air craft
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Transcript of air craft
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A Study on the Vibration Analysis for the Composite Multi-axial Optical Structure of an Aircraft
Dae-Young Kim*, Jae-Hyuck Kwak*, Jun-Ho Lee**, Kwang-Woo Park***, Kwang Young Jeong*, and Seong-Sik Cheon*+
ABSTRACT
In this paper, a dynamic model is proposed for multi-axis optical structure of an aircraft. Modal analysis, sine-wave analysis, and random vibration analysis are done using a muti-body dynamic program for the multi-axis optical structure. By applying Al 6061-T6 and two types of CFRP to the camera module, x, y, and z responses are found and compared according to each axis excitation. The results will be used for reducing the weight of the camera module.
, , . Al6061-T6 , x, y, z . .
Key Words : (Random Analysis), (Frequency Response), CFRP(Carbon Fiber Reinforced Plastic), (Modal analysis), PSD(Power Spectral Density), (Vibration)
* ** *** *+ , (E-mail:[email protected])
1.
, . , , , .
. (EOIR: Electro-optic/Infrared Ray) [1]. (Line of Sight) [2]. .
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, , / [3]. (CFRP) , [4]. CFRP , .
[3] [5] , [6] . Mondragn[7] .
CFRP , ADAMS . (Excitation) . , , , (Modal analysis) .
2.
2.1 Fig. 1
, , , , , .
, Fixed Joint , , Bushing Joint . 3 Part Mass Table. 1 . CFRP Type-1 fabric , Type-2 [8] fabric .
Al6061-T6 CFRP Type-1 40%, CFRP Type-2 33% .
, . Al6061-T6 Type CFRP . Al6061-T6 Al6061-T6 , CFRP Al6061-T6 CFRP .
Fig. 1 Shape and structure of test module.
Table 1 Mass of test modules(Unit: kg)
Part Al6061-T6 CFRP Type-1 CFRP Type-2
Gimbal frame including camera 60 36 40
Isolator Mounts 8 4 5
Module Jig 209 209 209
Total Mass 277 249 254
3 IDEAS , ADAMS .
2.2 Al6061-T6
CFRP , .
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Table 2 Materials of test modules
Material Density(kg/m3)Youngs
Modules(GPa)Poissons
ratio
Al6061-T6 2700 68.9 0.33
CFRPType-1 1600 120 0.30
CFRPType-2 1800 70 0.30
SUS304 8000 200 0.29
Table 3 Stiffness and Damping
Type Value
bearing
Radial Stiffness 65.1106 (N/m)
Axial Stiffness 24.3106 (N/m)
Moment Stiffness 53.4 (kN/rad)
IsolatorSpring Coefficient 12 (kN/m)
Damping Coefficient 484 (Ns/m)
Al6061-T6, CFRP, SUS304 Table 2 , SUS304 . Table 3 .
24 (Degrees of Freedom) , 30 . ground part . 59 Moving parts . , Fig. 1 PSD(Power spectral density) . Fig. 2 . 0.3Grms . PSD . PSD (Stationary random signal) (Auto spectral density) . , . [9].
Fig. 2 Random vibration test profile.
Fig. 3 Static analysis.
3.
3.1
Simulation , .
. Fig. 3 Table 1 .
18 36 (Equivalent stiffness) , (1) . , (2) .
eqF k z= (1)
eq
mgzk
= (2)
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g , m , , eqk .
Al6061-T6 Type CFRP Table 4 .
Table 4 Static deflection of Al6061-T6 and CFRP(Unit: mm)
Al6061_T6 Type-1 Type-2
Calculation 1.36 0.81 0.91
Simulation 1.40 0.84 0.94
Al6061-T6 2.9%. Type-1 CFRP 3.7% , Type-2 CFRP 3.3% . , . Type CFRP Al6061-T6 40%, 33% .
3.2
. , , . [10-12].
ADAMS Al6061-T6 CFRP , 8 Table 5 . Al6061_T6 13.31 13.32 Hz Y Z Translational mode . Table Al6061-T6 CFRP 8 Mode Shape . 1, 2, 3 Y, Z, X Translational mode , 4, 5, 6 X, Z, Y Rotational mode . 6 , 7 Translational, Rotational mode .
.
. Al6061_T6 60kg Table 1 . Y ( Z) 36 . .
12
eqkfm= (3)
eqk .Al6061_T6 CFRP
Table 6 . Al6061-T6 1.5% , Type-1 CFRP 1.7%, Type-2 CFRP 1.2% .
Type-1 Type-2 CFRP Al6061_T6 40% 33% 4Hz 3Hz 8 Mode Shape .
Table 5 Natural frequencies obtained from modal analysis
(Unit: Hz)
Mode Al6061_T6 Type-1 Type-2
1st 13.31 17.23 16.26
2nd 13.32 17.24 16.27
3rd 13.46 17.41 16.44
4th 15.63 20.22 19.10
5th 20.87 27.00 25.50
6th 23.50 30.42 28.71
7th 66.12 85.75 80.90
8th 124.26 161.23 152.06
Table 6 The lowest natural frequencies obtained from approximation and simulation
(Unit: Hz)
Al6061_T6 Type-1 Type-2
Approximation 13.5 17.5 16.5
Simulation 13.3 17.2 16.3
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(a)
(b)
(c)Fig. 4 Al6061-T6 excitation and response: (a) X Axial excitation, (b) Y
Axial excitation, (c) Z Axial excitation.
3.3 sine cosine
, [9,13]. , 0.3g . .
.
Al6061-T6 Fig. 4 . X X 100Hz 4, 6, 7 15Hz, 25Hz, 65Hz . 3 ,
(a)
(b)Fig. 5 X Axial excitation and response: (a) CFRP_Type-1, (b) CFRP_
Type-2.
(a)
(b)Fig. 6 Y Axial excitation and response: (a) CFRP_Type-1, (b) CFRP_
Type-2.
. Y, Z Y, Z 3 15Hz, 13Hz .
CFRP Figs. 5~7 . X X Fig. 5 , Type-1 CFRP
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(a)
(b)Fig. 7 Z Axial excitation and response: (a) CFRP_Type-1, (b) CFRP_
Type-2.
4, 6, 7 20, 30, 86Hz , Type-2 CFRP 19, 28, 81Hz . Y, Z Y, Z Fig. 6 7 Type-1 Type-2 CFRP 17~18Hz, 16~17Hz . Y, Z .
3.4
.
, , , [10]. [9,14-16]. ADAMS (Frequency response) FFT(Fast Fourier Transform) . . .
(a)
(b)
(c)Fig. 8 Al6061-T6 excitation and response: (a) X Axial excitation, (b) Y
Axial excitation, (c) Z Axial excitation.
Fig. 2 PSD(g2/Hz) , . X, Y, Z .
Al6061-T6 PSD Fig. 8 Fig. 4 . X 120Hz 220Hz Y . Fig. 2 120Hz 220Hz Power Spectral Density . Z Fig. 8(c) Fig. 4(c) 460Hz . 460Hz Test Profile 4 Z .
Al6061-T6 CFRP PSD Figs. 9~11 . X
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(a)
(b)Fig. 9 X Axial excitation and response: (a) CFRP_Type-1, (b) CFRP_
Type-2.
(a)
(b)Fig. 10 Y Axial excitation and response: (a) CFRP_Type-1, (b) CFRP_
Type-2.
CFRP Al6061-T6 17~18 Hz Al6061-T6 .
Y( ) Y CFRP Al6061-T6 .
Z Z Fig. 11 CFRP Al6061-T6 . 460Hz
(a)
(b)Fig. 11 Z Axial excitation and response: (a) CFRP_Type-1, (b) CFRP_
Type-2.
Al6061-T6 CFRP .
Fig. 2 PSD Al6061-T6 CFRP Y Y CFRP , Z Z Al6061-T6 . CFRP Al6061-T6 .
4.
, , Al6061-T6 , CFRP .
Al6061-T6 13.3Hz , CFRP 17.2Hz, 16.3Hz . CFRP . 6 , 1~3 Translational mode, 4~6 Rotational
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mode . , .
. Al6061-T6 CFRP Y Y CFRP , Z Z Al6061-T6 . CFRP .
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