Some standard content:
China State Shipbuilding Corporation Department Standard
CB1320--98
Torpedo vibration modal measurement method
Torpedo vibration modal measurement method1998-03-20 Issued
China State Shipbuilding Corporation
1998-08-01 Implementation
1 Scope
1.1 Subject Content
China State Shipbuilding Corporation Department Standard
Torpedo vibration modal measurement method
Torpedo vibration modal measurement method CB 1320-98
Classification Number: U74
This standard specifies the site environment, tested torpedo, test equipment and devices, test procedures, data processing and test result output of torpedo vibration modal test.
1.2 Scope of Application
This standard applies to the vibration modal test of the whole torpedo in the air medium. The systems and components on the torpedo can also be used for reference. 2 Reference documents
GB/T2298-91 Mechanical vibration and shock
GJB551-88 Explosives terms
3 Definitions
3.1 Mechanical vibration terms shall be in accordance with the provisions of GB/T2298. 3.2 Explosives terms shall be in accordance with the provisions of GJB551. 4 General requirements
4.1 Test site and environment
4.1.1 Test site
a. The test site floor should be smooth and flat. Ventilated and dustproof, with rubber sheets laid on the floor and sufficient lighting. b. The test site should be equipped with a stable and clean power supply. c. The test site should have a good grounding wire. d. The test site should be free of vibration and strong electromagnetic interference. 4.1.2 Test environment
a. The test environment temperature is 10~35C
b. The relative humidity of the test environment is not more than 75%. c. The test environment pressure is the ground atmospheric pressure. 4.2 Tested torpedoes: 4.2.1 Mass and stiffness The mass and mass distribution, stiffness and stiffness distribution of the tested torpedoes shall be the same as those of the selected torpedo configuration. 4.2.2 Liquid fuel substitute fluids Thermodynamic torpedoes undergoing vibration modal testing shall use non-toxic, non-corrosive substitute fluids of the same density to replace the actual fuel. 4.2.3 Explosives and pyrotechnics disposal Torpedoes with explosives and pyrotechnics shall not be used for vibration modal testing, such as loaded war mine sections, detonators, explosive bolts, and ignition devices. Approved by China State Shipbuilding Corporation on March 20, 1998, and implemented on August 1, 1998. CB1320-98. The dummy parts with the same mass and stiffness should be used instead, and the fixing and installation methods should be the same as the original parts. 4.2.4 Propulsion battery
The propulsion battery of the electric torpedo should be replaced by the dummy parts with the same mass and stiffness as the actual battery, and the fixing and installation methods should be the same as the original parts.
4.2.5 Precision sensitive elements
Original parts or dummy parts can be used according to the specific situation. 4.3 Support conditions
4.3.1 Support method
The support method of the torpedo under test can be elastic suspension support method or elastic base support method. 4.3.2 Support system natural frequency
No matter what support method is used, the natural frequency of the support system should be lower than 20% of the lowest modal frequency of the torpedo under test. 4.4 Excitation method
4.4.1 Small torpedo
Small torpedoes can use pulse excitation (hammer method) and random excitation (single point excitation or two point excitation). When the hammer method is used, the input energy should be sufficient to excite the first 10 or more modes of the torpedo structure without generating nonlinear excitation. 4.4.2 Large torpedoes
Large torpedoes should use two-point or multi-point random excitation. If hammer or single-point random excitation is used, a preliminary test should be carried out to confirm that the excitation energy is sufficient before use.
5 Detailed requirements
5.1 Test equipment and devices
5.1.1 Composition
The test equipment and devices consist of an excitation system, a measurement system, a data acquisition and processing system, and a support device. Mainly include: a. Signal source:
b. Power amplifier:
c. Hammer;
d. Electromagnetic exciter;
Electro-hydraulic exciter:
y. Flexible rod;
Force sensor:
h. Acceleration sensor:
Charge amplifier;
3. Tape recorder;
k. Signal analyzer:
1. Support frame;
m. Elastic rope;
n. Suspender;
0. Support base.
5.1.2 Requirements
5.1.2.1 Measurement of test equipment
The test equipment shall be qualified through metrological calibration and within the validity period of metrological calibration. 5.1.2.2 Excitation system
The excitation system shall meet the following requirements;
CB1320-98
, signal source, shall be able to provide a variety of excitation signals such as sine and random. It shall have compression control function to ensure constant force excitation; b. Power amplifier, shall be able to match the exciter; c. Force manganese, in order to obtain different pulse widths, the hammer head is allowed to use different materials; d. Electromagnetic exciter, the excitation force shall not be less than 100N; e. Electro-hydraulic exciter, its frequency response range shall cover the torpedo modal frequency; f. Flexible rod, shall have sufficient rigidity in the direction of excitation force transmission and shall be soft enough in other directions. The diameter and length of the flexible rod shall be appropriately selected so that the natural frequencies of its longitudinal compression vibration and transverse bending vibration avoid the excitation frequency. 5.1.2.3 Measurement system
a. Force sensor, with small self-weight, the measuring range shall be within the required range, and the operating frequency shall be not less than 10kHz. b. The acceleration sensor shall be small in weight, and its operating frequency shall be able to cover the torpedo modal frequency. The lateral sensitivity shall not be greater than 5% of the sensitivity in the main axis direction.
5.1.2.4 Data acquisition and processing system
5.1.2.4.1 Data acquisition
A microcomputer-controlled data acquisition system may be used. If a tape recorder is used, the tape recorder shall meet the following requirements: a. Frequency response: 5~20kHz;
b. Signal-to-noise ratio: greater than 40dB:
c. At rated output, the nonlinear distortion coefficient shall not be greater than 3%; d. There shall be an overload indication.
5.1.2.4.2 Data processing
Data processing shall include frequency response analysis and modal parameter identification, and the test results shall be plotted and printed out. The signal analysis function of the system shall meet the following requirements:
Sufficient frequency response range:
b. There shall be different signal input modes such as direct, charge and floating; c. There shall be low-pass filtering capability;
d. It shall be able to calculate three frequency response parameters: H, (output error estimation model), H (input error estimation model) and H (input-output error estimation model);
It shall be able to conduct coherence analysis;
f. It shall be able to provide the necessary window function and be able to adjust it on the screen; g. It shall have signal storage and refinement functions.
5.1.2.5 Support device
5.1.2.5.1 Elastic suspension support
a. Support frame. The frame for hanging torpedoes shall have sufficient rigidity and be firmly and stably installed on the ground. b. Elastic rope and sling. The elastic rope for hanging the torpedo should meet the weight of the torpedo, and its elongation should be approximately linear with the load size, so that when the torpedo is hung, its elongation is within the elastic range. The torpedo is connected to the elastic rope through a sling. The sling should be inelastic. 5.1.2.5.2 Elastic base support
The support base for fixing the torpedo should not constitute a constraint in any direction except the direction of gravity. The torpedo is fixed on the base through elastic support.
5.2 Test Procedure
5.2.1 Test System Block Diagram
5.2.1.1 The block diagram of the impulse excitation test system is shown in Figure 1.3
Elastic rope
Acceleration
Sensor
CB1320-98
Supporting frame
Charge amplifier
Force sensor
Tested fish eggs
Charge amplifier
Charge amplifier
Figure 1 Block diagram of impulse excitation test system
The block diagram of the random excitation test system is shown in Figure 2.
Supporting frame
Exciter
Elastic rope
Tested torpedo
Force sensor
5.2.2 Test Preparation
5.2.2.1 Installing the sensor
Flexible rod
Acceleration sensor
Power amplifier
Charge amplifier
Charge amplifier
Charge amplifier
Figure 2 Block diagram of random excitation test system
Oscilloscope
Data acquisition and processing system
Signal generator
Data acquisition and processing system
Oscilloscope
a. Sensor location and quantity: The location of the test sensor should take into account both longitudinal and circumferential aspects. It should be arranged according to the assumed digital mechanical model, and can be evenly arranged in the longitudinal direction or in the characteristic parts. The typical cross-section can be selected for circumferential arrangement, and each cross-section has more than 6 measuring points evenly arranged in the circumferential direction. The total number of measuring points should be no less than 50. 4
CB1320-98
b. Installation: The sensor can be fixed on the torpedo body to be tested through a pad or directly. The sensor axis should be perpendicular to the longitudinal axis of the torpedo. The installation should be firm and rigid in the sensor axis direction. No looseness or slippage is allowed. The installation method should not damage the torpedo surface. 5.2.2.2 Installation of the torpedo under test
The support position of the torpedo under test should be as close to the modal node as possible. Adjustment is allowed during the pre-test. The torpedo under test should remain horizontal.
5.2.2.3 Installation of the exciter
&. Pulse excitation. The pulse excitation point should be selected at the connection ring with greater rigidity. It should not be selected on the hole cover, hole plug and components that are not rigidly connected to the torpedo shell.
b. Random excitation. Single-point random excitation should be selected in the middle of the torpedo. Two-point or multi-point random excitation should be located at the front, middle and rear of the torpedo respectively.
c. The exciter should be elastically connected to the supporting frame. 5.2.2.4 Test equipment inspection
Connect all the equipment in the test system correctly. Turn on the equipment so that each equipment is in normal working condition. 5.2.2.5 Test system joint debugging and calibration
The test system should be pre-added with excitation signals for system debugging, and the test system should be calibrated with standard mass blocks. 5.2.3 Test implementation
5.2.3.1 Input physical model data
Input the coordinate values of the selected measuring points into the data processing system. 5.2.3.2 Adjust the measuring system
Apply excitation signals to the torpedo under test, observe the display of each measuring point through the oscilloscope, and appropriately adjust the amplification factor of each charge amplifier to make the system in the best signal-to-noise ratio state. And make records. 5.2.3.3 Test
If it is not possible to test all the measuring points at the same time, it is allowed to divide the measuring points into several groups for step-by-step testing. When measuring in steps, attention should be paid to maintaining the consistency of the excitation system and the test system.
5.2.3.4 On-site analysis of test records
Test records should be replayed and preliminarily analyzed on-site, and frequency response functions should be calculated to ensure that the test records are valid. 5.3 Data processing and test results
5.3.1 Data processing
The computer data processing program (software) should include the following functions: a. It can accommodate enough measuring points, which should generally be no less than 300 points; b. It can perform structural description and calculation of three types of coordinates (rectangular coordinates, cylindrical coordinates, spherical coordinates) and no less than 6 sub-components, including the conversion of local coordinates to overall coordinates;
c. It should have no less than four parameter identification methods and be able to identify real mode and complex mode parameters: d. It should be able to have a certain ability to judge the analysis accuracy force. Help the operator to select the analysis accuracy: e. Has the vibration mode animation display function;
f. Has the structure modification function.
5.3.2 Test results
5.3.2.1 Validity of test results
Multiple criteria should be used to prove the validity of the test results. 5.3.2.2 Test data requirements
The test results should include the modal frequency, modal damping ratio and modal vibration mode of at least 10 modes. 5.3.2.3 Test result report
The test result report format is shown in Appendix A (Supplement). 5| |tt||Parameters of the torpedo under test and test conditions are shown in Table A1. Main test equipment are shown in Table A2.
Test result data are shown in Table A3.
A4·The vibration shape diagrams of each mode should be given.
CB1320-98
Appendix A
Test result report
(Supplement)
Parameters of the torpedo under test and test conditions
Substitute working fluid
and substitute parts
Measurement point, support
bearing point and excitation
location||t t||Tester (signature):
Tester (signature):
Modal number
Tester (signature):
Additional instructions:
CB1320-98
Main test equipment
Table A3 Test result data
Modal cheek rate
This standard was proposed by the 601st Institute of China National Shipbuilding Corporation. This standard was drafted by the 705th Institute of China National Shipbuilding Corporation. The main drafters of this standard: Rate Changqing, Zeng Zhonglian, Wu Yaokun. Quantity
Modal bandit3 Test Result Report
The test result report format is shown in Appendix A (Supplement). 5
The parameters of the torpedo under test and the test conditions are shown in Table A1. The main test equipment is shown in Table A2.
The test result data is shown in Table A3.
A4·The vibration shape diagrams of each order mode are to be given.
CB1320-98
Appendix A
Test result report
(supplement)
Tested torpedo parameters and test conditions
Substitute working fluid
and substitute parts
Measurement point, support
bearing point and excitationbzxz.net
Location of test personnel (signature):
Test personnel (signature):
Modal number
Test personnel (signature):
Additional instructions:
CB1320-98
Main test equipment
Table A3 Test result data
Modal cheek rate
This standard was proposed by the 601st Institute of China National Shipbuilding Corporation. This standard was drafted by the 705th Institute of China National Shipbuilding Corporation. The main drafters of this standard are: Lu Changqing, Zeng Zhonglian, Wu Yaokun.3 Test Result Report
The test result report format is shown in Appendix A (Supplement). 5
The parameters of the torpedo under test and the test conditions are shown in Table A1. The main test equipment is shown in Table A2.
The test result data is shown in Table A3.
A4·The vibration shape diagrams of each order mode are to be given.
CB1320-98
Appendix A
Test result report
(supplement)
Tested torpedo parameters and test conditions
Substitute working fluid
and substitute parts
Measurement point, support
bearing point and excitation
Location of test personnel (signature):
Test personnel (signature):
Modal number
Test personnel (signature):
Additional instructions:
CB1320-98
Main test equipment
Table A3 Test result data
Modal cheek rate
This standard was proposed by the 601st Institute of China National Shipbuilding Corporation. This standard was drafted by the 705th Institute of China National Shipbuilding Corporation. The main drafters of this standard are: Lu Changqing, Zeng Zhonglian, Wu Yaokun.
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