Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.ssau.ru/files/education/metod_1/Reznichenko_Detail_Design_Laboratory_Work.pdf Äàòà èçìåíåíèÿ: Tue Dec 9 17:22:24 2014 Äàòà èíäåêñèðîâàíèÿ: Mon Apr 11 02:56:48 2016 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï ï

The Ministry of Education and Science of the Russian Federation Samara State Aerospace University (National Research University)

DETAIL DESIGN OF AIRFRAME PART

Laboratory Work Example

2011


Compilers:

Reznichenko Gennadiy A., Vyrypaev Artem A.

Translated by: Kancher Galina S. Lyaskin Anton S. Detail Design Of Airframe Part = [Electronic resource]: Laboratory Work Example / The Ministry of Education and Science of the Russian Federation, Samara State Aerospace University; Compilers G.A. Reznichenko, A.A. Vyrypaev. - Electronic text and graphic data (2,7 Mb). - Samara, 2011. - 1 CD-ROM. A method of executing laboratory works in accordance with the discipline of aircraft construction and design is described. A list of normative-technical documentation and reference materials that are needed for executing tasks, as well as examples of the work execution and preparation are offered. The manual is intended for fourth - year students of the specialty 160201 "Airplane and Helicopter Construction" that study the discipline of aircraft construction and design and for the Masters programme «Designing, construction and CALS-technologies in Aeronautical Engineering» for education direction 160100.68 «Aeronautical Engineering». Prepared by the Department of Aeronautical Engineering SSAU.

© Samara State Aerospace University, 2011

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CONTENTS
1 THE EXEMPLARY REPORT OF THE LABORATORY WORK 1. ANALYZING A TASK. SKETCHING PROTOTYPES. ...........................................................................................4 2 THE EXEMPLARY REPORT OF THE LABORATORY WORK 2. CHOOSING NORMALS. CHOOSING THE DESIGN SCHEME AND DEFINING STRESSES OF THE PART ELEMENTS .........................................................................................................................8 3 THE EXEMPLARY REPORT OF THE LABORATORY WORK 3. DEFINING THE PART DIMENSIONS OF THE REQUIRED STRENGTH WITH TAKING INTO ACCOUNT THE MANUFACTURING FACTORS AND RESTRICTIONS .................................................17 4 THE EXEMPLARY REPORT OF THE LABORATORY WORK 4.MAKING THE PART DRAWING.........................................................................................................................26 BIBLIOGRAPHY .........................................................................................................................27

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1

THE EXEMPLARY REPORT OF THE LABORATORY WORK 1. ANALYZING A TASK. SKETCHING PROTOTYPES. 1.1 The task is to design the control crank and make the part drawing

(Figure 1.1)

Figure 1.1 - The task of the laboratory work 1 1.2 The task analysis consists in defining the part function and work

conditions and developing the part requirements. It is necessary to design the control crank (Figure 1.1). The crank is fixed on the air-frame (the point 1). Control rods are led to the crank at the points 2 and 3. Force directions coincide with control rod axes. The crank is designed to: - change the control rode movement direction; - change the value of the control rode stress; - support the control rode linkage The crank work conditions: - the crank is located in the unpressurized compartment, the service access is troubled; - the environment is the air, the work temperature is 60 to +50°;
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- there are no the crank deflection restrictions of neighboring elements. Then the part requirements should be defined. These requirements are included in the requirements of the control rod that consists of the design crank: - the minimum friction and backlash between joins of the part and control rods and the suspension bracket; - excluding the possibility of jamming and seizure of joins in case of the maximum movements of the control rods and deformations of air-frame elements. There are also additional requirements of the part: - the minimum weight; - the acceptable strength and rigidity: - the crank life should be equal to the aircraft life; - the process plan of manufacturing this part should provide the minimum explicit costs; - the possibility of mounting the part without an additional adjustment of the control rod; - only approved solutions should be used for defining the part shape and sections. For the analysis we consider the cranks presented on the stand "Control parts and units" in the room of aircraft constructions and the crank of the stabilizer control unit of the aircraft MiG-17. The sketches of the cranks that are similar to the design crank are shown in the Figure 1.2. The crank I (Figure 1.2, ) is installed in the fin of the aircraft MIG - 17; it supports the control linkage and changes of the control rod directions. The part is made of the deformable aluminum alloy by the hot forming method. At the points 2 and 3 the control rods are fixed in the crank eyes. Bearings are inserted in these eyes. The part thickness between the points 2 and 3 is defined by the bearing width. At the point 1 the part is fixed to the fin frame. This part of the crank has the form of a hub with two inserted spaced bearings. The hub that is

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supported by lateral ribs provides the steady position of the crank while acting forces of the part plane. The part is manufacturable. Places under the bearings are machined. The part can be estimated as a beam with the rectangular cross-section.

Figure 1.2 - The sketches of the cranks

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The crank 2 (Figure 1.2, ) differs from the crank considered above by the planform. Each arm of the crank works as an I -beam. There is a hole in the crank body for lightening the part. The crank 3 (Figure 1.2,) is significantly different from the first two cranks by its implementation. It is made of the aluminum casting alloy by gravity die founding. In the junction with the rods the crank is made as a fork, the bearings are installed in the hub. Both crank arms work as beams with the small constructional height. At that, one arm is made as an I -beam. Another has the tubular cross-section. This crank has more machining operations then the first two cranks.

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2

THE EXEMPLARY REPORT OF THE LABORATORY WORK 2. CHOOSING NORMALS. CHOOSING THE DESIGN SCHEME AND DEFINING STRESSES OF THE PART ELEMENTS 2.1 Choosing normals. Ball bearings are set in joins between the part and

rods and suspension brackets according to the requirement of the minimum friction and backlashes (the points 1, 2, 3 in the task). Balancing the forces should be carried out for defining the stresses at the points 1, 2 and 3. The equilibrium equation should be made relative to the point 1 for defining the force 3: 2 12 = 3 13 12 20000 100 =8 = 16670 13 120


3

At the point 1 the stress is defined by projecting the forces 1 ,2 3 ,, on the axes X and Y. According to the task the angle between directions of the forces 3 and 2 and the axes Y is equal to 450 . Taking into account that sin 450 = cos 450 0, 71: = , - = , - = , = , + = , + = ,


=











+







=

+ = .

The results are shown in the Figure 2.1.

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1 = 26000N; 2 = 20000N; 3 = 16670N.

Figure 2.1 - Balancing the part The bearings are selected by the static breaking loads at the points 1, 2, 3 [5]. An outer diameter of the bearing defines an inner diameter and thickness of the part eye. At the point 1 two spaced bearings are set to ensure the efficiency of the control linkage work under acting unexpected loads of the part plane. The dimensions of the chosen bearings are in the Table 1. Table 1 - The dimensions of the chosen bearings
The point The bearing number 1 2 3 type 18 1007 1006 The static breaking load, N 13000 20000 17000 The design load, N 13000 20000 16670 1,0 1,0 1,02 8 7 6 22 22 19 7 7 6 d, mm D, mm , mm

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2.2

The sketches of the SLCS are shown in the Figure. 2.2.

Figure 2.2 - The structural and load-carrying schemes of the part The scheme 1 The crank is cut from the sheet with the thickness not less than 14 mm (it is the suggested width of the hub for two bearings at the point 1). All surfaces are milled according to the bearing thickness at the points 2 and 3.
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The part is manufacturable, and the complex and expensive equipment is not required for the manufacture. This method is profitable only for single-piece manufacture. The design scheme of the part is a beam that has the rectangular cross-section. The part can be made of any material that allows machining operations. The scheme 2 The crank is made as a three ring-eyes that are interconnected by rods. The whole part can be solid or welded from separate rings and rods. The welding will impose restrictions on the part material. The part is less manufacturable. It can be made by pressing or founding. The junction between the eye and rod (stress concentration zones) requires the more accurate machining. The design scheme of the part is three-rod truss that works on tension compression. It is important to mention that the real part has the rigid rod connection in place of the hinge connection of the rods . Using the design truss model the part stresses can be correctly evaluated only for long rods; the influence of the embedment method on the long rods can be neglected. The schemes 3 and 4 Both variants suppose manufacturing the crank by hot stamping and from the deformable aluminum alloy. The variants differ from each other by the planform and, accordingly, ways of transferring forces within the part. The part is manufacturable. Their shapes are simple, and a small amount of machining is required after stamping the part. The design schemes of both parts are beams with the constant height. The element stresses are easily defined by formulas of the theory of beams. The comparative evaluation of the part schemes shows: The scheme 1 has the "extra" material in the center of the part, so the requirement of minimum weight is not satisfied. The material usage ratio is low. The method of manufacturing the part does not satisfy the serial production; The scheme is less manufacturable. In addition, the selection of
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compressed rods sections with taking into account the buckling failure, obviously, requires a change in the section shape. And it is difficult to provide a long part life of the attaching points of rods and eyes. It also does not meet the technical requirements; The scheme 3 provides the longest way of transferring the forces between the control rods. The forces are transferred by bending the crank arms that have the small constructional heights. As you know, the bending method of transferring the forces is the most raw material intensive method. The crank of the scheme 3 will be the least rigid then all other considered cranks. The scheme 3 meets difficultly the technical requirements that concern the minimum weight and acceptable rigidity of the part; The scheme 4 also consists of beams; in comparison with the scheme 3 this scheme has the shortest way of transferring the forces between the rods. The main disadvantage of this scheme is the small constructional height of the crank arms. The analysis of the schemes led to developing the scheme 5 that has no most of these disadvantages (Figure 2.3).

Figure 2.3 - The scheme 5 The scheme 5 is close to the truss scheme according to the method of transferring the forces.
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At the same time the wall excludes the possibility of buckling the rods. The hole in the middle of the part removes the "extra" material. The forces between the rods are transferred by the shortest way. It is easy to provide the acceptable rigidity of the part. The part can be made by the hot stamping. 2.3 2.4). Choosing the design scheme of the part. We choose the design scheme in the form of the beam with convergent belts for the selected scheme 5 (Figure

Figure 2.4 - The design scheme:
1 - The flat eye that is loaded through the rigid insert; 2 - The ideal I-beam with the variable lengthwise height ; 3 - The support.

2.4. Defining the stresses of the part elements. Using the design scheme selected previously, the stresses of the crank wall and belts are defined by the formulas given in [2]. The initial data for calculations is shown in the Figure 2.5. The stresses of the belts N13, N23, N12 and the wall T are defined by the formulas (4.1) (4.2) (4.3).
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Figure 2.5 - The initial data for calculations Symbols: N133, N - the stress of the rod 1 - 3 at the point 3; N131,N - the stress of the rod 1 - 3 at the point 1; N233,N232,N212,N211 - similarly to the previous symbols; 3,N/mm ­ the shear flow of the wall at the point 3; 0, N/mm - the shear flow of the midsection; , mm - the distance to the design section; , ­ the belt angles ( = 00; = 370),

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3 13

13 - 1 = 12 - 1 + = 20968 ;

=

16670 120 - 100 1 100 - 100 0 + 0,841

1 13 =

16670 120 - 20 1 100 - 20 0 + 0,841

= 20041 .

Similarly, we obtain: N233 = 27416 N; N232 = 26198 N. 1 1 = 16670 1 - 0 = 16670 ; 12 100

1 21 =



1-

2 12

13 16670 120 = = 0,841 = 16823 ; 12 100

=

3

12

16670 = = 1048 /; - + 100 - 100 0 + 0,841 16670 100 - 50 0 + 0,841 1002

= 2 12 - 3 + 12
0

=

= 96,6 /. We decide that these stresses are constant and equal to the maximum value of the corresponding belt according to the fact, that the stresses of the root and tip belt parts are almost equal: N13 = 20968 N; N23 = 27418 N; N12 = 16823 N.
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It is easy to verify, that the shear flow of the wall has the maximum value nearby the point 3: 3 = 1084 N/mm, 0 = 96,6 N/mm.

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3 THE EXEMPLARY REPORT OF THE LABORATORY WORK 3. DEFINING THE PART DIMENSIONS OF THE REQUIRED STRENGTH WITH TAKING INTO ACCOUNT THE MANUFACTURING FACTORS AND RESTRICTIONS 3.1 Choosing the material. The choice of the material is made according

to characteristics of the material strength-to-weight ratio. In accordance with the chosen design scheme the part works on bend. In [3] the criterion of the bend strength-to-weight ratio is equal to 2/3 /. With regard to the fact, that the part is made by hot stamping, you should list the possible materials (use the recommendations [7]) and calculate their strengthto-weight ratios. The material 3 - 6 - 4 I4TI L, MPa 1100 370 900 270 [] ,MPa 900 340 800 250 7,85 2,8 4,55 1,8 []2/3 / 5,6 8,2 8,8 10,2

Where [] is the failing stress, which is defined with taking into consideration the part work conditions and the material characteristics [8]. The magnesium alloy is more appropriate, because it provides the minimum weight of the part according to the table data. Its disadvantage is the weak rustproof quality. The crank is placed in the tight open-type section, so it is difficult to check the antirust covering integrity of the part. The titanium and aluminum alloys have the equal strength-to-weight ratio values. But the aluminum alloy is cheaper, and its machining is easier, so -6 should be chosen as the part material. The heat treatment: hardening, and artificial tempering the part under the temperature 160° during 12 hours, [] = 340 MPa. 3.2. Making calculations of the eyes parameters. These calculations are carried out in accordance with the recommendations given in [9].
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The design conditions: The material is -6, []p = 340MPa. The failing stresses of the eyes: 1 = 26000N; 2 = 20000N; 3 = 16670N; The dimensions of the eye bearings, mm: D1 = 22, D2 = 22, D3 = 19, 1 = 7; 2 = 7; 3 = 6.

Figure 3.1 - The scheme of the eye at the point 2 and 3 1 The eye thickness, mm:

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= 2 + 2 = 7 + 20,2 = 1,4 , where - the bearing embedment allowance according to 1.0384I-76, =0,2 mm. In accordance with 8032-84 is equal to7.5. 2 The eye width, mm: = + where d = D2. is rounded up to 30 mm. The minimum eye width is defined (mm) under the condition of the bearing insertion: x
min



=

20000 + 22 = 29,8 7,5 340

= d + 2

min

= 22 + 24 = 30;

min

= 4 ( 1. 03841 - 76).

The eye width is equal to = 30 mm. The stress of the eye is defined (MPa): -


=



=

20000 = 333,3 ; 30 - 22 7,5 340 = 1,02. 333

=



=

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Figure 3.2 - The hub scheme (the point 1) The eye dimensions at the point 3 are defined similarly to the previous calculations. = 6,5 mm; = 27 mm; = 1,06 The hub calculations (the point 1, Figure 3.2.): 1 The eye thickness. Two bearings are inserted in the hub, the distance = 18 mm, so = 25 mm (taking into account the bearing embedment). 2 The eye width, mm = + 26000 + 22 = 25,06. 25 340 between two bearings is:



=

Taking into account the condition of the bearing insertion:
min

= 30 mm, if d = 22 mm.
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The width is accepted as = 30 mm. The hub stress (MPa) is: -


=






=

26000 = 130,2; 30 - 22 25 340 = 2,61. 130,2

=

=

The dimensions of the eyes are plotted on the part sketch (Figure 3.3). 3.3 Calculating the part sections parameters of the required strength The initial data: The material ­ 6, [] = 340 MPa. The stresses of the belts: N13 = 20968N, N12 = 16823N, N23 = 27418N. The shear flow of the eyes = 1048 N/mm, 0 of the part midsection = 96,6 /. The areas of the belt cross-sections (2) are: 13 20968 = = 61,7 , 340 F17 = 49,5 , F23 = 80,6.

13 =

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Figure 3.3 - The part configuration The thickness of the eye wall () is: 3 1048 = = = 4 ,7 , 221
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if [] = 0,65 [] = 221. The thickness of the eye wall in the centre 0 = 0,44 mm. The dimensions of the wall and belts are plotted on the part sketch (Figure 3.3,). 3.4 The modification of the sections with taking into account the manufacturing factors and restrictions. The part configuration that takes proper account of the hot stamping features is defined according to the recommendations [7]. 1 Choosing the die parting line. The part is symmetrical to the middle plane. The die parting line is straight, and it is generated by the intersection of the middle plane and the outer part profile (Figure 3.4)

Figure 3.4 -The die parting line 2 Choosing the stamping angles

The belt 1 ­ 3 The belt height is variable. The height at the point 3 is defined according to the belt area of the required strength. F = 62 mm2 Set up =7,5mm; 2R = 4mm, - the rib height, R - the radius .
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According to the Table 7,2 [7] the outer and inner angles are 50. At the point 1 the rib height is: =12,5mm (Table 7.2), the angle is 50. The belt 1 -2 The belt height is variable. At the point 2 F = 50 mm. Set up = 6 mm. According to the Table. 7.2 the outer and inner angles are 50. At the point 3 the rib height (in accordance with the hub thickness) is equal to 12,5 mm, the angles are 50 . The belt 2 - 3 The belt height is constant. The belt area F = 81 mm. The rib height = 10 mm and the thickness is constant, and the outer and inner angles are 50. 3 The calculations of the part wall thickness The minimum acceptable wall thickness is defined according to the part projection area (Table 7.7 [7]). If F. = 60 cm, the minimum thickness S = 2 mm. The wall thickness of the required strength is 4,7 mm that quickly decreases to the part centre up to 0,5 mm. Let us assume that the wall thickness is constant along the part and equal to 5 mm. In the part centre the hole is made for lightening the part, the minimum distance between the rib and the hole edge should be no less then 15 mm (The total wall height of each section should be no less 30 mm). 4 The radiuses of conjugations and are defined according to the Table 7.15 [7] (Figure 3.3, ). The radius of conjugation between the rib and the wall R = 5 mm. The radius of (at the interfaces between the rib and the eye) R=5 mm. 5 The limit deviations of the dimensions between the unmachined surfaces are defined by the 4th degree of finish:
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The vertical dimensions: +0,5 - 0,3 mm (Table 7.20) [7]. The horizontal dimensions: +0,6 - 0,3 mm (Table 7.22). The limit deviations of the radiuses : +2,0 - 1,0 mm (Table 7.24). The part sections should be modified under the condition of the strength (Figure 3.3, ) with taking into account the manufacturing factors and restrictions (Figure 3.3, ). The antirust covering should be chosen according to the work conditions and material of the part [12]: the sulphuric acid anodizing process with filling the oxide film by the bichromate; should be done and , no later than within 24 hours the covering - 1 with the hot drying process should be done.

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4

THE EXEMPLARY REPORT OF THE LABORATORY WORK 4.MAKING THE PART DRAWING 4.1. The execution of the part drawings. The part drawing is shown in the

Figure 4.1. 4.2. of the designed part. The control crank is designed to transfer the control force and support the control rods of an aircraft. It is located in the in the tight open-type section of an aircraft fuselage. It is made of the deformable aluminum alloy - 4 by the hot stamping method with the following mechanical operations of the eyes and the places of inserting ball bearings. The antirust covering of the part does not re quire the control during the operation life of the part. In case of the mechanical failure of the covering it is necessary to cover the fault location by the lacquer coating.

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BIBLIOGRAPHY 1. , .. []: [.

. ] / . . . - 3- ., . . - .: , 1971. - 415 . 2. []: [ ­ .: , «»]/.. , .. , .. -, .. . , 1987. ­ 416 . 3. , .. []: . . . . / . . . - 2- ., . . - . : , 1980. - 367 . 4. 5. . 6. 1970. 7. [] ( ) / . . , . .. ; .: , 1963. 8. 9. (). .: , 1964 [] : . .-. / . . - . . . ; [. . . ]. - : [. .], 1992. - 56 . 10. , .. []: . . ­ : , 1982.- 30 . : . . .: , .. , .., , .. []. ­ : , 1985 ­ 64 . [] / . .. ; .: , 1963. ­ 340

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11. 12. 13. 1987. 14. 15. 16.

,

..









[]: . . ­ : , 1981. -3620. .: . . .: , 13682-80. . 2.316-68. , .. []: . 4- . .: , 1979.

01.07.81. . 01.01.71. / .. , .. ; . . . - . . . . ­ , 2012.

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4.1 The part drawing

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The laboratory work tasks. The Appendix

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31


32


33


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