A unit cell structure design method and device based on nickel-titanium shape memory alloy

Abstract

The present invention provides a unit cell structure design method and device based on nickel-titanium shape memory alloy, which relates to the field of intelligent materials and structural technology. The present invention collects relevant characteristic parameters of nickel-titanium alloy, generates mechanical performance index, thermal stability index and reliability index, and then calculates the phase change temperature index comprehensively, and corrects the phase change temperature threshold, establishes the geometric shape and bonding method of the unit cell structure, and optimizes the design of the quasi-zero stiffness curved beam, support frame and connection part of the unit cell structure in combination with the corrected phase change temperature threshold. The present invention achieves excellent performance under different phase change states by preprocessing the characteristic parameters of nickel-titanium shape memory alloy, calculating the mechanical performance index and optimizing the unit cell structure geometry, and improves the buffering energy absorption and low-frequency vibration isolation functions of the alloy.

Description

Technical Field

[0001] The present invention relates to the field of intelligent materials and structural technologies, and in particular to a unit cell structure design method and device based on nickel-titanium shape memory alloy. Background Art

[0002] As a smart material, shape memory alloy has the property of being able to recover from one shape to another predetermined shape through phase change at different temperatures. Alloys, commonly known as memory alloys, have been widely used in many fields due to their excellent shape memory effect, superelasticity and corrosion resistance. The martensite-austenite phase transformation of nickel-titanium alloys allows them to automatically adjust their shape when the external temperature changes, thus providing a basis for innovative adaptive structures and devices.

[0003] With the continuous development of science and technology and engineering needs, the demand for intelligent structures and adaptive materials has become increasingly prominent. Especially in the fields of aerospace, robotics, medical equipment, construction engineering, etc., materials are required to automatically adjust their performance according to environmental changes. The unit cell structure design based on nickel-titanium shape memory alloy is precisely to meet this demand. By optimizing the unit cell structure, the adaptability, cushioning and vibration isolation of shape memory alloys can be fully utilized.

[0004] In the traditional unit cell structure design, the mechanical properties, thermal stability and reliability of the structure are often difficult to consider in a unified manner, and it is impossible to accurately adjust the shape change characteristics of the material at different temperatures. In addition, the design of traditional unit cell structures often ignores the influence of the phase change temperature of the material on the structural performance in practical applications. The specific temperature change range cannot be determined, resulting in unstable performance due to temperature changes. The traditional unit cell structure design often does not consider whether the thermal stability and mechanical properties will fail at different temperatures; traditional design often ignores the influence of the phase change temperature of the material on the structural performance, especially the phase change of the material at high or low temperature may cause a sudden change in the performance of the structure, and even cause the failure of the material.

[0005] Therefore, it is necessary to provide a unit cell structure design method and device based on nickel-titanium shape memory alloy to solve the above problems.

[0006] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0007] The purpose of the present invention is to provide a unit cell structure design method and device based on nickel-titanium shape memory alloy to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A unit cell structure design method based on nickel-titanium shape memory alloy, the specific steps comprising:

[0010] Step 1: Collect relevant characteristic parameters of nickel-titanium shape memory alloy, wherein the relevant characteristic parameters include nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate during thermal cycling, and yield strength of the nickel-titanium alloy;

[0011] Step 2: Generate a mechanical property index, thermal stability index, and reliability index related to the nickel-titanium shape memory alloy based on the collected nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate in thermal cycles, and yield strength of the nickel-titanium alloy;

[0012] Step 3: Comprehensively calculate the generated mechanical property index, thermal stability index and reliability index to obtain a phase change temperature index, and set a phase change temperature threshold. Use the obtained phase change temperature index to correct the phase change temperature threshold to obtain a phase change temperature threshold correction value;

[0013] Step 4: Determine the geometry and bonding method of the unit cell structure, and optimize the geometry and dimensions of the unit cell structure in two different states based on the calculated phase change temperature threshold correction value, including adjusting the quasi-zero stiffness curved beam, supporting frame and connection part of the unit cell structure to ensure that ideal performance is provided within the required phase change temperature range. The unit cell structures in the two different states are a martensitic structure and an austenitic structure.

[0014] Further, the mechanical property index, thermal stability index and reliability index related to the nickel-titanium shape memory alloy are generated according to the method:

[0015] The elastic modulus, strain recovery rate and yield strength of nickel-titanium alloy are used to evaluate its mechanical performance index. The mechanical performance index reflects the mechanical stability, load-bearing capacity and plasticity of nickel-titanium alloy. The formula for calculating the mechanical performance index is:

[0016] ;

[0017] in, Represents the mechanical property index related to nickel-titanium shape memory alloy, , , They are the elastic modulus, strain recovery rate and yield strength of nickel-titanium alloy;

[0018] Through the thermal cycle experiment, the temperature before and after the thermal cycle is obtained, and the thermal stability index is generated by combining the nickel-titanium ratio in the nickel-titanium alloy and the thermal expansion rate in the thermal cycle. The thermal stability index reflects the thermal expansion characteristics of the nickel-titanium alloy, the stability of the material at different temperatures, and the degree of temperature change that the material can withstand. The formula for calculating the thermal stability index is:

[0019] ;

[0020] in, Represents the thermal stability index associated with NiTi shape memory alloys, is the thermal expansion rate of NiTi alloy during thermal cycling, , are the temperature before and after thermal cycling of NiTi alloy, is the ratio of nickel to titanium, is the mass fraction of nickel, is the mass fraction of titanium;

[0021] The reliability index is generated based on the yield strength, elastic modulus and thermal expansion rate of nickel-titanium alloy during thermal cycling. The reliability index reflects the long-term durability and stability of the material. The reliability index is calculated based on the following method:

[0022] ;

[0023] in, Represents the reliability index associated with NiTi shape memory alloy.

[0024] Furthermore, the generated mechanical property index, thermal stability index and reliability index are comprehensively calculated to obtain the phase change temperature index, and the phase change temperature threshold correction value is established, based on the formula:

[0025] ;

[0026] in, represents the generated phase transition temperature index;

[0027] A phase change temperature threshold is established, and the phase change temperature threshold is corrected using the phase change temperature index to obtain a phase change temperature threshold correction value, based on the formula:

[0028] ;

[0029] in, represents the phase change temperature threshold correction value, is the phase transition temperature threshold established.

[0030] Furthermore, the geometry and bonding of the unit cell structure are determined based on the following method:

[0031] The unit cell structure includes a quasi-zero stiffness curved beam, a support frame and a connection part. The quasi-zero stiffness curved beam is made of nickel-titanium alloy by water jet cutting. Copper-based conductive glue is applied to both ends of the quasi-zero stiffness curved beam, and the two ends are respectively inserted into the grooves reserved in the support frame and the connection part.

[0032] Adjacent unit cell structures of different layers are bonded together by using copper-based conductive adhesive to bond the support frame of one unit cell to the connection part of another unit cell structure; adjacent unit cell structures of the same layer are bonded together by using copper-based conductive adhesive to bond the support frames of two adjacent unit cell structures.

[0033] Furthermore, according to the calculated phase change temperature threshold correction value, the geometric shape and size of the unit cell structure in different states are optimized, and the optimization includes adjusting the quasi-zero stiffness curved beam, the supporting frame and the connecting part of the unit cell structure, and the method is as follows:

[0034] The base material of the quasi-zero stiffness curved beam is nickel-titanium alloy. After memory training, nickel-titanium alloy can achieve a two-way memory effect. The temperature of nickel-titanium alloy can be adjusted by controlling the power-on time of the DC power supply to change the configuration of the quasi-zero stiffness curved beam, and the martensite configuration and austenite configuration of nickel-titanium alloy can be switched to achieve buffering energy absorption and low-frequency vibration isolation functions respectively.

[0035] If the temperature of the quasi-zero stiffness curved beam is greater than or equal to the phase change temperature threshold correction value, that is, , at this time the unit cell structure is in the austenite configuration; if the quasi-zero stiffness curved beam temperature is less than the phase transition temperature threshold correction value, that is , at this time the cell body is in the martensite configuration;

[0036] When the unit cell structure is in the martensitic configuration, the alloy has low stiffness and is used to absorb external impact or energy. By increasing the bending radius of the beam, the deformation process during energy absorption is ensured to be smooth and avoid local stress concentration. By increasing the length and width of the reserved groove and optimizing the connection point, the quasi-zero stiffness curved beam is allowed to deform freely during the buffering and energy absorption process.

[0037] When the unit cell structure is in the austenite configuration, the alloy has high stiffness and is used for low-frequency vibration isolation. By reducing the bending radius of the beam, that is, reducing the curvature of the beam, its effective vibration isolation performance under low-frequency vibration is ensured, and the length, width and height of the supporting frame are increased to ensure that it has the ability to enhance the overall stability of the structure, prevent deformation from affecting the vibration isolation effect, reduce the length and width of the reserved groove, and avoid gaps. Gaps will cause resonance under low-frequency vibration. The connection should match the dynamic performance of the quasi-zero stiffness curved beam to ensure that it can withstand the increased bearing capacity for high-frequency vibration impact under the austenite configuration, ensure long-term stable operation of the structure, and at the same time not affect the vibration isolation effect. Select characteristic materials with high damping to optimize the vibration isolation effect.

[0038] The present invention also provides a unit cell structure design device based on nickel-titanium shape memory alloy, the design device is used to execute the above-mentioned unit cell structure design method based on nickel-titanium shape memory alloy, comprising:

[0039] A characteristic parameter acquisition module, wherein the characteristic parameter acquisition module is used to acquire relevant characteristic parameters of the nickel-titanium shape memory alloy, wherein the relevant characteristic parameters include the nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate in thermal cycle, and yield strength of the nickel-titanium alloy;

[0040] A parameter preprocessing and performance index generation module, which is used to generate a mechanical performance index, a thermal stability index and a reliability index related to the nickel-titanium shape memory alloy according to the acquired nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate in thermal cycles and yield strength of the nickel-titanium alloy;

[0041] A phase change temperature calculation and threshold setting module, which is used to use the generated mechanical property index, thermal stability index and reliability index to comprehensively calculate to obtain a phase change temperature index, and to establish a phase change temperature threshold, and to correct the phase change temperature threshold using the obtained phase change temperature index to obtain a phase change temperature threshold correction value;

[0042] A unit cell structure optimization and size adjustment module, the unit cell structure optimization and size adjustment module is used to determine the geometric shape and bonding method of the unit cell structure, and optimize the geometric shape and size of the unit cell structure in two different states according to the calculated phase change temperature threshold correction value, including adjusting the quasi-zero stiffness curved beam, supporting frame and connecting part of the unit cell structure to ensure that ideal performance is provided within the required phase change temperature range. The unit cell structures in the two different states are martensitic structure and austenitic structure.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention is based on the unit cell structure design method of nickel-titanium shape memory alloy. By collecting and preprocessing the characteristic parameters of the alloy, calculating the performance index and optimizing the structure, the problem of difficult regulation of performance and stability in the unit cell structure design in the prior art is solved. By comprehensively analyzing various parameters of the nickel-titanium alloy, such as elastic modulus, strain recovery rate, thermal expansion rate in thermal cycle, etc., the mechanical performance index, thermal stability index and reliability index are generated, and the phase transition temperature index is used for precise regulation, so that the unit cell structure can exhibit excellent buffering energy absorption and low-frequency vibration isolation performance under different temperature conditions, effectively improving the accuracy and functionality of the design.

[0045] In addition, the present invention optimizes the geometry and bonding method of the unit cell structure by setting a precise phase change temperature threshold and combining the two-way memory effect of nickel-titanium alloy. This method can dynamically adjust the stiffness and performance of the structure when the material changes phase, thereby achieving excellent buffering and energy absorption functions under the martensite configuration and providing efficient low-frequency vibration isolation functions under the austenite configuration. By optimizing and adjusting the zero-stiffness curved beam, support frame and connection parts, the ideal performance of the unit cell structure within a specific temperature range is ensured, avoiding the problem of unstable performance caused by temperature changes. Overall, the present invention greatly improves the reliability and applicability of the unit cell structure design, and solves the deficiency of traditional design methods that cannot fully consider material properties and structural requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the overall method flow of the present invention;

[0047] Figure 2 It is a three-dimensional schematic diagram of the unit cell structure of the present invention;

[0048] Figure 3 It is a schematic diagram of the system module flow of the present invention.

[0049] In the figure: quasi-zero stiffness curved beam 1, supporting frame 2, connecting part 3. DETAILED DESCRIPTION

[0050] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0051] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0052] Example:

[0053] See also Figure 1-Figure 2 , a unit cell structure design method based on nickel-titanium shape memory alloy, the specific steps include:

[0054] Step 1: Collect relevant characteristic parameters of nickel-titanium shape memory alloy, wherein the relevant characteristic parameters include nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate during thermal cycling, and yield strength of the nickel-titanium alloy;

[0055] Step 2: Generate a mechanical property index, thermal stability index, and reliability index related to the nickel-titanium shape memory alloy based on the collected nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate in thermal cycles, and yield strength of the nickel-titanium alloy;

[0056] Step 3: Comprehensively calculate the generated mechanical property index, thermal stability index and reliability index to obtain a phase change temperature index, and set a phase change temperature threshold. Use the obtained phase change temperature index to correct the phase change temperature threshold to obtain a phase change temperature threshold correction value;

[0057] Step 4: Determine the geometry and bonding method of the unit cell structure, and optimize the geometry and dimensions of the unit cell structure in two different states based on the calculated phase change temperature threshold correction value, including adjusting the quasi-zero stiffness curved beam 1, support frame 2 and connection part 3 of the unit cell structure to ensure that ideal performance is provided within the required phase change temperature range. The unit cell structures in the two different states are a martensitic structure and an austenitic structure.

[0058] It should be noted that the mechanical performance index can comprehensively consider the elastic modulus, strain recovery rate and yield strength, reflect the mechanical stability, load-bearing capacity and plasticity of the alloy, and help predict its performance under load. The thermal stability index reflects the stability and thermal expansion characteristics of the alloy at different temperatures by combining the thermal expansion rate and temperature change in the thermal cycle, providing reliability guarantee for applications in high temperature environments. The reliability index starts from the perspective of durability and long-term stability. By combining the yield strength, elastic modulus and thermal expansion rate in the thermal cycle, it evaluates the performance of the material in long-term use to ensure its reliability and stability in various environments. Through the generation of these indices, the performance of nickel-titanium alloys can be evaluated more accurately, and a basis can be provided for their selection and optimization in practical applications.

[0059] The method for obtaining the relevant characteristic parameters of nickel-titanium shape memory alloy is based on:

[0060] For the nickel-titanium ratio, the mass ratio of nickel and titanium in the alloy can be determined by chemical analysis, and the ratio of nickel and titanium can be calculated by analyzing the relative content of each element in the alloy;

[0061] The elastic modulus is usually measured by tensile or compression tests. In the test, the sample is subjected to tensile or compressive forces, and the relationship between stress and strain is measured. Hawke's law is used to obtain the elastic modulus:

[0062] ;

[0063] in, is the elastic modulus of NiTi alloy, It is the stress of nickel-titanium memory alloy recorded during tensile test or compression test. It is the strain of nickel-titanium memory alloy recorded during tensile test or compression test;

[0064] Strain recovery rate is an important property of shape memory alloys, which is usually obtained through temperature-controlled tensile tests. In the test, the alloy sample is heated or cooled to measure its deformation recovery. By applying a certain strain, then heating or cooling to the phase transition temperature, it is observed whether the material can recover to its original shape. The strain recovery rate can be calculated by the following formula:

[0065] ;

[0066] in, is the strain recovery rate of NiTi alloy, is the length of deformation recovery after heating in temperature-controlled tensile test, is the initial applied deformation length;

[0067] The thermal expansion rate is measured by thermomechanical analysis. This method can detect the dimensional change of the sample at different temperatures, and then obtain the thermal expansion coefficient or expansion rate of the material within a specific temperature range. The thermal expansion rate can be obtained by changing the temperature and measuring the length change of the sample;

[0068] Yield strength is usually determined by tensile testing. During the tensile process, the stress and strain curves of the sample under different loads are plotted, and the yield strength corresponds to the yield point of the stress-strain curve. In shape memory alloys, the yield strength is usually affected by the phase transition temperature and alloy composition, so multiple tests are performed under different test conditions, such as temperature and strain rate, to ensure its accuracy.

[0069] Therefore, it is necessary to generate the mechanical property index, thermal stability index and reliability index related to nickel-titanium shape memory alloy, based on the following method:

[0070] The elastic modulus, strain recovery rate and yield strength of nickel-titanium alloy are used to evaluate its mechanical performance index. The mechanical performance index reflects the mechanical stability, load-bearing capacity and plasticity of nickel-titanium alloy. The formula for calculating the mechanical performance index is:

[0071] ;

[0072] in, Represents the mechanical property index related to nickel-titanium shape memory alloy, , , are the elastic modulus, strain recovery rate and yield strength of nickel-titanium alloy respectively; in the above formula, the yield strength The smaller, The larger the mechanical property index, the smaller the yield strength of the nickel-titanium shape memory alloy, the stronger the bending deformation ability, and the better the mechanical properties. Increase; elastic modulus Increase, It also increases, which means that the nickel-titanium shape memory alloy will deform less under the same stress, thus showing higher mechanical stability and load-bearing capacity; strain recovery rate Get bigger, The increase means that the nickel-titanium shape memory alloy can recover better after being deformed, and has higher plasticity and mechanical stability. This property is particularly important for materials such as shape memory alloys, which can effectively restore their original shape and withstand repeated load changes.

[0073] Through the thermal cycle experiment, the temperature before and after the thermal cycle is obtained, and the thermal stability index is generated by combining the nickel-titanium ratio in the nickel-titanium alloy and the thermal expansion rate in the thermal cycle. The thermal stability index reflects the thermal expansion characteristics of the nickel-titanium alloy, the stability of the material at different temperatures, and the degree of temperature change that the material can withstand. The formula for calculating the thermal stability index is:

[0074] ;

[0075] in, Represents the thermal stability index associated with NiTi shape memory alloys, is the thermal expansion rate of NiTi alloy during thermal cycling, , are the temperature before and after thermal cycling of NiTi alloy, is the ratio of nickel to titanium, is the mass fraction of nickel, is the mass fraction of titanium; in the above formula, the thermal expansion rate in thermal cycle The bigger, The larger the ratio, the more significant the volume change of nickel-titanium alloy will be when the temperature changes. When the nickel-titanium alloy is subjected to temperature changes, it can cope with expansion and contraction more effectively. The increase in the thermal expansion rate during thermal cycles usually leads to stronger thermal stability, indicating that it has strong adaptability in high or low temperature environments and can maintain its performance under large temperature differences. When the nickel-titanium ratio is higher, The larger the value, the greater the thermal stability of the alloy is, and therefore it can withstand a wider range of temperature changes. In other words, the alloy with a high nickel ratio undergoes less morphological changes during thermal cycling, thereby improving its thermal stability. The difference between the temperature before and after thermal cycling of the nickel-titanium alloy The smaller, The larger the value, the less thermal expansion of nickel-titanium alloy will be. The thermal stability is good. When the temperature difference is small, nickel-titanium alloy can maintain better structural stability and reduce internal stress and potential damage caused by temperature fluctuations. This situation shows that nickel-titanium alloy has a strong tolerance to temperature fluctuations and is suitable for long-term use in an environment with a small temperature difference.

[0076] The reliability index is generated based on the yield strength, elastic modulus and thermal expansion rate of nickel-titanium alloy during thermal cycling. The reliability index reflects the long-term durability and stability of the material. The reliability index is calculated based on the following method:

[0077] ;

[0078] in, represents the reliability index associated with nickel-titanium shape memory alloy; in the above formula, the elastic modulus Increase, The increase in the reliability index indicates that the nickel-titanium alloy can better withstand external forces and maintain stability during long-term use, so it has higher durability and reliability. The thermal expansion rate in thermal cycles Increase, This indicates that it can better adapt to temperature fluctuations in an environment with large temperature changes. The increase means that nickel-titanium alloy can not only maintain good thermal stability but also maintain its performance when experiencing temperature changes, indicating that it has strong thermal stability and durability and can withstand a wider range of use conditions; yield strength Reduce, Increased size means higher durability and reliability when experiencing stress, and can be used stably at lower stress levels, making it suitable for long-term low stress load conditions.

[0079] It should be noted that the phase transition temperature is a key parameter that determines whether the material can effectively perform the shape memory function during temperature changes. By combining the mechanical performance index, thermal stability index and reliability index, the phase transition temperature index can more accurately reflect the deformation response and stability of nickel-titanium alloy under different temperature conditions. It not only takes into account the mechanical properties, thermal expansion characteristics and durability of the material, but also combines the influence of various indexes through the nonlinear relationship in the formula, making the prediction of the phase transition temperature more comprehensive and accurate.

[0080] Therefore, it is necessary to use the generated mechanical property index, thermal stability index and reliability index to comprehensively calculate to obtain the phase change temperature index and establish the phase change temperature threshold correction value. The formula is as follows:

[0081] ;

[0082] in, represents the generated phase transition temperature index;

[0083] A phase change temperature threshold is established, and the phase change temperature threshold is corrected using the phase change temperature index to obtain a phase change temperature threshold correction value, based on the formula:

[0084] ;

[0085] in, represents the phase change temperature threshold correction value, is the phase transition temperature threshold established; in the above formula, the increase of mechanical properties index, thermal stability index and reliability index will lead to The phase transition temperature index increases; when the mechanical properties index increases, When it increases, it means that the nickel-titanium alloy can maintain a high deformation recovery ability when the temperature changes, and the phase change process at different temperatures is more stable. As the mechanical property index increases, the shape memory effect of the nickel-titanium alloy becomes more obvious, thereby promoting the increase in the phase change temperature; when the thermal stability index increases, it means that the nickel-titanium alloy can maintain good thermal stability when undergoing thermal cycles, can adapt to larger temperature differences, and will not experience large deformations or damage during thermal expansion. This enhanced thermal stability allows the alloy to maintain good phase change behavior at higher or lower temperatures, so the phase change temperature index will also increase; when the reliability index increases, It also increases, indicating that materials with higher reliability can maintain good shape memory properties for a longer period of time and can stably return to the preset shape even under temperature fluctuations and mechanical stress. Therefore, as the reliability index increases, the phase transition temperature of nickel-titanium alloy increases, indicating that its phase transition behavior in various environments is more reliable.

[0086] The larger the phase transition temperature index, the better the thermal stability of the nickel-titanium alloy. It can withstand large temperature changes without unexpected phase changes, which makes the alloy more stable in high temperature environments and suitable for high temperature applications. The larger the phase transition temperature index generated by comprehensively considering the mechanical property index, thermal stability index and reliability index, the better the mechanical properties of the nickel-titanium alloy, such as load-bearing capacity, plasticity, etc. and long-term stability. The bigger, It will become smaller. The correction of the phase change temperature threshold is to ensure that the alloy can recover to its required state more quickly during the temperature change process, maintain its excellent shape memory effect and superelastic properties, and lower the phase change temperature threshold, which can expand the stability and functional performance of nickel-titanium alloy in the working temperature range. In a larger temperature range, the alloy can effectively respond to external changes and show better mechanical properties and shape memory properties. For example, if the phase change temperature threshold is low, it may show shape memory effect at a lower temperature, so that it is more suitable for use under temperature conditions with large changes; and as the phase change temperature rises, the alloy may become more stable and can withstand higher temperatures without disordered phase change. However, in order to ensure that the appropriate phase change occurs within the appropriate temperature range, the reduction of the phase change temperature threshold helps to accurately control the occurrence of phase change and eliminate unnecessary phase change phenomena, thereby maintaining the performance stability of the material at different working temperatures; the reduction of the phase change temperature threshold can make the alloy more sensitive when working in a high temperature environment, and it is easier to start shape memory or superelastic effects within the appropriate temperature range. This adjustment can ensure that the nickel-titanium alloy responds in time under the required temperature conditions, rather than delaying the response due to excessively high phase change temperatures.

[0087] It should be noted that determining the geometry and bonding method of the unit cell structure is crucial in the design of nickel-titanium alloy materials, because it directly affects the overall performance, reliability and function of the material. Specifically, the design of the quasi-zero stiffness curved beam 1 determines the deformation characteristics of the material, so that the nickel-titanium alloy can effectively respond and restore its original shape under load or temperature changes. The precise design of the support frame 2 and the connection part 3 ensures the stability and load-bearing capacity of the unit cell structure. The various parts of the unit cell structure are connected by copper-based conductive adhesive to ensure good adhesion and conductivity of the structure, thereby achieving stable mechanical and electrical properties; the bonding method of adjacent unit cell structures in different layers ensures effective coupling between different layers, so that the entire unit cell array can maintain stable overall performance under large stress or temperature changes.

[0088] Therefore, it is necessary to determine the geometry and bonding method of the unit cell structure, based on the following method:

[0089] The unit cell structure includes a quasi-zero stiffness curved beam 1, a support frame 2 and a connection part 3. The quasi-zero stiffness curved beam 1 is made of nickel-titanium alloy by water jet cutting. Copper-based conductive glue is applied to both ends of the quasi-zero stiffness curved beam 1, and the two ends are respectively inserted into the grooves reserved in the support frame 2 and the connection part 3;

[0090] Adjacent unit cell structures of different layers are bonded together by copper-based conductive adhesive to bond the support frame 2 of one unit cell layer to the connecting portion 3 of another unit cell layer; adjacent unit cell structures of the same layer are bonded together by copper-based conductive adhesive to bond the support frames 2 of two adjacent unit cell structures.

[0091] It should be noted that by precisely adjusting the design of the quasi-zero stiffness curved beam 1, the support frame 2 and the connection part 3, the buffering energy absorption and low-frequency vibration isolation functions of the material in the martensitic configuration can be effectively realized. When the unit cell structure is in different configurations, the optimized geometric dimensions and morphology can ensure that the material maintains efficient stability and performance when responding to external impacts, vibrations or energy absorption. For example, by changing the bending radius of the beam and adjusting the size of the support frame 2, it is ensured that the structure has the required stiffness and deformation capacity at different temperatures, avoiding unnecessary stress concentration or resonance, thereby enhancing the durability and functionality of the material.

[0092] Therefore, it is necessary to optimize the geometric shape and size of the unit cell structure in different states according to the calculated phase change temperature threshold correction value. The optimization includes adjusting the quasi-zero stiffness curved beam 1, the supporting frame 2 and the connecting part 3 of the unit cell structure. The method is as follows:

[0093] The base material of the quasi-zero stiffness curved beam 1 is nickel-titanium alloy, which can achieve a two-way memory effect after memory training. The temperature of the nickel-titanium alloy is adjusted by controlling the power-on time of the DC power supply to change the configuration of the quasi-zero stiffness curved beam 1, and the switching between the martensite configuration and the austenite configuration of the nickel-titanium alloy is completed, so as to respectively achieve buffering energy absorption and low-frequency vibration isolation functions;

[0094] If the temperature of the quasi-zero stiffness curved beam 1 is greater than or equal to the phase change temperature threshold correction value, that is, , at this time the unit cell structure is in the austenite configuration; if the temperature of the quasi-zero stiffness curved beam 1 is less than the phase transition temperature threshold correction value, that is , at this time the cell body is in the martensite configuration;

[0095] When the unit cell structure is in the martensitic configuration, the alloy has low stiffness and is used to absorb external impact or energy. By increasing the bending radius of the beam, a smooth deformation process is ensured during energy absorption to avoid local stress concentration. By increasing the length and width of the reserved groove and optimizing the connection point, the quasi-zero stiffness curved beam 1 is allowed to deform freely during the buffering energy absorption process.

[0096] When the unit cell structure is in the austenite configuration, the alloy has high stiffness and is used for low-frequency vibration isolation. The effective vibration isolation performance under low-frequency vibration is ensured by reducing the bending radius of the beam, that is, reducing the curvature of the beam, and increasing the length, width and height of the support frame 2 to ensure that it has the ability to enhance the overall stability of the structure, prevent deformation from affecting the vibration isolation effect, reduce the length and width of the reserved groove, and avoid gaps. Gaps will cause resonance under low-frequency vibration. The connecting part 3 should match the dynamic performance of the quasi-zero stiffness curved beam 1 to ensure that it can withstand the increased bearing capacity for high-frequency vibration impact under the austenite configuration, ensure long-term stable operation of the structure, and at the same time not affect the vibration isolation effect. Select characteristic materials with high damping to optimize the vibration isolation effect.

[0097] In the three-dimensional schematic diagram of the unit cell structure, the base material of the quasi-zero stiffness curved beam 1 is nickel-titanium alloy, which can achieve a two-way shape memory effect after memory training. By controlling the temperature of the nickel-titanium alloy, the configuration and static properties of the quasi-zero stiffness curved beam 1 can be changed, and the switching of the martensite configuration and austenite configuration of the nickel-titanium alloy can be completed to achieve buffering energy absorption and low-frequency vibration isolation functions respectively; the base material of the support frame 2 and the connecting part 3 is aluminum alloy, which can be processed by additive manufacturing technology. The support frame 2 and the connecting part 3 are both equipped with grooves for bonding with the quasi-zero stiffness curved beam 1.

[0098] See also Figure 3 The present invention also provides a unit cell structure design device based on nickel-titanium shape memory alloy, the design device is used to execute the above-mentioned unit cell structure design method based on nickel-titanium shape memory alloy, comprising:

[0099] A characteristic parameter acquisition module, wherein the characteristic parameter acquisition module is used to acquire relevant characteristic parameters of the nickel-titanium shape memory alloy, wherein the relevant characteristic parameters include the nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate in thermal cycle, and yield strength of the nickel-titanium alloy;

[0100] A parameter preprocessing and performance index generation module, which is used to generate a mechanical performance index, a thermal stability index and a reliability index related to the nickel-titanium shape memory alloy according to the acquired nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate in thermal cycles and yield strength of the nickel-titanium alloy;

[0101] A phase change temperature calculation and threshold setting module, which is used to use the generated mechanical property index, thermal stability index and reliability index to comprehensively calculate to obtain a phase change temperature index, and to establish a phase change temperature threshold, and to correct the phase change temperature threshold using the obtained phase change temperature index to obtain a phase change temperature threshold correction value;

[0102] A unit cell structure optimization and size adjustment module, the unit cell structure optimization and size adjustment module is used to determine the geometric shape and bonding method of the unit cell structure, and optimize the geometric shape and size of the unit cell structure in two different states according to the calculated phase change temperature threshold correction value, including adjusting the quasi-zero stiffness curved beam 1, the supporting frame 2 and the connecting part 3 of the unit cell structure to ensure that ideal performance is provided within the required phase change temperature range. The unit cell structures in the two different states are a martensitic structure and an austenitic structure.

[0103] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0104] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. Those skilled in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0105] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0106] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A unit cell structure design method based on nickel-titanium shape memory alloy, characterized in that: The specific steps include: Step 1: Collect relevant characteristic parameters of nickel-titanium shape memory alloy, wherein the relevant characteristic parameters include nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate during thermal cycling, and yield strength of the nickel-titanium alloy; Step 2: Generate a mechanical property index, thermal stability index, and reliability index related to the nickel-titanium shape memory alloy based on the collected nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate in thermal cycles, and yield strength of the nickel-titanium alloy; Step 3: Comprehensively calculate the generated mechanical property index, thermal stability index and reliability index to obtain a phase change temperature index, and set a phase change temperature threshold. Use the obtained phase change temperature index to correct the phase change temperature threshold to obtain a phase change temperature threshold correction value; Step 4: Determine the geometry and bonding method of the unit cell structure, and optimize the geometry and dimensions of the unit cell structure in two different states based on the calculated phase change temperature threshold correction value, including adjusting the quasi-zero stiffness curved beam, supporting frame and connection part of the unit cell structure to ensure that ideal performance is provided within the required phase change temperature range. The unit cell structures in the two different states are a martensitic structure and an austenitic structure.

2. A unit cell structure design method based on nickel-titanium shape memory alloy according to claim 1, characterized in that: The method for generating the mechanical property index, thermal stability index, and reliability index related to nickel-titanium shape memory alloy is based on: The elastic modulus, strain recovery rate and yield strength of nickel-titanium alloy are used to evaluate its mechanical performance index. The mechanical performance index reflects the mechanical stability, load-bearing capacity and plasticity of nickel-titanium alloy. The formula for calculating the mechanical performance index is: ； in, Represents the mechanical property index related to nickel-titanium shape memory alloy, , , They are the elastic modulus, strain recovery rate and yield strength of nickel-titanium alloy; Through the thermal cycle experiment, the temperature of the nickel-titanium memory alloy before and after the thermal cycle is obtained, and the thermal stability index is generated in combination with the nickel-titanium ratio in the nickel-titanium alloy and the thermal expansion rate in the thermal cycle. The thermal stability index reflects the thermal expansion characteristics of the nickel-titanium alloy, the stability of the material at different temperatures, and the degree of temperature change that the material can withstand. The formula for calculating the thermal stability index is: ； in, Represents the thermal stability index associated with NiTi shape memory alloys, is the thermal expansion rate of NiTi alloy during thermal cycling, , are the temperature before and after thermal cycling of NiTi alloy, is the ratio of nickel to titanium, is the mass fraction of nickel, is the mass fraction of titanium; The reliability index is generated based on the yield strength, elastic modulus and thermal expansion rate of nickel-titanium alloy during thermal cycling. The reliability index reflects the long-term durability and stability of the material. The reliability index is calculated based on the following method: ； in, Represents the reliability index associated with NiTi shape memory alloy.

3. A unit cell structure design method based on nickel-titanium shape memory alloy according to claim 2, characterized in that: The generated mechanical property index, thermal stability index and reliability index are used for comprehensive calculation to obtain the phase change temperature index, and the phase change temperature threshold correction value is established. The formula is as follows: ； in, represents the generated phase transition temperature index; A phase change temperature threshold is established, and the phase change temperature threshold is corrected using the phase change temperature index to obtain a phase change temperature threshold correction value, based on the formula: ； in, represents the phase change temperature threshold correction value, is the phase transition temperature threshold established.

4. The unit cell structure design method based on nickel-titanium shape memory alloy according to claim 1, characterized in that: The geometry and bonding of the unit cell structure are determined based on the following method: The unit cell structure includes a quasi-zero stiffness curved beam, a support frame and a connection part. The quasi-zero stiffness curved beam is made of nickel-titanium alloy by water jet cutting. Copper-based conductive glue is applied to both ends of the quasi-zero stiffness curved beam, and the two ends are respectively inserted into the grooves reserved in the support frame and the connection part. Adjacent unit cell structures of different layers are bonded together by using copper-based conductive adhesive to bond the support frame of one unit cell to the connection part of another unit cell structure; adjacent unit cell structures of the same layer are bonded together by using copper-based conductive adhesive to bond the support frames of two adjacent unit cell structures.

5. The unit cell structure design method based on nickel-titanium shape memory alloy according to claim 1, characterized in that: According to the calculated phase change temperature threshold correction value, the geometric shape and size of the unit cell structure in different states are optimized, and the optimization includes adjusting the quasi-zero stiffness curved beam, supporting frame and connecting part of the unit cell structure, and the method is based on: The base material of the quasi-zero stiffness curved beam is nickel-titanium alloy. After memory training, nickel-titanium alloy can achieve a two-way memory effect. The temperature of nickel-titanium alloy can be adjusted by controlling the power-on time of the DC power supply to change the configuration of the quasi-zero stiffness curved beam, and the martensite configuration and austenite configuration of nickel-titanium alloy can be switched to achieve buffering energy absorption and low-frequency vibration isolation functions respectively. If the temperature of the quasi-zero stiffness curved beam is greater than or equal to the phase change temperature threshold correction value, that is, , at this time the unit cell structure is in the austenite configuration; if the quasi-zero stiffness curved beam temperature is less than the phase transition temperature threshold correction value, that is , at this time the cell body is in the martensite configuration; When the unit cell structure is in the martensitic configuration, the alloy has low stiffness and is used to absorb external impact or energy. By increasing the bending radius of the beam, the deformation process during energy absorption is ensured to be smooth and avoid local stress concentration. By increasing the length and width of the reserved groove and optimizing the connection point, the quasi-zero stiffness curved beam is allowed to deform freely during the buffering and energy absorption process. When the unit cell structure is in the austenite configuration, the alloy has high stiffness and is used for low-frequency vibration isolation. By reducing the bending radius of the beam, that is, reducing the curvature of the beam, its effective vibration isolation performance under low-frequency vibration is ensured, and the length, width and height of the supporting frame are increased to ensure that it has the ability to enhance the overall stability of the structure, prevent deformation from affecting the vibration isolation effect, reduce the length and width of the reserved groove, and avoid gaps. Gaps will cause resonance under low-frequency vibration. The connection should match the dynamic performance of the quasi-zero stiffness curved beam to ensure that it can withstand the increased bearing capacity for high-frequency vibration impact under the austenite configuration, ensure long-term stable operation of the structure, and at the same time not affect the vibration isolation effect. Select characteristic materials with high damping to optimize the vibration isolation effect.

6. A unit cell structure design device based on nickel-titanium shape memory alloy, characterized in that: The design device is used to execute a unit cell structure design method based on nickel-titanium shape memory alloy according to any one of claims 1 to 5, comprising: A characteristic parameter acquisition module, wherein the characteristic parameter acquisition module is used to acquire relevant characteristic parameters of the nickel-titanium shape memory alloy, wherein the relevant characteristic parameters include the nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate in thermal cycle, and yield strength of the nickel-titanium alloy; A parameter preprocessing and performance index generation module, which is used to generate a mechanical performance index, a thermal stability index and a reliability index related to the nickel-titanium shape memory alloy according to the acquired nickel-titanium ratio, elastic modulus, strain recovery rate, thermal expansion rate in thermal cycles and yield strength of the nickel-titanium alloy; A phase change temperature calculation and threshold setting module, which is used to use the generated mechanical property index, thermal stability index and reliability index to comprehensively calculate to obtain a phase change temperature index, and to establish a phase change temperature threshold, and to correct the phase change temperature threshold using the obtained phase change temperature index to obtain a phase change temperature threshold correction value; A unit cell structure optimization and size adjustment module, the unit cell structure optimization and size adjustment module is used to determine the geometric shape and bonding method of the unit cell structure, and optimize the geometric shape and size of the unit cell structure in two different states according to the calculated phase change temperature threshold correction value, including adjusting the quasi-zero stiffness curved beam, supporting frame and connecting part of the unit cell structure to ensure that ideal performance is provided within the required phase change temperature range. The unit cell structures in the two different states are martensitic structure and austenitic structure.

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