CN112109919A

CN112109919A - Strength test loading point layout method

Info

Publication number: CN112109919A
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: 2020-12-22
Anticipated expiration: 2040-04-30
Also published as: CN112109919B

Abstract

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

Description

Strength test loading point layout method

Technical Field

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

Background

The airplane structure strength test is to apply a simulated load to an airplane structure body and measure mechanical parameters such as stress, strain, displacement and the like, so that correct evaluation and estimation are carried out on the bearing capacity and the structure service life of the structure body, and a reliable basis is provided for verifying and optimizing the structure design. In a static strength verification test, load application is often carried out on an engine, a rotating cover and other part tests through joints, and the number of the joints is often reserved for facilitating test design. In the actual test design process, the limitation of test resources and the requirement for reducing the test scale are considered, and joints as few as possible 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 in the test process. In the conventional design process, a designer usually selects several loading connectors for trial calculation according to personal experience for the problems. This design method is time consuming and labor intensive 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 method for distributing loading points in an intensity test, which improves the design efficiency of the loading points, reduces the labor intensity of designers and optimizes the distribution of the loading points.

The method for distributing the loading points in the strength test comprises the following steps:

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

acquiring task load F of each working condition in test project_r；

Determining all loading connector selection schemes;

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

and selecting an optimal scheme from the selection scheme set.

Preferably, the optimal solution comprises a minimum number of loading joints under the solution.

Preferably, the optimal solution comprises that the sum of the loads applied to the loading joints under the solution is minimal.

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

Preferably, the enabling of the load to satisfy the distribution principle means that a feasible solution F is obtained when the task load of each working condition is distributed to each selected scheme, where:

wherein K is an equality constraint matrix and is determined by the loading direction vector (a) of the joint_i，b_i，c_i) Position coordinates (x) of load point_i，y_i，z_i) And loading a load f_iDetermination of f_maxi，f_miniThe maximum load and the minimum load which can be applied by the ith joint respectively, X is a diagonal matrix distributed to the joints and indicates whether the joints are selected, and X is_iWhen 0, the ith joint is not selected, otherwise, the ith 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 joints.

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

Drawings

FIG. 1 is a flow chart of the method of the present application for placement of the load points for strength testing.

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

Detailed Description

In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below 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 present application. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application, and should not be construed as limiting the present application. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application. Embodiments of the present application will be described in detail below with reference to the drawings.

The method for arranging the loading points in the strength test mainly comprises the following steps of:

acquiring task load F of each working condition in test project_r；

Determining all loading connector selection schemes;

and selecting an optimal scheme from the selection scheme set.

The details are as follows.

a) Creating a load distribution matrix

In the strength test, the test of parts such as an engine and the like is often carried out through reserved joints, and if the parts comprise n joints in total, the information of each joint can be recorded as L, the ith joint is expressed as 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 the loading direction vector of the joint, (x)_i，y_i，z_i) Position coordinates of joint loading point, f_maxi，f_miniRespectively the maximum load and the minimum load that can be applied by the ith joint. The test project has m working conditions, and the task load of each working condition is recorded as F_r＝[F_x F_y F_z M_x M_y M_z]^TNow, the m task loads are distributed to the selected loading joints, so that the loads meet 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 joint assignment diagonal matrix

Let X be the diagonal matrix describing the joint assignment, indicating whether a joint is selected, X_iWhen 0, the ith joint is not selected, otherwise, the ith joint is selected:

X＝diag(x₁,...,x_i,...,x_n)(x_i∈{0,1})

c) establishing an optimization model

Combining a) and b) to create a loading point layout optimization model as follows:

d) optimizing calculations

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

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

and (4) taking out the state information from the stack top, and judging whether the F has a feasible solution in the state according to a load distribution principle. If no feasible solution exists, deleting the state information from the stack, and repeating the operation (a); if feasible solutions exist and the same result exists or does not exist in the comparison result queue, if the same result does not exist, the state information is recorded in the result queue, and if the same result does not exist, 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 down, as described in (a).

And after all the traversals, respectively solving the objective function values of the state information of the result queue, and comparing and selecting the largest one as a final result.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A strength test loading point layout method is used for selecting loading points on a test piece, and is characterized by comprising the following steps:

acquiring task load F of each working condition in test project_r；

Determining all loading connector selection schemes;

and selecting an optimal scheme from the selection scheme set.

2. The method of claim 1, wherein the optimal solution comprises a minimum number of load joints under the solution.

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

4. The method of claim 1, wherein the optimal solution comprises a maximum value for an objective function for the solution, the objective function value being a sum of a first optimal quantity and a second optimal quantity, the first optimal quantity being an inverse of a number of loading joints, the second optimal quantity being an inverse of a sum of loads applied to each loading joint.

5. The strength test loading point layout method according to claim 1, wherein the enabling of the load to satisfy the distribution principle means that a feasible solution F is obtained when the task loads of the respective working conditions are distributed to the respective selection schemes, wherein:

wherein K is an equality constraint matrix and is determined by the loading direction vector (a) of the joint_i,b_i,c_i) Position coordinates (x) of load point_i,y_i,z_i) And loading a load f_iDetermination of f_maxi,f_miniMaximum load and minimum load applicable to the ith joint respectively, and X is the diagonal angle allocated to the jointArray, indicating whether a splice is selected, x_iWhen 0, the ith joint is not selected, otherwise, the ith joint is selected:

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

6. the method of intensity test load point placement according to claim 5, wherein the equality constraint matrix is:

wherein n is the number of joints.