Design method of variable stiffness composite shock absorber based on temperature control

Abstract

The invention relates to a design method of a variable stiffness composite shock absorber based on temperature control, which comprises the following steps of: 1, carrying out microscopic variable stiffness design on a raw material for preparing a shape memory alloy spring to generate a shape memory effect; 2, microcosmic variable stiffness design of the shape memory alloy micro-spring is carried out, wherein the design comprises the steps of determining the maximum shear strain, determining the shear strain in a high-temperature austenite state, determining the shear stress in the high-temperature austenite state and determining the spring wire diameter and the spring diameter of the shape memory alloy spring; 3, macroscopic variable stiffness design of the composite shock absorber is carried out; the method comprises the following steps: firstly, adhering the micro-spring designed in the step 2 and damping rubber in a mold through a vulcanization process to form a composite damping body; and then the composite vibration reduction body is solidified between the upper pressing plate and the base plate through gluing, and the resistor disc is fixedly connected to the base. According to the invention, the rigidity of the shock absorber is changed in three dimensions by utilizing the shape memory effect of the shape memory alloy under the action of temperature, so that the variable-rigidity shock absorption requirement of a hemispherical resonator gyroscope inertial navigation system is met.

Description

Technical Field

[0001] This invention relates to the field of hemispherical resonant gyroscope inertial navigation, and in particular to a design method for a temperature-controlled variable stiffness composite vibration damper. Background Technology

[0002] In hemispherical resonant gyroscope inertial navigation systems, the platform has limited installation space, high vertical accuracy requirements, and high vibration damping characteristics for its components. Hemispherical resonant gyroscope inertial navigation systems require varying stiffness for vibration damping under different environments. However, traditional dampers using rubber or metal-rubber have a narrow range of stiffness variation, which significantly affects the accuracy of hemispherical resonant inertial navigation systems. Therefore, developing a variable stiffness damper has become a crucial and urgent problem to be solved in the design of hemispherical resonant gyroscope inertial navigation systems. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a design method for a temperature-controlled variable stiffness composite vibration damper.

[0004] The above-mentioned objective of this invention is achieved through the following technical solution: A design method for a temperature-controlled variable stiffness composite vibration damper includes the following steps: Step 1: Perform micro-variable stiffness design on the raw material for preparing shape memory alloy springs to induce a shape memory effect; Step 2: Perform micro-variable stiffness design of shape memory alloy micro-springs, including determining the maximum shear strain, the shear strain in the high-temperature austenitic state, the shear stress in the high-temperature austenitic state, and the wire diameter and spring diameter of the shape memory alloy spring. Step 3: Perform macroscopic variable stiffness design of the composite vibration damper. The structure of the composite vibration damper includes an upper cover plate, damping rubber, shape memory alloy micro-springs, a lower base, and an electrothermal resistance sheet. First, the micro-springs and damping rubber designed in Step 2 are bonded together in the mold through a vulcanization process to form a composite vibration damper. Then, the composite vibration damper is cured between the upper pressure plate and the base plate by adhesive bonding, and the resistance sheet is fixed to the base.

[0005] Moreover, step 1 includes: Step 1.1, Material Selection: The selected material is Ni50.1Ti49.9 near-equal atomic ratio nickel-titanium alloy rod; Step 1.2: Heat treat the raw material to cause the bar to undergo thermoelastic martensitic phase transformation under temperature, resulting in shape recovery effect; Step 1.3: The bar material processed in Step 2 is subjected to repeated alternating heating and cooling to induce a shape memory effect.

[0006] Furthermore, in step 1.2, the heat treatment process temperature is 450℃, and the temperature is maintained for 30 minutes.

[0007] Moreover, in step 2, the maximum shear strain for: in, denoted as the shear strain value of the nickel-titanium alloy in the martensitic state.

[0008] Furthermore, in step 2, the shear strain in the high-temperature austenitic state... for: In the formula, -Shear modulus in the martensitic state; - The load force of a spring in the austenitic state; -Shear modulus in the austenitic state; - The load force of a spring in the martensitic state.

[0009] Furthermore, in step 2, the shear stress in the high-temperature austenitic state... .

[0010] Furthermore, in step 2, the diameter of the wire in the shape memory spring is: In the formula, The spring's helix ratio; The diameter of the shape memory spring is: Furthermore, in step 3, by heating the resistive element, the composite damper is activated, resulting in a total stiffness of: In the formula, , which represents the stiffness produced by the martensitic phase transformation at the microscale; This represents the stiffness generated by the micro-deformation of the shape memory microspring at a microscale. It is the force output by n shape memory alloy microsprings on a macroscopic scale. The additional preload applied to the rubber causes a change in the rubber's stiffness.

[0011] The advantages and positive effects of this invention are as follows: This invention is based on the excellent shape memory effect of nickel-titanium alloys, which can be "trained" to allow alloy components to repeatedly change their macroscopic structural shape during heating and cooling cycles. Through a vulcanization process, a nickel-titanium alloy micro-spring structure is embedded in traditional rubber. Utilizing the shape memory effect of the shape memory alloy under temperature, the stiffness of the vibration damper is altered at three scales: 1) Microscale: By "training," a specific dislocation field and a specifically oriented Ni4Ti3 phase are introduced, inducing a martensitic phase transformation, the transformation products of which change the stiffness of the matrix; 2) Mesoscale: Due to the nonlinear constitutive relation caused by the shape change of the shape memory microspring under thermal effects, the stiffness of the shape memory alloy microspring is changed; 3) Macroscale: Driven by the deformation of the shape memory microspring, the rubber itself is forced to generate internal pressure preload, thereby changing the stiffness of the rubber.

[0012] In summary, this invention leverages the memory effect of nickel-titanium alloys to create a vibration damper that combines nickel-titanium alloys and rubber, exhibiting variable stiffness characteristics that change with temperature. By combining a micro-nickel-titanium alloy spring with a rubber matrix, a temperature-controlled vibration damper is developed, addressing the variable stiffness vibration damping requirements of hemispherical resonant gyroscope inertial navigation systems. Attached Figure Description

[0013] Figure 1 This invention relates to a graph showing the relationship between martensite content and temperature in Ni50.1Ti49.9 near-equal atomic ratio nickel-titanium alloy bars under hot and cold training. Figure 2 This is a schematic diagram of the temperature-controlled variable stiffness composite vibration damper of the present invention. Detailed Implementation

[0014] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] For a design method of a temperature-controlled variable stiffness composite vibration damper, please refer to [link / reference]. Figures 1-2 The invention's key features are: the variable stiffness composite vibration damper of this invention adopts a composite structure of shape memory alloy spring and damping rubber, and the design method includes the following steps: Step 1: Microscopic variable stiffness design of the shape memory alloy spring raw material, mainly including: Step 1.1, Material Selection: The selected material is Ni50.1Ti49.9 near-equal atomic ratio nickel-titanium alloy rod, which is a shape memory alloy.

[0016] Step 1.2: Heat treatment of the raw material: To eliminate work hardening of shape memory alloy (SMA) and improve its mechanical properties, the rod needs to be heat treated. The heat treatment process is to hold at 450℃ for 30 minutes. Shape memory alloys undergo thermoelastic martensitic phase transformation under temperature, resulting in a shape recovery effect.

[0017] Step 1.3: The bar material processed in Step 2 is subjected to repeated alternating heating and cooling to induce a shape memory effect.

[0018] In this invention, the start and end temperatures of the martensitic phase transformation during the cooling of the bar are respectively... and The austenite phase transformation start temperature and end temperature during heating are respectively and .like Figure 1 It can be seen that cooling down the SMA when the temperature is below At that time, the SMA begins to undergo plastic deformation under the influence of temperature, and residual deformation will occur. When the temperature drops to... At this point, the SMA metallographic structure completely transforms into martensite, and the SMA shape transforms into a low-temperature morphology; when the low-temperature SMA is heated to a temperature higher than […], At this time, SMA begins to transform from low-temperature martensite to high-temperature austenite, restoring the parent phase morphology. During the shape restoration process, if it is constrained by external forces, a large restoring force will be generated inside to resist the constraint. When the temperature rises to... At that time, the SMA metallographic structure completely transforms into the high-temperature austenitic morphology, restoring its initial shape.

[0019] Shape memory alloys exhibit external shape changes under the influence of temperature, while internally they demonstrate a close relationship between their shear modulus and temperature. The relationship between the shear modulus of SMA and temperature can be approximately expressed by formula (1). (1) When T < And T < At this time, the shape memory alloy is in the low-temperature martensitic phase, and the stiffness of the low-temperature martensite is expressed as a constant. When T> And T> At this time, the shape memory alloy is in the high-temperature parent phase, and the stiffness of the high-temperature austenite can be expressed as a constant. .when ≤T≤ At this time, the shape memory alloy is in the elastic deformation stage, and its stiffness is... It can be represented as: (2) During the heating process, i.e., when the austenitic phase transformation occurs: (3) (4) During the cooling process, i.e., during the martensitic phase transformation, then: (5) (6) Step 2: Perform microscopic variable stiffness design of shape memory alloy microsprings. The design of shape memory alloy microsprings is a micro-variable stiffness design. In step 1, a nickel-titanium alloy rod with a shape memory effect is prepared to give it micro-variable stiffness characteristics. Based on the design in step 1, a microspring with micro-variable stiffness is designed.

[0020] When designing shape memory alloy springs, let the shape memory alloy springs have shear moduli of... and ( and The elastic modulus of austenite (A) and martensite (M) is the modulus of elasticity of the two phases (the specific values ​​can be measured experimentally). The axial loads at these conditions are respectively... and The spring displacements are respectively and The general design steps for shape memory alloy springs include: (1) Determine the maximum shear strain Since the shear modulus of SMA is the smallest in the martensitic state, its shear strain value is the largest, so let its value be [value missing]. Therefore, the maximum shear strain can be taken as: (7) (2) Determine the shear strain in the high-temperature austenitic state The spring displacement is proportional to the load force F. Inversely proportional to the shear modulus G, we have: (8) Since the shear strain on the spring wire is proportional to the spring displacement, then: (9) Based on equations (8) and (9), the shear strain in the high-temperature austenitic state can be determined. (10) In the formula, -Shear modulus in the martensitic state; - The load force of a spring in the austenitic state; -Shear modulus in the austenitic state; - The load force of a spring in the martensitic state.

[0021] (3) Determine the shear stress in the high-temperature austenitic state. (11) (4) Determine the wire diameter d and spring diameter D of the shape memory alloy spring. When calculating the spring wire diameter d based on strength conditions, the maximum working load selected is the load force in the high-temperature austenitic state. The wire diameter of the shape memory spring can be determined as follows: (12) In the formula, The spring's helix ratio; The diameter of the SMA spring can be deduced as: (13) The shear modulus G of shape memory alloys is closely related to temperature. In the fully martensitic state (below...),... The shear modulus is at its minimum value. In the fully austenitic state (higher than) The shear modulus has a maximum value. When the temperature is between these two values ​​( The shear modulus G changes significantly with temperature. Therefore, shape memory alloy springs are used at temperatures below [temperature range missing]. At this point, the spring is at its softest and has the lowest stiffness; the shape memory alloy spring has a temperature higher than [missing information]. At this temperature, the spring is at its stiffest and has the highest stiffness. For temperatures below [temperature value missing], [temperature value missing]. Shape memory alloy springs limit their axial displacement when the SMA spring is heated to... At this temperature, the martensitic phase begins to transform into the austenitic phase, increasing the stiffness of the SMA spring and generating a resistance force to limit displacement. The principle can be stated as follows: when the SMA spring temperature is at... At that time, the relationship between the output force of the SMA spring and the temperature can be obtained as follows: (14) Therefore, the formula for the stiffness of shape memory alloy springs as a function of temperature is obtained as follows: (15) Step 3: Perform macroscopic variable stiffness design of the composite vibration damper. The structure of the composite vibration damper is as follows Figure 2As shown: The main components include an upper cover plate 1, damping rubber 2, shape memory alloy microsprings 3, a lower base 5, and a heating element 4. First, a vulcanization process is used to bond the microsprings and damping rubber designed in step 2 within a mold to form a composite damping body. Then, the composite damping body is glued between the upper pressure plate and the base plate, and the heating element is fixed to the base. By heating the heating element, the composite damping body begins to operate, and the total stiffness generated at this time is: (16) In the formula, , which represents the stiffness produced by the martensitic phase transformation at the microscale; This represents the stiffness generated by the micro-deformation of the shape memory microspring at a microscale. It is the output force of n SMA springs on a macroscopic scale. The additional preload applied to the rubber causes a change in the rubber's stiffness.

[0022] In summary, this invention leverages the shape memory effect of nickel-titanium alloys to create a temperature-dependent stiffness variable in the composite vibration damper of nickel-titanium alloy and rubber. A nickel-titanium alloy micro-spring structure is embedded within the conventional rubber. Utilizing the shape memory effect of the alloy under temperature, the damper stiffness is altered across three scales. Through the combination of the nickel-titanium alloy micro-spring and the rubber matrix, a temperature-controlled vibration damper is developed, addressing the variable stiffness vibration damping requirements of hemispherical resonant gyroscope inertial navigation systems.

[0023] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A design method for a temperature-controlled variable stiffness composite vibration damper, characterized in that, Includes the following steps: Step 1: Perform micro-variable stiffness design on the raw material for preparing shape memory alloy springs to induce a shape memory effect; Step 2: Perform micro-variable stiffness design of shape memory alloy micro-springs, including determining the maximum shear strain, the shear strain in the high-temperature austenitic state, the shear stress in the high-temperature austenitic state, and the wire diameter and spring diameter of the shape memory alloy spring. Step 3: Perform macroscopic variable stiffness design of the composite vibration damper. The structure of the composite vibration damper includes an upper cover plate, damping rubber, shape memory alloy micro-springs, a lower base, and an electrothermal resistance sheet. First, the micro-springs and damping rubber designed in Step 2 are bonded together in the mold through a vulcanization process to form a composite vibration damper. Then, the composite vibration damper is cured between the upper pressure plate and the base plate by adhesive bonding, and the resistance sheet is fixed to the base.

2. The design method of the temperature-controlled variable stiffness composite vibration damper according to claim 1, characterized in that, Step 1 includes: Step 1.1, Material Selection: The selected material is Ni50.1Ti49.9 near-equal atomic ratio nickel-titanium alloy rod; Step 1.2: Heat treat the raw material to cause the bar to undergo thermoelastic martensitic phase transformation under temperature, resulting in shape recovery effect; Step 1.3: The bar material processed in Step 2 is subjected to repeated alternating heating and cooling to induce a shape memory effect.

3. The design method of the temperature-controlled variable stiffness composite vibration damper according to claim 2, characterized in that: In step 1.2, the heat treatment process temperature is 450℃ and the temperature is held for 30 minutes.

4. The design method of the temperature-controlled variable stiffness composite vibration damper according to claim 1, characterized in that: In step 2, the maximum shear strain for: ； in, denoted as the shear strain value of the nickel-titanium alloy in the martensitic state.

5. The design method of the temperature-controlled variable stiffness composite vibration damper according to claim 4, characterized in that: In step 2, the shear strain in the high-temperature austenitic state for: ； In the formula, -Shear modulus in the martensitic state; - The load force of a spring in the austenitic state; -Shear modulus in the austenitic state; - The load force of a spring in the martensitic state.

6. The design method of the temperature-controlled variable stiffness composite vibration damper according to claim 5, characterized in that: In step 2, the shear stress in the high-temperature austenitic state for: 。 7. The design method of the temperature-controlled variable stiffness composite vibration damper according to claim 6, characterized in that: In step 2, the diameter of the wire in the shape memory spring is: ； In the formula, The spring's helix ratio; The diameter of the shape memory spring is: 。 8. The design method of the temperature-controlled variable stiffness composite vibration damper according to claim 7, characterized in that: In step 3, the composite vibration damper is activated by heating the resistive element, resulting in a total stiffness of: ； In the formula, , which represents the stiffness produced by the martensitic phase transformation at the microscale; This represents the stiffness generated by the micro-deformation of the shape memory microspring at a microscale. It is the force output by n shape memory alloy microsprings on a macroscopic scale. The additional preload applied to the rubber causes a change in the rubber's stiffness.

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