A reliability assessment method for folding wing systems considering failure correlation

Abstract

This invention relates to the technical field of reliability assessment for folding wings, specifically to a reliability assessment method for a folding wing system considering failure-related factors. The method includes: establishing an aerodynamic load model based on the aerodynamic loads experienced by the folding wing during deployment, the aerodynamic load model including normal wind load and axial wind load on the wing surface; establishing a reliability model for the folding wing system, the folding wing system including a deployment mechanism and a locking mechanism, the deployment mechanism being arranged in series on the wing surface; calculating the reliability of the deployment mechanism and the locking mechanism based on a stress-strength interference model; establishing a reliability model for the folding wing system based on the reliability of the mechanisms and the aerodynamic load model; and achieving reliability prediction and assessment of the folding wing system based on the system reliability model. This invention enables accurate prediction of the reliability of folding wing systems.

Description

Technical Field

[0001] This invention relates to the technical field of reliability assessment of folding wings, and more specifically to a reliability assessment method for folding wing systems that considers failure-related factors. Background Technology

[0002] As a critical component in the aerospace field, the reliability of folding wing systems directly impacts the safety and lifespan of aircraft. These systems consist of multiple folding mechanisms working collaboratively, each subjected to complex dynamic loads during operation. In engineering practice, the core of system reliability assessment lies in accurately quantifying the failure correlation characteristics between components. Traditional reliability theories typically rely on probabilistic statistical methods, deriving system-level reliability indicators by establishing component failure probability models. However, these methods face fundamental challenges when applied to folding wing systems: the failure behaviors of individual mechanisms within the system are not independent events, but rather correlated processes driven by shared external loads, material degradation, and other factors. This failure correlation is essentially due to the mutual influence of stress states caused by load transmission path coupling, making the failure of a single component potentially trigger a chain reaction.

[0003] Currently, two main methods are used in engineering to model and assess the reliability of such systems: one is the classical reliability theory based on series-parallel models, which simply multiplies the reliability of each mechanism to obtain the system reliability; the other is a simplified approach where the reliability of a single critical mechanism represents the overall system. The former ignores the failure mode coupling caused by load correlation, and the calculation results are often overly optimistic; the latter underestimates the true reliability of the system due to oversimplification. Summary of the Invention

[0004] To address the technical problem that traditional reliability methods neglect the failure correlation of internal mechanisms within folding wing systems, leading to overly optimistic or conservative evaluation results, this invention provides a reliability assessment method for folding wing systems that considers failure correlation. This invention primarily utilizes random loads (wind speed) as driving variables, combining aerodynamic load models and stress-strength interference theory to construct a system-level reliability model based on a full probability formula. This allows for a more accurate quantification of the overall reliability of folding wing systems under real random load environments, overcoming the evaluation bias caused by neglecting failure correlation in traditional methods, and providing a more reliable theoretical basis for system design and safety assessment.

[0005] The technical means employed in this invention are as follows: A reliability assessment method for a folding wing system considering failure-related factors includes the following steps: Based on the aerodynamic loads experienced by the folding wing during deployment, an aerodynamic load model is established, which includes the normal wind load and the axial wind load of the wing surface. A failure model of the deployment mechanism of the folding wing system is established. The deployment mechanism includes a deployment component and a locking component, and the deployment structure is arranged in series on the wing surface of the folding wing. Based on the stress-intensity interference model, the reliability of the components in the deployment mechanism is calculated; Based on the component reliability and aerodynamic load model, a system reliability model of the folding wing deployment mechanism is established using the full probability formula. Based on the system reliability model, the folding wing system is tested and maintained.

[0006] Furthermore, the failure mode of the unfolding component is that the unfolding time exceeds the required range, and the failure of the locking component is that the shear stress on the locking pin exceeds the shear strength.

[0007] Furthermore, the reliability of the components in the deployment mechanism includes the reliability of the deployment member and the reliability of the locking member.

[0008] Furthermore, the formula for calculating the reliability of the deployed component is as follows:

[0009] in, To ensure the reliability of the unfolded components, p i For probability, T 1 represents the left range of the specified unfolding time. T 2 represents the right range of values ​​for the specified unfolding time. s i For a given wind speed, t For time, Let be the probability density function for the unfolding time at a given wind speed. The formula for calculating the probability is:

[0010] in, Let be the probability density function of wind speed level. The range of wind speed levels. n The number of unfolded components.

[0011] Furthermore, the formula for calculating the reliability of the locking component is as follows:

[0012] in, To ensure the reliability of the locking components, p i For probability, F The shear stress on the pin. Let be the probability density function of the shear stress on the hinge at a given wind speed. Let be the probability density function of the hinge shear strength. The shear strength of the locking pin. The formula for calculating the probability is:

[0013] in, Let be the probability density function of wind speed level. The range of wind speed levels. n This represents the interval number of the wind speed.

[0014] Furthermore, the aerodynamic load model includes a normal wind load model of the airfoil and an axial wind load model of the airfoil.

[0015] Furthermore, the expression for the normal wind load model of the airfoil is:

[0016] in, For the normal wind load of the wing surface, The angle of wing deployment. The normal wind load increment is calculated using the following formula:

[0017] in, s This refers to wind speed level.

[0018] Furthermore, the expression for the axial wind load model of the airfoil is:

[0019] in, For the axial wind load of the airfoil, The angle of wing deployment. The axial wind load increment is calculated using the following formula:

[0020] in, s This refers to wind speed level.

[0021] Furthermore, the calculation formula for the system reliability model of the folding wing deployment mechanism is as follows:

[0022] in, For the system reliability model of the folding wing deployment mechanism, Let be the probability density function of wind speed level. To ensure the reliability of the unfolded components, T 1 represents the left range of the specified unfolding time. T 2 represents the right range of values ​​for the specified unfolding time.s i For a given wind speed, t For time, Let be the probability density function for the unfolding time at a given wind speed. p i For probability, F The shear stress on the pin. Let be the probability density function of the shear stress on the hinge at a given wind speed. Let be the probability density function of the hinge shear strength. The shear strength of the locking pin. n The number of unfolded components.

[0023] Compared with the prior art, the present invention has the following advantages: 1. By analyzing the aerodynamic loads experienced by the folding wing during deployment, the distribution of the normal and axial wind loads on the wing surface was clarified, providing key aerodynamic data for the design and strength calculation of the deployment mechanism and realizing accurate simulation of aerodynamic loads.

[0024] 2. This invention combines the characteristics of the unfolding component and the locking component to establish a failure scenario for the folding wing unfolding mechanism, and calculates the reliability of the components based on the stress-strength interference model. Through reliability analysis, it realizes the performance prediction and potential failure risk assessment of the key components of the unfolding mechanism.

[0025] 3. Based on the reliability of the components and the established aerodynamic load model, this invention comprehensively considers the failure probability of each link using the full probability formula, and finally constructs a system reliability model for the folding wing deployment mechanism.

[0026] Based on the above reasons, this invention can be widely applied in fields such as folding wing reliability assessment. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a flowchart illustrating a reliability assessment method for a folding wing system that considers failure-related factors according to the present invention.

[0029] Figure 2 This is a schematic diagram illustrating the relationship between system reliability and the number of deployment mechanisms in an embodiment of the present invention.

[0030] Figure 3This is a schematic diagram of the folding wing deployment system of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] like Figure 1 As shown, the present invention provides a reliability assessment method for a folding wing system considering failure-related factors, comprising the following steps: S1. Based on the aerodynamic loads experienced by the folding wing during deployment, an aerodynamic load model is established, which includes the normal wind load and the axial wind load of the wing surface.

[0034] The aerodynamic load model includes a normal wind load model and an axial wind load model. Aerodynamic loads are the main loads borne by the folding wing. During deployment, the wing surface is subjected to aerodynamic forces, which can be decomposed into normal wind loads and axial wind loads. The normal wind load model is then established. (Always perpendicular to the wing surface) and wing surface axial wind load (Located in the horizontal direction, parallel to the wing surface, and always opposite to the direction of wing surface movement), wing surface normal wind load Axial wind load on the airfoil All are related to wind speed level and the angle of wing surface deployment (Units are in radians) related, including wind speed level Directly affects the increase in normal wind load per unit deployment angle of the folding wing and axial wind load increment .

[0035] The expression for the normal wind load model of the wing surface is:

[0036] in, For the normal wind load of the wing surface, The angle of wing deployment. The formula for calculating the normal phase wind load increment is:

[0037] in, s This refers to wind speed level.

[0038] The expression for the axial wind load model of the airfoil is:

[0039] in, For the axial wind load of the airfoil, The axial wind load increment is calculated using the following formula:

[0040] S2. Establish a failure model for the deployment mechanism of the folding wing system. The deployment mechanism includes deployment components and locking components, and the deployment structure is arranged in series on the wing surface of the folding wing.

[0041] Furthermore, the failure mode of the deploying component is that the deployment time exceeds the required range, and the failure mode of the locking component is that the shear stress on the locking pin exceeds the shear strength.

[0042] Based on dynamic simulation analysis, the changes in the folding wing deployment angle and the locking pin impact force over time can be obtained.

[0043] Structurally, such as Figure 3 As shown, the folding wing deployment system has four deployment mechanisms, each including a deployment component and a locking component. The failure mode corresponding to the deployment component is that the wing fails to deploy to the design position within the specified time range, and the failure mode corresponding to the locking component is that the locking pin is sheared off by impact. The occurrence of any of these failure modes will lead to the failure of the folding wing deployment system. Therefore, from a reliability perspective, the folding wing deployment system is a cascaded failure system with eight failure units, including the deployment and locking components.

[0044] During the deployment of the folding wing, the wings are subjected to dispersed random wind loads, leading to a correlation between the loads borne by the deployment and locking components. This results in a correlation between deployment failure and locking failure. Furthermore, uncertainties in the manufacturing and assembly processes of the folding wing, as well as uncertainties in material properties, cause uncertainties in the wing deployment time and the shear strength of the locking pin.

[0045] For a given material and structure, wind load is the only factor that determines the deployment performance parameters of the folding wing (deployment time and shear stress on the locking pin). Therefore, the key to calculating the reliability of a folding wing deployment system lies in reasonably describing the relationship between deployment performance parameters and wind load distribution using a probabilistic framework.

[0046] S3. Based on the stress-intensity interference model, calculate the reliability of the components in the deployment mechanism.

[0047] The reliability of the components in the deployment mechanism includes the reliability of the deployment components and the reliability of the locking components.

[0048] The traditional stress-strength interference model can be understood as a calculation model that statistically averages the failure probability of a component under a given load (i.e., the probability that the strength is less than the given load) over the entire load domain. When both the stress and strength of the component are random variables, the conditional failure probability of the component (conditional on stress) is defined as:

[0049] in, This represents the probability of condition failure.

[0050] The stress intensity interference model for component reliability is as follows:

[0051] in, For the stress intensity interference model of component reliability, for.

[0052] In a mathematical sense, the stress-intensity interference model can be understood as the statistical average of the function k(s) over the domain of the random variable s. The interpretation of the statistical average of the interference model can be extended to the probability average of any continuously integrable function k(s) over the domain of the random variable s with probability density function h(s).

[0053] Assuming a deterministic wind speed s, the probability density function of the wing deployment time is: The probability density function of the shear stress on the locking pin is: , where s i Given the wind speed level, the reliability of the missile wings deploying to the design position within the specified time range T1~T2 under the above conditions is as follows:

[0054] in, To ensure the reliability of the unfolded components, T 1 represents the left range of the specified unfolding time. T 2 represents the right range of values ​​for the specified unfolding time. s i For a given wind speed, t For time, Let be the probability density function for the unfolding time at a given wind speed.

[0055] Based on the stress-strength interference model, the reliability of the locking pin in locking under impact is as follows:

[0056] in, To ensure the reliability of the locking components, F The shear stress on the pin. Let be the probability density function of the shear stress on the hinge at a given wind speed. Let be the probability density function of the hinge shear strength. The shear strength of the locking pin.

[0057] The above equation only considers the impact of the uncertainties in the dimensions and friction of the folding wing deployment mechanism on the uncertainty in deployment time, as well as the uncertainty in the shear strength of the locking pin caused by the uncertainty in material properties. Considering that the uncertainty in wind speed is not negligible, the reliability problem of the folding wing deployment mechanism system needs to comprehensively consider the reliability problems corresponding to both failure modes, and treat random wind speed as a random variable. For this situation, a corresponding reliability model can be established according to the following approach. First, let's consider the probability p... i (i=1,2, ,n;Σp i =1) Take n possible wind speed levels s i (i=1,2, According to the law of total probability, the reliability of the wing deployment component is:

[0058] in, p i Let be the probability.

[0059] The reliability of the locking component is:

[0060] If the wind speed level is a continuous random variable with probability density function h(s), then in the above formula... p iIt can be approximated as:

[0061] in, Let be the probability density function of wind speed level. The range of wind speed levels. n The number of unfolded components.

[0062] In the formula, the continuously distributed wind speed level is approximated as several intervals of discrete wind speed levels. The wind speed level of the i-th interval is represented by its average level s. i This indicates that its probability of occurrence is .

[0063] The reliability of the unfolded components is:

[0064] The reliability of the locking component is:

[0065] make The reliability expression for the folding wing deployment component under a random wind speed level with probability density function h(s) is:

[0066] In the formula, Let be the probability density function of the wing deployment time at wind speed level s. Similarly, the reliability expression of the locking component at a random wind speed level with probability density function h(s) is:

[0067] In the formula, It is the probability density function of the shear stress on the locking pin under wind speed level s. It is the probability density function of the shear strength of the locking pin.

[0068] At a specific wind speed level, the deployment reliability of the folding wing is related to the deployment time, and the deployment times of each component in the system are considered to be independent and identically distributed random variables. For a specific wind speed level, the probability that all n deployable components in the system deploy reliably at the same time is:

[0069] At a specific wind speed level, the locking reliability of the folding wing is related to the strength of the locking pins, and the strength of each locking pin in the system is considered to be an independent and identically distributed random variable. For a specific wind speed level (corresponding to a fixed shear stress on the locking pin), the probability that all n locking pins in the system will lock reliably at the same time is:

[0070] S4. Based on the component reliability and aerodynamic load model, a system reliability model of the folding wing deployment mechanism is established using the full probability formula.

[0071] The calculation formula for the system reliability model of the folding wing deployment mechanism is as follows:

[0072] in, For the system reliability model of the folding wing deployment mechanism, Let be the probability density function of wind speed level. To ensure the reliability of the unfolded components, T 1 represents the left range of the specified unfolding time. T 2 represents the right range of values ​​for the specified unfolding time. s i For a given wind speed, t For time, Let be the probability density function for the unfolding time at a given wind speed. p i for, F for, Let be the probability density function of the shear stress on the hinge at a given wind speed. Let be the probability density function of the hinge shear strength. The shear strength of the locking pin. n This represents the interval number of the wind speed.

[0073] S5. Based on the system reliability model, implement the testing and maintenance of the folding wing system.

[0074] Example For a certain folding wing system, the parameterized variable affecting the deployment time is the nose width of the wing, DV. head Pin radius DV shaft The coefficient of friction DV between the missile wing and the spring seat friction1 The coefficient of friction DV between the shaft hole and the rotating shaft friction2 Normal load increment DV FT Axial load increment DV FL , spiral spring stiffness DV spring1 Numerical relationships between various parameterized variables and development time were obtained based on multiple simulation analyses and the response surface methodology.

[0075] The response surface model was randomly sampled 10,000 times according to the distribution parameters of all input variables in Table 1 to obtain the wing deployment time for each iteration. After KS test, the wing deployment time t follows a normal distribution of N(0.19147, 0.0047092).

[0076] The response surface model was randomly sampled 10,000 times according to the distribution parameters of all input variables in Table 1 to obtain the wing deployment time for each iteration. After KS test, the wing deployment time t follows a normal distribution of N(0.19147, 0.0047092).

[0077] Table 1 Statistical Table of Distribution Parameters of Influencing Factors

[0078] The main factor affecting the impact force on the locking pin when the missile wings are deployed to the designated position is the coefficient of friction (DV) between the missile wings and the spring seat. friction1 The coefficient of friction DV between the shaft hole and the rotating shaft friction2 wing surface normal load increment DV FT wing surface axial load increment DV FL , spiral spring stiffness DV spring1 and compression spring stiffness DV spring2 In the ADAMS / Insight module, the parameterized variables were set according to the parameters in Table 1, and the unfolding time was set as the output response. Multiple simulations of the virtual prototype were performed using the Monte Carlo stochastic simulation method to obtain multiple sets of locking pin impact force data. Matlab software was then used to statistically fit the simulation results. After KS test, the impact force Q on the locking pin follows the law of N(8030.4098, 295.3221). 2 The normal distribution of ).

[0079] The locking pin is machined from a medium carbon steel. Its shear strength is 390 MPa. Due to factors such as machining processes, the shear strength of the pin exhibits some variation. Taking a coefficient of variation of 0.1, the shear strength of the locking pin follows the law of N(390, 39...). 2 The normal distribution of ) can be obtained. The reliability of the folding wing locking stage can be calculated to be 0.99405 by the stress-strength interference model, where k(F) is the probability density function of shear stress and g(τ) is the probability density function of shear strength.

[0080] The reliability model for a folding wing system considering failure-related factors is as follows:

[0081] Substituting the above data, the reliability of the folding wing system can be calculated to be 0.9584.

[0082] The calculated value indicates the reliability of the system. Reliability is a value between 0 and 1, where 1 means 100% reliable.

[0083] Current research on the reliability of folding wing deployment mechanisms mostly treats the reliability of a single deployment mechanism as the overall reliability of the folding wing system, or simply uses the assumption of independent failure for reliability assessment. This section compares the system reliability model of folding wing deployment mechanisms considering failure correlation with current methods for calculating the reliability of deployment systems, and verifies the accuracy using Monte Carlo sampling results. Table 2 shows that the results of using the reliability of a single deployment mechanism as the overall reliability of the folding wing system differ significantly from those of Monte Carlo sampling, and cannot accurately measure the system reliability of the deployment mechanism. Compared with the results of the system reliability model considering failure correlation, the system reliability model using the assumption of independent failure differs significantly from the Monte Carlo results, and is overly conservative in its assessment of system reliability.

[0084] Table 2 Comparison of results for different reliability models

[0085] To verify the advantages of failure-dependent folding wing mechanism system reliability models in calculating reliability, system reliability assessments were performed on systems containing 1-100 mechanisms using both independent system reliability models and failure-dependent system reliability models. Figure 2 As can be seen, when the number of mechanisms in the system is less than or equal to 5, the system reliability calculated by the two models is similar. However, when the number of mechanisms in the system exceeds 5, the difference between the two models gradually increases, and the calculation results of the independent system model are more conservative.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for reliability evaluation of a folding wing system considering failure correlation, characterized in that, Includes the following steps: Based on the aerodynamic loads experienced by the folding wing during deployment, an aerodynamic load model is established, which includes the normal wind load and the axial wind load of the wing surface. A failure model of the deployment mechanism of the folding wing system is established. The deployment mechanism includes a deployment component and a locking component, and the deployment structure is arranged in series on the wing surface of the folding wing. The reliability of components in the deployment mechanism is calculated based on the stress-intensity interference model. Based on the component reliability and aerodynamic load model, a system reliability model of the folding wing deployment mechanism is established using the full probability formula. Based on the system reliability model, the folding wing system is tested and maintained.

2. The reliability assessment method for a folding wing system considering failure-related factors according to claim 1, characterized in that, The failure mode of the unfolding component is that the unfolding time exceeds the required range, and the failure of the locking component is that the shear stress on the locking pin exceeds the shear strength.

3. The reliability assessment method for a folding wing system considering failure-related factors according to claim 1, characterized in that, The reliability of the components in the deployment mechanism includes the reliability of the deployment member and the reliability of the locking member.

4. The reliability assessment method for a folding wing system considering failure-related factors according to claim 3, characterized in that, The formula for calculating the reliability of the deployed component is: in, To ensure the reliability of the unfolded components, p i For probability, T 1 represents the left range of the specified unfolding time. T 2 represents the right range of values ​​for the specified unfolding time. s i For a given wind speed, t For time, Let be the probability density function for the unfolding time at a given wind speed. The formula for calculating the probability is: in, Let be the probability density function of wind speed level. The range of wind speed levels. n The number of unfolded components.

5. The reliability assessment method for a folding wing system considering failure-related factors according to claim 3, characterized in that, The formula for calculating the reliability of the locking component is as follows: in, To ensure the reliability of the locking components, p i For probability, F The shear stress on the pin. Let be the probability density function of the shear stress on the hinge at a given wind speed. Let be the probability density function of the hinge shear strength. The shear strength of the locking pin. The formula for calculating the probability is: in, Let be the probability density function of wind speed level. The range of wind speed levels. n This represents the interval number of the wind speed.

6. The reliability assessment method for a folding wing system considering failure correlation according to claim 1, characterized in that, The aerodynamic load model includes a normal wind load model for the airfoil and an axial wind load model for the airfoil.

7. The reliability assessment method for a folding wing system considering failure-related factors according to claim 6, characterized in that, The expression for the normal wind load model of the airfoil is: in, For the normal wind load of the wing surface, The angle of wing deployment. The normal wind load increment is calculated using the following formula: in, s This refers to wind speed level.

8. The reliability assessment method for a folding wing system considering failure-related factors according to claim 6, characterized in that, The expression for the axial wind load model of the airfoil is: in, For the axial wind load of the airfoil, The angle of wing deployment. The axial wind load increment is calculated using the following formula: in, s This refers to wind speed level.

9. The reliability assessment method for a folding wing system considering failure-related factors according to claim 1, characterized in that, The calculation formula for the system reliability model of the folding wing deployment mechanism is as follows: in, For the system reliability model of the folding wing deployment mechanism, Let be the probability density function of wind speed level. To ensure the reliability of the unfolded components, T 1 represents the left range of the specified unfolding time. T 2 represents the right range of values ​​for the specified unfolding time. s i For a given wind speed, t For time, Let be the probability density function for the unfolding time at a given wind speed. p i For probability, F The shear stress on the pin. Let be the probability density function of the shear stress on the hinge at a given wind speed. Let be the probability density function of the hinge shear strength. The shear strength of the locking pin. n The number of unfolded components.

Images