SJ 20594-1996 Manual on Vibration and Shock of Military Electronic Equipment

SJ 20594-1996 Military Electronic Equipment Vibration and Shock Manual SJ20594-1996 Standard download decompression password: www.bzxz.net

Military Standard of the Electronic Industry of the People's Republic of China FL 0120
SJ20594-96
Vibration and Shock Handbook for Military Electronic Equipments Issued on August 30, 1996
Implementation on January 1, 1997
Approved by the Ministry of Electronics Industry of the People's Republic of China 1 Scope
1.1 Subject content
1.2 Scope of application
2 Reference standards
3 Definitions
3.1 Terms
3.2 Symbols
4 Linear vibration theory
4.1 Mechanical model and basic elements
Single degree of freedom system
4.3 Multi-degree of freedom system·
4.4 Longitudinal vibration of the rod·
Torsional vibration of the shaft·||t t||4.6 Transverse vibration of beams·
5 Nonlinear vibration theory
5.1 Nonlinear vibration in engineering
5.2 Classification of nonlinear vibration systems
5.3 Physical characteristics of nonlinear vibration·
5.4 Common methods for solving nonlinear vibration problems: 6 Random vibration
Statistical characteristics of random processes
6.2 System response under random excitation...
7 Shock and transient vibration·
7.1 Differential equation of motion of single-degree-of-freedom system...7.2 Convolution integral method
7.3 Laplace transform method,
7.4 Shock response Response spectrum:
7.5 Shock response spectrum of various typical pulses.8 Vibration of rigid frame and arch of military electronic equipment components8.1
Vibration of rigid frame·
Vibration of arch
8.3 Vibration calculation of electronic components
Vibration calculation of guide spring
Stiffness of gyroscope flexible wire
8.6 Fatigue curve
9 Vibration of a plate of a military electronic equipment component
9.1 Analysis method of thin plate vibration
9.2 Vibration of rectangular plate
9.3 Vibration transmissibility of printed circuit board
|9.4 Calculation of circuit board vibration
9.5 Maximum allowable static deflection of circuit board
10 Vibration of shell of military electronic equipment components...10.1 Vibration of cylindrical shells
10.2 Axisymmetric vibration of spherical shells
10.3 Vibration of flat shells
11 Vibration of thin-walled box structures of military electronic equipment...11.1 Bending vibration of box on elastic basis.11.2 Bending vibration of box caused by ground and support movement.11.3 Vibration calculation of thin-walled electronic chassis...12 Vibration and shock test instrument for military electronic equipment...12.1 Vibration and shock sensor...
12.2 Vibration and shock Shock measurement instruments...·
12.3 Vibration and shock analysis instruments...·
13 Digital analysis of vibration signals of military electronic equipment 13.1 Vibration signal characteristics...
13.2 Fourier series and discrete spectrum
13.3 Fourier transform and continuous spectrum
13.4 Digital frequency analysis technology...
14 Vibration and shock measurement of military electronic equipment 14.1 Vibration quantity measurement
14.2 Measurement of shock and transient vibration
15 Modal analysis of military electronic equipment test...·15.1 Theory of experimental modal analysis
15.2 Modal test
15.3 Pure modal method for modal parameter identification 16 Environmental testing of military electronic equipment
16.1 General requirements for environmental testing
16.2 Sinusoidal vibration test
16.3 Random vibration test·
16.4 Shock test·
Collision test
16.6 Acceleration test
17 Vibration isolation theory for military electronic equipment
（114)
..（143)
17.1 Single degree of freedom vibration isolation system…
17.2 Design of multi-degree of freedom vibration isolation system
17.3 Nonlinear vibration isolation System
17.4 Vibration isolation design for random vibration
17.5 Vibration isolation of nonlinear system
18 Shock isolation theory for military electronic equipment
18.1 Evaluation index of shock isolation effect…18.2 Expected dynamic characteristics of vibration isolation buffer system18.3 Design of linear shock isolation system:
19 Vibration isolators for military electronic equipment…
19.1 Design and selection principles of vibration isolators…
19.2 Characteristic test method of vibration isolators
19.3 Model naming method of vibration isolators
19.4 Quality assurance specification of vibration isolators
19.5 Product specifications for commonly used vibration isolators for electronic equipment 19.6 Acceptance rules for vibration isolators
Design of elastic characteristics of vibration isolators ·
19.8 Metal vibration isolators
19.9 Rubber vibration isolators
19.10 Metal rubber type vibration isolators
Appendix A Commonly used symbol table (supplementary)
Appendix B Performance indicators of vibration and shock sensors (reference) ·Appendix C Commonly used vibration isolators (reference)
Additional instructions ·
: (292)
Military standards for the electronics industry of the People's Republic of China Manual on vibration and shock of military electronic equipment
Vibration and shock handbookfor military electronic equipments1Scope
1.1Subject content
SJ20594-96
This standard provides the basic theory of vibration and shock for military electronic equipment: vibration calculation and analysis methods and examples of typical military electronic equipment structures; vibration and shock test and analysis technology and instruments for military electronic equipment; vibration and shock environmental specifications and test methods for military electronic equipment: vibration, shock and noise control design methods for military electronic equipment. 1.2Scope of application
This standard applies to the analysis and calculation, environmental testing, test analysis and control design of vibration and shock for military electronic equipment. 2Referenced standards
The valid versions of the following standards, within the scope specified in this standard, constitute a part of this standard. GB2298-93
GB2828-81
GB2423.6-95
GJB150.15-86
GJB150.16-86| |tt||GJB150.17-86
GJB150.18-86
GJB150.20-86
GJB510-88
GJB4.7-83
SJ93-78
SJ2555-84
SJ2608-85
SJ2609-85
SJ2610-85
SJ/Z2924- 88
SJ/T10160-91
SJ/T10163-91
Terms and terms of mechanical vibration and shock
Batch inspection, sampling procedures and sampling tables for counting Basic environmental test procedures for electrical and electronic products Environmental test methods for military equipment Acceleration test Environmental test methods for military equipment Vibration test Environmental test methods for military equipment Noise test Environmental test methods for military equipment Shock test Environmental test methods for military equipment
Aircraft gun vibration test
General specification for vibration isolators without resonance peak
Environmental test for ship electronic equipment Vibration test Vibration absorber
Technical guidelines for the design and application of vibration isolators for electronic equipment Metal dry friction vibration isolators
Flat plate and bowl type vibration isolators
Air damping and metal mesh damping vibration isolators
Guidelines for the optimal design of vibration and shock isolation systems GFD low frequency vibration isolators
Test methods for dangerous frequencies| |tt||The Ministry of Electronics Industry of the People's Republic of China issued it on August 30, 1996 and implemented it on January 1, 1997
SJ20594—96
SJ/T10165-91 Model naming method of vibration isolator SJ/T10178-91 Test method of vibration isolator characteristics SJ/T10179-91 General specification of metal vibration isolators SJ/T10180-91 General specification of metal rubber vibration isolators SJ/T10181- 91 General specification for rubber vibration isolators SJ/T
Test methods for vibration and shock of printed circuits
Shock measurement and data processing
SJ/T20134-91 Requirements for noise control of military electronic equipment SJ2013-92
3 Definitions
3.1 Terms
Methods for vibration detection and fault diagnosis of electronic equipment This standard adopts the terms specified in the standard GB2298 Mechanical vibration and shock terminology. 3.2 Symbols
The symbols used in this standard are shown in Appendix A.
Linear vibration theory
The vibration system can be divided into linear vibration and nonlinear vibration according to the structural parameter characteristics of the motion system, and can be divided into concentrated parameter (discrete) system and distributed parameter (continuous) system according to the characteristics of the system mechanical model; according to the cause of vibration, it can be divided into free vibration, forced vibration, parameter vibration and self-excited vibration, etc.; according to the law of vibration, it can be divided into simple harmonic vibration, random vibration, transient vibration, etc. This chapter studies the theory of free vibration and forced vibration of single-degree-of-freedom systems, including undamped and damped systems. It also discusses concepts such as multi-degree-of-freedom systems and distributed parameter systems, Lagrange equations, and admittance and transfer functions. 4.1 Mechanical model and basic elements
4.1.1 Mechanical model of discrete vibration system Any discrete vibration system is generally composed of three basic elements. The three basic elements that make up a discrete system are mass, spring, and damper. The simplest discrete system consists of a mass, spring, and damper, as shown in Figure 4.1.1. The number of degrees of freedom of a discrete system is finite, and its motion state is expressed by a second-order ordinary differential equation. The number of equations should be equal to the number of degrees of freedom of the system.
Figure 4.1.1 Single-degree-of-freedom vibration system
Figure 4.1.2 Electronic equipment mounted on a linear vibration isolator When the electronic equipment is mounted on a linear vibration isolator, as shown in Figure 4.1.2, if only the vertical vibration characteristics of the equipment are discussed, it can be simplified to the mechanical model shown in Figure 4.1.3. The total mass m of the equipment and the spring stiffness k and damping c of the vibration isolator respectively constitute a single degree of freedom system consisting of a mass m, a linear damping element c and a linear spring k as shown in Figure 4.1.3.
Figure 4.1.3 Mechanical model of electronic equipment
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Figure 4.1.4 Discrete multi-degree-of-freedom system
If the vibration characteristics of each plug-in box (1, 2, 3, 4) and rack (5) in the equipment are further discussed, it becomes a discrete multi-degree-of-freedom system as shown in Figure 4.1.4. Since the system has 5 masses and requires 5 independent coordinates to determine their vibration state, they are a five-degree-of-freedom linear vibration system. 4.1.2 Basic elements of discrete systems
Mass (including moment of inertia) The mass model (Figure 4.1.5) is a rigid body with only inertia. Its acceleration is proportional to the resultant force acting on the mass block, that is,
Figure 4.1.5 Mass
Figure 4.1.6 Linear spring
Spring The spring model (Figure 4.1.6) has only elasticity, and its own mass can be ignored. The force on the spring is related to its deformation. The ratio of the spring force to the deformation is called the spring constant or stiffness. If the spring constant or stiffness increases with the increase of deformation, the spring is called a hard characteristic spring. If the spring constant or stiffness decreases with the increase of deformation, the spring is called a soft characteristic spring. In the case of small deformation, the spring force is proportional to the first power of the spring deformation, which is called a linear spring, that is, F=k(2)
Where: 2>
k spring constant or stiffness.
(4.1.2）
In a linear vibration system, the restoring force of an elastic element is proportional to the power of the displacement, and its proportionality coefficient is the force required to produce a unit displacement, which is called stiffness. For a torsional vibration system, the torque required to produce a unit angular displacement is called torsional stiffness. The reciprocal of stiffness, that is, the displacement caused by a unit force, is called compliance. Stiffness is one of the main factors affecting the vibration characteristics of a mechanical system. The stiffness and torsional stiffness of simple elastic elements are shown in Table 4.1.1 and Table 4.1.2 respectively. The stiffness of a complex element or the entire system is measured by experimental methods. 3
D,-mid-diameter of large end cm
D2-mid-diameter of small end cm
SJ20594—96
Stiffness of elastic element
Cylindrical tension or compression
Conical tension or compression
Series spring
Parallel spring
Hybrid spring
Lever spring
Circular section| |tt||Rectangular section
4Ghb3n
元ND3
0.1410.1960.2290.263/0.281
N-effective number of spring turns
Circular section
Rectangular section
2N(D+D)(D,+D2)bZxz.net
16Ghb3n
N(D+ D)(D+D2)
0.276(h/6)2
1+(h/6)2
N-effective number of spring turns
-+++"+-2 yuan
n-number of springs in series
n-number of springs in parallel
(+k2)k3
k,+kz+k
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Continued Table 4.1.1
Cantilever beam with uniform cross-section
Triangular cantilever beam with uniform thickness
Cantilever leaf spring (the plates are arranged
to form a beam with uniform strength)
Simply supported beam
Beam fixed at both ends
Circular plate with simple support around the periphery and loaded
in the center
Circular section
Rectangular section
k= nbh'E
n-number of steel plates
when 1=12
when=2
3R2(1-μ)(3 +μ)
3 yuand\E
where! Circular plate thickness; u-Poisson's ratio; R-circular plate radius
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Continued Table 4.1.1
Circular plate with fixed periphery and loaded at the center
3R2(1 - μ)
Wherein t-thickness of circular plate; u-Poisson's ratio; R-radius of circular plate T-tension of chord
E-elastic modulus Pa; G-shear modulus Pa; I-section moment of inertia cm Table 4.1.2
Torsional stiffness of elastic element
Cylindrical torsion spring
Cylindrical bending spring
Rectangular strip with twisted ends
(b/h=1 .75~20)
Flat plate subjected to torsion at both ends
(b/h>20)
Torsional stiffness
N-effective number of spring turns
32ND (1+E/2G)
N-effective number of spring turns
-total length of steel bar
kg=aGbh3
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Continued Table 4.1.2
Solid shaft
Hollow shaft
Tapered shaft
Stepped shaft
Tight-fit shaft
Couple acts on the end of the county arm beam
Couple acts on the midpoint of the simply supported beam
Torsional stiffness
(a) kg =
(c) ke
(e) ke= 1.1
Gr(D* - d')
(b) ke
(d) ke
(f) ke
3G,D(D2-D,)
321(DD)
k. ko + kz
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