CN112109919B

CN112109919B - Loading point layout method for strength test

Info

Publication number: CN112109919B
Application number: CN202010366364.7A
Authority: CN
Inventors: 高建; 孙安晔; 夏龙
Original assignee: AVIC Aircraft Strength Research Institute
Current assignee: AVIC Aircraft Strength Research Institute
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2024-04-19
Anticipated expiration: 2040-04-30
Also published as: CN112109919A

Abstract

The application belongs to the technical field of aircraft strength test design, and particularly relates to a method for distributing loading points of a strength test, which comprises the following steps: marking information of each joint on the test piece, wherein the information comprises a loading direction vector, loading point position coordinates and loading load of the joint; acquiring a task load F _r of each working condition in a test project; determining all loading joint selection schemes; distributing the task load of each working condition to each selection scheme, and acquiring a selection scheme set for enabling the load to meet a distribution principle; and selecting an optimal scheme from the selected scheme set. The application can automatically calculate the optimal selection scheme of the loading points by using a computer, thereby realizing automatic layout, reducing manual intervention factors, improving efficiency and realizing automation.

Description

Loading point layout method for strength test

Technical Field

The application belongs to the technical field of aircraft strength test, and particularly relates to a method for distributing loading points in a strength test.

Background

The aircraft structural strength test is to apply simulated load to an aircraft structural body and measure mechanical parameters such as stress, strain, displacement and the like, so that the bearing capacity and the structural life of the structural body are correctly evaluated and estimated, and reliable basis is provided for verifying and optimizing structural design. In the static strength verification test, load application is often carried out on the parts such as an engine, a rotating cover and the like through joints, and the number of the joints is often reserved more for facilitating test design. In the actual test design process, considering the limitation of test resources and the requirement of reducing the test scale, few joints are often selected to meet the loading requirement of multiple working conditions. Therefore, the problem of joint selection becomes one of the problems that must be considered during the test. In conventional designs, for such problems, a designer typically selects several load joints for trial-and-error based on personal experience. This design method is time consuming and laborious and does not necessarily meet the test requirements. Therefore, the optimization of the design of the loading point is of great significance.

Disclosure of Invention

In order to solve at least one of the technical problems, the application provides a loading point layout method for an intensity test, which improves the design efficiency of loading points, reduces the labor intensity of a designer and optimizes the loading point layout.

The application relates to a layout method of loading points for an intensity test, which comprises the following steps:

marking information of each joint on the test piece, wherein the information comprises a loading direction vector, loading point position coordinates and loading load of the joint;

acquiring a task load F _r of each working condition in a test project;

Determining all loading joint selection schemes;

distributing the task load of each working condition to each selection scheme, and acquiring a selection scheme set for enabling the load to meet a distribution principle;

and selecting an optimal scheme from the selected scheme set.

Preferably, the optimal solution includes a minimum number of load joints under the solution.

Preferably, the optimal solution includes that the sum of the loads applied on the respective loading joints under the solution is minimum.

Preferably, the optimal solution includes that the objective function value is the largest under the solution, the objective function value is the sum of a first optimization quantity and a second optimization quantity, the first optimization quantity is the inverse of the number of loading joints, and the second optimization quantity is the inverse of the sum of the loads applied to each loading joint.

Preferably, the load meeting allocation principle means that the task load under each working condition is allocated to each selected scheme with a feasible solution F, wherein:

Wherein K is an equality constraint matrix, which is determined by a loading direction vector (a _i,b_i,c_i) of the joint, a loading point position coordinate (X _i,y_i,z_i) and a loading load f _i, f _maxi,f_mini is a maximum load and a minimum load which can be applied by the ith joint respectively, X is a diagonal matrix allocated to the joint, and represents whether the joint is selected, X _i represents that the ith joint is not selected when the joint is 0, otherwise, the joint is selected:

X＝diag(x₁,...,x_i,...,x_n)(x_i∈{0,1})。

Preferably, the equality constraint matrix is:

wherein n is the number of linkers.

The application can automatically calculate the optimal selection scheme of the loading points by using a computer, thereby realizing automatic layout, reducing manual intervention factors, improving efficiency and realizing automation.

Drawings

FIG. 1 is a flow chart of a method of intensity test load point placement of the present application.

FIG. 2 is a flow chart of the intensity test loading point calculation of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application become more apparent, the technical solutions in the embodiments of the present application will be described in more detail with reference to the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of the application. The embodiments described below by referring to the drawings are exemplary and intended to illustrate the present application and should not be construed as limiting the application. All other embodiments, based on the embodiments of the application, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the application. Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

The method for distributing the loading points of the strength test, as shown in figure 1, mainly comprises the following steps:

acquiring a task load F _r of each working condition in a test project;

Determining all loading joint selection schemes;

and selecting an optimal scheme from the selected scheme set.

The following is a detailed description.

A) Creating a load distribution matrix

In the strength test, the part such as an engine is often loaded through reserved joints, and assuming that the part comprises n joints in total, and the information of each joint can be recorded as L, the ith joint is denoted by L_i＝[x_i,y_i,z_i,a_i,b_i,c_i,f_i]^T,(f_mini≤f_i≤f_maxi)., wherein (a _i,b_i,c_i) is a loading direction vector of the joint, and (x _i,y_i,z_i) is the joint loading point position coordinate, and f _maxi,f_mini is the maximum load and the minimum load which can be applied by the ith joint respectively. The test project has m working conditions, the task load of each working condition is recorded as F _r＝[F_x F_y F_z M_x M_y M_z]^T, the m task loads are distributed to the selected loading joints, so that the load meets the distribution principle, and the number of the selected loading joints is as small as possible.

The load distribution principle is as follows:

Where K is an equality constraint matrix, expressed as:

b) Creating a joint assignment diagonal matrix

Let X be the diagonal matrix describing the joint assignment, indicating whether the joint is selected, X _i be 0 indicating that the i-th joint is not selected, otherwise, it is selected:

X＝diag(x₁,...,x_i,...,x_n)(x_i∈{0,1})

c) Establishing an optimization model

The loading point layout optimization model is created by combining the steps a) and b) as follows:

d) Optimization calculation

Performing iterative operation on the model established in the step c) by using a computer program, as shown in fig. 2, mainly including:

its child node states are created from the root node states down the state tree shown in fig. 2 and saved in the state stack. The state stack is a stack structure, each element is an n-dimensional integer array, the data of the corresponding position is 1 to indicate that the joint is selected, and 0 to indicate that the joint is not selected;

And (5) taking out the state information from the stack top, and judging whether a feasible solution exists in the F under the state according to a load distribution principle. Deleting the state information from the stack if no feasible solution exists, and repeating (a); if a feasible solution exists, and whether the same result exists in the result queue is compared, if not, the state information is recorded in the result queue, otherwise, the current solution is abandoned. The result queue is a queue structure with elements that are n-dimensional arrays of integers.

If the current state is listed in the result queue, then under this node condition, the child nodes in its state tree are traversed downward, as described in (a).

After all the traversals, the state information of the result queue is respectively calculated as the objective function value, and the largest one is compared and selected as the final result.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The method for arranging the loading points of the strength test is used for selecting the loading points of the load on the test piece and is characterized by comprising the following steps:

acquiring a task load F _r of each working condition in a test project;

Determining all loading joint selection schemes;

selecting an optimal scheme from the selected scheme set;

The load meeting distribution principle means that a feasible solution F exists when task loads of all working conditions are distributed to all selected schemes, wherein:

Wherein K is an equality constraint matrix, which is determined by a loading direction vector (a _i,b_i,c_i) of the joint, a loading point position coordinate (X _i,y_i,z_i) and a loading load f _i, f _maxi,f_mini is a maximum load and a minimum load which can be applied by the ith joint, X is a diagonal matrix allocated to the joint, and represents whether the joint is selected, X _i represents that the ith joint is not selected when the joint is 0, otherwise, the joint is selected:

X＝diag(x₁,...,x_i,...,x_n)(x_i∈{0,1})；

The equality constraint matrix is:

wherein n is the number of linkers.

2. The method of intensity test loading point placement according to claim 1, wherein the optimal solution comprises a minimum number of loading joints under the solution.

3. The method of claim 1, wherein the optimal solution includes a minimum sum of loads applied to each load joint under the solution.

4. The method of laying out a load point for an intensity test according to claim 1, wherein the optimal solution includes a maximum objective function value under the solution, the objective function value being a sum of a first optimization amount which is a reciprocal of the number of load joints and a second optimization amount which is a reciprocal of a sum of loads applied to the respective load joints.