CN103454101A - Method for obtaining torsional equivalent stiffness of skin stiffened cylindrical shell structure - Google Patents
Method for obtaining torsional equivalent stiffness of skin stiffened cylindrical shell structure Download PDFInfo
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- CN103454101A CN103454101A CN201210181252XA CN201210181252A CN103454101A CN 103454101 A CN103454101 A CN 103454101A CN 201210181252X A CN201210181252X A CN 201210181252XA CN 201210181252 A CN201210181252 A CN 201210181252A CN 103454101 A CN103454101 A CN 103454101A
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Abstract
The invention relates to a method for obtaining the torsional equivalent stiffness of a skin stiffened cylindrical shell structure. The method comprises the following steps: step 1, the skin torsional elasticity modulus, stringer torsional elasticity modulus, skin shell diameter and skin thickness of the skin stiffened cylindrical shell structure are collected respectively, wherein collected stringers are of m categories totally, and then the number, sectional area and polar moment of inertia of the stringers in each category are collected; step 2, the sum of the polar moment of inertia of all the stringers relative to shafts of the stringers are obtained; step 3, the polar moment of inertia of skin is obtained; step 4, the total torsional equivalent stiffness of the skin stiffened cylindrical shell structure is obtained. The method for obtaining the torsional equivalent stiffness of the skin stiffened cylindrical shell structure fundamentally solves the problem that the computation of rocket torsional stiffness is too perplexing, and can be used for obtaining a more accurate torsional stiffness result.
Description
Technical field
The present invention relates to a kind of torsion equivalent stiffness acquisition methods, be mainly concerned with the acquisition methods that carrier rocket and liquid missile typical case covering Stiffened Cylindrical Shell Structure reverse equivalent stiffness.
Background technology
The covering Stiffened Cylindrical Shell Structure is comprised of covering, stringer, ring frame, has high strength, rigidity, lighting characteristic, application widely in rocket structure.Wherein covering can Bending, torsion, Tensile or Compressive Loading, and stringer is as longitudinal member, its cross sectional dimensions relative length is very little, only bears the load axial along himself, bear reverse and self transverse curvature very low, can ignore.
Based on covering Stiffened Cylindrical Shell Structure dynamic modeling method, study, particularly torsional rigidity equivalent method research, set up rational covering Stiffened Cylindrical Shell Structure and reverse kinetic model, obtain rocket low order torque characteristic accurately, very crucial for the rocket development.
For the covering Stiffened Cylindrical Shell Structure, current driving force is learned modeling method three kinds:
Model 1: equivalent thickness model
This equivalence computation model is a bare hull with uniform cross-section thickness, can directly utilize equivalent thickness to calculate torsional rigidity.When calculating torsional rigidity, can be equivalent to beam to this shell.
Model 2: Varying-thickness model
In this model, the covering with vertical stringer is partly thickeied.It is that face is connected with shell that this method is equivalent to stringer, and because stringer is considered to identical and along circumferentially being uniformly distributed, so the cross section of this Varying-thickness shell while reversing still can regard plane as, there is no warpage.
Model 3: shell-beam model
In this model, simulate covering with shell unit, simulate stringer with beam element, and practical structures is more approaching.
The first model modeling is simple, and calculated amount is less, but the result that current computing method obtain is bigger than normal than actual value; Second model modeling complexity, calculated amount is larger, but result of calculation is bigger than normal equally than actual value; The third model and practical structures are more approaching, but modeling is more complicated, and calculated amount is larger, and the result and the actual value that obtain are more approaching.
Therefore, urgently provide a kind of computing method that can obtain accurately and fast covering Stiffened Cylindrical Shell Structure torsional rigidity.
Summary of the invention
The technical matters that will solve of the present invention is to provide a kind of for covering Stiffened Cylindrical Shell Structure commonly used in rocket, can accurately reflect the equivalent stiffness acquisition methods of its torsional rigidity.
In order to solve the problems of the technologies described above, technical scheme of the present invention is that a kind of covering Stiffened Cylindrical Shell Structure reverses the equivalent stiffness acquisition methods, comprises the following steps:
The number N of the i class stringer that step 2, basis collect
iwith polar moment of inertia J
bi, by single stringer relatively the polar moment of inertia of self axle superposeed, obtain the stringer polar moment of inertia summation J of all stringers for self axle
b;
Step 3, according to the covering shell diameter D that collects, covering thickness δ, obtain the polar moment of inertia J of covering
δ;
Step 4, the stringer polar moment of inertia summation J obtained according to step 2 and step 3
band the polar moment of inertia J of covering
δ, obtain the total torsion equivalent stiffness K of covering Stiffened Cylindrical Shell Structure
n;
K
N=G
δJ
δ+G
bJ
b。
The present invention has fundamentally solved puzzlement rocket torsional rigidity and has calculated a difficult problem bigger than normal, has obtained torsional rigidity result more accurately.
The accompanying drawing explanation
Fig. 1 is covering Stiffened Cylindrical Shell Structure schematic diagram involved in the present invention.
In figure: 1-covering shell, 2-stringer.
Embodiment
A kind of covering Stiffened Cylindrical Shell Structure of the present invention reverses the equivalent stiffness acquisition methods, comprises the following steps:
Step 3, for stressed-skin construction, polar moment of inertia
because the relative D of δ is very little, therefore can ignore δ
3, the polar moment of inertia of covering
Step 4, for T-shaped, the L-type stringer that extensively adopt in rocket, its torque characteristic all is similar to Open Thin-walled Members.When Cylindrical Shell produces torsional deflection, the micro-shear stress in the stringer xsect forms micro-couple, the geometric properties thickness that the length of the arm of couple is stringer.Therefore, for the stringer structure, to the total polar moment of inertia of total, contribution does not need to consider polar moment of inertia to its polar moment of inertia moves the axle effect.
Consider covering and stringer polar moment of inertia action effect, can obtain the total torsion equivalent stiffness K of covering Stiffened Cylindrical Shell Structure
n=G
δj
δ+ G
bj
b.
Above mentioned for the covering Stiffened Cylindrical Shell Structure, three kinds of modeling methods that current driving force is learned, the first model modeling is simple, and calculated amount is less, but the result that current computing method obtain is bigger than normal than actual value; Second model modeling complexity, calculated amount is larger, but result of calculation is bigger than normal equally than actual value; The third model and practical structures are more approaching, but modeling is more complicated, and calculated amount is larger, and the result and the actual value that obtain are more or less the same.
Method of the present invention is applied to the first model, the effect that can realize that modeling is simple, calculated amount is little, result of calculation and actual value is more or less the same simultaneously.
Concrete case analysis:
With an example, demonstrate: to structure shown in Fig. 1, under fixed boundary condition, gather covering and stringer correlation parameter, the material shear modulus G
δ=G
b=26.7GPa, covering diameter D=3m, thickness δ=0.0012m, all adopting the round stringer of a class is m=1; The stringer number is N
1=60, polar moment of inertia J
b1=5.374e-8m
3.
Be the existence function relation between the total actual torsional rigidity of covering Stiffened Cylindrical Shell Structure torsion frequency and covering Stiffened Cylindrical Shell Structure, in the engineering custom, usually adopt this frequency as analysis indexes, but they be of equal value in fact.
Under fixed boundary condition, covering Stiffened Cylindrical Shell Structure torsion frequency computing formula
In formula, ρ is density of material ρ=2800Kg/m
3, l is shell length l=51m, the order that n is frequency.Utilize quadrangular plate unit and beam element in finite element method to simulate, axially divide 200 unit, circumferentially divide 60 unit.Three kinds of the model calculation are in Table 1.
The torsion frequency value that above various model calculates is in Table 1:
Table 1 torsion frequency (Hz)
As can be seen from Table 1, the frequency values that model 1 and model 2 relative models 3 calculate is bigger than normal, known according to formula, and corresponding torsional rigidity value is also bigger than normal.The frequency values that improved model 1 calculated value and model 3 calculate is basic identical, and corresponding torsional rigidity value is also basic identical.
Claims (1)
1. a covering Stiffened Cylindrical Shell Structure reverses the equivalent stiffness acquisition methods, it is characterized in that: comprise the following steps:
Step 1, gather respectively the covering modulus of torsion G of covering Stiffened Cylindrical Shell Structure
δ, stringer modulus of torsion G
b, covering shell diameter D, covering thickness δ; The stringer gathered has m class stringer, and then gathers the number N of i class stringer
i, polar moment of inertia J
bi, i=1 wherein, 2 ..., m;
The number N of the i class stringer that step 2, basis collect
iwith polar moment of inertia J
bi, by single stringer relatively the polar moment of inertia of self axle superposeed, obtain the stringer polar moment of inertia summation J of all stringers for self axle
b;
Step 3, according to the covering shell diameter D that collects, covering thickness δ, obtain the polar moment of inertia J of covering
δ;
Step 4, the stringer polar moment of inertia summation J obtained according to step 2 and step 3
band the polar moment of inertia J of covering
δ, obtain the total torsion equivalent stiffness K of covering Stiffened Cylindrical Shell Structure
n;
K
N=G
δJ
δ+G
bJ
b。
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103994869A (en) * | 2014-05-21 | 2014-08-20 | 东北大学 | Thin-wall cylinder shell structural piece experiment table and measuring method |
CN112623255A (en) * | 2020-12-29 | 2021-04-09 | 中国航空工业集团公司西安飞机设计研究所 | Method for calculating torsional rigidity of section of door frame area of airplane body |
Citations (1)
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CN102446241A (en) * | 2011-10-27 | 2012-05-09 | 北京航空航天大学 | Wing surface structural rigidity simulation method |
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2012
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Patent Citations (1)
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CN102446241A (en) * | 2011-10-27 | 2012-05-09 | 北京航空航天大学 | Wing surface structural rigidity simulation method |
Non-Patent Citations (2)
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潘忠文等: "基于梁模型的火箭纵横扭一体化建模技术", 《宇航学报》 * |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103994869A (en) * | 2014-05-21 | 2014-08-20 | 东北大学 | Thin-wall cylinder shell structural piece experiment table and measuring method |
CN103994869B (en) * | 2014-05-21 | 2016-08-31 | 东北大学 | A kind of method of testing of thin wall cylindrical hull structure component experimental bench |
CN112623255A (en) * | 2020-12-29 | 2021-04-09 | 中国航空工业集团公司西安飞机设计研究所 | Method for calculating torsional rigidity of section of door frame area of airplane body |
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