Gap-considered cabin door stop block strength analysis method for large amphibious aircraft

Abstract

The invention discloses a gap-considered cabin door stopper strength analysis method for a large amphibious aircraft. The method comprises the following steps: 1, establishing detail models of a cabin door, cabin door stop blocks, cabin door stop block connection and a door frame; 2, calculating the stress of each check block under the pressurization load of the cabin door based on a detail model when the check blocks are gapless, and recording the maximum value as Fn, 3, numbering the check blocks 1-n according to the magnitude of the stress of the check blocks calculated in the step 2 from large to small, and n is the number of the check blocks; 4, calculating the stress of each check block under the pressurization load of the cabin door when the clearance exists in the first check block, and recording the maximum value as Fs1; 5, the step 3 is repeated, the stress of each check block under the pressurization load of the cabin door is calculated when gaps exist between the second check block, the third check block and the fourth check block, the maximum value is recorded as Fsi, and i is equal to 2, 3 and 4; step 6, calculating a gap influence coefficient, and determining a possible maximum load of the stop block, and recording the possible maximum load as Fmax; and 7, checking the strength of the check block by using Fmax. The method is simple to operate and can improve the calculation precision.

Description

Technical Field

[0001] This invention belongs to the field of aircraft structural strength calculation technology, and relates to a method for strength analysis of door stop blocks of large amphibious aircraft considering clearance. Background Technology

[0002] Aircraft doors provide access for personnel and cargo, facilitate passage through internal compartments, serve as water rescue routes, ground maintenance access, air drop routes, and emergency evacuation routes, making them a crucial component of aircraft. The door stop is a critical part of the door mechanism, a key structure that limits the door's range of motion and withstands opening, closing, and pressurization loads. Its strength directly affects the door's sealing performance, safety, and reliability. Traditional verification methods rely on empirical formulas or simplified finite element models. With the development of commercial finite element methods, detailed finite element models are also applied to stop strength verification. While these methods are either computationally simple or yield high accuracy, their calculations of stop loads are relatively coarse, particularly regarding the load distribution among multiple stops under conditions such as single-point failure or initial gaps. Summary of the Invention

[0003] The purpose of this invention is to propose a method for strength analysis of door stop blocks in large amphibious aircraft, taking into account clearance. This invention is simple to operate and can greatly improve calculation accuracy.

[0004] The technical solution of this invention is: a method for strength analysis of door stop blocks for large amphibious aircraft considering clearance, comprising the following steps: Step 1: Create detailed models of the hatch, hatch stop blocks, hatch stop block connections, and door frame; Step 2: Calculate the forces on each block under pressurized load on the hatch when the blocks have no clearance based on the detailed model, and record the maximum value as Fn. Step 3: Number the blocks from 1 to n according to the magnitude of the force on the blocks calculated in Step 2, from largest to smallest, where n is the number of blocks; Step 4: Calculate the force on each block of the hatch under the pressurized load when there is a gap in block 1, and take the maximum value as Fs1; Step 5: Repeat step 3 to calculate the force on each block under the pressurized load when there is a gap between blocks 2, 3 and 4 respectively, and take the maximum value as Fsi, i=2, 3, 4; Step 6: Calculate the gap influence coefficient to determine the maximum possible load on the stop, denoted as Fmax; Step 7: Use the Fmax obtained in Step 5 to check the strength of the stop.

[0005] In the aforementioned method for strength analysis of door blocks for large amphibious aircraft considering gaps, in step 1, the door blocks and door block connections in the established detailed model can be simplified: the blocks are simplified to multiple triangular units surrounding each other, and the block connections are simplified to Bush units.

[0006] In the aforementioned method for strength analysis of door stop blocks for large amphibious aircraft considering gaps, in step 2, the calculation software selected is Abaqus finite element analysis software.

[0007] Optionally, in the aforementioned method for strength analysis of door stop blocks for large amphibious aircraft considering gaps, in step 2, the calculation software selected is Nastran finite element analysis software.

[0008] In the aforementioned method for strength analysis of door blocks for large amphibious aircraft considering clearance, the number of blocks in step 3 is determined based on the actual design of the door.

[0009] In the aforementioned method for strength analysis of door blocks for large amphibious aircraft considering gaps, in step 4, the gap of the block is simulated by adjusting the stiffness of the connecting unit, which is set to nonlinear stiffness.

[0010] In the aforementioned method for strength analysis of door blocks for large amphibious aircraft considering gaps, in step 6, the gap influence coefficient is equal to the result of dividing the maximum value of Fs1, Fs2, Fs3, and Fs4 by Fn plus an uncertainty coefficient of 0.15.

[0011] In the aforementioned method for analyzing the strength of door blocks for large amphibious aircraft considering clearances, step 7 involves verifying the block strength using either a detailed model analysis or an engineering method analysis.

[0012] Beneficial effects: This invention obtains the gap influence coefficient proposed in this invention through the synergy of steps 2-6, creatively solving the technical problem of load distribution uncertainty in the presence of initial gaps in the stop, avoiding the exhaustive method to determine the maximum load of the stop, and improving analysis efficiency; compared with traditional analysis methods, the maximum load of the stop calculated by the gap influence coefficient is closer to the actual load, which is more conducive to structural optimization; the introduction of an uncertainty coefficient of 0.15 in the calculation of the gap influence coefficient ensures the conservatism of the final stop analysis load, thereby improving the accuracy of the stop strength verification results and increasing the credibility of the strength conclusions; in the simulation of the stop gap, the invention creatively uses nonlinear stiffness Bush elements to simulate the existing gap, greatly reducing the difficulty of finite element analysis and simplifying the finite element model; the entire analysis process has fewer steps, a clear principle, and simple operation, which can greatly improve the calculation accuracy and has great practical application value. Attached Figure Description

[0013] Figure 1 Model detailed models of the amphibious aircraft door, door block, block connection, and door frame in the embodiment; Figure 2 A comparison between the actual and simplified models of the hatch stop and the stop connection in the embodiment; Figure 3 The nonlinear stiffness curve set for the connection unit simulating the initial gap of the stop block in the embodiment; Figure 4 This is the detailed model used in the block strength verification of the embodiment. Detailed Implementation

[0014] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific design details are set forth in the following detailed description to provide a more complete understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setup and method set forth below, but covers any improvements, substitutions, and modifications to the structures, methods, and devices without departing from the spirit of the invention. In the drawings and the following description, any parts not exhaustively described are considered to be common knowledge or conventional practices in the art.

[0015] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0016] Example 1. A method for strength analysis of door stop blocks for large amphibious aircraft considering clearances, see [link to relevant documentation]. Figures 1-4 ,include: Step 1: Create detailed models of the hatch, hatch stop blocks, hatch stop block connections, and door frame; Step 2: Calculate the force on each block under the pressurized load when the blocks have no gaps, and take the maximum value as Fn; Step 3: Number the blocks from 1 to n according to the magnitude of the force on the blocks calculated in Step 2, from largest to smallest, where n is the number of blocks; Step 4: Calculate the force on each block under the pressurized load when there is a gap in block 1, and take the maximum value as Fs1; Step 5: Repeat step 3 to calculate the force on each block under the pressurized load when there is a gap between blocks 2, 3, and 4. Take the maximum value as Fsi, i=2, 3, 4; Step 6: Calculate the gap influence coefficient to determine the maximum possible load on the stop, denoted as Fmax; Step 7: Use the Fmax obtained in Step 5 to check the strength of the stop block.

[0017] This invention introduces a gap influence coefficient, which is used to multiply the block load when there is no gap by the gap influence coefficient, thereby analyzing the block strength considering the gap condition. The amphibious aircraft door block strength analysis method provided by this invention has a clear and straightforward process. Compared with traditional methods, it simplifies calculations, effectively reduces the workload of strength analysis, and the analysis results are conservative, thus having significant practical value.

[0018] Finally, the gap influence coefficient was determined, and the strength analysis of the door stop considering the gap was completed.

[0019] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A method for strength analysis of door stop blocks for large amphibious aircraft considering clearance, characterized in that, Includes the following steps: Step 1: Create detailed models of the hatch, hatch stop blocks, hatch stop block connections, and door frame; Step 2: Calculate the forces on each block under pressurized load on the hatch when the blocks have no clearance based on the detailed model, and record the maximum value as Fn. Step 3: Number the blocks from 1 to n according to the magnitude of the force on the blocks calculated in Step 2, from largest to smallest, where n is the number of blocks; Step 4: Calculate the force on each block of the hatch under the pressurized load when there is a gap in block 1, and take the maximum value as Fs1; Step 5: Repeat step 3 to calculate the force on each block under the pressurized load when there is a gap between blocks 2, 3 and 4 respectively, and take the maximum value as Fsi, i=2, 3, 4; Step 6: Calculate the gap influence coefficient to determine the maximum possible load on the stop, denoted as Fmax; Step 7: Use Fmax to check the strength of the stop block.

2. The method for strength analysis of door stop blocks for large amphibious aircraft considering clearances as described in claim 1, characterized in that: In step 1, the hatch stop blocks and hatch stop block connections in the detailed model can be simplified: the stop blocks are simplified to multiple triangular units surrounding each other, and the stop block connections are simplified to Bush units.

3. The method for strength analysis of door stop blocks for large amphibious aircraft considering clearances as described in claim 1, characterized in that: In step 2, the calculation software selected is Abaqus finite element analysis software.

4. The method for strength analysis of door stop blocks for large amphibious aircraft considering clearances as described in claim 1, characterized in that: In step 2, the Nastran finite element analysis software is selected for the calculation.

5. The method for strength analysis of door stop blocks for large amphibious aircraft considering clearances as described in claim 1, characterized in that: The number of blocks in step 3 is determined based on the actual design of the hatch.

6. The method for strength analysis of door stop blocks for large amphibious aircraft considering clearances as described in claim 1, characterized in that: In step 4, the gap of the stop is simulated by adjusting the stiffness of the connecting unit, which is set to nonlinear stiffness.

7. The method for strength analysis of door stop blocks for large amphibious aircraft considering clearances as described in claim 1, characterized in that: In step 6, the gap influence coefficient is equal to the result of dividing the maximum value of Fs1, Fs2, Fs3, and Fs4 by Fn, plus an uncertainty coefficient of 0.

15.

8. The method for strength analysis of door stop blocks for large amphibious aircraft considering clearances as described in claim 1, characterized in that: In step 7, the strength of the stop block is checked by either detailed model analysis or engineering method analysis.

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