CN107655650B - Collision Detection Method for Lever Loaded System for Structural Testing - Google Patents

Abstract

The invention relates to a collision detection method for a lever loading system used in structural tests. Given the connection relationship, size and initial position of each lever, and the displacement of the loading point on the surface of the structure and the displacement of the fixed point of the actuator are known, Calculate the coordinates of each lever end point in the lever loading system, which is used for the demonstration and rationality analysis of the test plan, and predict whether the lever loading system will collide during the test. Compared with the prior art, the present invention has the advantages of high prediction accuracy and the like.

Description

Collision Detection Method for Lever Loaded System for Structural Testing

technical field

The invention relates to a structure static strength test, in particular to a collision detection method of a lever loading system used for a structure test.

Background technique

In the whole machine or component structural test of the aircraft, the ground test is an important method to verify the design scheme and reduce the design risk. It is necessary to simplify the loads on the structure (aerodynamic loads, inertial loads, concentrated loads, etc.) The level-connected lever can realize the loading of one actuator to multiple points. At present, the status quo of domestic structural test design and research work is that some factories have compiled some auxiliary calculation programs, such as distributed load calculation, lever calculation, counterweight calculation, etc.

If the aircraft structure undergoes a large deformation during the test, the lever system will also produce a large displacement, which may cause internal collisions, interference, and collisions with other test facilities. In order to predict the interference of this loading system, The three-dimensional model of the lever loading system can be established with computer-aided design software, and then the coordinates of the lever can be changed according to the displacement of the lever, so as to identify the interference of the lever system in the deformed state. But how to achieve it has become a problem that needs to be solved now.

Contents of the invention

The object of the present invention is to provide a collision detection method for a lever loading system for structural tests with high prediction accuracy in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

A collision detection method for a lever loading system used in structural tests. Given the connection relationship, size and initial position of each lever, and the displacement of the loading point on the surface of the structure and the displacement of the fixed point of the actuator are known, the lever is calculated. The coordinates of each lever end point in the loading system are used for test program demonstration and rationality analysis, and to predict whether the lever loading system will collide during the test.

Preferably, the calculated coordinates of each lever end point in the lever loading system are specifically:

A nonlinear equation system is established for each lever in the lever loading system, and the equation system satisfies the equilibrium relationship in the initial state; in the state of structural deformation, the coordinates of the structure surface point and the fixed point of the actuator are known variables, which are substituted into Equations, the coordinates of the end points of each lever are solved using a nonlinear equation solution method.

Preferably, the establishment of the nonlinear equation system is specifically as follows:

For the i-th lever, its two ends are i ₁ (x _i1 ,y _i1 ,z _i1 ) and i ₂ (x _i2 ,y _i2 ,z _i2 ), and the end point of the lever connected to the upper level lever is h ₁ (x _h1 , y _h1 , z _h1 ), which is a known quantity in the initial state and a quantity to be obtained when the structure deforms;

The lengths from the middle point of the lever to the two ends are m and n respectively, which are fixed values when the test plan is determined; the loading point on the lever is i ₃ , and its coordinates are

vector is the connection line between the end point i ₁ of the lever and the loading point on the lower level lever j, the length L _j , is the connection line between the end point i ₂ of the lever and the loading point of the lower level lever k, the length is L _k , and L _j and L _k remain unchanged during the loading process

Introduce the vector i ₁ j ₃ and its unit vector The unit vector of is

On lever i, the vectors from the end point to its loading point i ₃ are respectively and

Introduce coefficient R

Introduce vector and

h ₁ is the endpoint of the upper lever;

Set up a system of nonlinear equations for lever i

the last of these After expansion, three equations can be obtained, which constitute a system of equations about the coordinates of the end point of the lever i.

Preferably, for the lowest level of lever, i ₃ and k ₃ in the equations are points on the structure surface, and for the highest level of lever, h ₁ in the above calculation process is the fixed point of the actuator.

Preferably, a system of equations as shown in formula (10) is established for all levers according to the above equation, and then combined into a system of nonlinear equations for the displacement of the entire lever system.

Preferably, the predictive test process of whether the lever loading system will collide is specifically: solving the nonlinear equations of the displacement of the entire lever system, the displacement of the lever can be obtained when the structure is displaced; according to each lever The endpoint position and the external dimensions of the actual lever used can be calculated or drawn to obtain the space occupied by it, and judge whether the space occupied by adjacent levers interferes. If there is interference, it means that the actual levers will collide and interfere; at the same time To determine whether the space occupied by other test facilities interferes with the space occupied by the lever. If there is interference, it means that there will be a collision.

Compared with the prior art, the present invention is aimed at the deformation simulation part of the lever loading system of the static strength test of the aeronautical structure, and can solve the position of the entire lever loading system in space when the aerostructure undergoes large deformation driven by the actuator, thereby further accurately Predict whether a lever-loaded system will crash during a test.

Description of drawings

Fig. 1 is a schematic diagram of a lever system;

Fig. 2 is a flow chart for gradually solving calculations with smaller deformation increments when the structural deformation is large;

Fig. 3 is a schematic diagram of coordinates before deformation in a specific embodiment;

Fig. 4 is a schematic diagram of coordinates after deformation in a specific embodiment.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

The definition of the loading point of the lever loading system and the surface of the structure is shown in Fig. 1. For the i-th lever, its two endpoints are i ₁ (x _i1 ,y _i1 ,z _i1 ) and i ₂ (x _i2 ,y _i2 ,z _i2 ), and one endpoint of the upper level lever is h ₁ (x _h1 ,y _h1 ,z _h1 ), which is a known quantity in the initial state and a quantity to be obtained when the structure is deformed. The lengths from the middle point of the lever to the two ends are m and n respectively, which are fixed values when the test plan is determined; the loading point on the lever is i ₃ , and its coordinates are vector and They are the connecting lines between the two end points of the lever and the intermediate points of the lower level lever j and lever k, the lengths of which are L _j and L _k respectively, which remain unchanged during the loading process.

Introduce the vector i ₁ j ₃ and its unit vector

Introduce coefficient R

Introduce vector and

Set up a system of nonlinear equations for lever i

the last of these After the expansion of the obtained vector, three equations can be obtained, which are the equations about the coordinates of the end point of the lever i. For the lowest level of lever, i ₃ and k ₃ in the equations are points on the structure surface, and for the highest level of lever, h ₁ in the above calculation process is the fixed point of the actuator.

According to the above equations, establish a system of equations as shown in formula (10) for all levers, and then combine them into a system of nonlinear equations for the displacement of the entire lever system. In the initial state, the equation system satisfies the equilibrium relationship; in the structural deformation state, the coordinates of the structure surface point and the fixed point of the actuator are known variables, which are substituted into the equation system, and each lever end point is obtained by using the nonlinear equation solution method coordinate of.

If the structural deformation is large, it is necessary to gradually solve the equation with a small deformation increment. The calculation flow chart is shown in Figure 2:

The present invention will be described in detail below in conjunction with specific embodiments.

Take a lever system with the highest level 2 as the simulation object (all length units are mm), the initial situation is shown in Figure 3: the lengths of the two level 1 levers are 994.3mm, 1003.3mm, 1006.6mm and 1004.1mm respectively (according to In Fig. 3, the lowest level point is from left to right order); the length of the secondary lever is 1000mm; the structure surface point coordinates (according to the order of the lowest level point from left to right in Fig. 3) are (38141.3, 605.7, 1400), (38365 , 596.7, 1600), (38594.4, 593.4, 1800) and (38823.8, 595.9, 2000); the coordinates of the fixed point of the actuator are (38543.6, 4600, 1754.9).

The coordinates of the primary lever endpoints in the figure: (38141.3, 1600, 1400), (38365.3, 1600, 1600), (38594.4, 1600, 1800), (38823.8, 1600, 2000).

Coordinates of the secondary lever endpoints: (38268.7, 2600, 1513.9), (38719.6, 2600, 1909.2).

Assume that under the action of the actuator, the coordinates of the surface points of the structure become (38141.3, 610.13, 1400), (38365, 621.6, 1400), (38594.4, 648.56, 1400), (38823.8, 684.61, 1400). Bring the changed coordinates into the equations, and calculate the coordinates of each point of the deformed lever, as shown in Figure 4.

The calculated coordinates of the end points of each lever after deformation are:

Primary leverage endpoints: (38156.7, 2025.6, 1413.6), (38367.6, 2125.6, 1602.2),

(38596.8, 2228.7, 1802.1), (38812.1, 2333.7, 1989.1).

Secondary leverage endpoints: (38284.9, 3082.5, 1528.2), (38709.1, 3286.0, 1899.9).

The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of various equivalents within the technical scope disclosed in the present invention. Modifications or replacements shall all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (4)

1. a kind of lever load system collision checking method for structural test, which is characterized in that giving each lever Connection relationship, size and initial position, and under the premise of the displacement of body structure surface load(ing) point and actuator Anchor displacement are known, meter The coordinate of each lever endpoint in lever load system is calculated, testing program demonstration and analysis on its rationality, and prediction experiment are used for Whether lever load system can collide in the process；

The coordinate for calculating each lever endpoint in lever load system specifically:

Nonlinear System of Equations is established to each lever in lever load system, equation group meets balance and closes in the initial state System；Under malformation state, the coordinate of body structure surface point and actuator fixed point is known variables, is substituted into equation group, The coordinate of each lever endpoint is solved using Solving Nonlinear Systems of Equations method；

The Nonlinear System of Equations is established specific as follows:

For i-th of lever, two-end-point i₁(x_i1, y_i1, z_i1) and i₂(x_i2, y_i2, z_i2), higher level's lever is connect with the lever Endpoint be h₁(x_h1, y_h1, z_h1), it is in the initial state known quantity, is amount to be asked when structure deforms；

Length of the lever midpoint apart from two-end-point is respectively m and n, is definite value in the case where testing program determines；On lever Load(ing) point is i₃, coordinate is

VectorFor the endpoint i of lever₁With the line of load(ing) point on low primary lever j, length L_j,For the endpoint of lever i₂With the line of low primary lever k load(ing) point, length L_k, L_jAnd L_kIt remains unchanged during loading；

Introduce vector i₁j₃And its unit vector Unit vector be

On lever i, endpoint to its load(ing) point i₃Vector be respectivelyWith

Inlet coefficient R

Introduce vectorWith

h₁For the endpoint of upper level lever；

Nonlinear System of Equations is established to lever i

Wherein lastThree equations can be obtained after expansion, constitute the equation about lever i extreme coordinates Group.

2. collision checking method according to claim 1, which is characterized in that the i for minimum primary lever, in equation group₃ And k₃H for the point of body structure surface, for lever at the highest level, in above-mentioned calculating process₁For the fixed point of actuator.

3. collision checking method according to claim 1, which is characterized in that establish all levers as public by above-mentioned equation Equation group shown in formula (10) is combined into the Nonlinear System of Equations of entire lever system displacement.

4. collision checking method according to claim 3, which is characterized in that lever-loading during the prediction experiment Whether system can collide specifically: structure can be obtained in the Nonlinear System of Equations for solving the entire lever system displacement In the case where being subjected to displacement, the displacement of lever；According to the outer dimension of each lever endpoint location and actually used lever, pass through It calculates or obtains its occupied space with drawing, judge whether space shared by adjacent lever interferes, if interfering Then representing lever in practice can collide and interfere；Similarly, judge other test facilities take up space whether with shared by lever Space interferes, and representative conference collides if interfering.