A structural thermal stress analysis method considering high temperature cumulative damage

Abstract

This invention relates to a structural thermal stress analysis method that considers high-temperature cumulative damage, belonging to the field of structural thermal protection analysis. It describes the change in material load-bearing capacity through a high-temperature cumulative damage factor and, combined with finite element analysis, presents the high-temperature damage accumulation of elements at different locations under thermal loads. Through iterative updates of material properties, it directly simulates the high-temperature cumulative damage process of the thermal structure, providing a method for analyzing the structural thermal stress response under different force and thermal load histories. This method is superior to traditional thermal stress analysis methods that only consider the current highest operating temperature. This invention comprehensively considers the damage accumulation effects of material thermal conductivity, elastic modulus, and strength at different operating temperatures, and features high calculation accuracy and wide applicability.

Description

Technical Field

[0001] This invention relates to a structural thermal stress analysis method that takes into account the cumulative damage caused by high temperatures, and belongs to the field of structural thermal protection analysis. Background Technology

[0002] Structural thermal protection is one of the bottleneck technologies restricting the improvement of aircraft performance. During long-term flight, the thermal protection structure of an aircraft is subjected to severe aerodynamic and thermal loads for extended periods. Materials working in a high-temperature and oxygen-rich environment for extended periods may undergo significant physicochemical changes. Especially for composite materials, pyrolysis, oxidation, ablation, and other processes can cause a significant decrease in the load-bearing capacity of the aircraft. Under the cumulative damage caused by prolonged high temperatures, the thermal protection load-bearing performance of the aircraft may fail, seriously threatening flight safety.

[0003] Currently, there are various prediction methods for damage prediction of metallic materials under mechanical loads. However, for the thermal structure analysis of a wider range of material components under combined mechanical and thermal loads, especially the changes in thermal conductivity and the decrease in mechanical load-bearing capacity of composite materials under long-term high-temperature accumulation, most of the methods rely on ground-based tests for simulation assessment. These methods are time-consuming, costly, and lack complete and effective numerical simulation tools. Summary of the Invention

[0004] The problem addressed by this invention is to provide a structural thermal stress analysis method that considers high-temperature cumulative damage. Based on the damage accumulation process of material thermal conductivity, elastic modulus, and strength at different operating temperatures and times, a finite element structural thermal stress analysis method incorporating high-temperature cumulative damage is established. The method provides the structural damage evolution process and thermal stress flow considering the loading history of force and thermal loads, enabling effective prediction of the structural force and thermal load bearing capacity.

[0005] The technical solution of the present invention is as follows:

[0006] A structural thermal stress analysis method considering high-temperature cumulative damage includes:

[0007] S1. Based on the thermal conductivity, elastic modulus, and material strength of the structural components at different operating temperatures and durations, establish a database of high-temperature cumulative damage factors, where the high-temperature cumulative damage factor is represented by f. i =f i (T,t), where i represents thermal conductivity, elastic modulus or material strength, T is the current operating temperature and t is the operating time;

[0008] S2. Establish the initial finite element model of the structural component before force and heat loading;

[0009] S3. Apply the force and thermal load environmental conditions at the j-th load step to the structural component, and solve for the structural temperature field and thermal stress field at the j-th load step; the structural temperature field includes the current operating temperature T.j The current load step duration is expressed as Δt. j The j-th load step is represented as t = t j j = 1, 2, 3...;

[0010] S4. Iterate through the mesh elements of the initial finite element model, and obtain the increment of the high temperature cumulative damage factor of the mesh element based on the structural temperature field and thermal stress field at the j-th load step, combined with the high temperature cumulative damage factor database established in step S1.

[0011] S5. Update the high-temperature cumulative damage factor of the grid unit according to the increment of the high-temperature cumulative damage factor of the grid unit;

[0012] S6. Calculate the thermal conductivity, elastic modulus, and material strength of the updated mesh unit based on the high-temperature cumulative damage factor of the updated mesh unit.

[0013] S7. Compare the thermal stress of the mesh element in step S3 with the material strength of the updated mesh element in step S6 to determine whether the mesh element has been completely destroyed.

[0014] S8. Apply the force and thermal load environmental conditions at the next load step, solve the structural temperature field and thermal stress field at the next load step, and return to step S4;

[0015] S9, until the structural components can no longer bear the mechanical load.

[0016] In the above-mentioned structural thermal stress analysis method considering high-temperature cumulative damage, the initial high-temperature cumulative damage factor value of the finite element initial model established in step S2 is set to zero, i.e., f i (T0, t0) = 0.

[0017] In the above-mentioned structural thermal stress analysis method considering high-temperature cumulative damage, the increment of the high-temperature cumulative damage factor of the mesh element obtained in step S4 is expressed as Δf. i (T j ,Δt j ), where T j Let Δt be the temperature at the current j-th load step. j Let be the time step of the current j-th load step, and i be the thermal conductivity, elastic modulus, or material strength, respectively.

[0018] In the above-mentioned structural thermal stress analysis method considering high-temperature cumulative damage, step S5 updates the high-temperature cumulative damage factor of the mesh elements based on the increment of the high-temperature cumulative damage factor of the mesh elements, including:

[0019] f i (T j+1 ,t j+1 )=fi (T j ,t j )+Δf(T j ,Δt j )

[0020] Among them, f i (T j+1 ,t j+1 f represents the cumulative high-temperature damage factor of the element at the next time step, i.e., the (j+1)th load step. i (T j ,t j ) represents the cumulative high-temperature damage factor of the element at the current time, i.e., the j-th load step.

[0021] In the above-mentioned structural thermal stress analysis method considering high-temperature cumulative damage, step S6, which calculates the updated unit's thermal conductivity, elastic modulus, and material strength based on the updated unit's high-temperature cumulative damage factor, includes:

[0022] k j+1 =k*(1-f k (T j+1 ,t j+1 )),

[0023] E j+1 =E*(1-f E (T j+1 ,t j+1 )),

[0024] S j+1 =S*(1-f S (T j+1 ,t j+1 ))

[0025] Where, k j+1 E represents the updated unit thermal conductivity. j+1 For the updated element elastic modulus, S j+1 The value represents the updated unit material strength, where k is the initial thermal conductivity, E is the initial elastic modulus, and S is the initial material strength.

[0026] In the above-mentioned structural thermal stress analysis method considering high-temperature cumulative damage, in step S7, if the thermal stress is greater than the material strength, the mesh element is determined to be completely destroyed and the elastic modulus of the element is taken as a minimum value; otherwise, the mesh element is determined to be not destroyed.

[0027] A structural thermal stress analysis system considering high-temperature cumulative damage includes:

[0028] The database creation module establishes databases for high-temperature cumulative damage factors based on the thermal conductivity, elastic modulus, and material strength of structural components at different operating temperatures and durations. The high-temperature cumulative damage factor is denoted as f. i =f i (T,t), where i represents thermal conductivity, elastic modulus or material strength, T is the current operating temperature and t is the operating time;

[0029] The model building module creates an initial finite element model of the structural component before force and heat loading.

[0030] The first calculation module applies the force and thermal load environmental conditions at the j-th load step to the structural component, and solves for the structural temperature field and thermal stress field at the j-th load step; the structural temperature field includes the current operating temperature T. j The current load step duration is expressed as Δt. j The j-th load step is represented as t = t j j = 1, 2, 3...;

[0031] The second calculation module iterates through the mesh elements of the initial finite element model and obtains the increment of the high temperature cumulative damage factor of the mesh element based on the structural temperature field and thermal stress field at the j-th load step, combined with the high temperature cumulative damage factor database established in step S1.

[0032] The update module updates the high-temperature cumulative damage factor of the grid unit according to the increment of the high-temperature cumulative damage factor of the grid unit;

[0033] The third calculation module calculates the thermal conductivity, elastic modulus, and material strength of the updated mesh unit based on the high-temperature cumulative damage factor of the updated mesh unit.

[0034] The comparison module compares the thermal stress of the mesh elements with the material strength of the updated mesh elements to determine whether the mesh elements have reached complete failure.

[0035] A computer device includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described above.

[0036] A computer program product includes a computer program that, when executed by a processor, implements the steps of the above-described method.

[0037] Compared with the prior art, the present invention has at least the following beneficial effects:

[0038] (1) The structural thermal stress analysis method provided in this embodiment of the invention describes the change of the material's load-bearing capacity by describing the damage accumulation process of the material under high temperature and long time through the high temperature cumulative damage factor, and gives the high temperature damage accumulation of different parts of the unit under thermal load by combining finite element analysis. It directly simulates the high temperature cumulative damage process of the thermal structure through the iterative update of material properties, and gives the structural thermal stress response analysis method under different force and heat bearing history. It is superior to the traditional thermal stress analysis method that only considers the current highest working temperature. This invention considers in detail the damage accumulation effect of the material's thermal conductivity, elastic modulus and strength at different working temperatures, and has the characteristics of high calculation accuracy and wide applicability.

[0039] (2) The structural thermal stress analysis method provided in the embodiments of the present invention comprehensively considers the influence of different working temperatures and working times of materials, and reflects the cumulative effect of high temperature damage;

[0040] (3) The structural thermal stress analysis method provided in this embodiment of the invention comprehensively considers the influence of thermal conductivity, elastic modulus and strength data on high temperature cumulative damage, covers the main performance parameters of heat transfer and load bearing, and provides a more refined and accurate description of the influence of high temperature cumulative damage.

[0041] (4) The structural thermal stress analysis method provided in the embodiments of the present invention gives the structural damage evolution process and thermal stress flow considering the loading history of force and thermal load, which can effectively predict the structural force and thermal load bearing capacity.

[0042] (5) The structural thermal stress analysis method provided in this embodiment of the invention takes into account the damage accumulation effect of material thermal conductivity, elastic modulus and strength at different working temperatures, and has the characteristics of high calculation accuracy and wide applicability. Attached Figure Description

[0043] Figure 1 This is a flowchart of a structural thermal stress analysis method considering high-temperature cumulative damage in an embodiment of the present invention. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0045] like Figure 1 As shown, the structural thermal stress analysis method considering high-temperature cumulative damage provided in this embodiment of the invention specifically includes the following steps:

[0046] S1. Based on the thermal conductivity, elastic modulus, and material strength of the structural components at different operating temperatures and durations, establish a database of high-temperature cumulative damage factors, where the high-temperature cumulative damage factor is represented by f. i =f i(T,t), where i=k represents thermal conductivity, i=E represents elastic modulus, i=S represents material strength, T is the current working temperature, and t is the working time;

[0047] S2. Establish the initial finite element model of the structural component before thermal loading; set the initial high-temperature cumulative damage value to zero, f(T0, t0) = 0;

[0048] S3. Apply the force and thermal load environmental conditions at the j-th load step to the structural component, and solve for the structural temperature field and thermal stress field at the j-th load step; the structural temperature field includes the current operating temperature T. j and the current load step duration Δt j The j-th load step is represented as t = t j ;

[0049] S4. Iterate through the mesh elements of the initial finite element model. Based on the structural temperature field and thermal stress field at the j-th load step, and combined with the high-temperature cumulative damage factor database established in step S1, obtain the increment of the high-temperature cumulative damage factor of the mesh element, expressed as Δf. i (T j ,Δt j ), where T j The temperature at the current load step, Δt j The cumulative time of the current load step is denoted as , where i represents the thermal conductivity, elastic modulus, or material strength, respectively.

[0050] S5. Update the high-temperature cumulative damage factor of the mesh elements based on the increment of the high-temperature cumulative damage factor, including:

[0051] f i (T j+1 ,t j+1 )=f i (T j ,t j )+Δf(T j ,Δt j )

[0052] Among them, f i (T j+1 ,t j+1 f represents the cumulative high-temperature damage factor of the element at the next time step, i.e., the (j+1)th load step. i (T j ,t j ) represents the cumulative high-temperature damage factor of the element at the current time, i.e., the j-th load step.

[0053] S6. Based on the updated high-temperature cumulative damage factor of the mesh elements, calculate the updated thermal conductivity, elastic modulus, and material strength of the mesh elements, including:

[0054] kj+1 =k*(1-f k (T j+1 ,t j+1 )),

[0055] E j+1 =E*(1-f E (T j+1 ,t j+1 )),

[0056] S j+1 =S*(1-f S (T j+1 ,t j+1 ))

[0057] Where, k j+1 E represents the updated unit thermal conductivity. j+1 For the updated element elastic modulus, S j+1 The value represents the updated unit material strength, where k is the initial thermal conductivity, E is the initial elastic modulus, and S is the initial material strength.

[0058] S7. Compare the thermal stress of the mesh element in step S3 with the updated material strength of the mesh element in step S6 to determine whether the mesh element has been completely destroyed. If the thermal stress is greater than the material strength, the mesh element is completely destroyed, the elastic modulus of the element is taken to a minimum value, and the process proceeds to step S8. Otherwise, the mesh element is not destroyed and the process proceeds to step S8.

[0059] S8. Apply the force and thermal load environmental conditions at the next load step, solve the structural temperature field and thermal stress field at the next load step, and return to step S4;

[0060] S9, until the structural components can no longer bear the mechanical load.

[0061] This invention provides a structural thermal stress analysis method considering high-temperature cumulative damage. A high-temperature cumulative damage factor is defined to describe the performance changes of material thermal conductivity, elastic modulus, and strength under different operating temperatures and durations, serving as the material performance input conditions for structural temperature field and thermal stress analysis. Based on the finite element method, the high-temperature cumulative damage factor for each element is calculated in real time according to the element temperature and thermal stress state during thermal loading. The thermal conductivity, elastic modulus, and strength properties of the element material are updated in real time. Through iterative calculation, the heat conduction and thermal stress re-equilibrium state after local high-temperature cumulative damage can be simulated, realizing a structural thermal stress analysis method considering high-temperature cumulative damage.

[0062] The present invention also provides a structural thermal stress analysis system that considers high-temperature cumulative damage, comprising:

[0063] The database creation module establishes databases for high-temperature cumulative damage factors based on the thermal conductivity, elastic modulus, and material strength of structural components at different operating temperatures and durations. The high-temperature cumulative damage factor is denoted as f. i =f i (T,t), where i represents thermal conductivity, elastic modulus or material strength, T is the current operating temperature and t is the operating time;

[0064] The model building module creates an initial finite element model of the structural component before force and heat loading.

[0065] The first calculation module applies the force and thermal load environmental conditions at the j-th load step to the structural component, and solves for the structural temperature field and thermal stress field at the j-th load step; the structural temperature field includes the current operating temperature T. j The current load step duration is expressed as Δt. j The j-th load step is represented as t = t j j = 1, 2, 3...;

[0066] The second calculation module iterates through the mesh elements of the initial finite element model and obtains the increment of the high temperature cumulative damage factor of the mesh element based on the structural temperature field and thermal stress field at the j-th load step, combined with the high temperature cumulative damage factor database established in step S1.

[0067] The update module updates the high-temperature cumulative damage factor of the grid unit according to the increment of the high-temperature cumulative damage factor of the grid unit;

[0068] The third calculation module calculates the thermal conductivity, elastic modulus, and material strength of the updated mesh unit based on the high-temperature cumulative damage factor of the updated mesh unit.

[0069] The comparison module compares the thermal stress of the mesh elements with the material strength of the updated mesh elements to determine whether the mesh elements have reached complete failure.

[0070] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above method.

[0071] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described method.

[0072] This invention, based on the damage accumulation process of materials under prolonged high temperatures, describes the changes in the material's load-bearing capacity through a high-temperature cumulative damage factor. Combined with finite element analysis, it presents the high-temperature damage accumulation of different elements under thermal loads. Through iterative updates of material properties, it directly simulates the high-temperature cumulative damage process of the thermal structure, providing a method for analyzing the structural thermal stress response under different force-thermal load histories. Superior to traditional thermal stress analysis methods that only consider the current highest operating temperature, this invention comprehensively considers the damage accumulation effects of material thermal conductivity, elastic modulus, and strength at different operating temperatures, offering high computational accuracy and wide applicability.

[0073] The structural thermal stress analysis method considering high-temperature cumulative damage provided in this invention comprehensively considers the influence of different operating temperatures and operating times of materials, reflecting the cumulative effect of high-temperature damage; it comprehensively considers the influence of high-temperature cumulative damage on thermal conductivity, elastic modulus, and strength data, covering the main performance parameters of heat transfer and load bearing; and it establishes corresponding high-temperature cumulative damage factors f for different material properties such as thermal conductivity, elastic modulus, and strength data. i =f i (T,t), where i=k represents thermal conductivity, i=E represents elastic modulus, i=S represents material strength, T is the current operating temperature, and t is the current cumulative duration, provides a more refined and accurate description of the impact of high-temperature cumulative damage.

[0074] The method for calculating the high-temperature cumulative damage factor at different times in this embodiment of the invention is based on the differences in the mechanical and thermal responses of different parts of the thermal structure, i.e., different parts have different temperature fields and stress lengths. Therefore, the high-temperature cumulative damage factor is calculated for each unit, which provides a more detailed characterization of the damage propagation process. For each load step increment, the temperature field and thermal stress field of the unit are used to extract the increment Δf of the high-temperature cumulative damage factor of the calculated unit. i (T j ,t j The data is accumulated, where j represents the load step, thus realizing the evolution and superposition of high-temperature damage factors over time.

[0075] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0076] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A structural thermal stress analysis method considering high-temperature cumulative damage, characterized in that: include: S1. Based on the thermal conductivity, elastic modulus, and material strength of the structural components at different operating temperatures and durations, establish a database of high-temperature cumulative damage factors, where the high-temperature cumulative damage factor is represented by f. i =f i (T,t), where i represents thermal conductivity, elastic modulus or material strength, T is the current operating temperature and t is the operating time; S2. Establish the initial finite element model of the structural component before force and heat loading; S3. Apply the force and thermal load environmental conditions at the j-th load step to the structural component, and solve for the structural temperature field and thermal stress field at the j-th load step; the structural temperature field includes the current operating temperature T. j The current load step duration is expressed as Δt. j The j-th load step is represented as t = t j j = 1, 2, 3...; S4. Iterate through the mesh elements of the initial finite element model, and obtain the increment of the high temperature cumulative damage factor of the mesh element based on the structural temperature field and thermal stress field at the j-th load step, combined with the high temperature cumulative damage factor database established in step S1. S5. Update the high-temperature cumulative damage factor of the grid unit according to the increment of the high-temperature cumulative damage factor of the grid unit; S6. Calculate the thermal conductivity, elastic modulus, and material strength of the updated mesh unit based on the high-temperature cumulative damage factor of the updated mesh unit. S7. Compare the thermal stress of the mesh element in step S3 with the material strength of the updated mesh element in step S6 to determine whether the mesh element has been completely destroyed. S8. Apply the force and thermal load environmental conditions at the next load step, solve the structural temperature field and thermal stress field at the next load step, and return to step S4; S9, until the structural components can no longer bear the mechanical load.

2. The structural thermal stress analysis method considering high-temperature cumulative damage according to claim 1, characterized in that: The initial high-temperature cumulative damage factor value of the finite element initial model established in step S2 is set to zero, i.e., f i (T0, t0) = 0.

3. The structural thermal stress analysis method considering high-temperature cumulative damage according to claim 1, characterized in that: The increment of the high-temperature cumulative damage factor of the grid cell obtained in step S4 is represented as Δf. i (T j ,Δt j ), where T j Let Δt be the temperature at the current j-th load step. j Let be the time step of the current j-th load step, and i be the thermal conductivity, elastic modulus, or material strength, respectively.

4. The structural thermal stress analysis method considering high-temperature cumulative damage according to claim 3, characterized in that: Step S5 involves updating the high-temperature cumulative damage factor of the mesh cells based on the increment of the high-temperature cumulative damage factor of the mesh cells, including: f i (T j+1 ,t j+1 )=f i (T j ,t j )+Δf(T j ,Δt j ) Among them, f i (T j+1 ,t j+1 f represents the cumulative high-temperature damage factor of the element at the next time step, i.e., the (j+1)th load step. i (T j ,t j ) represents the cumulative high-temperature damage factor of the element at the current time, i.e., the j-th load step.

5. The structural thermal stress analysis method considering high-temperature cumulative damage according to claim 1, characterized in that: Step S6 involves calculating the thermal conductivity, elastic modulus, and material strength of the updated unit based on the high-temperature cumulative damage factor of the updated unit, including: k j+1 =k*(1-f k (T j+1 ,t j+1 )), E j+1 =E*(1-f E (T j+1 ,t j+1 )), S j+1 =S*(1-f S (T j+1 ,t j+1 )) Where, k j+1 E represents the updated unit thermal conductivity. j+1 For the updated element elastic modulus, S j+1 The value represents the updated unit material strength, where k is the initial thermal conductivity, E is the initial elastic modulus, and S is the initial material strength.

6. The structural thermal stress analysis method considering high-temperature cumulative damage according to claim 1, characterized in that: In step S7, if the thermal stress is greater than the material strength, the mesh element is determined to be completely destroyed and the elastic modulus of the element is taken to a minimum value; otherwise, the mesh element is determined to be not destroyed.

7. A structural thermal stress analysis system considering high-temperature cumulative damage, characterized in that: include: The database creation module establishes databases for high-temperature cumulative damage factors based on the thermal conductivity, elastic modulus, and material strength of structural components at different operating temperatures and durations. The high-temperature cumulative damage factor is denoted as f. i =f i (T,t), where i represents thermal conductivity, elastic modulus or material strength, T is the current operating temperature and t is the operating time; The model building module creates an initial finite element model of the structural component before force and heat loading. The first calculation module applies the force and thermal load environmental conditions at the j-th load step to the structural component, and solves for the structural temperature field and thermal stress field at the j-th load step; the structural temperature field includes the current operating temperature T. j The current load step duration is expressed as Δt. j The j-th load step is represented as t = t j j = 1, 2, 3...; The second calculation module iterates through the mesh elements of the initial finite element model and obtains the increment of the high temperature cumulative damage factor of the mesh element based on the structural temperature field and thermal stress field at the j-th load step, combined with the high temperature cumulative damage factor database established in step S1. The update module updates the high-temperature cumulative damage factor of the grid unit according to the increment of the high-temperature cumulative damage factor of the grid unit; The third calculation module calculates the thermal conductivity, elastic modulus, and material strength of the updated mesh unit based on the high-temperature cumulative damage factor of the updated mesh unit. The comparison module compares the thermal stress of the mesh elements with the material strength of the updated mesh elements to determine whether the mesh elements have reached complete failure.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method of claim 1.

9. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method of claim 1.

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