A strain sensing sensitive unit based on a nickel-titanium alloy wire

Abstract

The application provides a strain sensing sensitive unit based on a nickel-titanium alloy wire, which comprises a base material, a plating layer and a micro-slit structure, wherein the base material is a nickel-titanium alloy wire; the application has the advantages that the plating layer is formed on the surface of the nickel-titanium alloy wire, and the nickel-titanium alloy wire after plating is subjected to cyclic loading and unloading training with a maximum strain of 8%, so that the plating layer on the nickel-titanium alloy wire forms a stable micro-slit structure; compared with the prior art, the strain sensing sensitive unit can realize high sensitivity and large strain sensing simultaneously during use, and has important significance for the application field of strain sensing of intelligent systems.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, specifically to a strain sensing sensitive unit based on nickel-titanium alloy wire. Background Technology

[0002] Deformation of structures or materials is extremely critical engineering information. In engineering, deformation information is mainly obtained by placing strain sensors on the surface of the object or embedding them inside the object.

[0003] Existing strain sensors are mostly general sensors, including metal strain gauges, fiber optic strain sensors, capacitive strain sensors, and piezoelectric strain sensors; however, general strain sensors cannot simultaneously achieve high sensitivity and large range strain sensing.

[0004] To address this problem, this invention introduces a novel smart material—nickel-titanium alloy. Nickel-titanium alloy possesses characteristics such as shape memory effect, superelasticity, and high corrosion resistance. Furthermore, the maximum recoverable strain value of nickel-titanium alloy can reach 8%, and its resistance changes with strain, with an intrinsic sensitivity (the ratio of resistance change rate to strain) of approximately 4-5. In addition, the recoverable strain value and sensitivity of nickel-titanium alloy are both higher than those of conventional metal strain gauges (conventional metals have a recoverable strain value <2% and a sensitivity of approximately 2).

[0005] Correspondingly, micro-slit structures can be designed and fabricated on the surface of nickel-titanium alloys. Since the sensitivity of the micro-slit structure is greater than 200, it can achieve the effect of both high sensitivity and large range characteristics during use. Summary of the Invention

[0006] The purpose of this invention is to solve the problems mentioned above, and in this regard, a strain sensing sensitive unit based on nickel-titanium alloy wire is provided.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A strain sensing sensitive unit based on nickel-titanium alloy wire, the strain sensing sensitive unit comprising: a substrate, a coating, and a microslit structure formed by coating the surface of the substrate and cyclic loading and unloading training.

[0009] The strain sensing sensitive unit based on nickel-titanium alloy wire provided by the present invention may also have the following technical feature: the substrate is nickel-titanium alloy wire.

[0010] The strain sensing sensitive unit based on nickel-titanium alloy wire provided by the present invention may also have the following technical features: the nickel-titanium alloy wire is made of near-equiatomic material, and the mass percentage of nickel in the material is 54.5% to 57.0%.

[0011] The strain sensing sensitive unit based on nickel-titanium alloy wire provided by the present invention may also have the following technical feature: the austenitic phase transformation end temperature of the nickel-titanium alloy wire material is less than 15°C.

[0012] The strain sensing sensitive unit based on nickel-titanium alloy wire provided by the present invention may also have the following technical features: the diameter of the nickel-titanium alloy wire is less than or equal to 0.2 mm, and the maximum recoverable strain of the hyperelastic property of the nickel-titanium alloy wire is 8%.

[0013] The strain sensing sensitive unit based on nickel-titanium alloy wire provided by the present invention may also have the following technical features: the resistance of the nickel-titanium alloy wire changes with strain, and its sensitivity is 4 to 5.

[0014] The strain sensing sensitive unit based on nickel-titanium alloy wire provided by the present invention may also have the following technical features: the micro-slit structure is formed by a coating material; the coating material is any one of graphene or copper, zinc, aluminum or other materials with low resistivity.

[0015] The strain sensing sensitive unit based on nickel-titanium alloy wire provided by the present invention may also have the following technical features: the coating material forms a uniform coating on the surface of the substrate by electroplating, and the thickness of the coating is 1 to 10 μm.

[0016] The strain sensing sensitive unit based on nickel-titanium alloy wire provided by the present invention may also have the following technical features: cyclic loading and unloading training with a maximum strain of 8% is performed on the substrate after the coating is obtained, and the cycle is repeated 500 to 1000 times, thereby obtaining the micro-slit structure.

[0017] The strain sensing sensitive unit based on nickel-titanium alloy wire provided by this invention may also have the following technical feature: the strain sensing sensitive unit divides deformation into two stages according to different sensitivities, including:

[0018] First stage: strain < 0.5%, the microslit structure gradually opens, and the overall resistance is determined by the contact resistance of the microslit structure;

[0019] Second stage: strain > 0.5%, the microslit structure has fully opened, and the overall resistance is determined by the resistance of the substrate itself.

[0020] The role and effect of invention

[0021] The strain sensing sensitive unit according to the present invention has a simple structure. It forms a stable micro-slit structure by coating the surface of a nickel-titanium alloy wire and subjecting the coated nickel-titanium alloy wire to cyclic loading and unloading training with a maximum strain of 8%. Compared with the prior art, this strain sensing sensitive unit can achieve both high sensitivity and large strain sensing during use, which is of great significance for the application of strain perception in intelligent systems. Attached Figure Description

[0022] Appendix Figure 1 This is a schematic diagram of the strain sensing sensitive unit based on nickel-titanium alloy wire in an embodiment of the present invention.

[0023] Appendix Figure 2 This is an embodiment of the present invention, showing the cyclic loading and unloading training of a nickel-titanium alloy wire.

[0024] Appendix Figure 3 This is a schematic diagram illustrating the dual-sensitivity characteristics of the strain sensing sensitive unit based on nickel-titanium alloy wire in an embodiment of the present invention.

[0025] Appendix Figure 4 This is a schematic diagram of the dual sensitivity characteristics of the strain sensing sensitive unit based on nickel-titanium alloy wire in an embodiment of the present invention. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the description of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0027] The reference numerals and components involved in the accompanying drawings are shown below:

[0028] 1. Substrate (nickel-titanium alloy wire); 2. Coating; 3. Micro-slit structure;

[0029] <Example 1>

[0030] Appendix Figure 1 This is a schematic diagram of the strain sensing sensitive unit based on nickel-titanium alloy wire in an embodiment of the present invention.

[0031] like Figure 1 As shown, the present invention mainly provides a strain sensing sensitive unit based on nickel-titanium alloy wire, which mainly includes: a substrate 1, a coating 2, and a micro-slit structure 3 formed by coating the surface of the substrate 1 and cyclic loading and unloading training of the coated substrate.

[0032] In this invention, the base material 1 is a nickel-titanium alloy wire; and the nickel-titanium alloy wire 1 is made of a near-equiatomic ratio, containing 56.6% nickel by mass, with a diameter of 0.1 mm, an austenitic phase transformation end temperature of 10°C, and a maximum recoverable strain of 8% due to the superelastic properties of the nickel-titanium alloy wire 1. If the strain exceeds 8%, the nickel-titanium alloy wire will not be able to recover to its initial length.

[0033] Correspondingly, coating 2 mainly involves uniformly depositing the coating material on the surface of substrate 1 through electroplating, forming a coating thickness of 2μm on the surface of substrate 1. The coating material used in this invention is any one of graphene or materials with low resistivity such as copper, zinc, or aluminum, and graphene is preferred as the coating material in this invention.

[0034] Next, after the coating 2 is obtained on the substrate 1, the nickel-titanium alloy wire 1 is subjected to cyclic loading and unloading training.

[0035] Appendix Figure 2 This is an embodiment of the present invention, showing the cyclic loading and unloading training of a nickel-titanium alloy wire.

[0036] like Figure 2 As shown, during the cyclic loading and unloading training of nickel-titanium alloy wire 1, a testing device (a microcomputer-controlled electronic universal testing machine, which is a mature existing device and will not be described in detail here) was used to conduct the cyclic loading and unloading training; the specifics are as follows:

[0037] 1. Set the number of loops to 500;

[0038] 2. Repeat the looping action;

[0039] 3. Entering the loading stage: The nickel-titanium alloy wire rises rapidly under the action of the crossbeam, with a rising speed (i.e., stretching speed) of 12 mm / min;

[0040] The crossbeam rises by 8mm (the gauge length of the specimen is 100mm, and an 8mm tensile length is sufficient to achieve 8% strain).

[0041] 4. Unloading process: The nickel-titanium alloy wire descends rapidly under the action of the crossbeam, with a descent speed of 12 mm / min.

[0042] The crossbeam returns to the 0mm position (due to sensor error, it cannot be directly set to 0mm in the program, but should be set to a number close to zero).

[0043] Therefore, through the above demonstration, it is possible to perform cyclic loading and unloading training on nickel-titanium alloy wire with a maximum strain of 8%, and set the number of cycles to 500, which can make the substrate surface form a stable micro-slit structure 3.

[0044] Appendix Figure 3 This is a schematic diagram illustrating the dual-sensitivity characteristics of a strain sensing sensitive unit based on nickel-titanium alloy wire.

[0045] like Figure 3 In the embodiments of the present invention, the strain sensing sensitive unit can divide the deformation into two stages according to different sensitivities.

[0046] First stage: strain < 0.5%, microslit structure 3 gradually opens, and the overall resistance is determined by the contact resistance of the microslit structure.

[0047] Second stage: strain > 0.5%, microslit structure 3 has fully opened, and the overall resistance is determined by the resistance of the nickel-titanium alloy wire itself.

[0048] Appendix Figure 4 This is a schematic diagram of the dual sensitivity characteristics of the strain sensing sensitive unit based on nickel-titanium alloy wire in an embodiment of the present invention.

[0049] As attached Figure 4 As shown, the first stage is a high-sensitivity, low-strain segment with a sensitivity of 200 and a strain range of 0% to 0.5%; the second stage is a low-sensitivity, high-strain segment with a sensitivity of 5 and a strain range of 0.5% to 8%.

[0050] The role and effect of the embodiments

[0051] The strain sensing sensitive unit according to the present invention has a simple structure. It forms a stable micro-slit structure by coating the surface of a nickel-titanium alloy wire and subjecting the coated nickel-titanium alloy wire to cyclic loading and unloading training with a maximum strain of 8%. Compared with the prior art, this strain sensing sensitive unit can achieve both high sensitivity and large strain sensing during use, which is of great significance to the application of strain perception in intelligent systems.

[0052] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the principle of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A strain sensing sensitive unit based on nickel-titanium alloy wire, characterized in that, include: The substrate is a nickel-titanium alloy wire with a diameter of less than or equal to 0.2 mm and a maximum recoverable strain of 8% under superelastic tensile stress. The coating is formed uniformly on the surface of the substrate by electroplating. The coating material is any one of graphene, copper, zinc, and aluminum, and the thickness of the coating is 1 to 10 μm. as well as The microslit structure was obtained by subjecting the substrate after coating to cyclic loading and unloading training at 8% maximum strain for 500-1000 cycles. The strain sensing sensitive unit divides the deformation into two stages based on different sensitivities, including: Phase 1: Strain < 0.5%, the microslit structure gradually opens, and the overall resistance of the strain sensing unit is determined by the contact resistance of the microslit structure. The sensitivity of the strain sensing unit is 200. Second stage: 0.5% < strain < 8%, the microslit structure is fully opened, the overall resistance of the strain sensing unit is determined by the resistance of the substrate itself, and the sensitivity of the strain sensing unit is 5.

2. The strain sensing sensitive unit based on nickel-titanium alloy wire according to claim 1, characterized in that, The nickel-titanium alloy wire is made of near-equiatomic material, and the mass percentage of nickel in the material is 54.5% to 57.0%.

3. The strain sensing sensitive unit based on nickel-titanium alloy wire according to claim 2, characterized in that, The austenitic phase transformation end temperature of the nickel-titanium alloy wire material is less than 15℃.

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