WO2023004760A1 - 一种可变范围的温度补偿光纤应变仪 - Google Patents

一种可变范围的温度补偿光纤应变仪 Download PDF

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WO2023004760A1
WO2023004760A1 PCT/CN2021/109641 CN2021109641W WO2023004760A1 WO 2023004760 A1 WO2023004760 A1 WO 2023004760A1 CN 2021109641 W CN2021109641 W CN 2021109641W WO 2023004760 A1 WO2023004760 A1 WO 2023004760A1
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optical fiber
strain gauge
temperature
strain
fiber strain
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PCT/CN2021/109641
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English (en)
French (fr)
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F·欧莱特
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F·欧莱特
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Priority to PCT/CN2021/109641 priority Critical patent/WO2023004760A1/zh
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet

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  • the invention relates to an optical fiber sensor, in particular to an athermal optical fiber strain gauge.
  • Strain gauges are ubiquitous tools in many applications such as: weighing, stress analysis, force sensing, pressure sensing, etc.
  • the most widely used technology for strain sensing is the resistive strain gauge, which is based on a pattern of printed electrodes on a plastic film substrate, which changes resistance when stretched.
  • Resistance strain gages are inexpensive and perform well, but are delicate to install and operate. The small resistance changes to be measured require sophisticated electronics, and the measurement is sensitive to disturbances and resistance changes in the wires running through the gage. They are also temperature sensitive and a number of techniques can be used to reduce this dependence.
  • Fiber Bragg Grating is a short length of optical fiber imprinted with a longitudinal periodic perturbation of the refractive index that reflects light in a narrow bandwidth around a specific wavelength (the Bragg wavelength).
  • FBG Fiber Bragg Grating
  • stretching or compressing the fiber section containing the FBG affects this period and causes a shift in the Bragg wavelength, which can be detected by various methods.
  • a feature of fiber grating sensors is that wavelength division multiplexing can measure multiple sensors along one fiber by making each sensor have a different Bragg wavelength. Most applications of FBG strain sensors have used this approach so far.
  • a typical resistance strain gauge has a measuring range of 2000 to 5000 ⁇ .
  • a strain of 5000 ⁇ causes a shift of 6048pm in the Bragg wavelength and a stretch of 0.4% in the fiber.
  • the typical operating temperature range of -20 to 50°C also results in a wavelength shift of about 700pm.
  • any sensor should be allocated a spectral bandwidth of at least 7nm to avoid overlapping with sensors at other wavelengths. Since typical light sources used by commercial interrogators are in the 40-50nm range, this limits the number of sensors to around seven. This is sometimes done to compensate for temperature if a second set of FBGs is used to measure temperature because of the temperature dependence of the strain sensor. They also take up valuable bandwidth and further limit the number of sensors in an instrument, which in turn increases the cost of measurement per sensor.
  • FBG strain sensors Another problem with FBG strain sensors is their dependence on temperature. Many schemes for temperature compensation have been proposed.
  • the FBG can be fixed on a mount where an optical fiber is attached to two different materials with different thermal expansion coefficients that expand in opposite directions so that an increase in temperature causes tension on the optical fiber Weakening, the tension applied to the fiber by the thermo-optic effect cancels the wavelength shift due to the expansion of the fiber and its change in refractive index, US Patent No. 5,042,898 discloses such a device.
  • US Patent 7116846 proposes a similar solution using aluminum and Invar.
  • a geometric arrangement for a pressure sensor is also proposed in US Patent 790,072.
  • Patent WO2009128040 describes a similar athermal sensor with a mechanism to amplify the strain response.
  • European Patent 2295946 describes an athermal strain sensor with a cantilever-like segment arrangement using a single cantilever segment made of a different material than the support material on which the strain is measured. All of these techniques use a combination of materials with high and low coefficients of thermal expansion to eliminate temperature-induced shifts. Another major technique proposed is to measure temperature using a second FBG that is not affected by strain, as proposed in US Patents 8,282,276 and 6,668,105.
  • Patent WO2009128040 actually makes the problem worse by amplifying the strain sensitivity.
  • the reason is that most commercial FBG sensor interrogators have a limited fixed resolution of about 1pm.
  • a typical resistance strain gauge has a typical resolution of 0.01% of its measurement range, which corresponds to a strain of 0.5 ⁇ for a range of 5000 ⁇ and a wavelength shift of 0.41 pm. Therefore, even with a maximum range of 5000 ⁇ s, commercial interrogators cannot achieve a resolution that matches that of typical resistive strain gauges. The problem is even worse for smaller ranges (eg 2000 ⁇ ) since they require 0.16pm resolution.
  • a prior art invention (US Patent 9810556) describes a different method of measuring FBG sensors. Using this method, the light source does not sweep the wavelength spectrum, but instead emits a fixed pair of wavelengths spaced apart by a fraction of the FBG's spectral bandwidth.
  • This technique has recently been called “Dual Wavelength Differential Detection” (DWDD), and we will use that acronym here.
  • DWDD ual Wavelength Differential Detection
  • the measurement range is limited by the FBG bandwidth. Therefore, in that case, a larger bandwidth is preferred, while for the spectral scanning measurement method, a smaller FBG bandwidth is preferred due to its increased resolution.
  • the spectral bandwidth of the FBG is inversely proportional to the bandwidth, so in this case, a shorter FBG can be used. According to experience, the bandwidth of 1mm long FBG is about 1000pm. FBG sensing systems typically use 10 mm long FBGs with a bandwidth of about 100 pm.
  • DWDD technology uses time-division multiplexing instead of wavelength-division multiplexing to simultaneously interrogate multiple identical sensors.
  • the sensor can be along a single fiber, but can also be in multiple parallel fibers, and the performance of the two solutions is similar.
  • the cost of an interrogator using DWDD can be very low since the light source is a single inexpensive commercial laser diode and the circuit uses widely available electronic components for signal digitization and processing.
  • the resolution can be less than 0.01% of the measurement range, ultimately limited to around 0.02pm. Therefore, even with a resolution of 0.1pm, a 1000pm range equivalent to 827 ⁇ s provides a resolution of 0.01%, similar to a resistance strain gauge.
  • a strain gauge design is therefore required that has two functions: (1) subject the FBG to only a fraction of the strain measured by the entire strain gauge; (2) perform temperature compensation to Eliminates measurement ranges caused by temperature-induced wavelength shifts. Since temperature compensation is rarely 100%, allowing a second FBG for temperature measurement is also a desirable feature.
  • the present invention adopts the following technical solutions.
  • the invention discloses a non-thermal optical fiber strain gauge, comprising:
  • the two ends are respectively provided with attachment points for fixing on the tested material
  • the detection part is located between the two end parts, and the height of the detection part is smaller than the height of the two end parts;
  • the detection part is sequentially provided with a first part and a second part;
  • the first part is provided with a passage part
  • the second part is provided with a cantilever beam section, and the size of the cantilever beam section is smaller than the size of the passing part;
  • the detection part is also provided with a fiber Bragg grating sensor and a second sensor for measuring strain;
  • the strain-measuring Fiber Bragg Grating sensor and the second sensor are located between two attachment points;
  • the fiber Bragg grating sensor and the second sensor for measuring strain are located on both sides of the cantilever beam section.
  • the second sensor is a fiber Bragg grating.
  • a third portion is also provided, the second portion being disposed between the first portion and the third portion.
  • the third portion includes one or more components, and the third portion has a cross-sectional area smaller than the cross-sectional areas of the first and second portions.
  • the end material is the same material as the material to be tested or a material with higher rigidity than the material to be tested.
  • the material of the cantilever beam section has a higher coefficient of thermal expansion than the material of the first section
  • the material of the first part is the same as that of the two end parts.
  • a seal having a structure to allow passage of the optical fiber.
  • the space between the two ends is filled with waterproof sealant.
  • the cross-sectional areas of the first part and the second part are determined according to preset calculation rules.
  • An athermal fiber optic strain gauge of the present invention enables the second FBG to be used for temperature sensing, while being easy to manufacture and assemble, and very compact.
  • the present invention can change the measurement range by changing the overall size or only the size ratio of its internal parts, keeping the same overall length and using the same standard design for the FBG itself.
  • it is possible to achieve performance and form factors similar to commercial resistive strain gauges, with other inherent advantages of fiber optic sensors, such as resistance to electromagnetic interference and insensitivity to changes in lead resistance.
  • the FBG of the present invention has a short length and a small maximum strain, which greatly reduces the possibility of fiber breakage, improves long-term reliability, eliminates the need for recoating the FBG as much as possible, and simplifies the manufacturing process. Standardization of the FBG design of all gauges of the present invention, including their length and period, also facilitates mass production, thereby helping to reduce manufacturing costs.
  • Figure 1 shows the general schematic of the structural strain reduction
  • Figure 2 shows the general schematic for temperature compensation using two materials with different thermal expansion coefficients
  • Fig. 3 shows a kind of non-thermal optical fiber strain gauge of the present invention
  • Figure 4 shows an arrangement of the present invention with multiple sensors along an optical fiber
  • FIG. 5 shows the structural diagram of another embodiment of a non-thermal optical fiber strain gauge of the present invention.
  • the sensor assembly in order to maintain the desired strain range of the Fiber Bragg Grating sensor while allowing a larger strain range for the entire strain gauge, the sensor assembly should be constructed so that the strain distribution in different parts of the assembly is uneven and the FBG sensor Mount to parts with less strain. This is possible because the material strain caused by an applied longitudinal force is a function of its Young's modulus and cross-section according to the well-known formula:
  • the second component is to incorporate temperature compensation.
  • the cantilever beam segment is connected at the other end to the first on a material.
  • the cantilever segment expands to the left because it is free to move in that direction, and the overall expansion of the support material moves the right end of the cantilever segment to the right by an equal amount.
  • Thermal expansion of the support material results in a decrease in tension on the fiber, which can result in a shift in the Bragg wavelength equal and opposite to that normally caused by temperature changes.
  • the formula for the ratio of the length L of the cantilever section section L to the length L can be derived for perfect temperature compensation:
  • ⁇ f is the thermal expansion coefficient of the fiber and ⁇ ⁇ is the stress optics coefficient of the fiber.
  • the thermal expansion coefficients of the support material and the cantilever beam section material are ⁇ M and ⁇ B , respectively.
  • FIG. 3 shows a structure diagram of an athermal optical fiber strain gauge of the present invention.
  • the present invention discloses a non-thermal optical fiber strain gauge, comprising:
  • the two ends 1 and 2 are respectively provided with an attachment point 3 for fixing on the tested material 4;
  • the height of the detection part is smaller than the height of the two end parts
  • the detection part is sequentially provided with a first part 5 and a second part 7;
  • the first part is provided with a passage part
  • the second part is provided with a cantilever beam segment 8, and the size of the cantilever beam segment is smaller than the size of the passing portion;
  • the detection part is also provided with a fiber Bragg grating sensor 12 and a second sensor 13 for measuring strain;
  • the strain-measuring Fiber Bragg Grating sensor and the second sensor are located between two attachment points;
  • the fiber Bragg grating sensor and the second sensor for measuring strain are located on both sides of the cantilever beam section.
  • the length of the two ends (1) and (2) is L e , the width is W e , and the height is He.
  • the end portion acts as an attachment point (3) to the surface of the material M (4) whose strain is being measured and to which it should be bonded or attached by any other means such as brazing, welding or screwing.
  • the central part of the assembly is not in contact with the surface of the material M and is therefore constrained to expand or compress by the ends (1) and (2).
  • the tip is preferably made of the same material as material M, or another material with similar or greater stiffness, that is to say, the tip is made of the same material as the material to be tested or of a ratio The material to be tested has a higher stiffness.
  • the total elongation ⁇ L M of the central portion of a total length L M is the same as the elongation of material M over the same length, and the measured strain is ⁇ L M /L M .
  • the first part (5) has a U-shape, and there is also a space cut off in the center of the first part (6) to allow the optical fiber consisting of the fiber grating sensor to expand or compress freely in its length, so that the compression or expansion will only be affected by the two sides Fiber optic attachment points are limited.
  • the detection part is further provided with a fiber Bragg grating sensor 12 for measuring strain and a second sensor 13, and the second sensor 13 may also be a fiber Bragg grating sensor.
  • the fiber Bragg grating sensor and the second sensor for measuring strain are located on both sides of the cantilever beam section.
  • the detection part is located between the two ends, and the height of the detection part is smaller than the height of the two ends; the detection part is provided with a first part and a second part in sequence.
  • the first part is provided with a passing part, the passing part allows the cantilever beam segment 8 and the fiber Bragg grating sensor to pass through and can enter by means of embedding, etc. There may be a gap between the entering part and the first part.
  • the cantilever beam section is used as a temperature compensation device.
  • the material of the cantilever beam segment has a higher coefficient of thermal expansion than the material of the first portion.
  • the material of the first part is the same as that of the two end parts.
  • the second sensor (13) is a Fiber Bragg Grating sensor.
  • a third part 9 is also provided, and the second part is arranged between the first part and the third part 9 .
  • the third part 9 comprises one or more parts, and the cross-sectional area of the third part is smaller than the cross-sectional areas of the first part and the second part.
  • the second part (7) can be made of the same material as the first part (5), or made of the same or different material as the third part (9), and is mainly used as a U-shaped section ( The opening space of 5) is supported by the structure of the cantilever beam segment (8) extending to the left, so the width and length are slightly smaller than the opening.
  • the material of the section of the cantilever beam section (8) has a higher coefficient of thermal expansion than the material of the section (5).
  • the third part (9) may contain one or more components.
  • the total cross-section A9 of the third part ( 9 ) is smaller than the cross-sections of the first part (5) and the second part (7), and the Young's modulus Y9 is preferably smaller than the cross-section of the first part (5), and the length L 9 makes the product of L 9 /A 9 Y 9 smaller than the sum of the products of L 5 /A 5 Y 5 and L 7 /A 7 Y 7 in the first part (5) and the second part (7).
  • the fiber section includes a Fiber Bragg Grating sensor, and the fiber section is attached to the left end (1) and right to the cantilever beam section section (8), using adhesive or glass solder, or other prior art , to provide strong and stable adhesion with minimal slip and change over time.
  • the fiber optics run outside the mounting structure to the left to connect to the measuring instrumentation and can be cut past the connection point on the cantilever beam section (8) or extended further and have another Bragg grating sensor (13) available in the The right side moves freely, so it only responds to temperature.
  • the optical fiber can also extend to the outside of the right side of the installation structure, where one or more other sensors can be included, and these sensors have similar or different installation structures, as shown in FIG. 4 .
  • a seal is further included, and the seal has a structure allowing the optical fiber to pass through.
  • the whole structure can be closed with a lid closure, the bottom of which can be made of the same material M, the rest covering the structure and having a structure for the passage of optical fibers, without hindering the movement of the central section and without affecting the structure Total elongation under strain.
  • the airtight cover protects the structure inside from adverse environmental elements such as humidity.
  • the gap between the two ends is filled with waterproof sealant.
  • FIG. 5 shows a structural view of another embodiment of an athermal optical fiber strain gauge of the present invention.
  • the length of the two ends (1) and (2) is L e , the width is W e , and the height is He.
  • the ends are used as attachment points (3) for the material M (4) whose strain is being measured and are bonded or attached in any other way (such as soldering, welding or screwing) to the surface on which they are not connected to the material M The contact is thus limited by the expansion or compression of the end parts (1) and (2).
  • the ends are preferably made of the same material as material M. Therefore, under the applied strain, the total elongation ⁇ L M of the central portion of a total length L M is the same as that of material M over the same length, and the measured strain is ⁇ L M /L M .
  • the first portion (5) has a length L 1 and is divided into two sub-parts, one of length L f and the other of length L B .
  • parts (1) and (5) can be cut into U-shaped individual parts from the same material.
  • a cantilever section (7) of length L B made of the same material is attached to the center of the section and protrudes to the left, the cantilever section (8) of the passage between the two side cantilevers of the first section The opening extends, so the width W b is slightly smaller than W o .
  • the width of the cantilever beam segment should be substantially greater than the width of the fiber.
  • the second part (7) and the cantilever beam segment (8) can be cut from a single piece of material and glued to the first part (5) on the left and the right end section (2) on the right, leaving The lower cantilever beam section is free to expand under the influence of temperature changes without itself being affected by the strains affecting the entire structure.
  • the optical fiber is connected to the left end end, on which a V-shaped groove can be cut to guide the position of the optical fiber 14 conveniently.
  • An optical fiber 14 is also attached to the cantilever beam section (10), and a fiber Bragg grating sensor for strain measurement is located between these two attachment points.
  • the connection can be made by adhesive or so-called glass solder or any other method that provides a strong and stable connection. It should be noted that a small hole can also be provided, and the optical fiber can also pass through the small hole, the left end, or the cantilever beam, or both.
  • the cross-sectional areas of the first part and the second part are determined according to a preset calculation rule.
  • the preset calculation rules in the present invention can also be dynamically changed by means of a neural network model.
  • the neural network can be a pre-trained neural network model obtained by training a large amount of historical data and result data, and the specific training method can adopt an existing neural network training method.
  • various parameters of the strain gauge and specific application material parameters can be input into the neural network model, and the data of the cross-sectional area of the first part and the second part can be output.
  • the temperature measuring FBG sensor is represented by (13) in Fig. 5, and its Bragg wavelength should be different from that of the strain measuring FBG sensor.
  • Such additional temperature measurements can be added to ensure more perfect temperature compensation. This is because the thermal expansion coefficients used in equations (5) and (6) typically vary slightly with temperature, and it is impossible to fully eliminate this effect. This does not mean that temperature compensation itself is useless, because one of the functions of temperature compensation is also to reduce the spectral range of the FBG sensor due to the possible operating temperature range.
  • An athermal fiber optic strain gauge of the present invention enables the second FBG to be used for temperature sensing, while being easy to manufacture and assemble, and very compact.
  • the present invention can change the measurement range by changing the overall size or only the size ratio of its internal parts, keeping the same overall length and using the same standard design for the FBG itself.
  • it is possible to achieve performance and form factors similar to commercial resistive strain gauges, with other inherent advantages of fiber optic sensors, such as resistance to electromagnetic interference and insensitivity to changes in lead resistance.
  • the FBG of the present invention has a short length and a small maximum strain, which greatly reduces the possibility of fiber breakage, improves long-term reliability, eliminates the need for recoating the FBG as much as possible, and simplifies the manufacturing process. Standardization of the FBG design of all gauges of the present invention, including their length and period, also facilitates mass production, thereby helping to reduce manufacturing costs.
  • connection refers to two or more, unless otherwise clearly defined.
  • installation means for example, “connection” can be fixed connection, detachable connection, or integral connection; “connection” can be directly or indirectly through an intermediary.
  • connection can be fixed connection, detachable connection, or integral connection; “connection” can be directly or indirectly through an intermediary.

Abstract

一种可变范围的温度补偿光纤应变仪，可以使得第二个FBG用于温度传感，同时易于制造和组装，并且非常紧凑。可以通过改变整体尺寸或仅改变其内部零件的尺寸比例，保持相同的总长度以及对FBG本身使用相同的标准设计来改变测量范围。因此，可以使性能和形状因数类似于商用电阻应变仪，并具有光纤传感器的其他固有优势，例如对电磁干扰的抵抗力以及对引线电阻变化的不敏感性。另外， FBG的长度短且受到的最大应变小，大大降低了光纤断裂的可能性，提高了长期可靠性，并尽可能消除了重新涂覆FBG的需要，简化了制造工艺。所有量规的FBG设计标准化，包括其长度和周期，也有利于大批量生产，从而有助于降低制造成本。

Description

[根据细则91更正 10.09.2021]　一种可变范围的非热式光纤应变仪 技术领域
[根据细则91更正 10.09.2021]　
本发明涉及光纤传感器，尤其涉及一种非热式光纤应变仪。
背景技术
应变仪是许多应用中普遍存在的工具，例如：称重、应力分析、力传感、压力传感等。用于应变传感最广泛的技术是电阻应变仪，该电阻应变仪基于塑料薄膜基板上的印刷电极图案，其拉伸时电阻会发生变化。电阻应变计价格便宜，并且具有良好的性能，但是安装和操作都很精细。要测量的小电阻变化需要精密的电子设备，并且该测量对通向量规的电线中的干扰和电阻变化敏感。它们也对温度敏感，可以使用许多技术来减少这种依赖性。
使用光纤的应变仪也已经存在很多年。主要技术是光纤布拉格光栅(FBG)，它是一小段上面印有折射率的纵向周期性扰动的光纤，可以反射特定波长(布拉格波长)附近窄带宽内的光。因此，拉伸或压缩包含FBG的光纤截面会影响该周期，并导致布拉格波长发生偏移，可以通过各种方法检测到该偏移。
光纤光栅传感器的一个特点是波分复用可以通过使每个传感器具有不同的布拉格波长来测量沿一根光纤的多个传感器。到目前为止，FBG应变传感器的大多数应用都使用这种方案。
另一方面，使用电阻式应变计的单个FBG应变计(单根导线连接到询问器)并不常见。是由于测量设备的成本太高(仅适用于大量传感器而已)以及传感器本身的高成本。然而，具有与电阻应变仪相同性能的光学应变仪将具有明显的优势，因为它具有抗扰性和对电气和电磁干扰的不敏感性。
但是，除了成本以外，基于FBG的应变测量还存在一些问题。典型的电阻应变仪的测量范围为2000至5000με。5000με应变会导致布拉格波长发生6048pm的偏移，并使光纤的拉伸度达到0.4％。此外，-20至50℃的典型工作温度范围也会导致约700pm的波长偏移。这意味着对于波分复用方案，任何传感器均应分配至少7nm的光谱带宽，以避免与其他波长的传感器重叠。由于商用询问器使用的典型光源范围是40-50nm，因此将传感器的数量限制在7个左右。如果使用第二组FBG来测量温度，因为应变传感器的温度依赖性，有时会这样做以补偿温度。它们还将占用宝贵的带宽，并进一步限制了一种仪器的传感器数量，这反过来又增加了每个传感器的测量成本。
其次，必须格外小心以确保光纤具有足够的机械可靠性，以在更长的时间内维持0.4％或更高的拉伸率。FBG的写入过程通常会削弱光纤，而FBG写入之后的步骤或剥皮以及重新涂覆光纤会使制造过程复杂化。存在一些通过光纤涂层写入FBG的技术，但是与未涂层的光纤相比，粘合的涂层光纤随着时间的流逝更容易滑落，这会影响测量。光纤失效的概率也与被 拉伸的光纤长度成正比，对于FBG应变传感器，该长度通常约为10-20mm。
FBG应变传感器的另一个问题是它们对温度的依赖性。目前已经提出了许多用于温度补偿的方案。可以将FBG固定在安装座上，在该固定座上将光纤连接到具有不同热膨胀系数的两种不同材料上，这些材料在相反的方向上膨胀，从而使温度的升高导致对光纤施加的张力减弱，通过热光效应施加到光纤上的张力消除了由于光纤膨胀及其折射率变化而引起的波长偏移，美国专利5,042,898公开了这种装置。美国专利7116846提出了使用铝和殷钢的类似方案。在美国专利790,072中也提出了一种用于压力传感器的几何装置。专利WO2009128040描述了一种类似的无热传感器，其具有放大应变响应的机制。欧洲专利2295946描述了一种具有类似悬臂梁段布置的无热应变传感器，该传感器使用的是由与所测量的应变的支撑材料不同的材料制成的单个悬臂梁段。所有这些技术使用具有高和低热膨胀系数的材料的组合来消除温度引起的偏移。提出的另一项主要技术是使用第二个不受应变影响的FBG来测量温度，如美国专利8,282,276和6,668,105中提出的。
这些专利均未解决与大应变测量范围(例如5000με)相关的问题。专利WO2009128040实际上通过放大应变敏感性使问题变得更糟。原因是大多数商用FBG传感器询问器的固定分辨率有限，约为1pm。但是，典型的电阻应变仪的典型分辨率为其测量范围的0.01％，对于5000με的范围，其对应的应变为0.5με，波长偏移为0.41pm。因此，即使在最大范围为5000μs的情况下，商用询问器也无法实现与典型电阻应变计相匹配的分辨率。对于较小的范围(例如2000με)，问题甚至更严重，因为它们需要0.16pm的分辨率。
现有技术的发明(美国专利9810556)描述了一种测量FBG传感器的不同方法。使用该方法，光源不会扫描波长光谱，而是发射一对固定波长，其间距为FBG光谱带宽的一部分。该技术最近被称为“双波长差分检测”(DWDD)，在此我们将使用该缩写词。使用DWDD技术，测量范围受到FBG带宽的限制。因此，在那种情况下，较大的带宽是优选的，而对于光谱扫描测量方法，由于其提高了分辨率，较小的FBG带宽是优选的。但是，FBG的频谱带宽与带宽成反比，因此在这种情况下，可以使用更短的FBG。根据经验，1mm长的FBG的带宽约为1000pm。FBG传感系统通常使用10毫米长的FBG，带宽约为100pm。
DWDD技术使用时分复用而不是波分复用来同时询问多个相同的传感器。传感器可以沿着单根光纤，但是也可以在多根平行光纤中，两种方案的性能相似。使用DWDD的询问器的成本可以非常低，因为该光源是单个便宜的商用激光二极管，并且该电路使用广泛可用的电子组件进行信号数字化和处理。此外，正如Ouellette等人在2020年所讨论的那样，分辨率可以小于测量范围的0.01％，最终限制为0.02pm左右。因此，即使分辨率为0.1pm，与电阻应变仪相似，相当于827μs的1000pm范围也可提供0.01％的分辨率。另一方面，使用DWDD 技术时，使用具有较宽光谱的FBG传感器，同时导致较大的测量范围，及分辨率的逐渐降低。因此，大约1000pm的范围似乎是一个很好的折衷方案，可以最大程度地提高范围与分辨率的比率，并获得电阻应变仪典型的0.01％分辨率。在这种情况下，所需的1mm长的FBG具有吸引力，因为该较短的长度使测量仪器安装座更加紧凑。
但是，1000pm的范围仅导致827με应变范围。此外，温度引起的位移也需要700pm的范围，因此可用于应变感测的范围仅为127με。为了利用DWDD仪器的高分辨率，因此需要一种应变仪设计，该应变仪设计具有两个功能：(1)使FBG仅承受整个应变仪测得的一部分应变；(2)执行温度补偿，以消除温度引起的波长偏移所导致的测量范围。由于温度补偿很少达到100％，允许第二个FBG进行温度测量也是一个可取的特点。
现有技术存在缺陷，急需解决。
发明内容
为实现上述目的，本发明采用如下技术方案。
[根据细则91更正 10.09.2021]　
本发明公开了一种非热式光纤应变仪，包括：
两个端部，分别设置有附着点用于固定在被测材料上；
检测部，位于两个端部之间，所述检测部的高度小于两个端部的高度；
所述检测部依次设置有第一部分、第二部分；
所述第一部分设置有通过部；
所述第二部分设置有悬臂梁段，所述悬臂梁段尺寸小于所述通过部尺寸；
检测部还设置有测量应变的光纤布拉格光栅传感器和第二传感器；
所述测量应变的光纤布拉格光栅传感器和第二传感器位于两个附着点之间；
所述测量应变的光纤布拉格光栅传感器和第二传感器位于悬臂梁段两侧。
本方案中，包括：
所述第二传感器为光纤布拉格光栅。
本方案中，包括：
还设置有第三部分，所述第二部分设置在第一部分和第三部分之间。
本方案中，包括：
所述第三部分包含一个或多个部件，所述第三部分的截面积小于第一部分和第二部分的截面积。
本方案中，包括：
所述端部材料采用与被测材料相同的材料或采用比被测材料刚度更大的材料。
本方案中，包括：
所述悬臂梁段的材料具有比第一部分的材料更高的热膨胀系数
本方案中，包括：
所述第一部分的材料与两个端部材料相同。
本方案中，包括：
还包括密封件，所述密封件具有使得光纤穿过的结构。
本方案中，包括：
两个所述端部之间的空隙填充满防水密封胶。
本方案中，包括：
所述第一部分和第二部分的截面积根据预设的计算规则确定。
[根据细则91更正 10.09.2021]　
本发明的一种非热式光纤应变仪，可以使得第二个FBG用于温度传感，同时易于制造和组装，并且非常紧凑。本发明可以通过改变整体尺寸或仅改变其内部零件的尺寸比例，保持相同的总长度以及对FBG本身使用相同的标准设计来改变测量范围。因此，可以使性能和形状因数类似于商用电阻应变仪，并具有光纤传感器的其他固有优势，例如对电磁干扰的抵抗力以及对引线电阻变化的不敏感性。另外，本发明FBG的长度短且受到的最大应变小，大大降低了光纤断裂的可能性，提高了长期可靠性，并尽可能消除了重新涂覆FBG的需要，简化了制造工艺。本发明所有量规的FBG设计标准化，包括其长度和周期，也有利于大批量生产，从而有助于降低制造成本。
附图说明
图1示出了结构减少应变的一般原理图；
图2示出了使用两种热膨胀系数不同的材料进行温度补偿的一般原理图；
[根据细则91更正 10.09.2021]　
图3示出了本发明一种非热式光纤应变仪；
图4示出了本发明沿着一条光纤具有多个传感器的布置图；
[根据细则91更正 10.09.2021]　
图5示出了本发明一种非热式光纤应变仪另一实施例的结构图；
图中编号：端部1、端部2、附着点3、被测材料4、第一部分5、第一部分中心6、第二部分7、悬臂梁段8、第三部分9、通孔10、悬梁臂段通孔11、光纤布拉格光栅传感器12、第二传感器13、光纤14。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。
在本发明的描述中，需要理解的是，术语“上”、“下”、“前”、“后”、“左”、“右”、“顶”、“底”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位 或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。
如图1所示，为了保持光纤布拉格光栅传感器的所需应变范围，同时又使整个应变仪具有更大的应变范围，传感器组件的构造应使组件不同部分的应变分布不均，并将FBG传感器安装到应变较小的部分。这是可能的，因为根据众所周知的公式，由施加的纵向力导致的材料应变是其杨氏模量和横截面的函数：
Figure PCTCN2021109641-appb-000001
其中F是力，Y是杨氏模量，A是横截面。因此，如果将给定力施加到结构的两端，该结构包括具有不同横截面的不同部分和不同的杨氏模量，则影响每个截面的应变将不同。此外，根据应变ε＝δL/L的定义，每个部分的伸长率δL取决于其长度。如果将结构附着到材料上，使得结构的总伸长率被约束为等于材料本身的伸长率，则不同的截面将具有不同的伸长率，所有部分的伸长率L T之和等于其附着的材料的伸长率。一个截面相对于总伸长率的伸长率，可以通过考虑沿结构受力相同来发现。用该伸长率除以截面本身的长度，就可以得到该截面所见的应变。该应变与整个结构所见应变的比率。在图1的情况下，对于两种材料，由杨氏模量Y 1、横截面A 1和长度L 1的材料制成的截面1看到的应变相对于总应变的比率为：
Figure PCTCN2021109641-appb-000002
特别是，如果Y 2和A 2小于Y 1和A 1，并且L 2大于L 1，则该比率可以小于1。这可以用固定在另一侧的刚性材料块上的弹性的例子直观地理解。拉出弹性会使它伸展，而块本身几乎不会受到拉伸。使用与图1类似的结构是制作具有应变降低和温度补偿功能的应变仪的第一个基本模块。
第二个组成部分是合并温度补偿。如图2所示，其中，FBG的一端连接到热膨胀系数较低的材料上，而另一端连接到由热膨胀系数较大的材料制成的一端上，该悬臂梁段在另一端连接到第一种材料上。当温度变化量为ΔΤ时，悬臂梁段向左扩展，因为它可以在该方向上自由移动，而支撑材料的整体膨胀使悬臂梁段的右端向右移动了相等的量。支撑材料的热膨胀。沿相反方向的这两个不同的膨胀之间的差异导致光纤上的张力减小，这可以导致布拉格波长的偏移等于和相反于温度变化通常导致的偏移。可以得出悬臂梁段截面L B长度与长度L 1之比的公式，从而实现完美的温度补偿：
Figure PCTCN2021109641-appb-000003
其中，α f是光纤的热膨胀系数，而β ε是光纤的应力光学系数。支撑材料和悬臂梁段材料的热膨胀系数分别为α M和α B。
[根据细则91更正 10.09.2021]　
图3示出了本发明一种非热式光纤应变仪的结构图。
[根据细则91更正 10.09.2021]　
如图3所示，本发明公开了一种非热式光纤应变仪，包括：
两个端部1和2，分别设置有附着点3用于固定在被测材料4上；
检测部，位于两个端部1和2之间，所述检测部的高度小于两个端部的高度；
所述检测部依次设置有第一部分5、第二部分7；
所述第一部分设置有通过部；
所述第二部分设置有悬臂梁段8，所述悬臂梁段尺寸小于所述通过部尺寸；
检测部还设置有测量应变的光纤布拉格光栅传感器12和第二传感器13；
所述测量应变的光纤布拉格光栅传感器和第二传感器位于两个附着点之间；
所述测量应变的光纤布拉格光栅传感器和第二传感器位于悬臂梁段两侧。
需要说明的是，两个端部(1)和(2)的长度为L e，宽度为W e，高度为H e。末端部分作为附着点(3)到材料M(4)的表面，其应变正在测量，并应以任何其他方式(例如钎焊，焊接或拧紧)粘结或附接到其上。组件的中央部分不与材料M的表面接触，因此受端部(1)和(2)约束其膨胀或压缩。端部优选地由与材料M相同的材料制成，或者由具有相似或更大刚度的另一种材料制成，也就是说，所述端部材料采用与被测材料相同的材料或采用比被测材料刚度更大的材料。因此，在施加应变的情况下，总长度为L M的中央部分的总伸长率δL M与相同长度上的材料M的伸长率相同，所测量的应变为δL M/L M。第一部分(5)有一个U形，并且在第一部分中心(6)也有空间被切断，以允许由光纤光栅传感器组成的光纤在其长度上自由膨胀或压缩，这样压缩或膨胀将仅受两侧光纤的附着点的限制。
需要说明的是，在两个端部中间的所有其他部分的高度H略小于H e，以确保其运动不受与下方材料M的摩擦的约束或限制，也就是说，两个端部中间的部分高度要小于端部的高度。其中，检测部还设置有测量应变的光纤布拉格光栅传感器12和第二传感器13，所述的第二传感器13也可以是光纤布拉格光栅传感器。所述测量应变的光纤布拉格光栅传感器和第二传感器位于悬臂梁段两侧。
需要说明的是，检测部，位于两个端部之间，所述检测部的高度小于两个端部的高度；所述检测部依次设置有第一部分、第二部分。其中在第一部分设置有通过部，所述的通过部允许悬臂梁段8和光纤布拉格光栅传感器通过并可以通过嵌入等方式进入，其进入部分可以与第一部分存在间隙。悬臂梁段部分用作温度补偿装置。所述悬臂梁段的材料具有比第一部分的材料更高的热膨胀系数。所述第一部分的材料与两个端部材料相同。
根据本发明实施例，所述第二传感器(13)为光纤布拉格光栅传感器。
根据本发明实施例，还设置有第三部分9，所述第二部分设置在第一部分和第三部分9之间。所述第三部分9包含一个或多个部件，所述第三部分的截面积小于第一部分和第二部分的截面积。
需要说明的是，第二部分(7)可以由与第一部分(5)相同的材料制成，或者由与第三部分(9)相同或不同的材料制成，主要用作在U形截面(5)的开放空间向左延伸的悬臂梁段(8)的结构支撑，因此宽度和长度略小于该开口。悬臂梁段(8)截面的材料具有比截面(5)的材料更高的热膨胀系数。在本实施例中，第三部分(9)可以包含一个或多个构件。优选地，第三部分(9)的总截面A 9小于第一部分(5)和第二部分(7)的截面，并且杨氏模量Y 9优选地小于第一部分(5)的截面，并且长度L 9使得L 9/A 9Y 9的乘积小于第一部分(5)和第二部分(7)中L 5/A 5Y 5和L 7/A 7Y 7的乘积之和。所述光纤截面包括光纤布拉格光栅传感器，所述光纤截面连接在左至端部(1)上，右至悬臂梁段截面(8)上，使用粘合剂或玻璃焊料，或其他的现有技术，以可以提供较强和稳定的附着力，使得随着时间的推移，滑动和变化最小。光纤在安装结构的外部延伸到左侧，以连接到测量仪器，并且可以被切割越过悬臂梁段部分(8)上的连接点，或者进一步延伸，并具有另一个布拉格光栅传感器(13)可以在右侧自由移动，因此其仅对温度有反应。又或者，光纤也可以延伸到安装结构的右侧外部，在此处可以包含一个或多个其他传感器，这些传感器具有相似或不同的安装结构，如图4所示。
根据本发明实施例，还包括密封件，所述密封件具有使得光纤穿过的结构。
需要说明的是，整个结构可以用盖封闭进行封闭，其底部可以由相同的材料M制成，其余的覆盖该结构并具有使光纤穿过的结构，不妨碍中心截面的移动，也不影响结构在应变下的总伸长率。密封盖可以保护内部的结构免受不利的环境因素(例如湿度)的影响。
根据本发明实施例，两个所述端部之间的空隙填充满防水密封胶。
[根据细则91更正 10.09.2021]　
图5示出了本发明一种非热式光纤应变仪另一实施例的结构图。
如图5所示，两个端部(1)和(2)的长度为L e，宽度为W e，高度为H e。端部用作正在测量其应变的材料M(4)的附接点(3)，并以任何其他方式(例如钎焊，焊接或拧紧)粘结或附接到其上它们不与材料M的表面接触，因此受到端部部分(1)和(2)的膨胀或压缩的限制。端部优选地由与材料M相同的材料制成。因此，在施加的应变下，总长度为L M的中央部分的总伸长率δL M与相同长度上的材料M相同，所测量的应变为δL M/L M。
在末端部分之间是三个其他部分，所有其他部分的高度H略小于H e，例如小0.5mm，以确保其运动不受与基础材料M摩擦的约束或限制。这三个部分的总宽度为W。第一部分(5)具有长度L 1，并且被分为两个子部分，一个为长度L f，另一个为长度L B。该部分优选地由与 端部部分和材料M相同的材料制成，并且因此具有杨氏模量Y 1＝Y M。此外，它由两个在中央具有宽度W o的开口的侧面制成。因此，该部分的总横截面为A 1＝(W-W o)H。因此，可以从同一材料中将部分(1)和(5)切成U形的单个部分。
第二部分(7)由不同的材料制成，其杨氏模量Y 2明显较小，并且具有长度L 2，相同的高度H和宽度W，但在中心没有间隙，因此其横截面为A 2＝W H。由同一材料制成的长度为L B的悬臂梁部分(7)附着在该部分的中心并向左突出，该悬臂梁段(8)在第一部分的两个侧悬臂梁之间的通过部的开口中延伸，因此宽度W b略小于W o。悬臂梁段的宽度应实质上大于光纤的宽度。
因此，可以从单块材料中切出第二部分(7)和悬臂梁段(8)，并粘接到左侧的第一部分(5)和右侧的右端端部截面(2)上，剩下悬臂梁截面在温度变化的影响下可以自由膨胀，而本身不会受到影响整个结构的应变的影响。
光纤连接到左端端部，可以在其上切割V形槽以方便地引导光纤14的位置。光纤14也附着在悬臂梁部分(10)上，用于测量应变的光纤布拉格光栅传感器位于这两个附着点之间。可以通过粘合剂或所谓的玻璃焊料或任何其他提供牢固稳定连接的方法进行连接。需要说明的是，还可以设置一个小孔，光纤还可以穿过所述的小孔，穿过左端端部，或者穿过悬臂梁，或者两者都穿过。
根据本发明实施例，所述第一部分和第二部分的截面积根据预设的计算规则确定。
为了实现应变减小和温度补偿，必须根据下列公式选择各截面的尺寸。
为了减小应变，发现软材料将吸收总伸长的很大一部分。光纤截面所承受的应变ε f与材料M所承受的应变ε M之比R s由下式给出：
Figure PCTCN2021109641-appb-000004
这与等式(3)略有不同，因为经受变形的光纤部分L f的长度不同于L 1。为了进行温度补偿，存在一个比率L B/L 1，该比率可以完美地补偿具有热膨胀系数α 2的突出悬臂梁，其端点具有效热膨胀系数α eff的突出悬臂梁和具有热膨胀系数α f的光纤本身的布置，而其应力光学系数为β ε：
Figure PCTCN2021109641-appb-000005
在如图2所示的原理图中，具有由较低热膨胀系数的材料支撑的高膨胀系数悬臂梁，系数α eff简单地是较低膨胀系数的材料的系数。然而，在图3中，部分(5)和(6)的总膨胀受到材料M的膨胀的限制，但是其一部分被部分(6)的软材料吸收。结果，有效膨胀系数 α eff将略小于材料M的有效膨胀系数，并且可以通过以下公式计算：
Figure PCTCN2021109641-appb-000006
需要说明的是，本发明中的预设的计算规则还可以通过神经网络模型的方式进行动态变化。所述的神经网络可以是预先训练好的神经网络模型，通过大量的历史数据以及结果数据进行训练得到，具体的训练方法可以采用现有的神经网络训练方法。在进行第一部分和第二部分截面积计算时，可以将应变仪的各种参数以及具体的应用材料参数输入至神经网络模型中，输出第一部分和第二部分的截面积的数据。
为了更好的说明本发明的实施例，下面针对具体的实施例进行说明。
考虑使用长度为1mm的FBG传感器，该传感器的半峰光谱宽度约为1000pm。对于DWDD测量仪器，对应于有用的测量范围。与应变与波长偏移相关联的规格因子通常为1.21pm/με，因此FBG传感器的应变测量范围为821με。为了在5000με的量规上具有有效范围，以将其用于热膨胀系数α Μ＝15x 10 -6℃ -1且杨氏模量Y M＝180GPa的不锈钢材料，可以使用诸如Tecatron GF-40，这是一种玻璃增强塑料，具有6.5GPa的杨氏模量和热膨胀系数α 2＝40x 10 -6℃ -1。获得一个温度补偿比L B/L 1＝0.47。然后，以下尺寸将提供比率R s＝0.164，以使5000με的范围将在FBG上产生821με的应变以及热补偿：
Figure PCTCN2021109641-appb-000007
对于长度分别为2mm的端部(1)和(2)，如果在第一部分(5)和(6)下留有0.5mm的间隙，则总长度为9mm，而宽度为8mm，总高度为1.5mm。光纤段L f的长度足够大，可以容纳1mm长的FBG。
为了获得具有相同FBG长度的2000με范围，可以对部分(5)和(6)保持相同的总长度L M，而只改变它们的相对长度。在这种情况下，尺寸为：
Figure PCTCN2021109641-appb-000008
可以看到有足够的空间将光纤延伸到其在光束截面上的附着点，以增加第二个FBG传感器的附加长度，该第二个FBG传感器未连接在其右端端部。该温度测量FBG传感器在图5中用(13)表示，其布拉格波长应与应变测量FBG传感器不同。可以添加此类额外的温度测量以确保更完美的温度补偿。这是因为等式(5)和(6)中使用的热膨胀系数通常随温度而略有变化，不可能完全消除此影响。这并不意味着温度补偿本身就没有用，因为由于可能的工作温度范围，温度补偿的功能之一也是减小FBG传感器的光谱范围。
可以想到这种基本设计的变体，所有变体都使用相同的基本原理进行应变降低和温度补偿，并且可能使最终设备或多或少可靠，或多或少紧凑并且或多或少易于制造。长度和其他尺寸的多种组合可以提供所需的R s值以及温度补偿。
[根据细则91更正 10.09.2021]　
本发明的一种非热式光纤应变仪，可以使得第二个FBG用于温度传感，同时易于制造和组装，并且非常紧凑。本发明可以通过改变整体尺寸或仅改变其内部零件的尺寸比例，保持相同的总长度以及对FBG本身使用相同的标准设计来改变测量范围。因此，可以使性能和形状因数类似于商用电阻应变仪，并具有光纤传感器的其他固有优势，例如对电磁干扰的抵抗力以及对引线电阻变化的不敏感性。另外，本发明FBG的长度短且受到的最大应变小，大大降低了光纤断裂的可能性，提高了长期可靠性，并尽可能消除了重新涂覆FBG的需要，简化了制造工艺。本发明所有量规的FBG设计标准化，包括其长度和周期，也有利于大批量生产，从而有助于降低制造成本。
以上所述，仅为本发明较佳的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，根据本发明的技术方案及其发明构 思加以等同替换或改变，都应涵盖在本发明的保护范围之内。
在本发明中，术语“多个”则指两个或两个以上，除非另有明确的限定。术语“安装”、“相连”、“连接”、“固定”等术语均应做广义理解，例如，“连接”可以是固定连接，也可以是可拆卸连接，或一体地连接；“相连”可以是直接相连，也可以通过中间媒介间接相连。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。
在本说明书的描述中，术语“一个实施例”、“一些实施例”、“具体实施例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或特点包含于本发明的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不一定指的是相同的实施例或实例。而且，描述的具体特征、结构、材料或特点可以在任何的一个或多个实施例或示例中以合适的方式结合。
以上所述仅为本发明的优选实施例而已，并不用于限制本发明，对于本领域的技术人员来说，本发明可以有各种更改和变化。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. [根据细则91更正 10.09.2021]
    一种非热式光纤应变仪，其特征在于，包括：
    两个端部，分别设置有附着点用于固定在被测材料上；
    检测部，位于两个端部之间，所述检测部的高度小于两个端部的高度；
    所述检测部依次设置有第一部分、第二部分；
    所述第一部分设置有通过部；
    所述第二部分设置有悬臂梁段，所述悬臂梁段尺寸小于所述通过部尺寸；
    检测部还设置有测量应变的光纤布拉格光栅传感器和第二传感器；
    所述测量应变的光纤布拉格光栅传感器和第二传感器位于两个附着点之间；
    所述测量应变的光纤布拉格光栅传感器和第二传感器位于悬臂梁段两侧。
  2. [根据细则91更正 10.09.2021]
    根据权利要求1所述的一种非热式光纤应变仪，其特征在于，包括：
    所述第二传感器为光纤布拉格光栅传感器。
  3. [根据细则91更正 10.09.2021]
    根据权利要求1所述的一种非热式光纤应变仪，其特征在于，包括：
    还设置有第三部分，所述第二部分设置在第一部分和第三部分之间。
  4. [根据细则91更正 10.09.2021]
    根据权利要求1所述的一种非热式光纤应变仪，其特征在于，包括：
    所述第三部分包含一个或多个部件，所述第三部分的截面积小于第一部分和第二部分的截面积。
  5. [根据细则91更正 10.09.2021]
    根据权利要求1所述的一种非热式光纤应变仪，其特征在于，包括：
    所述端部材料采用与被测材料相同的材料或采用比被测材料刚度更大的材料。
  6. [根据细则91更正 10.09.2021]
    根据权利要求1所述的一种非热式光纤应变仪，其特征在于，包括：
    所述悬臂梁段的材料具有比第一部分的材料更高的热膨胀系数
  7. [根据细则91更正 10.09.2021]
    根据权利要求1所述的一种非热式光纤应变仪，其特征在于，包括：
    所述第一部分的材料与两个端部材料相同。
  8. [根据细则91更正 10.09.2021]
    根据权利要求1所述的一种非热式光纤应变仪，其特征在于，包括：
    还包括密封件，所述密封件具有使得光纤穿过的结构。
  9. [根据细则91更正 10.09.2021]
    根据权利要求1所述的一种非热式光纤应变仪，其特征在于，包括：
    两个所述端部之间的空隙填充满防水密封胶。
  10. [根据细则91更正 10.09.2021]
    根据权利要求1所述的一种非热式光纤应变仪，其特征在于，包括：
    所述第一部分和第二部分的截面积根据预设的计算规则确定。
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