Prediction method based on stress relaxation model considering temperature

Abstract

A prediction method based on a temperature-considered stress relaxation model is used in the field of metal material properties to address the inaccurate stress predictions of metal materials by existing stress relaxation models. A temperature-considered stress relaxation model is established to obtain the six parameter values ​​of #imgabs0#j, k, l, and b. These six parameter values ​​of #imgabs1#j, k, l, and b are then applied to a temperature-considered stress relaxation model to obtain the output stress relaxation model. The current temperature of the metal material is then input into the output stress relaxation model to predict the stress of the metal material at that temperature. This method is used to predict the stress of metal materials.

Description

Technical Field

[0001] The invention relates to a stress relaxation model and belongs to the field of metal material properties. Background Art

[0002] Under the dual effects of time and temperature, the orderly arranged microscopic substances (crystals) of metal materials will gradually grow larger, such as Figure 1 As shown, this is the microscopic mechanism of stress relaxation in metallic materials. The essence of stress relaxation in metallic materials is reflected in stress or Young's modulus. However, existing stress relaxation models only consider the single factor of time from a macroscopic perspective and lack a comprehensive description of the microscopic and macroscopic properties of metallic materials. As a result, the stress predictions of metallic materials using existing stress relaxation models are inaccurate. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem that the stress of metal materials predicted by the existing stress relaxation model is inaccurate, and a prediction method based on the stress relaxation model considering temperature is proposed.

[0004] A prediction method based on a stress relaxation model taking temperature into account, the method comprising:

[0005] Step 1: Establish a stress relaxation model considering temperature:

[0006]

[0007] Where h is Planck's constant, v is the quantum fundamental frequency, and k B is the Boltzmann constant, is the average vibration energy of the crystal, a and b are model coefficients, p is the threshold, σ is the standard deviation of the crystal vibration energy, F(T,t) is the stress of the metal material, T is the temperature, x is the integral variable, t is the time, d is the differential, j, k and l are all fitting coefficients;

[0008] Step 2: Keep the time t in the temperature-considered stress relaxation model constant while changing the temperature T. Each time the temperature T changes, a temperature-considered stress relaxation model is obtained. Let the temperature T change multiple times to obtain multiple temperature-considered stress relaxation models. Combine multiple temperature-considered stress relaxation models to form a model group. Assume that each temperature-considered stress relaxation model in the model group is All are given values, solve the model group No. 1, and obtain b three parameter values;

[0009] The temperature T in the temperature-considered stress relaxation model is kept constant while the time t is varied. Each time the time t is varied, a time-varying temperature-considered stress relaxation model is obtained. By varying the time t multiple times, multiple time-varying temperature-considered stress relaxation models are obtained. Multiple time-varying temperature-considered stress relaxation models are combined to form the second model group. Substitute the three parameter values ​​of b into the second model group to obtain the three parameter values ​​of k, l, and j;

[0010] Step 3: The six parameter values ​​of b, k, l, and j are brought into a stress relaxation model that takes temperature into consideration to obtain the stress relaxation model to be output. The current temperature and current time of the metal material are input into the stress relaxation model to be output to predict the stress of the metal material at the current temperature and current time.

[0011] Preferably, the method further comprises step 4;

[0012] Step 4: Verify the correctness of the stress relaxation model to be output.

[0013] Preferably, the correctness of the stress relaxation model to be output is verified, specifically:

[0014] Measure the current temperature of the metal material, and measure the stress of the metal material at the current temperature and the current time, bring the current temperature and the current time into the stress relaxation model to be output, output the predicted value of the stress of the metal material, and judge whether the predicted value of the stress of the metal material at the current temperature and the current time is the same as the measured stress of the metal material. If so, judge that the stress relaxation model to be output is correct; if not, judge that the stress relaxation model to be output is incorrect.

[0015] Preferably, in step 1, the average vibration energy of the crystal Expressed as:

[0016]

[0017] Preferably, the stress relaxation model considering temperature is established based on crystal vibration energy in statistical mechanics.

[0018] Preferably, the specific process of establishing the stress relaxation model considering temperature is:

[0019] Obtain a stress relaxation model in which the vibration energy of the metal material crystal is normally distributed:

[0020]

[0021] Transform formula 3 into:

[0022]

[0023] use Substitute the value in Formula 4 Get formula 1.

[0024] The beneficial effects of the present invention are:

[0025] In order to address the limitations of existing stress relaxation models, this application provides a stress relaxation model that takes temperature into account. Based on the crystal vibration energy in statistical mechanics, this method proposes an assumption between microscopic properties and macroscopic properties, establishes a model of temperature, time and macroscopic properties, and replaces the existing stress relaxation model.

[0026] This application provides a temperature-based stress relaxation model. Compared to existing stress relaxation models, this model not only considers the effect of temperature on stress relaxation but also establishes a link between microscopic and macroscopic properties. Therefore, this model more accurately characterizes the forces in metal materials. Compared to existing models, this model can more accurately predict the stresses in metal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the microscopic mechanism of stress relaxation. Reference numerals represent metal materials, reference numeral 2 represents a crystal, and reference numeral 3 represents a grown crystal.

[0028] Figure 2 is a flow chart of a prediction method based on a stress relaxation model taking temperature into account;

[0029] Figure 3 This is a diagram showing the effect of simulating a stress relaxation model taking temperature into account, where reference numeral 4 represents a threshold value p;

[0030] Figure 4 The temperature characteristics of the spring force are used to preliminarily verify the stress relaxation model. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0034] Example 1:

[0035] Combine Figure 2 This embodiment describes a prediction method based on a stress relaxation model taking temperature into consideration, the method comprising:

[0036] Step 1: Establish a stress relaxation model considering temperature:

[0037]

[0038] Where h is Planck's constant, v is the quantum fundamental frequency, and k B is the Boltzmann constant, is the average vibration energy of the crystal, a and b are model coefficients, p is the threshold, σ is the standard deviation of the crystal vibration energy, F(T,t) is the stress of the metal material, T is the temperature, x is the integral variable, t is the time, d is the differential, j, k and l are all fitting coefficients;

[0039] Step 2: Keep the time t in the temperature-considered stress relaxation model constant while changing the temperature T. Each time the temperature T changes, a temperature-considered stress relaxation model is obtained. Let the temperature T change multiple times to obtain multiple temperature-considered stress relaxation models. Combine multiple temperature-considered stress relaxation models to form a model group. Assume that each temperature-considered stress relaxation model in the model group is All are given values, solve the model group No. 1, and obtain b three parameter values;

[0040] The temperature T in the temperature-considered stress relaxation model is kept constant while the time t is varied. Each time the time t is varied, a time-varying temperature-considered stress relaxation model is obtained. By varying the time t multiple times, multiple time-varying temperature-considered stress relaxation models are obtained. Multiple time-varying temperature-considered stress relaxation models are combined to form the second model group. Substitute the three parameter values ​​of b into the second model group to obtain the three parameter values ​​of k, l, and j;

[0041] Step 3: The six parameter values ​​of b, k, l, and j are brought into a stress relaxation model that takes temperature into consideration to obtain the stress relaxation model to be output. The current temperature and current time of the metal material are input into the stress relaxation model to be output to predict the stress of the metal material at the current temperature and current time.

[0042] In this embodiment, the stress and Young's modulus of the metal material are in a linear relationship. Therefore, based on this relationship, after obtaining the stress of the metal material, the Young's modulus of the metal material can be obtained.

[0043] In a preferred embodiment, the method further comprises step 4;

[0044] Step 4: Verify the correctness of the stress relaxation model to be output.

[0045] A preferred embodiment verifies the correctness of the stress relaxation model to be output, specifically:

[0046] Measure the current temperature of the metal material, and measure the stress of the metal material at the current temperature and the current time, bring the current temperature and the current time into the stress relaxation model to be output, output the predicted value of the stress of the metal material, and judge whether the predicted value of the stress of the metal material at the current temperature and the current time is the same as the measured stress of the metal material. If so, judge that the stress relaxation model to be output is correct; if not, judge that the stress relaxation model to be output is incorrect.

[0047] In this embodiment, the metal material can be a spring. Figure 4 The following is a comparison of the curve of the measured spring stress as it changes with temperature and the stress obtained by the model of this application. Figure 4 It can be seen that the stress-temperature characteristics of the spring show an inverse "S" shape. This phenomenon is similar to Figure 3 The error function model results obtained by simulation are the same. Therefore, it can be considered that the model is reasonable. Figure 4 It can be seen that the temperature characteristics of spring stress present an "S" type, or an inverse "S" type. In addition, Figure 4 The force loss in the example is the integrated representation of the model in this application.

[0048] In a preferred embodiment, in step 1,

[0049] Average vibration energy of the crystal Expressed as:

[0050]

[0051] In this embodiment, the orderly arrangement of microscopic matter within a macroscopic object is called a crystal. Atoms are bound together through the activity of bound electrons, forming a single, large crystal molecule. Thermal motion of atoms cannot occur through translational motion, but each atom can vibrate around its equilibrium position or lattice point. As temperature increases, the average amplitude of each atomic vibration increases accordingly. Furthermore, the average vibrational energy of a crystal is proportional to temperature, as shown in Equation 2.

[0052] In a preferred embodiment, the stress relaxation model is established based on crystal vibration energy in statistical mechanics.

[0053] In a preferred embodiment, the specific process of establishing a stress relaxation model taking temperature into consideration is as follows:

[0054] Obtain a stress relaxation model in which the vibration energy of the metal material crystal is normally distributed:

[0055]

[0056] Transform formula 3 into:

[0057]

[0058] use Substitute the value in Formula 4 Get formula 1.

[0059] In this embodiment, it is assumed that the macroscopic performance of the object is proportional to the sum of the vibration energies of the crystals greater than a threshold value p:

[0060]

[0061] Among them, F(T,t) is the stress relaxation of the metal material, is the vibration energy of the wth crystal, M is the sum of the number of crystals, M p is the sum of the number of crystals whose vibration energy is greater than the threshold p, and a and b are model coefficients.

[0062] The distribution of crystal vibration energy can be approximated as a normal distribution, so we have formula 3:

[0063] In order to facilitate calculation, Formula 3 is transformed to obtain Formula 4. The specific transformation process is to replace use Indicated by using formula 3 and To express the formula 4 Empirically So use Substitute the value in Formula 4 Thus, the model of formula 1 is obtained; it must be pointed out that: σ does not change significantly in a short period of time at non-ultra-high temperatures (below 200°C), so it can be considered a constant value in the temperature characteristic test. Therefore, in step 2, a temperature-dependent stress relaxation model considering temperature is obtained each time the temperature T changes. The σ in each temperature-dependent stress relaxation model obtained is a constant value. Through simulation, the model should be as follows Figure 4 Solid line shown.

[0064] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. A prediction method based on a stress relaxation model taking temperature into account, characterized in that: The method comprises: Step 1: Establish a stress relaxation model considering temperature: Where h is Planck's constant, v is the quantum fundamental frequency, and k B is the Boltzmann constant, is the average vibration energy of the crystal, a and b are model coefficients, p is the threshold, σ is the standard deviation of the crystal vibration energy, F(T,t) is the stress of the metal material, T is the temperature, x is the integral variable, t is the time, d is the differential, j, k and l are all fitting coefficients; Step 2: Keep the time t in the temperature-considered stress relaxation model constant while changing the temperature T. Each time the temperature T changes, a temperature-considered stress relaxation model is obtained. Let the temperature T change multiple times to obtain multiple temperature-considered stress relaxation models. Combine multiple temperature-considered stress relaxation models to form a model group. Assume that each temperature-considered stress relaxation model in the model group is All are given values, solve the model group No. 1, and obtain b three parameter values; The temperature T in the temperature-considered stress relaxation model is kept constant while the time t is varied. Each time the time t is varied, a time-varying temperature-considered stress relaxation model is obtained. By varying the time t multiple times, multiple time-varying temperature-considered stress relaxation models are obtained. Multiple time-varying temperature-considered stress relaxation models are combined to form the second model group. Substitute the three parameter values ​​of b into the second model group to obtain the three parameter values ​​of k, l, and j; Step 3: The six parameter values ​​of b, k, l, and j are brought into a stress relaxation model that takes temperature into consideration to obtain a stress relaxation model to be output. The current temperature and current time of the metal material are input into the stress relaxation model to be output to predict the stress of the metal material at the current temperature and current time. In step 1, the average vibration energy of the crystal Expressed as:

2. The prediction method based on the temperature-considered stress relaxation model according to claim 1, characterized in that: The method further comprises step 4; Step 4: Verify the correctness of the stress relaxation model to be output.

3. The prediction method based on the temperature-considered stress relaxation model according to claim 2, characterized in that: Verify the correctness of the stress relaxation model to be output, specifically: Measure the current temperature of the metal material, and measure the stress of the metal material at the current temperature and the current time, bring the current temperature and the current time into the stress relaxation model to be output, output the predicted value of the stress of the metal material, and judge whether the predicted value of the stress of the metal material at the current temperature and the current time is the same as the measured stress of the metal material. If so, judge that the stress relaxation model to be output is correct; if not, judge that the stress relaxation model to be output is incorrect.

4. The prediction method based on the temperature-considered stress relaxation model according to claim 1, characterized in that: The stress relaxation model considering temperature is based on the crystal vibration energy in statistical mechanics.

5. The prediction method based on the temperature-considered stress relaxation model according to claim 4, characterized in that: The specific process of establishing a stress relaxation model considering temperature is as follows: Obtain a stress relaxation model in which the vibration energy of the metal material crystal is normally distributed: Transform formula 3 into: use Substitute the value in Formula 4 Get formula 1.

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