A method for evaluating the stress magnitude at the stress focus points on a structural member after superposition of separate loadings in multiple regions
By dividing the aircraft structural parts into multiple measurement areas, applying loads and recording the strain gauge stress values, establishing a relationship curve, and using sensors to estimate the stress magnitude, the problem of failure of the adhesion strain gauge glue is solved, and the structural load monitoring is achieved throughout the life span is achieved.
Patent Information
- Application Number
- CN202210135130.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-02-15
- Publication Date
- 2025-07-04
- Estimated Expiration
- 2042-02-15
AI Technical Summary
In the prior art, the adhesive strain gauge is used to measure the stress of the aircraft structure and the glue failure problem cannot be effectively monitored during the entire life period, especially the parts where the strain gauge cannot be replaced after the aircraft is delivered.
By dividing the structural parts into finite measurement areas, applying loads and recording the strain gauge stress values, establishing a relationship curve, using sensors to estimate the stress values during the delivery stage, and multi-region superposition to evaluate the stress magnitude.
It realizes efficient and rapid estimation of the total stress value at the focus of structural stress during the entire life of the aircraft, and realizes effective monitoring of structural load.
Smart Images
Figure CN114444324B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of structural design and strength testing, and in particular relates to a method for evaluating the stress magnitude at a structural stress focus point on a structural component after multiple regions are loaded and superimposed. Background Art
[0002] To evaluate the life of an aircraft structure, it is necessary to know the load conditions during the use of the aircraft. Generally, the load conditions of hundreds of key parts of the aircraft structure are tracked by pasting strain gauges at the corresponding points for measurement and recording. The advantage of measuring stress through strain gauges is that the structural stress at a certain point can be accurately measured, but the glue used to paste the strain gauges will fail after a certain number of years, which is generally much lower than the service life of the aircraft structure. After failure, the strain gauges need to be re-pasted, which is a lot of work. At the same time, the strain gauges in some parts are pasted during the assembly process of the aircraft. After the aircraft is delivered, the strain gauges in these parts cannot be replaced. Therefore, when it is necessary to monitor the structural load for the entire life of the fuselage, the method of pasting strain gauges is not very practical. Summary of the invention
[0003] In view of the above problems, the purpose of the present invention is to provide a method for evaluating the stress magnitude at the structural stress focus points on a structural component after superimposing loads on multiple areas. This method can efficiently and quickly estimate the total stress value at each structural stress focus point, thereby realizing structural load monitoring throughout the life cycle of the aircraft.
[0004] A method for evaluating the stress magnitude at a structural stress focus point on a structural component by superimposing multiple loads separately. When it is necessary to track the loading condition of any structural stress focus point inside the structural component during its entire life cycle, the structural component is divided into a finite number of measurement areas, and then the contribution of the loading condition of each measurement area to the stress value at the structural stress focus point is measured. The contribution of all measurement areas is superimposed to evaluate the loading condition at the structural stress focus point inside the structural component.
[0005] Furthermore, when there are multiple structural stress focus points that need to be evaluated, the steps described in claim 1 are continuously repeated to complete the evaluation of the loading conditions of all other structural stress focus points.
[0006] Furthermore, the structural member is an aircraft wing.
[0007] A method for evaluating the stress magnitude at a structural stress focus point on a structural member by superimposing loads on multiple regions, comprising the following steps:
[0008] S1. When the stress magnitude at a certain structural stress focus point needs to be evaluated, the wing is divided into a finite number of measurement areas. The more measurement areas are divided, the more accurate the stress evaluation of the structural stress focus point is;
[0009] S2. When the aircraft is in the test phase, strain gauges are pasted at the stress focus points of the structure on the wing.
[0010] S3. First, apply different magnitudes of loads to a certain measurement area separately, then record the stress values of the strain gauges at the stress focus points of the structure under different loads respectively, and then establish a relationship curve between the load and the stress focus point of the structure.
[0011] S4. Continuously change the measurement area and repeat step S3 until the relationship curves between the load and the stress focus point of the structure are established for all measurement areas respectively.
[0012] S5. When the aircraft is in the delivery and use phase, the load at the stress focus point of the structure described in step S1 is not accurately measured through the strain gauge, and sensors are installed in each measurement area; the measurement areas in this phase are the same as those in the test phase.
[0013] S6. By reading the values of each sensor, interpolate and fit the load of each measurement area, and this load is an estimated value; combine this load with the relationship curve corresponding to this measurement area obtained in step S3 to estimate the contribution of the load of this measurement area to the stress value at the stress focus point of the structure.
[0014] S7. After superimposing the contributions of the loads of all measurement areas to the stress value at the stress focus point of the structure, the total stress value at the stress focus point of the structure can be estimated.
[0015] Further, when it is necessary to evaluate the stress magnitudes at multiple stress focus points of the structure, continuously repeat steps S1 - S7, and the total stress values at all stress focus points of the structure can be estimated respectively.
[0016] Further, when estimating the total stress value at the first stress focus point of the structure, in step S2, strain gauges are pasted at each stress focus point of the structure on the wing respectively. When estimating the total stress values at other stress focus points of the structure subsequently, directly skip step S2.
[0017] Further, when estimating the total stress value at the first stress focus point of the structure, in steps S3 and S4, when recording the stress values of the strain gauges at the first stress focus point of the structure under different loads for a certain measurement area respectively and establishing the relationship curve between the load and the first stress focus point of the structure, the stress values of the strain gauges at other stress focus points of the structure under different loads can also be recorded respectively, and the relationship curves between the load and other stress focus points of the structure can be established respectively. When estimating the total stress values at other stress focus points of the structure subsequently, directly use the obtained relationship curves and skip steps S3 and S4.
[0018] Further, the sensor is a pneumatic load sensor.
[0019] Further, the sensor is installed at the center of each measurement area, and the load application position in step S3 is also at the center of each measurement area.
[0020] Further, the number of the measurement areas is more than 6 and can be increased according to actual requirements.
[0021] The present invention is scientific and reasonable, easy to operate, and can efficiently and quickly estimate the total stress value at each structural stress focus point, realizing the structural load monitoring during the whole life cycle of the airframe. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will be further described in detail below with reference to the drawings.
[0023] Figure 1 It is a schematic diagram of wing zoning;
[0024] Figure 2 It is a schematic diagram of the installation position of the pneumatic load sensor in the delivery and use stage;
[0025] As shown in the figure:
[0026] 1, 2, 3, 4, 5, 6, 7, 8, 9 are respectively each measurement area on the wing;
[0027] 1-1 and 1-2 are respectively the structural stress focus points on the wing;
[0028] 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9 are respectively the schematic diagrams of the installation positions of the pneumatic load sensors. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0029] The embodiments of the present invention will be described below by specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0030] It should be noted that the structures, proportions, sizes, etc. depicted in the accompanying drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present invention. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the efficacy that the present invention can produce and the purpose that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of description and clarity, and are not used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention.
[0031] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0032] Embodiment 1:
[0033] As Figure 1 And Figure 2 shown in the method of the present invention for evaluating the stress magnitude at the structural stress focus point on a structural member by superimposing the loads on multiple regions respectively, the structural member is an aircraft wing, and the method includes the following steps:
[0034] S1. When it is necessary to evaluate the stress magnitude at a certain structural stress focus point 1-1, divide the wing into 9 measurement regions ( Figure 1 the regions shown by the reference numerals 1 to 9 in the drawing). The more measurement regions are divided, the more accurate the evaluation of the stress at the structural stress focus point will be.
[0035] S2. When the aircraft is in the test stage, paste a strain gauge at the structural stress focus point 1-1 on the wing.
[0036] S3. First, apply different magnitudes of loads to the center of a certain measurement region (such as Figure 1 the measurement region shown by the reference numeral 1 in the drawing) (such as Figure 2 the positions shown by the reference numerals 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9 in the drawing), then record the stress values of the strain gauge at the structural stress focus point 1-1 under different loads respectively, and then establish a relationship curve between the load and the structural stress focus point 1-1.
[0037] S4. Continuously change the measurement area and repeat step S3 until the relationship curves between the load and the structural stress focus 1-1 are established for all measurement areas respectively. For each measurement area (such as Figure 1 the areas shown by the reference numerals 1 to 9 in the attached drawings), a relationship curve between the load and the structural stress focus 1-1 is established one by one.
[0038] S5. When the aircraft is in the delivery and use stage, the load at the structural stress focus 1-1 described in step S1 is not accurately measured by the strain gauge. Place pneumatic load sensors at the center of each measurement area (such as Figure 1 the areas shown by the reference numerals 1 to 9 in the attached drawings); the installation positions of the pneumatic load sensors are as shown by the reference numerals 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9 in Figure 2 the attached drawings; the measurement areas of the wing in this stage are the same as those of the wing in the test stage.
[0039] S6. By reading the values of each pneumatic load sensor, the load of each measurement area is obtained by mathematical interpolation and fitting. This load is an estimated value; combining this load with the relationship curve corresponding to this measurement area obtained in step S3, the contribution amount of the load of this measurement area to the stress value at the structural stress focus 1-1 is estimated.
[0040] S7. After superimposing the contribution amounts of the loads of all measurement areas to the stress value at the structural stress focus 1-1, the total stress value at the structural stress focus 1-1 can be estimated.
[0041] The principle of the present invention is as follows:
[0042] Within the elastic deformation range of metal parts, stress and strain can be approximately regarded as a linear relationship. Therefore, the stress change at a specific point on a structural member caused by multiple points being loaded can be regarded as the linear superposition of the stresses caused by applying loads to individual points separately. For a complex system such as an aircraft wing, during the test phase, the wing can be divided into several regions. A load is applied to a certain region alone, and the stress magnitude at a certain structural focus point is accurately measured by strain gauges pasted at this point and the stress value is recorded. Then, the load applied to this region is cancelled, and after applying a load to another region, the stress value at this structural focus point is recorded again. Repeat this process until all regions have been loaded separately and the stress values at this structural focus point have been recorded. Finally, add up the stress values at this structural focus point under each load, and the stress value at this structural focus point when loads are applied to all regions of the wing simultaneously can be calculated. For mass-produced aircraft, during the test phase, pneumatic load sensors are installed at specific points (such as the center of the region) within each region to measure the pneumatic load at that point. Then, the pneumatic load of this region is estimated by means of mathematical interpolation and fitting. By comparing the corresponding relationship curve between the load applied to the region and the stress value at the structural focus point obtained during the test phase, the load at this structural focus point can be evaluated.
[0043] Embodiment 2:
[0044] As Figure 1 And Figure 2 As shown in the method for evaluating the stress magnitude at the structural stress focus point on a structural member by separately loading multiple regions and then superimposing, the structural member is an aircraft wing, and the method includes the following steps:
[0045] S1. When it is necessary to evaluate the stress magnitudes at two structural stress focus points 1-1 and 1-2, divide the wing into 9 measurement regions ( Figure 1 the regions shown by reference numerals 1 to 9 in the figure). The more measurement regions are divided, the more accurate the evaluation of the stress at the structural stress focus point will be.
[0046] S2. When the aircraft is in the test phase, paste strain gauges at all structural stress focus points 1-1 and 1-2 on the wing.
[0047] S3. First, apply different magnitudes of loads to the center of a certain measurement region (such as Figure 1 the measurement region shown by reference numeral 1 in the figure), such as Figure 2 the positions shown by reference numerals 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, and 2-9 in the figure). Then, record the stress values of the strain gauges at each structural stress focus point 1-1 and 1-2 under different loads respectively. Then, establish the relationship curves between the load and structural stress focus point 1-1 and between the load and structural stress focus point 1-2 respectively.
[0048] S4. Continuously change the measurement area and repeat step S3 until the relationship curves between the load and the structural stress focus points 1-1 and the load and the structural stress focus point 1-2 are established for all measurement areas respectively. For each measurement area (such as Figure 1 the areas shown by the reference numerals 1 to 9 in the attached drawing), a relationship curve between the load and the structural stress focus point 1-1 is established one by one. At the same time, for each measurement area (such as Figure 1 the areas shown by the reference numerals 1 to 9 in the attached drawing), a relationship curve between the load and the structural stress focus point 1-2 is established one by one.
[0049] S5. When the aircraft is in the delivery and use stage, the load at the structural stress focus point 1-1 described in step S1 is not accurately measured by the strain gauge. Place pneumatic load sensors at the center of each measurement area (such as Figure 1 the areas shown by the reference numerals 1 to 9 in the attached drawing). The installation positions of the pneumatic load sensors are as shown by the reference numerals 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9 in Figure 2 the attached drawing; the measurement area of the wing in this stage is the same as that of the wing in the test stage.
[0050] S6. By reading the values of each pneumatic load sensor, the load of each measurement area is obtained by mathematical interpolation and fitting. This load is an estimated value; combining this load with the relationship curve corresponding to this measurement area obtained in step S3, the contribution amount of the load of this measurement area to the stress value at the structural stress focus point 1-1 is estimated.
[0051] S7. After superimposing the contribution amounts of the loads of all measurement areas to the stress value at the structural stress focus point 1-1, the total stress value at the structural stress focus point 1-1 can be estimated.
[0052] S8. Repeat the method shown in steps S5 - S7 to estimate the total stress value of another structural stress focus point 1-2
[0053] Embodiment Three:
[0054] The difference between this embodiment and Embodiment One is that:
[0055] When it is necessary to evaluate the stress magnitudes at multiple structural stress focus points, continuously repeat steps S1 - S7, and the total stress values at all structural stress focus points can be estimated respectively.
[0056] When estimating the total stress value at the first structural stress focus point 1-1, strain gauges are pasted at each structural stress focus point on the wing respectively in step S2. When estimating the total stress values at other structural stress focus points subsequently, step S2 is directly skipped.
[0057] When estimating the total stress value at the first structural stress focus point 1-1, in steps S3 and S4, record the stress values of the strain gauges at the first structural stress focus point 1-1 under different loads for a certain measurement area respectively, and establish the relationship curve between the load and the first structural stress focus point 1-1. At the same time, the stress values of the strain gauges at other structural stress focus points under different loads can also be recorded respectively, and the relationship curves between the load and other structural stress focus points can be established respectively. When estimating the total stress values at other structural stress focus points subsequently, directly use the obtained relationship curves and skip steps S3 and S4.
[0058] It should be noted that the term "including", "comprising" or any other variant is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent in such process, method, article or device.
[0059] The protection scope of the present invention is not limited to the technical solutions disclosed in the specific embodiments. Any modifications, equivalent replacements, improvements, etc. made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.
Claims
1. A method for evaluating the stress magnitude at the stress focus point on a structural member after superposition of separate loadings in multiple regions, characterized in that: When it is necessary to track the loading conditions of any structural stress focus point inside a structural member throughout its entire life cycle, the structural member is divided into a finite number of measurement regions. Then, the contribution of the loading condition of each measurement region to the stress value at this structural stress focus point is measured, and the contributions of all measurement regions are superimposed to evaluate the loading condition at this structural stress focus point inside the structural member; The method specifically includes the following steps: S1. When it is necessary to evaluate the stress magnitude at a certain structural stress focus point, the wing is divided into a finite number of measurement regions; S2. When the aircraft is in the test phase, strain gauges are pasted at the structural stress focus point on the wing; S3. First, different magnitudes of loads are applied to a certain measurement region alone. Then, the stress values of the strain gauges at this structural stress focus point under different loads are recorded respectively. Then, a relationship curve between the load and the structural stress focus point is established; S4. The measurement regions are continuously changed and step S3 is repeated until relationship curves between the load and the structural stress focus point are established for all measurement regions; S5. When the aircraft is in the delivery and use phase, sensors are installed in each measurement region; the measurement regions in this phase are the same as those in the test phase; S6. By reading the values of each sensor, the load of each measurement region is interpolated and fitted. This load is an estimated value; the contribution of this load to the stress value at this structural stress focus point is estimated by combining the relationship curve corresponding to this measurement region obtained in step S3; S7. The contributions of the loads of all measurement regions to the stress value at this structural stress focus point are superimposed to estimate the total stress value at this structural stress focus point.
2. The method for evaluating the stress magnitude at the structural stress focus point on the structural member after superposition of multi-region separate loadings according to claim 1, wherein: When the number of structural stress focus points to be evaluated is multiple, the steps described in claim 1 are continuously repeated to complete the evaluation of the loading conditions of all other structural stress focus points.
3. The method for evaluating the stress magnitude at the structural stress focus point on the structural member after superposition of separately loaded multi-regions according to claim 1, wherein: The structural member is an aircraft wing.
4. The method for evaluating the stress magnitude at the structural stress focus point on the structural member after superposition of separately loaded multi-regions according to claim 1, characterized in that: When it is necessary to evaluate the stress magnitudes at multiple structural stress focus points, steps S1 - S7 are continuously repeated to separately complete the estimation of the total stress values at all structural stress focus points.
5. The method for evaluating the stress magnitude at the structural stress focus point on the structural member after superposition of separately loaded multi-regions according to claim 4, characterized in that: When estimating the total stress value at the first structural stress focus point, strain gauges are pasted at each structural stress focus point on the wing in step S2. When estimating the total stress values at other structural stress focus points subsequently, step S2 is directly skipped.
6. The method for evaluating the stress magnitude at the stress focus point on the structural member after superposition of separately loaded multi-regions according to claim 5, characterized in that: When estimating the total stress value at the first structural stress focus point, when recording the stress values of the strain gauges at the first structural stress focus point under different loads for a certain measurement region in steps S3 and S4 and establishing the relationship curve between the load and the first structural stress focus point, the stress values of the strain gauges at other structural stress focus points under different loads can also be recorded respectively, and the relationship curves between the load and other structural stress focus points are established respectively. When estimating the total stress values at other structural stress focus points subsequently, the obtained relationship curves are directly used and steps S3 and S4 are skipped.
7. The method for evaluating the stress magnitude at the stress focus point on the structural member after superposition of multi-region separate loadings according to claim 1, characterized in that: The sensor is a pneumatic load sensor.
8. The method for evaluating the stress magnitude at the structural stress focus point on the structural member after superposition of multi-region separate loadings according to claim 1, characterized in that: The sensor is installed at the center of each measurement region, and the load application position in step S3 is also at the center of each measurement region.
9. The method for evaluating the stress magnitude at the structural stress focus point on the structural member after superposition of multi-region separate loadings according to any one of claims 1-8, characterized in that: The number of the measurement regions is more than 6 and can be increased according to actual requirements.
Citation Information
Patent Citations
Method applied to analysis of damage tolerance feature of stiffened wall panel
CN104330253A