VALIDATION OF DIGITAL REPRESENTATIONS OF PARTS OF AN AIRCRAFT SEAT

Abstract

The invention relates to a method (200) for validating digital representations of parts of an aircraft seat, these digital representations being designed for use in a digital simulation of the seat, the method being characterized in that it comprises: - a determination (216) of a primary force path of the seat; - for each of at least one part of the primary force path, a classification (218) of the part considered in one of several predefined levels of importance, each level of importance requiring none, one or more predefined tests, the required tests being different from one level of importance to another;and - for each part for which a level of importance associated with at least one of the tests has been determined: a simulation (220-2) of the associated test(s), using the digital representation of the part considered, a realization (220-4) of the associated test(s), and a validation (220-6) of the digital representation of the part considered by comparing a result of the simulated test with a result of the test carried out. Figure for the abstract: Fig. 2;

Description

Title of the invention: VALIDATION OF DIGITAL REPRESENTATIONS OF PARTS OF AN AIRCRAFT SEAT Technical field of the invention

[0001] The present invention relates to a method for validating digital representations of parts of an aircraft seat. Technological background

[0002] The document "Notification of a Proposal to issue a Certification Memorandum, Modelling & Simulation - CS-25 Structural Certification Specifications", published by EASA, describes a method for validating digital representations of parts of an aircraft seat, in which the following tests are provided: - a material test on a specimen in the material of the part considered; - a component test on a copy of the part considered; - an assembly test on an assembly comprising a copy of the part considered; and in which the test results are compared with the simulated results, by means of the digital representation of the part.

[0003] This known approach is generally called the “modular approach” (from the English “building block approach”).

[0004] This known approach has the disadvantage of requiring numerous tests, if this known approach is treated exhaustively.

[0005] It may thus be desirable to provide a method for validating digital representations of parts of an aircraft seat which makes it possible to dispense with at least some of the tests and simulations. Summary of the invention

[0006] A method is therefore proposed for validating digital representations of parts of an aircraft seat, these digital representations being designed for use in a digital simulation of the seat, the method being characterized in that it comprises: - a determination of a primary seat force path; - for each of at least one part of the primary stress path, a classification of the part considered in one of several predefined levels of importance, each level of importance requiring none, one or more predefined tests, the required tests being different from one level of importance to another; and - for each part for which a level of importance associated with at least one of the tests has been determined: • a simulation of the associated test(s), using the digital representation of the part considered, • completion of the associated test(s), and • a validation of the digital representation of the part considered by comparing a result of the simulated test with a result of the test carried out.

[0007] Thus, thanks to the invention, the need to carry out or not the tests and simulations depends on the level of importance of the part, which makes it possible to plan fewer tests and simulations to validate all the parts.

[0008] The invention may further comprise one or more of the following optional features, in any technically possible combination.

[0009] Optionally, the determination of the level of importance includes: - a determination of one of several predefined levels of complexity, representing the geometric complexity of the part considered; - a determination of one of several predefined margin levels, representing a risk of failure of the part considered; and - a determination of one of several predefined levels of criticality, representing an impact of a failure of the part considered on a result of the simulated test(s) of the seat; and the level of importance is determined from the levels of complexity, margin and criticality of the part considered.

[0010] Also optionally, the margin levels include, in ascending order of margin, a “low” margin level, a “medium” margin level and a “high” margin level.

[0011] Also optionally, the determination of the margin level includes: - a calculation of a margin score from a rupture threshold of the material of the part considered and a simulated value of plastic deformation of the material of the part considered; and - a comparison of the margin score with several ranges of values ​​respectively associated with the predefined margin levels.

[0012] Also optionally, the margin score is given by the equation: SM = (EPS / max_FEM_plastic_strain_result) - 1, where SM is the margin score, EPS is the failure threshold and max_FEM_plastic_strain_result is the simulated plastic strain value.

[0013] Also optionally, a margin score less than 0.5 is associated with the “low” margin level; a margin score between 0.5 and 1 is associated with the “high” margin level. “medium” margin; and a margin score greater than 1 is associated with the “high” margin level.

[0014] Also optionally, the importance levels include, in ascending order of importance, a “low” importance level, a “medium” importance level and a “high” importance level; the complexity levels include, in ascending order of complexity, a “low” complexity level, a “medium” complexity level and a “high” complexity level; the criticality levels include, in ascending order of criticality, a “low” criticality level, a “medium” criticality level and a “high” criticality level; the “high” importance level is determined for the part considered if the latter has a “low” margin level and a “high” criticality level, whatever the complexity level; the “medium” importance level is determined for the part considered if the latter has a “high” margin level or a “high” criticality level or a “high” complexity level;and the “low” importance level is determined for the part considered if the latter has a margin level different from the “high” margin level, a criticality level different from the “high” criticality level and a complexity level different from the high complexity level.;

[0015] Also optionally, the predefined tests include at least one of: - a material test on a test piece in the material of the part considered; - a component test on a copy of the part considered; and - an assembly test on an assembly comprising a copy of the part considered.

[0016] Also optionally, the "high" importance level is associated with the material test, the component test and the assembly test, the "medium" importance level is associated with the assembly test, but with none of the component and assembly tests, and the "low" importance level is not associated with any of the material, component and assembly tests. Brief description of the figures

[0017] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: - [Fig. 1] is a simplified view of a seat in an aircraft cabin, and - [Fig.2] is a block diagram of a representation validation process digital parts of the seat of [Fig.l]. Detailed description of the invention

[0018] With reference to [Fig.l], a seat 100 of an aircraft, for which the invention can be implementation, will now be described.

[0019] The seat 100 is designed to accommodate a passenger and is generally provided in an aircraft cabin. The seat 100 comprises one or more elements 100, 104, 106, 108, 110 which can be movable relative to each other in order to be able to change the configuration of the seat 100. This or these elements 102, 104, 106, 108, 110 include for example one or more of: a headrest 102, a backrest 104, a seat 106, a legrest 108, and armrests 110. To allow the mobility of the elements 102, 104, 106, 108, 110, the seat 100 may comprise one or more actuators 112, 114, 116, 118 designed to move this or these movable elements 102, 104, 106, 108, 110.This or these actuators 112, 114, 116, 118 include for example at least one of: an actuator 112 of the headrest 102 relative to the backrest 104, an actuator 114 of the backrest 104 relative to the seat 106, an actuator 116 of the seat 106 relative to a floor of the aircraft cabin and an actuator 118 of the legrest 108 relative to the seat 106. The seat 100 is supported by a frame 120, such as a floor of the aircraft cabin.

[0020] The parts of the seat 100 are represented by respective digital representations. These digital representations are designed for use in a digital simulation of the seat, in particular in simulations of certification tests, for example dynamic certification.

[0021] For the purposes of the present invention, a part may sometimes be a connecting part, that is to say an element holding two other parts, such as a pin, or even glue between two other parts or even a weld bead between two parts.

[0022] With reference to [Fig.2], an example of a method 200 for validating digital representations of parts of a seat, such as the seat 100, will now be described.

[0023] During a step 202, tests of the parts are defined. These tests are hierarchized into respective test levels. Thus, each test level is associated with a test. For the purposes of the present invention, a test is a generic term that can group together one or more actual tests.

[0024] Preferably, the test(s) of the first test level(s) are non-specific, while the test(s) of the other (higher) test level(s) are specific. A non-specific test does not apply to a copy of the part under consideration, but to a test specimen representing at least one characteristic of this part. A specific test applies to a copy of the part under consideration.

[0025] The tests include, for example, at least one of the following tests: a material test TM, a component test TC, and an assembly test TA.

[0026] The TM material test aims to define the mechanical behavior law of the material from which the part in question is made. For this, the material test is conducted on a test piece in the material to be tested.

[0027] The purpose of the TC component test is to define the deformation of the part considered, in isolation. For this, the TC component test is carried out on a complete or partial copy of the part considered.

[0028] The purpose of the TA assembly test is to define the deformation of the part considered, when assembled with one or more other parts of the seat. For this, the assembly test is conducted on an assembly grouping together examples of the part considered and the other part(s), as provided in the seat, for example according to a plan of the seat.

[0029] For example, the following test hierarchy is used: Test level Test 1 Material test (MT) 2 Component test (TC) 3 Assembly test (TA)

[0030] During a step 204, part sensitivity levels NI are defined. The sensitivity NI of a part represents the level of importance and detail to be attributed to the digital representation of the part considered to maintain the representativeness of the complete digital seat compared to the real seat. For example, three part sensitivity levels are defined: “high”, “medium” and “low”.

[0031] For example, the importance level NI of a part can be determined from a complexity, a margin and / or a criticality of the part.

[0032] The complexity of the part represents its complexity in terms of shape and depends on the geometric complexity of the part. This geometric complexity is reflected for example by a complexity in modeling the part, for example by the number of dimensions to be taken into account in the representation of the part: a single dimension (1D), two dimensions (2D), three dimensions (3D). The complexity is all the higher as the geometry of the part is complex and it includes mechanisms.

[0033] The part margin represents a margin of a physical quantity of the part before mechanical failure of the part. The margin is generally positive and the lower (close to zero) the higher the risk. The margin can be negative in which case the probability of failure of the part is very high. The physical quantity is for example the plastic deformation of the part considered, or the stress of the part considered.

[0034] The criticality of the part represents a magnitude of an impact of a failure of the part considered on the certification tests. The criticality is all the higher as the magnitude of the impact is high.

[0035] Thus, the method 200 may for example comprise the following steps 206 to 210.

[0036] During a step 206, several levels of complexity NCx are defined. For example For example, three levels of NCx complexity are defined, called respectively “low”, “medium” and “high”.

[0037] During a step 208, several NM margin levels are defined. For example, three NM margin levels are defined, called respectively “high”, “medium” and “low”.

[0038] During a step 210, several NC criticality levels are defined. For example, three NC criticality levels are defined, called respectively “low”, “medium” and “high”.

[0039] Furthermore, during a step 212, each importance level NI is associated with none, one or more of the predefined tests. The test(s) associated with an importance level NI is a test required for a part of this importance level NI. The required tests are different from one importance level NI to another, that is to say that there cannot be two importance levels NI requiring the same tests (or no tests). If two importance levels NI required the same tests, they would constitute a single importance level for the purposes of the invention. Preferably, the importance levels NI require different numbers of tests. More preferably, the number of required tests increases with the importance level NI. Still preferably, except for the importance level(s) NI which do not require any tests, each importance level NI requires one or more tests of successive levels starting from the highest test level.So, in the example where the test levels are 1 to 4, an importance level NI may require the level 4 test, the levels 4 and 3 tests, the levels 4, 3 and 2 tests, or the levels 4, 3, 2 and 1 tests, but not the levels 3 and 2 tests, or the levels 3 and 1 tests, for example.

[0040] For example, the following associations are used: Level of Importance (LI) Required test(s) “high” Level 1 to 3 tests “medium” Level 3 test “low” (none)

[0041] During a step 214, input data are obtained, this data relating to the seat 100. For example, this input data comprises at least one of: a nomenclature (from the English “Bill Of Material”, also designated by the acronym BOM) of the seat 100 listing the parts of the seat 100, a plan of the seat 100 making it possible to know the assemblies to be considered for the assembly test TA, and a or more loading scenarios of the seat 100, subject to the targeted certification test(s).

[0042] The nomenclature may include connecting parts.

[0043] During a step 215, digital representations of the parts of the nomenclature are obtained. In addition, the complete seat 100 is optionally simulated by a finite element model (FEM) using these digital representations, in at least one of the load scenario(s), in order to calculate, from this simulation, a maximum plastic strain result (from the English “max FEM plastic strain result”) for each part.

[0044] During a step 216, a primary force path of the seat 100 is determined, in particular from the input data. As is known per se, a primary force path is a list of parts of the seat 100 connected to each other and through which the majority of the force passes from the user of the seat 100 to the frame supporting the seat. The primary force path thus lists parts of the seat 100 forming the primary force path. For example, the primary force path is in the following form: Room 1 Room 2 Room 3 Room 4

[0045] During a step 218, the importance level NI of each of at least one part of the primary effort path, preferably for each part of the primary effort path, is determined. Thus, each part is classified into one of the predefined importance levels NI.

[0046] For this, step 218 includes for example the following steps 218-2 to 218-6.

[0047] During a step 218-2, the level of complexity NCx of the part is determined, for example according to the difficulty of its digital representation, this can be the complexity of its geometric shape to be meshed (complex inertia) or the complexity of its behavior which requires the association of elements with different dimensions. For example, the level of complexity “low”, respectively “medium”, respectively “high”, is attributed to the part when the digital representation of the latter is in one dimension (1D), respectively in only two dimensions (2D), respectively in three dimensions (3D).

[0048] During a step 218-4, the margin level NM of the part is determined. For example, determining the margin level of each part comprises the steps 218-4-2 and 218-4-4 following.

[0049] During a step 218-4-2, a margin score SM is calculated from an EPS (Effective Plastic Strain) rupture threshold of the material of the part considered and the maximum plastic deformation of the material of the part considered, obtained during the simulation of step 215 or by feedback. For example, the margin score SM is given by the equation: SM = (EPS / max_FEM_plastic_strain_result) - 1.

[0050] During a step 218-4-4, the margin score SM is compared with several ranges of values ​​respectively associated with the margin levels NM. For example, in particular when the margin score SM is calculated according to the equation above, a margin score SM less than 0.5 is associated with the margin level NM “low”, a margin score SM between 0.5 and 1 is associated with the margin level NM “medium”, and a margin score SM greater than 1 is associated with the margin level NM “high”.

[0051] During a step 218-6, the criticality level NC of the part is determined.

[0052] During a step 218-8, the importance level of the part is determined from the criticality levels NC, margin NM and complexity NCx of the part.

[0053] The different levels assigned to the parts of the example above are for example the following. Part Complexity Level (CLx) Margin Level (ML) Criticality Level (CL) Importance Level (IL) Test Level(s) Part 1 Medium high low “low” (none) Part 2 Low LOW HIGH “high” 1,2,3 Part 3 HIGH medium HIGH “high” 1,2,3 Part 4 Low LOW medium “medium” 3

[0054] During a step 220, the parts whose importance level NI has been determined are validated, test level after test level, starting with the lowest test level. For this, for each part whose importance level NI is associated with the test of the current test level, the following steps 220-2 to 220-6 are implemented.

[0055] During a step 220-2, the test of the current level is simulated using the digital representation of the part considered, and possibly other parts when the test requires it (for example, for the TA assembly test).

[0056] During a step 220-4, the test of the current level is carried out for each part. The verb “carried out” means that the test is done for real, in the physical world.

[0057] During a step 220-6, the digital representation of the part is validated by comparing a result of the simulated test with a result of the test carried out.

[0058] If the digital representation of the part is validated at the current test level, steps 220-2 to 220-6 are repeated taking the next (higher) test level as the current level.

[0059] During a step 222, if the digital representation of the part considered is not validated for at least one test, the digital representation of the part considered is calibrated, that is to say modified, to correspond to the result of the test(s).

[0060] Thus, when the importance level of a part is not associated with the test of the current level, none of the predefined tests are performed. Thus, the total number of tests to be performed is reduced.

[0061] Taking the example above, at test level 1, only parts 2 and 3 are validated. Parts 1 and 4 are automatically considered valid, due to their importance level NI. Thus, the material test TM is carried out for part 2 and for part 3.

[0062] At test level 2, parts 2 and 3 are validated. Parts 1 and 4 are automatically considered valid, due to their importance level NI. Thus, the TC component test is carried out for part 2 and for part 3.

[0063] At test level 3, parts 2, 3 and 4 are validated. Part 1 is automatically considered valid, due to its importance level NI. Thus, the assembly test TA is carried out on an assembly comprising part 2, on an assembly comprising part 3 and on an assembly comprising part 4.

[0064] In conclusion, it appears clearly that a method such as that described above makes it possible to reduce the number of tests to be carried out, depending on the importance of the parts.

[0065] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to the person skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to him.

[0066] In particular, the order of the steps could be different than that illustrated in [Fig.2]

[0067] In the detailed presentation of the invention which is made above, the terms used should not be interpreted as limiting the invention to the embodiments set forth in this description, but should be interpreted to include all equivalents the foreseeability of which is within the ability of a person skilled in the art by applying his general knowledge to the implementation of the teaching just disclosed to him.

Claims

Claims

1. Method (200) for validating digital representations of parts of a seat (100) of an aircraft, these digital representations being designed for use in a digital simulation of the seat (100), the method being characterized in that it comprises: - a determination (216) of a primary force path of the seat (100); - for each of at least one part of the primary stress path, a classification (218) of the part considered in one of several predefined levels of importance, each level of importance requiring none, one or more predefined tests, the required tests being different from one level of importance to another; and - for each part for which a level of importance associated with at least one of the tests has been determined: • a simulation (220-2) of the associated test(s), using the digital representation of the part considered, • a performance (220-4) of the associated test(s), and • a validation (220-6) of the digital representation of the part considered by comparing a result of the simulated test with a result of the test carried out.

2. The method (200) of claim 1, wherein determining the level of importance comprises: - a determination (218-2) of one of several predefined levels of complexity, representing the geometric complexity of the part considered; - a determination (218-4) of one of several predefined margin levels, representing a risk of failure of the part considered; and - a determination (218-6) of one of several predefined levels of criticality, representing an impact of a failure of the part considered on a result of the simulated test(s) of the seat; and in which the level of importance is determined from the levels of complexity, margin and criticality of the part considered.

3. The method (200) of claim 2, wherein the margin levels comprise, in ascending order of margin, a "low" margin level, a "medium" margin level, and a "high" margin level.

4. Method (200) according to claim 2 or 3, wherein the determination (218-4) of the margin level comprises: - a calculation (218-4-2) of a margin score from a rupture threshold of the material of the part considered and a simulated value of plastic deformation of the material of the part considered; and - a comparison (218-4-4) of the margin score with several ranges of values ​​respectively associated with the predefined margin levels.

5. The method (200) of claim 4, wherein the margin score is given by the equation: SM = (EPS / max_FEM_plastic_strain_result) -1, where SM is the margin score, EPS is the failure threshold, and max_FEM_plastic_strain_result is the simulated plastic strain value.

6. Method (200) according to claims 3 and 5 taken together, wherein: - a margin score less than 0.5 is associated with the “low” margin level; - a margin score between 0.5 and 1 is associated with the “medium” margin level; and - a margin score greater than 1 is associated with the “high” margin level.

7. Method (200) according to any one of claims 2 to 6, in which: - the levels of importance comprise, in increasing order of importance, a “low” level of importance, a “medium” level of importance and a “high” level of importance; - the levels of complexity comprise, in increasing order of complexity, a “low” complexity level, a “medium” complexity level and a “high” complexity level; - the criticality levels include, in ascending order of criticality, a “low” criticality level, a “medium” criticality level and a “high” criticality level; - the “high” importance level is determined for the part considered if the latter has a “low” margin level and a “high” criticality level, regardless of the level of complexity; - the “medium” importance level is determined for the part considered if the latter has a “high” margin level or a “high” criticality level or a “high” complexity level;and - the “low” importance level is determined for the part considered if the latter has a margin level different from the “high” margin level, a criticality level different from the “high” criticality level and a complexity level different from the high complexity level.;

8. Method according to any one of claims 1 to 7, in which the predefined tests comprise at least one of: - a material test on a test piece in the material of the part considered; - a component test on a copy of the part considered; and - an assembly test on an assembly comprising a copy of the part considered.

9. A method according to claims 7 and 8 taken together, wherein the "high" level of importance is associated with the material test, the component test and the assembly test, wherein the "medium" level of importance is associated with the assembly test, but with none of the component and assembly tests, and wherein the "low" level of importance is not associated with any of the material, component and assembly tests.

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