoring systems. The aircraft structure technical state monitoring system contains sensors of technical condition of helicopter blades of an oar or airplane outer wing panels and onboard recorder unit. On each helicopter blade of an oar or airplane outer wing panel there are not less than two fibre-optic Bragg grating strain sensors and not less than two vibroacoustic sensors. The system includes fibre-optic trunk cables, optical connectors, electric control buses, optical switches, fibre-optic measuring lines. Helicopter monitoring system additionally comprises optical rotating connector. The recorder unit contains reference signal unit, fibre-optic switching unit, light source unit, spectrum analysis unit, control and data analysis unit, data storage unit, The recorder unit has electric control signal input/output and electric power supply input, electric power supply unit. Strain sensors and vibroacoustic sensors are imbedded into the mass of composite material in top-loaded parts of helicopter blades of an oar spars and airplane outer wing panels.
EFFECT: possibility to monitor technical condition of blade spars and outer wing panels made of composite materials in manufacturing and in service.
4 cl, 5 dwg
FIELD: measurement technology.
SUBSTANCE: invention refers to measurement equipment and is applied to determine mechanical stress in surface layer of an object. Method involves direction of unfocused visible range radiation flow of any intensity onto the test surface and registration of reflected flow by photodetector, comparison of the result with reference value obtained with known mechanical stress, temperature and surface layer roughness values for this radiation source. Stress gauge includes laser, defocusing devices for beam directed onto the test surface and focusing devices for flow reflected by the surface; photodetector of reflected signal; photodetector signal amplifier; comparator comparing voltage supplied by the amplifier with variable voltage of generator and generating voltage pulse; AND circuit encoding comparator pulse to short pulse string of reference frequency generator; temperature measurement unit; test surface roughness measurement unit; reference code storage device; digital comparator comparing signal obtained from the test surface with reference signals obtained with definite temperature and roughness; indicator displaying stress value for the test surface.
EFFECT: voltage determination in surface layer of examination object.
2 cl, 2 dwg
FIELD: measuring instrumentation.
SUBSTANCE: strain-gauge sensor includes loading element in the form of a hollow cylinder attached to the monitored object, pieso-optic converter converting tension value in stress-optical element attached in preloaded state into electrical signal, and signal processing unit. Optic axis of pieso-optic converter coincides with the cylinder axis and is perpendicular to measured deformation plane, loading element is a continuous hollow cylinder out of tensile material with wall thickness ensuring required elasticity of loading element in direction of deformations measured and determining sensitivity of strain-gauge sensor sealed at the ends and featuring hard lugs on the outside for attachment of the sensor to a monitored object and transmission of object deformation to stress-optical element.
EFFECT: enhanced functional capabilities of device.
9 cl, 14 dwg
FIELD: measuring instrumentation.
SUBSTANCE: strain-gauge converter includes loading element attached to the monitored object, pieso-optic converter converting tension value in stress-optical element attached in preloaded state into electrical signal, and signal processing unit. Loading element is a plate with cylindrical hole where stress-optical element of cylindrical form is clamped adjustably in direction of measured deformations by two rods made of material with thermal expansion factor larger than respective factor of the plate. Rod length is designed so as to ensure independence of preloading compression from temperature.
EFFECT: enhanced measurement accuracy, simpler device design.
7 cl, 3 dwg
SUBSTANCE: invention relates to the system of "smart" cable for bridge with the use of built-in sensors based on fibre Bragg gratings (FBG) and can be used in cable load-bearing structures of cable, suspension, arched and other types of bridges. System comprises anchor glass, plate for separating wires, connecting clutches, sensor based on fibre diffraction grating and cable itself. Sensor based on fibre diffraction grating comprises strain gauge 9 with fibre diffraction grating and temperature sensor with fibre diffraction grating. The ends of optical fibres of strain gauge 9 and temperature sensor are led outwards. Assembled strain gauge 9 is rigidly connected with the steel wire in the connection coupling. Assembled temperature sensor is suspended on the steel wire in the connection coupling. Openings are punched in the plate to separate wires. Protective steel tube is dipped in advance in the front part into the connecting sleeve and anchor glass.
EFFECT: system improves survival of sensors and optic fibre during manufacture and operation of cable, provides reliable sealing of sensors and permits to transmit signals effectively and accurately from fibre diffraction gratings outward from cable.
SUBSTANCE: problem is solved by designing a fibre-optic pressure sensor, having a housing with two tubular elements, having at least one plugged end, mounted in the housing such that the second end of the first tubular element is connected to the housing and is linked with a channel for feeding working medium, and the second end of the second tubular element is open and linked with the inside of the housing through which is passed an optical fibre with two Bragg gratings, attached by areas with the Bragg gratings directly to the outer cylindrical surface of the tubular elements such that one of the gratings is located on the first tubular element and the second grating is located on the second tubular element. The problem is also solved by mounting the second tubular element to the inner wall of the housing and by mounting the second tubular element to the inner wall of the housing coaxially to the first tubular element. The tubular elements are made of the same material and have identical geometrical dimensions. The problem is also solved directing portions of the optical fibres equipped with Bragg gratings along the edge of the cylindrical surface of the tubular elements. The disclosed design of the fibre-optic pressure sensor enables to solve the problem of quality and reliable measurement of pressure of working medium of remote objects with transmission of information over a fibre-optic link for long-term operation, up to several years, without intermediate maintenance and adjustment procedures.
EFFECT: simple design of a fibre-optic pressure sensor, assembly thereof and avoiding the need to adjust sensor elements thereof during assembly, smaller size of the sensor and high reliability and accuracy of measuring pressure.
6 cl, 3 dwg
FIELD: engines and pumps.
SUBSTANCE: proposed system comprises light source to transmit light onto shaft surface via multiple optic fibres made at multiple points nearby said surface in, in fact, axial direction between the ends of at least one shaft, high-temperature reflection probe built around fibre bundle to detect light reflected from shaft surface and mechanism to measure torque or oscillation at the shaft. The latter comprise coding mechanism composed of changed texture shaped to wedge-like groove on shaft surface of variable depth. Said depth generates the front and rear working point signals so that appropriate time delay can be detected from whatever two positions of said groove for determination of shaft twist angle by differentiation of reflection pattern characteristics during every rotation cycle.
EFFECT: higher precision of measurements.
23 cl, 24 dwg
FIELD: measuring equipment.
SUBSTANCE: invention belongs to fibre-optical sensors and can be used for check and measurement of parameters of voltage. The fibre-optical sensor of spiral structure is the multi-turn spiral element created by a spring wire. The set of a teeth of deformation is continuously distributed on the top surface and the bottom surface of a spring wire in the longitudinal direction along a spring wire; in two adjacent turns of the spring wire the deformation teeth on the bottom surface of the top turn of the spring wire and deformation teeth on the top surface of the bottom turn of the spring wire are arranged in staggered order to each other. An alarm optical fibre is clamped between deformation teeth on the bottom surface of the top wire of the spring wire and deformation teeth on the top surface of the bottom turn of the spring wire and is connected to the test facility by the optical fibre of transfer.
EFFECT: increase of accuracy of measurement.
10 cl, 10 dwg
FIELD: measuring equipment.
SUBSTANCE: invention belongs to area of instrumentation and can be used for creation of distributive systems of measurement of temperature and deformation. The Brillouin system for tracking of temperature and deformation contains one - or bilateral fibre with a set of fibre Bragg gratings (FBG) on different lengths of waves and a laser system with the setting excitation, adjusted in a range essentially bigger, than Brillouin shift. FBG are distributed along the length of the placed fibre and serve as chosen reflectors of length of the wave, allowing to support operation of the device even in case of a rupture of fibre.
EFFECT: increase of accuracy and reliability of these measurements.
7 cl, 4 dwg
SUBSTANCE: invention is referred to electric cable with in-built strain-gage fit specifically to measure static and dynamic deformations, in particular, bending strain. Method of bending strain control for electric cable includes stages of the cable equipment with peripheral and mechanically unsymmetrical bearing element having higher resistance to tensile loads than to compression ones and with fibre-optical sensor.
EFFECT: invention provides for high duty cables, in particular, in mobile units, controllability and traceability of bending strain area.
9 cl, 15 dwg
FIELD: measurement technology; electric-power industry; geological prospecting; aircraft industry.
SUBSTANCE: device can be used for inspecting deformations in big structures, for measuring temperature modes of transformers and temperature distributions along wells and for checking structural deformations in flying vehicles. Device has comparator, pulse former and pulse sampling unit for selecting optical pulses after they were reflected from reference point. As reference points the optical connectors are used mounted among sections of fiber-optic cable, which is used as measuring transformer. Selected pulses run auto-oscillating mode through positive feedback circuit. Oscillation repetition period defines delay in propagation of optical signal to selected reference point. Changes in temperature and influence of mechanical stresses resulting to deformation of optical fiber change refraction factor of material of optical fiber core. Due to change in refraction factor the delay of optical signal changes. Value of temperature or value of deformation acting on any section of measuring transformer are determined by change in delay of optical signals from any reference point.
EFFECT: simplified design; improved precision; widened dynamic range of operation.
FIELD: measurement technology.
SUBSTANCE: sensor has tactile part and image forming aid. Tactile part of sensor has transparent flexible case and many groups of markers disposed inside flexible case. Any group of markers is made of many dyed markers. Markers composing different groups have different color in any group. Behavior of dyed markers is photographed by means of image forming aid in case when object touches flexible case. Different groups of markers preferably have different spatial disposition. Measurement is carried out by means of multi-channel reading-out which uses color or optical spectrum for tactile optical sensor to get info for many degrees of freedom at any point on surface.
EFFECT: improved precision of measurement.
33 cl, 21 dwg
FIELD: measuring technique.
SUBSTANCE: deformation measuring aid has at least one light guide for supplying light from wide band light source or at least from one narrow band light source to case and removal of light away from case to optical signal reception and processing unit. Case of detector is capable of resilient twisting. There is light polarization aid in case and/or outside case. At least one end of light guide is disposed in case. It forms at least one light radiator, supplied to case, and at least one light receiver for removal light away from case. There is polarizer in case, which polarizer is disposed in series behind radiator and receiver and is motionless connected with case. Plane of polarization of polarizer is oriented at angle to plane of light polarization. There is mirror behind polarizer. Optical signal receiving and processing unit provides procession of light reflected from mirror, and measurement of deformation of twist. Selective light reflector is disposed between end of light guide and polarizer. Selective light reflector is motionless connected with case to provide reflection of second part of wide band light spectrum or second part of light spectrum from second narrow band light source, differing from first part of wide band light spectrum or from first part of narrow band first light source reflected by mirror. Longitudinal-lateral deformation and/or vertical deformation (compression-extension deformations), twist deformations and/or curve deformations can be measured simultaneously.
EFFECT: widened functional abilities of deformation detector; simplified process of manufacture; improved reliability of detector.
44 cl, 4 dwg
SUBSTANCE: invention concerns polymer material displaying optically detectable response to load (pressure) change, including polyurethane elastomer adapted for load change detection, containing aliphatic diisocyanate, polyol with end hydroxyl, and photochemical system including fluorescent molecules for distance probing, modified and transformed into chain-extending diols, with molar diol to polyol ratio approximately within 10:1 to 1:2 range, and photochemical system selected out of group of exciplex and fluorescence resonance energy transfer (FRET) systems. The invention also concerns solution containing the said polymer material, and polymer material displaying detectable response to pressure change, including polyacryl or silicon elastomer and photochemical system including definite number of fluorescent molecules for distance probing, modified for penetration into the said elastomer, selected out of group including exciplex and fluorescence resonance energy transfer (FRET), and solution containing this polymer material. To eliminate oxygen sensitivity in pressure detection the material includes photochemical system selected out of group including exciplex and fluorescence resonance energy transfer (FRET). Systems including these photochemical systems enable fast response to pressure change; in addition, compression of material containing these systems is reversible, therefore elimination of oxygen influence on pressure change detection allows shorter response time and higher sensitivity when the claimed material is used.
EFFECT: increased material sensitivity to loads and reduced sensitivity to oxygen presence.
24 cl, 2 ex, 6 dwg
FIELD: physics, measuring.
SUBSTANCE: invention concerns the electronic technics, in particular, to microelectronics, and can be used at manufacturing of IS crystals and discrete semiconductor devices. The essence of declared expedient of the control of mechanical voltages in structure film - substrate consists in formation between a film and a substrate of the intermediate stratum which is selectively etched through windows in a film of the round shape with formation in a backlash film - substrate of the interference figure reflecting quantity and a direction of a vector of mechanical voltages.
EFFECT: expansion of technical possibilities of method at expense of possibility of control of direction of vector of mechanical voltages.
FIELD: physics; measurement.
SUBSTANCE: present invention relates to a device and method of determining a force vector and can be used in a touch sensor of a robot arm. The optical touch sensor has a sensitive part and photographic unit. The sensitive part comprises a transparent flexible case and several groups of markers, placed inside the flexible case. Each group of markers contains several coloured markers and the markers, which make up different groups, have a different colour in each group. The flexible case has an arbitrary curved surface. Behaviour of the coloured markers when an object touches the curved surface of the flexible case is interpreted as information about the markers in form of an image using the photographic unit. The sensor also has a device for reproducing force vector distribution, meant for reproducing the force applied to the surface, based on information on the behaviour of markers, which is obtained based on the given information on markers in form of an image.
EFFECT: design of an optical touch sensor with an arbitrary curved surface, which allows for measuring three-dimensional distribution of a force vector, which can be used as a touch sensor for a manipulator (robot arm).
26 cl, 13 dwg
FIELD: measurement technology.
SUBSTANCE: declared invention refers to the measurement of the stress of wall in hollow product. Method of determination of circumferential stress of wall in the hollow product is based on the polarization optical method. When implementing the method the hollow product located in immersion liquid is X-rayed with polarized light. The analysis made of the image of double refraction of polarised light rays from their passing through the mentioned product. Upon the results of the analysis the circumferential stresses in the mentioned product is determined. When determining the circumferential stresses the Y-raying of the hollow product located in the immersion liquid with polarised light is realised from inside of the hollow product, and the analysis of the watched image of double refraction of polarised light rays is made from the their passing through one of the diametrically opposite parts of the mentioned product's wall.
EFFECT: improvement of the measurement accuracy, simplification of construction and expansion of the features.
2 cl, 1 dwg, 1 ex
SUBSTANCE: proposed transducer comprises load secured on controlled element and strain-gage transducer to convert voltage across stress-optical element into electric signal, and signal processing unit. Load is made up of plate to concentrate strain at stress-optical element. Stress-optical element is fixed in said plate as-stressed so that initial stress force acts in two mutually perpendicular directions. Note that stress-optical element is fixed at plate thinned center by means of Morse taper. Note also that, additionally, two mutually perpendicular through cuts are made not corrupting plate integrity, cuts axes being directed at 45° to loads axis. Cuts axes are aligned with that of taper hole for stress-optical element attachment.
EFFECT: higher sensitivity, thermal compensation.
5 cl, 1 dwg
SUBSTANCE: optical fibre structure with Bragg lattices is put into composite material during production thereof. The spectral position of peaks of the Bragg lattices is measured after making the structure from the composite material and distribution of mechanical and thermal deformations inside the structure of the composite material is determined by solving the system of equations: , where f(T,ε) is the distribution function of mechanical and thermal deformations on the structure made from composite material (T is the temperature value, ε is the deformation value); f(Ex, y, z) is the distribution function of elastic properties of the structure made form composite material, Ex, y, z is the Young 's modulus tensor; f(αx, y, z, vx, y, z) is the distribution function of thermal characteristics of the composite material (αx, y, z is the coefficient of volume expansion tensor, vx, y, z is the thermal conductivity coefficient tensor);f(Fload, FT) is the distribution of mechanical and temperature effects on the structure made from composite material (Fload is the value of the mechanical effect, FT is the value of the temperature effect); fFBG(T,ε) is the function of total deformation on the path of the optical fibre with Bragg lattices (T is the temperature value, ε is the deformation value); fi-FBG(Δλ) is shift transformation function of the position of the i-th peak of the Bragg lattice to the temperature value and deformation (Δλ is the displacement of the peak of the Bragg lattice). The optical fibre contains two or more Bragg lattices which are not more than 5 mm long. The distance between the Bragg lattices and one optical fibre is not less than 5 mm.
EFFECT: high measurement accuracy.
3 cl, 15 dwg
FIELD: process engineering.
SUBSTANCE: glass fibre is introduced in composition used for forming controlled object as a material similar to that used as a filler for forming part carcass matrix, that glass fibre allows channeling light beam there through. Note here that glass fibre intact lengths, longer than said part, are used to be arranged to cross paths of probable defect development in part sections not subjected to processing. Occurrence of defect is detected by light beam passage or decreased in emergent light flux brightness.
EFFECT: efficient detection of defects.
6 cl, 1 dwg