阅读说明：本技术 一种摩擦间隙配合的支杆连接结构动特性分析方法 (Dynamic characteristic analysis method for friction clearance fit support rod connection structure ) 是由 王一凡 崔慧永 孙晓玲 王捷冰 高鹏 肖振 贺峥光 陈岩 王淑玉 于 2021-06-07 设计创作，主要内容包括：本发明是一种基于等效能量理论的摩擦间隙配合的支杆连接结构动特性分析方法。包括步骤：采用模态叠加的稳态动力学分析方法,对完全连接关系的有限元模型进行基于频域的正弦扫频分析,获得正弦扫频分析结果；提取出连接支杆在对应响应强度振动下的截面力载荷作为支杆截面载荷；将支杆截面载荷和摩擦力f进行对比；若支杆截面载荷大于摩擦力,则进行等效处理,获得等效后的有限元分析模型；对等效后的有限元分析模型再次进行正弦扫频分析,得到考虑摩擦间隙配合下的结构动特性响应。本发明能够解决支撑结构接头摩擦间隙配合导致的大尺寸结构动特性预示难的问题。(The invention relates to a dynamic characteristic analysis method of a friction clearance fit support rod connecting structure based on an equivalent energy theory. The method comprises the following steps: performing frequency domain-based sine frequency sweep analysis on the finite element model with the complete connection relation by adopting a steady state dynamics analysis method of modal superposition to obtain a sine frequency sweep analysis result; extracting the section force load of the connecting support rod under the vibration of the corresponding response strength as the section load of the support rod; comparing the cross-section load of the strut with the friction force f; if the load of the section of the strut is larger than the friction force, performing equivalent treatment to obtain an equivalent finite element analysis model; and performing sinusoidal frequency sweep analysis on the equivalent finite element analysis model again to obtain the structural dynamic characteristic response under the condition of considering friction clearance fit. The invention can solve the problem that the dynamic characteristic prediction of a large-size structure is difficult due to the friction clearance fit of the joints of the supporting structure.)

1. A dynamic characteristic analysis method of a friction clearance fit support rod connecting structure is characterized by comprising the following steps:

1) establishing a complete connection relation finite element analysis model of the strut connection structure;

2) performing frequency domain-based sine frequency sweep analysis on the finite element model with the complete connection relation in the step 1) by adopting a modal superposition steady-state dynamics analysis method to obtain a sine frequency sweep analysis result;

3) extracting the section force load of the connecting support rod (1) under the vibration of corresponding response strength from the sine sweep frequency analysis result obtained in the step 2) as the section load of the support rod;

4) comparing the cross-section load of the strut with the friction force f; if the section load of the strut is smaller than the friction force, obtaining a final dynamic characteristic result of the structure according to the sine frequency sweep analysis of the complete connection relation finite element model in the step 2), and not performing the subsequent steps; if the cross-section load of the support rod is larger than the friction force, the step 5) is carried out;

5) performing equivalence treatment to obtain an equivalent finite element analysis model;

6) and (3) performing sinusoidal frequency sweep analysis on the finite element analysis model after the equivalence of the step 5) again by adopting a steady-state dynamics analysis method of modal superposition with the same conditions as the conditions of the step 2) to obtain the structural dynamic characteristic response under the condition of considering friction clearance fit.

2. The method according to claim 1, wherein the method comprises the following steps: a strut connecting structure comprising: the connecting support rod (1), the connecting joint (2) and the connecting bolt (4);

the connecting block (3) is fixedly arranged on the front end frame of the main body structure, and the connecting joint (2) is fixedly connected with the main body structure through the connecting block (3); one end of the connecting joint (2) is connected with the connecting block (3) through a thread pair, the other end of the connecting joint (2) is inserted into the upper end of the connecting support rod (1), the other end of the connecting joint (2) is fixedly connected with the upper end of the support rod through a connecting bolt (4), and the lower end of the support rod is fixedly arranged on a bearing structure in the main body structure.

3. The method according to claim 2, wherein the method comprises the following steps: and step 2) the friction force f is generated by the tightening torque between the connecting support rod (1) and the connecting bolt (4).

4. A method of analyzing the dynamic characteristics of a friction clearance fit strut connecting structure according to claim 3, wherein: step 2) the friction force f is specifically as follows:

f＝sKT

wherein s is a friction coefficient, K is a tightening torque coefficient of the connecting bolt (4), and T is a tightening torque of the connecting bolt (4).

5. The method according to claim 4, wherein the method comprises the following steps: the method for performing equivalent treatment in the step 5) specifically comprises the following steps:

the method comprises the steps of removing complete binding among a connecting support rod (1), a connecting joint (2) and a connecting bolt (4), establishing an equivalent spring unit between the connecting support rod (1) and the connecting joint (2), binding and connecting the lower end of the connecting support rod (1) with a main structure, and binding and connecting the connecting joint (2) with the main structure.

6. The method according to claim 5, wherein the method comprises the following steps: equivalent stiffness K of the equivalent spring unit_eqAnd determining based on an equivalent energy method.

7. The method according to claim 5, wherein the method comprises the following steps: equivalent stiffness K of the equivalent spring unit_eqAccording to the clearance tolerance design value delta between the connecting strut (1) and the connecting joint (2)_gcStiffness K of the connecting strut (1)_zgAnd step(s)Step 3) axial deformation δ of the connecting strut (1) under strut section force load_zgAnd (4) determining.

8. The method according to claim 7, wherein the method comprises the following steps: equivalent stiffness K of the equivalent spring unit_eqThe method specifically comprises the following steps:

f＝sKT。

9. the method for analyzing the dynamic characteristics of a friction clearance fit strut connecting structure according to any one of claims 2 to 8, wherein: the step 1) of establishing the complete connection relationship of the strut connection structure specifically comprises the following steps:

the degree of freedom of the lower end of the connecting support rod (1) and the main structure connecting area and the degree of freedom of the connecting joint (2) and the main structure connecting area are defined as a completely binding state, the connecting joint (2) and the connecting bolt are set to be elastic bodies, and the degree of freedom among the connecting support rod (1), the connecting joint (2) and the connecting bolt is completely bound.

Technical Field

The invention belongs to the technical field of dynamic characteristic analysis of a strut connecting structure, and particularly relates to a dynamic characteristic analysis method of a strut connecting structure in friction clearance fit.

Background

With the continuous exploration and development of the aircraft in the future, higher requirements on speed and range are put forward, so that the lightening of the aircraft structure becomes an important performance index.

Compared with the traditional aluminum/magnesium alloy material, the carbon/bismaleimide and other resin-based composite material has similar rigidity performance, high-temperature performance, higher strength performance and lower density, and the resin-based composite material gradually becomes an important choice for the structural system of the future aircraft.

Due to the limitation of a manufacturing process, the resin-based composite material force-bearing structures are usually in a multi-structure splicing form, and the structures are connected by adopting a large number of fasteners, so that the dynamic characteristics of the structures under a large number of levels of vibration loads are obviously reduced due to the friction clearance fit relationship among the force-bearing structures and exceed the design range, and the traditional frequency domain-based structure dynamic characteristic calculation method is difficult to accurately predict due to the fact that the clearance fit is a boundary nonlinear problem. Therefore, a new dynamic characteristic prediction method aiming at the characteristics of the splicing structure of the large-scale resin matrix composite material is needed, the nonlinear characteristic of the structure can be accurately predicted, and the requirement of efficient engineering analysis can be met.

Disclosure of Invention

The technical problem solved by the invention is as follows: the method for analyzing the dynamic characteristics of the friction clearance fit strut connecting structure is based on an equivalent energy theory and aims to solve the problem that the dynamic characteristics of a large-size structure are difficult to predict due to friction clearance fit of joints of a supporting structure.

The technical solution of the invention is as follows:

a dynamic characteristic analysis method of a friction clearance fit support rod connecting structure comprises the following steps:

1) establishing a complete connection relation finite element analysis model of the strut connection structure;

2) performing frequency domain-based sine frequency sweep analysis on the finite element model with the complete connection relation in the step 1) by adopting a modal superposition steady-state dynamics analysis method to obtain a sine frequency sweep analysis result;

3) extracting the section force load of the connecting support rod (1) under the vibration of corresponding response strength from the sine sweep frequency analysis result obtained in the step 2) as the section load of the support rod;

4) comparing the cross-section load of the strut with the friction force f; if the section load of the strut is smaller than the friction force, obtaining a final dynamic characteristic result of the structure according to the sine frequency sweep analysis of the complete connection relation finite element model in the step 2), and not performing the subsequent steps; if the cross-section load of the support rod is larger than the friction force, the step 5) is carried out;

5) performing equivalence treatment to obtain an equivalent finite element analysis model;

6) and (3) performing sinusoidal frequency sweep analysis on the finite element analysis model after the equivalence of the step 5) again by adopting a steady-state dynamics analysis method of modal superposition with the same conditions as the conditions of the step 2) to obtain the structural dynamic characteristic response under the condition of considering friction clearance fit.

A strut connecting structure comprising: the connecting support rod (1), the connecting joint (2) and the connecting bolt (4);

the connecting block (3) is fixedly arranged on the front end frame of the main body structure, and the connecting joint (2) is fixedly connected with the main body structure through the connecting block (3); one end of the connecting joint (2) is connected with the connecting block (3) through a thread pair, the other end of the connecting joint (2) is inserted into the upper end of the connecting support rod (1), the other end of the connecting joint (2) is fixedly connected with the upper end of the support rod through a connecting bolt (4), and the lower end of the support rod is fixedly arranged on a bearing structure in the main body structure.

And step 2) the friction force f is generated by the tightening torque between the connecting support rod (1) and the connecting bolt (4).

Step 2) the friction force f is specifically as follows:

f＝sKT

wherein s is a friction coefficient, K is a tightening torque coefficient of the connecting bolt (4), and T is a tightening torque of the connecting bolt (4).

The method for performing equivalent treatment in the step 5) specifically comprises the following steps:

the method comprises the steps of removing complete binding among a connecting support rod (1), a connecting joint (2) and a connecting bolt (4), establishing an equivalent spring unit between the connecting support rod (1) and the connecting joint (2), binding and connecting the lower end of the connecting support rod (1) with a main structure, and binding and connecting the connecting joint (2) with the main structure.

Equivalent stiffness K of the equivalent spring unit_eqAnd determining based on an equivalent energy method.

Equivalent stiffness K of the equivalent spring unit_eqAccording to the clearance tolerance design value delta between the connecting strut (1) and the connecting joint (2)_gcStiffness K of the connecting strut (1)_zgAnd step 3) axial deformation delta of the connecting strut (1) under the strut section force load_zgAnd (4) determining.

Equivalent stiffness K of the equivalent spring unit_eqThe method specifically comprises the following steps:

f＝sKT。

the step 1) of establishing the complete connection relationship of the strut connection structure specifically comprises the following steps:

the degree of freedom of the lower end of the connecting support rod (1) and the main structure connecting area and the degree of freedom of the connecting joint (2) and the main structure connecting area are defined as a completely binding state, the connecting joint (2) and the connecting bolt are set to be elastic bodies, and the degree of freedom among the connecting support rod (1), the connecting joint (2) and the connecting bolt is completely bound.

Compared with the prior art, the method has the advantages that:

the invention judges the friction clearance fit influence degree by identifying the friction state and linearizes the nonlinear boundary condition by the equivalent energy theory, thereby reducing the time cost of design and accurately predicting the structure dynamic characteristic result, and the prediction accuracy of the design can reach within 5 percent.

Drawings

FIG. 1 is a flow chart of the method of the present invention;

FIG. 2 is a schematic view of the connecting structure of the strut of the present invention.

Detailed Description

The method is based on the equivalent energy theory, combines with the friction state pre-judgment analysis, and can accurately and efficiently predict the dynamic characteristics of the friction clearance fit structure.

A dynamic characteristic analysis method of a friction clearance fit support rod connecting structure comprises the following steps:

1) establishing a complete connection relation finite element analysis model of a strut connection structure

The freedom degrees of the connecting region of the lower end of the connecting support rod 1 and the main body structure and the connecting region of the connecting joint 2 and the main body structure are defined as a completely bound state, the connecting joint 2 and the connecting bolt are set as elastic bodies, and the freedom degrees among the connecting support rod 1, the connecting joint 2 and the connecting bolt are completely bound;

as shown in fig. 2, the strut connecting structure includes: connecting strut 1, connecting joint 2 and connecting bolt 4. The connection is shown in fig. 2. The connecting block 3 is fixedly arranged on a front end frame of the main body structure (cabin section), and the connecting joint 2 is fixedly connected with the main body structure through the connecting block 3; the one end of attach fitting 2 and connecting block 3 are connected through the screw thread pair, and the other end of attach fitting 2 inserts connecting rod 1 upper end, and the other end of attach fitting 2 and branch upper end are through connecting bolt 4 fixed connection (connecting bolt threaded connection plays the effect of pin simultaneously), and the inside load of branch lower extreme fixed mounting major structure is structural.

2) Performing frequency domain-based sine frequency sweep analysis on the finite element model with the complete connection relation in the step 1) by adopting a modal superposition steady-state dynamics analysis method to obtain a sine frequency sweep analysis result;

3) extracting the section force load of the connecting support rod 1 under the vibration of corresponding response strength from the sine sweep frequency analysis result obtained in the step 2) as the section load of the support rod;

4) comparing the cross-section load of the strut with the friction force f; the friction force f is generated by the tightening torque between the connecting support rod 1 and the connecting bolt 4;

f＝sKT；

wherein s is a friction coefficient, K is a bolt tightening torque coefficient, and T is a bolt tightening torque;

if the section load of the strut is smaller than the friction force, obtaining a final dynamic characteristic result of the structure according to the sine frequency sweep analysis of the complete connection relation finite element model in the step 2), and not performing the subsequent steps;

if the cross-section load of the support rod is larger than the friction force, the complete binding among the connecting support rod 1, the connecting joint 2 and the connecting bolt is released, and the step 5) is carried out;

5) performing equivalent treatment

An equivalent spring unit is established between the connecting support rod 1 and the connecting joint 2, the lower end of the connecting support rod 1 is bound and connected with the main structure, the connecting joint 2 is bound and connected with the main structure, and a design value delta of the clearance tolerance between the upper end of the connecting support rod 1 and the connecting joint 2 is obtained_gcThe rigidity K of the connecting strut 1 is obtained according to the sectional dimension and the material used of the connecting strut 1_zgObtaining the axial deformation delta of the connecting strut 1 under the load of the strut section force in the finite element model of the complete connection relationship_zgBased on the equivalent energy method, the equivalent stiffness K of the spring unit can be obtained_eqComprises the following steps:sKT. Thereby obtaining an equivalent finite element analysis model;

6) and (3) performing sinusoidal frequency sweep analysis on the equivalent finite element analysis model again by adopting a steady-state dynamics analysis method of modal superposition with the same conditions as the conditions in the step 2) to obtain the structural dynamic characteristic response under the condition of considering friction clearance fit.

Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.