CB 1146.9-1996 Environmental testing and engineering guidelines for ship equipment Vibration (sinusoidal)
Some standard content:
Department Standard of China State Shipbuilding Corporation
CB 1146.1~1146. 18--96
Environmental test and engineering guide for ship equipment
Issued on 1996-12-23
Issued by China State Shipbuilding Corporation
Implementation on 1997-06-01
1 Subject content and scope of application
Department Standard of China State Shipbuilding Corporation
Environmental test and engineering guide for ship equipment
Vibration (sinusoidal)
CB1146.996
Replaces CB1146.9-85
Classification number: U08
This standard specifies the test conditions, severity levels, test procedures, and qualification criteria for environmental vibration (sinusoidal) tests of ship equipment, and provides engineering guidelines.
This standard applies to environmental tests for evaluating the working adaptability and structural integrity of ship equipment under specified vibration conditions. 2 Referenced documents
CB/T2423.10-1995 Basic environmental testing for electrical and electronic products Part 2: Test methods Test Fc and guidelines: Vibration (sinusoidal)
·CB1146.1-96 Marine equipment environmental testing and engineering guidelines General 3 Terminology
3.1 Fixed point
The point where the test piece contacts the fixture or the vibration table, usually the place where the test piece is fixed during use. If a part of the actual mounting structure is used as a fixture, the point where the part contacts the vibration table should be taken as the fixed point, and the point where the test piece contacts the mounting structure should not be taken as the fixed point. 3.2 Measuring point
Certain specific points where data is collected during the test. The collected data is used to check or control the test parameters. Note: The measurement points arranged on the surface in order to evaluate the performance of the test piece or to explore the vibration response characteristics of various parts of the test piece are not considered as measurement points in this standard. 3.2.1 Test point
A point located on the fixture, vibration table or test piece, and as close to the fixed point as possible. If there are four or fewer fixed points, each of them can be used as a test point; if there are more than four fixed points, the relevant standards should specify four representative fixed points as test points.
In special cases, such as large or complex test pieces, if the test points are required to be located elsewhere (not close to the fixed points), they shall be specified by the relevant standards or determined by the test engineering.
When several small test pieces are installed on a fixture, or when a small test piece has many fixed points, in order to derive the control signal, a single test point can be selected. This point should be selected from the fixed points of the test piece and the fixture, but not from the fixed points of the fixture and the vibration table. This is only feasible when the lowest resonant frequency of the fixture after the test piece is installed exceeds the upper limit frequency of the test. 3.2.2 Reference point
A point selected from the test points, the signal at this point is used to control the test. 3.3 Control Points
3.3.1 Single Point Control
Single point control is achieved by using the signal from the sensor at the reference point to keep the vibration parameters of the point within the specified range.
Approved by China State Shipbuilding Corporation on December 23, 1996 and implemented on June 1, 1997
3.3.2 Multi-point Control
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Multi-point control is achieved by using the sensor signals at each selected detection point, performing continuous arithmetic averaging or using comparison technology to generate a control signal. 4 Test conditions
4.1 Requirements for the characteristics of the vibration table
When the vibration table is equipped with the test specimen and the fixture, it shall have the following characteristics: 4.1.1 Basic motion
The basic motion shall be a sinusoidal function of time, the fixed points in the test specimen shall be essentially the same, move along parallel straight lines, and meet the tolerance requirements of 4.1.2 and 4.1.3.
4.1.2 Lateral motion
The maximum amplitude at any axial detection point perpendicular to the main vibration direction shall not exceed 50% of the specified amplitude in the main vibration direction, and shall not exceed 25% for small specimens.
The measurement of lateral motion only needs to be carried out within the specified frequency range. It may be difficult to achieve the above requirements for large specimens or for higher test frequencies. In this case, the lateral motion shall be recorded in the test report.
4.1.3 Distortion
The distortion of the acceleration waveform shall not exceed 25%. In some cases, e.g. large or complex test pieces, it may be difficult to achieve this requirement at certain frequencies within the test frequency range. In this case, the fundamental frequency amplitude may be controlled to the specified value. If a tracking filter is used, the distortion may exceed 25%.
If the distortion exceeds 25% and the fundamental frequency amplitude cannot be controlled to the specified value, the distortion and frequency range shall be stated in the test report.
The distortion of the acceleration waveform shall be measured at the reference point. The upper frequency limit of the measurement shall include 5000 Hz. For mechanical and hydraulic vibration tables, the upper frequency limit of the measurement may be only 5 times the highest frequency of the vibration table itself. 4.1.4 Amplitude tolerance
The actual amplitude at the test point and the reference point in the vibration direction shall be equal to the specified value and shall be within the following tolerance range: a. Test point: ±25%;
b. Reference point: ±15%.
4.1.5 Frequency tolerance
When conducting endurance test at dangerous frequency, the tolerance is; a. Below 5Hz: ±20%;
b. 5~50Hz: ±1Hz;
c. Above 50Hz: ±2%
When comparing dangerous frequencies before and after endurance test: a. Below 5Hz: ±10%;
b. 5~100Hz: ±0.5Hz;
c. Above 100Hz: ±0.5%.
4.1.6 Frequency sweeping requirements
The frequency should be able to change continuously, and the frequency should change exponentially with time. The frequency sweeping rate should be one octave per minute, and the tolerance is ±10%.
4.2 Installation of the test piece
4.2.1 Installation status
The test piece shall be installed in the same installation posture as on the ship and firmly fixed on the vibration table. 58
CB 1146.9—96
Equipment installed on bulkheads and ceilings shall be fixed to the vibration table together with transition mounting frames (hereinafter referred to as clamps) that simulate bulkheads and ceilings. When the test piece has several installation postures on the ship, the most unfavorable installation posture shall be selected for installation. Test pieces with vibration dampers in actual use shall be installed together with the vibration dampers. Mobile or portable equipment can be installed on the vibration table in the way it is used and stored on board or by appropriate fixing methods. Any connections of the test piece, such as cables, conduits, etc., shall impose constraints on the test piece similar to the actual state. 4.2.2 Installation fixture
The fixture should have sufficient rigidity, and its natural frequency should be higher than the upper limit frequency of the test; the lowest natural frequency of the fixture should be higher than three times the resonance frequency of the test system.
5 Severity level
The severity level of the vibration test is determined by three parameters: frequency range, amplitude and duration. 5.1 Frequency range and amplitude
If the vibration environment of the equipment is known, the test parameters of the test product can be specified according to the known environment. If the environment is unknown, the appropriate test parameters can be selected from Table 1.
5.2 Duration of endurance test (or number of sweep frequency cycles) 5.2.1 Sweep frequency endurance
The duration of the sweep frequency endurance in the entire test frequency range on each axis can be selected from Table A1 according to the number of sweep frequency cycles or time. The duration should be greater than the time required for the fixed frequency endurance test. It is recommended to use 10 and 20 cycles and their corresponding time.
5.2.2 Fixed frequency endurance
The endurance test time at the dangerous frequency of each axis shall be selected from the following values: 30.60, 90, 120min.
Vibration test parameters
Environmental classification
Frequency range
35~160
Displacement amplitude
Acceleration amplitude
Note: ①Eaves area refers to the stabilizing rod part; main body area refers to all parts other than the eaves rod part. Application examples
Equipment in the main area of surface ships and submarines
Equipment in the main area of high-speed oil engine speedboats
Equipment in the gun area of various ships
Equipment on various ship reciprocating engines and directly connected to reciprocating engines
General communication and navigation equipment on ships
Electrical, electronic and automation equipment on ships
Other compasses on ships except the main compass
②If it is known that the equipment is only installed on a specific ship, the upper limit rate of the test is the highest blade rate of the ship (the maximum speed of the propeller per minute × the number of propeller blades + 60); if there are special requirements, they shall be stipulated by relevant standards, specifications or order contracts. 59
6 Test procedures
6.1 Initial test
CB1146.9-96
Before the test, the test product shall be visually inspected and its electrical and mechanical properties shall be tested according to the product test outline or technical conditions. If the requirements are not met, this test shall not be carried out. 6.2 Condition test
The test product shall be subjected to two tests: vibration response test and vibration endurance test. For the case where only the frequency sweep endurance test is carried out, the above two tests can be combined into one.
Unless otherwise specified in the product standard or technical document, these two tests shall be carried out in three mutually perpendicular axes. The test sequence is that two tests may be carried out in one axis before two tests in another axis; or one test may be carried out in three axes before another test in three axes.
6.2.1 Vibration response test
According to the amplitude specified in Table 1, within the test frequency range, the frequency shall be swept back and forth 1 to 2 times from low to high and then from high to low at a rate of one octave per minute.
Unless otherwise specified in the product standard or technical document, during the vibration response check, the test product shall be in normal working condition; if the mechanical vibration characteristics of the test product cannot be determined because it is in working condition, the test product shall be placed in non-working condition for additional response check. During the vibration response check, the vibration response of the main structure and internal local structure of the test product shall be checked, and the current, voltage and other performance changes displayed by the indicator instrument or other performance detection methods on the test product shall be observed. Based on this, the dangerous frequency of the following phenomena shall be judged: a. Failure of the test product and (or) performance degradation; b. Mechanical resonance or other response phenomena.
The tester shall record the dangerous frequency, amplitude and performance changes of the above phenomena. 6.2.2 Vibration durability test
The product standard or technical document shall specify the use of swept frequency durability or fixed frequency durability. This standard recommends the use of swept frequency durability as a priority. During the entire durability test or at an appropriate stage, the test product shall work according to its typical functional conditions, and the test product shall be functionally tested at an appropriate stage and before the end of the test.
6.2.2.1 Sweep frequency endurance
Unless otherwise specified in the product standard or technical documents, the reciprocating frequency sweep may be carried out at a rate of one octave per minute according to the frequency range, amplitude and number of sweep frequency cycles or test time selected in Chapter 5. When only the sweep frequency endurance test is specified, the vibration response check may not be carried out. During the sweep frequency endurance test, the test product shall be in normal working condition and the performance of the test product shall be tested. 6.2.2.2 Fixed frequency endurance
The rated endurance test shall generally be carried out at the dangerous frequency found during the vibration response check. When there is more than one dangerous frequency, the endurance test shall be carried out at the most dangerous frequency selected by the supplier and the demander or by the test engineer. If no dangerous frequency is found, it is recommended to carry out the endurance test at 30Hz unless otherwise specified. The amplitude and duration of the endurance test shall be in accordance with the product standard or the provisions of Appendix B (reference). 6.2.3 Additional vibration response check
When the product standard requires it, a vibration response check shall be carried out again after the fixed-frequency endurance test to compare the changes in the dangerous frequency before and after the endurance test. If the dangerous frequency changes, the product standard shall specify the measures to be taken. The two vibration response checks before and after the endurance test shall be carried out under the same amplitude, the same method and other conditions. 6.3 Intermediate test
During the conditional test, the main performance of the test product shall be tested. 6.4 Recovery
CB 1146.9~96
When the relevant specifications require it, a recovery period shall be given after the conditional test so that the test product can return to the same conditions as the initial test. 6.5 Final inspection
After recovery, the test product shall be inspected for appearance and tested for electrical and mechanical properties according to the product test outline or technical documents. 7 Test interruption handling
During the test, if the test product has a major fault, such as structural damage, or malfunction, and the performance exceeds the allowable range specified in the product test outline or technical conditions, the test should be interrupted. After repair, repeat the vibration test, and the test party can also provide a new test product for retesting. If there is a small non-repetitive fault that is easy to replace and repair, such as indicator lights, component damage and welding defects, the test should also be interrupted. After repair, only the test item with the fault needs to be repeated, and there is no need to repeat the entire vibration test. Regardless of which of the above test interruptions occurs, it should be explained in detail in the test report. 8 Qualification Criteria
The test product is considered qualified if there are no following faults during and after the test: a. Mechanical damage or injury that affects the completion of the main function; b. One performance index does not meet the requirements during the final inspection; c. All performance indicators meet the requirements during the final inspection, but the test product works disorderly or abnormally during the vibration response inspection and during the sweep frequency endurance test; However, when conducting an endurance test at a dangerous frequency, if similar situations occur, the supply and demand parties and the test engineer should conduct a specific analysis.
d. Loosening of connectors (excluding the connection between the test product and the fixture or vibration table); e. Faults that are not allowed to occur as specified in the product test outline or technical conditions. 9 Test records and documents
The preparation of test documents shall comply with the relevant provisions of Chapter 8 of CB1146.1. 10 Engineering Guidelines
The engineering guidelines are shown in Appendix A (reference).
11 Details to be specified when citing this standard
a. Frequency range;
b. Vibration amplitude;
c. Type and duration of endurance test; d. Contents of initial and final tests; e. Contents of intermediate tests;
f. Whether additional vibration response checks are required, and how to deal with dangerous frequency changes found in two response checks. 61
A1 Introduction
CB1146.996
Appendix A
Guidelines for vibration environment test engineering for ship equipment (reference)
The purpose of this standard is to provide a method for simulating the effects of the vibration environment to which the product is subjected on the ship in a test room, rather than reproducing the actual vibration environment on the ship.
This standard brings together the test parameters and methods in the main domestic and foreign standards on environmental vibration test methods for ship equipment to adapt to international standards.
The purpose of this test is to reveal the mechanical weaknesses and changes in electrical properties of the test product in terms of its design and manufacturing process under the specified vibration test conditions, and to evaluate the test's work adaptability and structural integrity in the vibration environment of the ship in combination with the product technical conditions. It is not a fatigue life test.
Vibration tests always have a certain engineering judgment nature, and both the supply and demand parties must fully recognize this. A2 Environmental Effects
Vibration can cause:
a. Friction of wires;
b. Loosening of fasteners;
c. Intermittent electrical contacts;
d. Contact and short circuit between live components;
e. Seal failure;
f. Component fatigue;
g. Optical misalignment;
h. Cracks and fractures;
i. Loose particles or components cause system circuits or mechanical jams; j. Strong electrical noise.
A3 Measurement and Control
A3.1 Test Fixture
The installation of the test product cannot be separated from the fixture. The basic purpose of the fixture is to simulate the installation of the product on the ship and faithfully transfer the stress generated by the vibration table to the test product. The dynamic characteristics of the fixture have a great influence on the test results. Therefore, it is generally required that the fixture has sufficient rigidity and its natural frequency should be higher than the upper limit frequency of the test; at the very least, its natural frequency should be higher than three times the resonance frequency of the test product system. For the fixture of large and heavy equipment, it may be difficult or even impossible to meet the above requirements. The main reason is that the bearing capacity of the vibration table that can meet the environmental vibration characteristics requirements of ship equipment in China is relatively small. In reality, the resonance of the fixture often causes the test product to withstand excessive vibration exceeding the specified amplitude, that is, over-test. In view of this situation, the only effective method is to use multi-point control. A3.2 Selection of control points
The location and number of control points have a great relationship with the test results. Improper selection often results in over-testing or under-testing. For small specimens, or when the dynamic characteristics of the test fixture meet the requirements of 4.2.2, single-point control can be used, and the control point can be selected from any detection point. For large and complex specimens, or when the dynamic characteristics of the test fixture do not meet the requirements of 4.2.2, multi-point control should be used, and the control points should generally not exceed four. When the specimen has two mounting surfaces, control points should be selected on each mounting surface. When multi-point control is used, relevant regulations may specify the method of deriving the control signal. This standard recommends the use of multi-point average control signals, that is, the arithmetic average of the acceleration (or displacement) signals at each control point. When the difference in the signal values of each control point exceeds 5dB, 62
CB1146.9-96
Number average. Then convert the average signal into (for example, through a DC voltage through an averager. A3.3 Sweep
A3.3.1 Sweep rate
Under a certain amplitude and frequency continuously changing excitation, the response of the vibration system depends on the frequency change rate, that is, the sweep rate. If the sweep rate is too large, the response amplitude of the vibration system will not reach the theoretical value of steady-state vibration, and the resonant frequency will also be higher than the theoretical value. For the sake of standardization, this standard stipulates that the sweep rate is one octave per minute. This is appropriate under normal circumstances. However, for a vibration system with low-frequency and high-Q resonance, a rate of one octave per minute may not be appropriate. At this time, the maximum allowable sweep rate can be calculated according to formula (A1): β=1.443log.(23.6f/Q*+1)***
Where: 3-
-sweep rate, 10Ct/min;
-resonant frequency of the system, Hz;
Q-quality factor of the system.
A3.3.2 The number of sweep cycles and the corresponding time logarithmic sweep, the frequency changes exponentially with time, that is: f/f,=ekt
Where: f.
-upper limit frequency of the sweep, Hz;
f. Lower limit frequency of the sweep, Hz;
k-factor depending on the sweep rate;
t-time, min.
, if the time is in minutes and the sweep rate is one octave per minute, then k=iog.2=0.693bZxz.net
++.·(A1 )
.*(A2）
For a given frequency range, the time (or number of octaves) required for a frequency sweep cycle (from f, to f2, and then from f to f,>) can be calculated according to formula (A3):
N=2log2(f,/f,)=2/logto2×logio(fg/f)=6.644log1e(fa/f,).*Where: N——number of octaves;
f1, f lower and upper limit frequencies of the frequency sweep, Hz. For the frequency range given in 5.1, the number of frequency sweep cycles and the corresponding time are calculated according to formula (A3) and are listed in Table A1. A1 Number of frequency sweep cycles and corresponding time
Frequency range
10~160
A4 Test procedure||t t||Vibration response inspection
Rated sweep cycle number
Sweep frequency time
·(A3)
CB1146.9-96
.In vibration tests, previous specifications usually first conduct resonance inspections and then conduct durability tests on the test piece at its resonant frequency. The resonant frequency here not only includes the overall resonant frequency of the test piece, but also the resonant frequency of the internal local structure. However, some testers tend to only focus on the overall resonance and ignore the local resonance. Practice has proved that the overall resonance is certainly the main factor causing equipment performance abnormality or damage, but the resonance of the local structure is also an important factor causing equipment failure. It may be difficult to conduct resonance inspections on the internal local structure of large and complex test pieces. The main reason is that there are too many components and it is impossible to detect them one by one. Therefore, there may be resonance, but it is not detected; it is almost impossible to detect the vibration characteristics of the internal structure for closed equipment or modern small devices. Even if vibration sensors can be used for detection, the mass-stiffness distribution characteristics of the structure may be changed, so they are usually not used. Even if it can be used, the key to success or failure depends entirely on the test engineer's selection skills and experience of the measurement points. The vibration response inspection emphasized in this standard also includes the detection of mechanical resonance, but it is not the only one. The main purpose is to check the "dangerous frequency" that causes abnormal performance, out-of-tolerance or damage to the test product. Regardless of whether it is caused by resonance, it does not consider whether it is caused by overall resonance or local resonance or other reasons. When the product standard or relevant specifications have requirements for the magnification of resonance, the overall or local resonance must be detected. Therefore, the vibration response inspection can reduce the dependence on the test engineer. It is important to observe the performance of the test product at any time during the vibration response inspection. It is worth pointing out that in the case of nonlinearity, the test product may have different responses with the change of the sweep direction (upward or downward sweep), that is, the resonant frequency during the upward sweep and the resonant frequency during the downward sweep may be inconsistent. The vibration response inspection before and after the endurance test can be used to determine the changes in the resonant frequency and certain other response frequencies. The change in frequency may indicate the loosening of fasteners or the occurrence of certain fatigue. The product standard should specify the measures to be taken for this. When the specimen is tested with a vibration damper, the system resonance frequency may change due to temperature effects and other reasons. Therefore, if the frequency changes before and after the durability test, a careful analysis should be conducted.
A4.2 Durability Test
The swept frequency durability test is most suitable for simulating the stress effects that the specimen is subjected to during use: the swept frequency durability test can avoid the trouble and difficulty of mechanical resonance and dangerous frequency detection; when the dangerous frequency is not obvious, such as flutter, or several independent specimens are tested at the same time, or there are many dangerous frequencies and it is difficult to determine which dangerous frequency is the most harmful, and it is necessary to distinguish between dangerous frequencies that are likely to cause specimen failure and dangerous frequencies that are unlikely to cause specimen failure under long-term vibration, the swept frequency durability test is more suitable. The use of swept frequency durability test can also reduce the dependence on the technical level of the test engineering.
However, when the dangerous frequency is obvious and small, the use of swept frequency durability test may result in too long a duration to achieve the effect of a long-term test at the dangerous frequency. However, swept frequency durability is a development trend and is recommended to be used first. Fixed frequency durability test is usually conducted at the dangerous frequency found in the vibration response inspection. When no dangerous frequency is found, this standard recommends to conduct it above 30Hz. This is mainly based on the viewpoints of b. probability of occurrence of the environment, e. expected impact on the function and execution of the task of the equipment, and f. possibility of revealing problems by this method, as described in Chapter A5. Some specifications require durability test to be conducted at the upper limit frequency of the test, which is considered from the perspective of the number of vibration cycles. Fixed frequency durability test is suitable for products used in a limited range. In this case, the main frequency is known or predictable. It is suitable to determine the ability of the test product to withstand vibration and verify whether fatigue problems occur at certain discrete frequencies. It can avoid the duration of sweep frequency durability being too long; it is also suitable when the dangerous frequencies are obvious and not many. Fixed frequency durability test requires a lot of engineering judgment, and it is also necessary to constantly adjust the vibration frequency of the vibration table to keep it at the resonant frequency of the test sample system. Especially for the test product with shock absorber, the resonant frequency of the system may change due to the temperature effect of the shock absorber and other reasons. It can be seen from the above that for the same test product, if the test amplitude is the same, in order to keep the test intensity of the test product similar, the duration of the swept frequency endurance and the fixed frequency endurance is very different. This difference varies with the dynamic characteristics of the test product. In particular, the greater the dynamic magnification of the test product with obvious resonance, the greater the difference. Since the dynamic characteristics of the test product are very different, it is difficult to give an accurate correspondence between the durations of the two. In any case, the duration of the swept frequency endurance should be greater than the duration of the fixed frequency endurance. Appendix A of the national standard GB/T2423.10 recommends that the duration of the swept frequency endurance of ship equipment is 20 cycles. 64
A5 Severity level selection
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In order to include the vibration environment of various types of ship equipment, the frequency range, amplitude and duration of the endurance test given in this standard are selected from the current domestic main relevant ship equipment environmental vibration test standards. It is worth pointing out that as a general environmental vibration test standard, it neither reproduces the actual vibration environment of ship equipment nor has the nature of simulating actual environmental vibration. In essence, it provides a method to simulate the effect of environmental vibration on the product on the ship and reveal the defects in design and manufacturing process. Products that meet the test requirements can generally work satisfactorily on the ship. Due to the relatively short test time, fatigue issues are not fully considered.
When the environmental vibration characteristics of the equipment in actual use are known, it is best to determine the test parameters based on the actual environmental vibration characteristics. In this case, the following issues must be carefully analyzed and studied: a. Whether the vibration environment is normal and whether the measurement point layout is reasonable; b. The probability of the environment occurring and whether the data is sufficient; c. Data recording and analysis instruments and their calibration; d. Data analysis and induction methods;
e. The expected impact and failure mode on the equipment function and execution of the task; f. The possibility of revealing problems by this method; g. The current status of the test equipment.
For example, the frequency components of the environmental vibration of the equipment on the ship are quite rich, some of which are as high as several kHz. However, the current standards for ship equipment environmental vibration tests in various countries around the world stipulate that the upper limit frequency of the test is the blade frequency of the propeller's maximum shaft speed. This is mainly due to the above-mentioned defg. It is well known that the resonance caused by the natural frequency of the equipment system being consistent with the frequency of the disturbance force is often the main cause of equipment failure. The natural frequency of ship equipment is relatively low, generally below 80Hz. Large equipment is usually below 40Hz. The natural frequency of the shock absorber used in the equipment is generally in the range of 6 to 40Hz, and the frequency range exceeding this range is generally attenuated by 6 to 12dB/octave; in addition, although some parts of the ship have rich vibration frequencies, in terms of amplitude, the amplitude below the blade frequency is much larger than the amplitude of the high-frequency component. Therefore, the blade frequency range is the best frequency band to reveal whether there are quality problems in the equipment.
If the vibration characteristics of the actual environment of the equipment are unknown, the appropriate test parameters can be selected according to Chapter 5 or the specific severity level and corresponding test method can be selected from Appendix B (reference). A6 Transfer characteristics of shock absorbers
For test pieces that should normally be equipped with shock absorbers and have already been equipped with shock absorbers or when the test pieces are installed in a common elastic system, if the characteristics of the shock absorbers are known, the test should be carried out by multiplying the known characteristic coefficient by the specified test amplitude; if the characteristics of the shock absorbers are unknown, the transfer rate corresponding to the test frequency can be found in the general transfer characteristic curve of the shock absorber given in Appendix A of GB/T2423.10 and then multiplied by the specified test amplitude for testing.
CB1146.9-96
Appendix B
Examples of application of severity levels and test methods
(reference)
To facilitate the application of this standard, Table B1 gives examples of application of commonly used severity levels and test methods. Table B1
Environmental classification
Frequency range
35~160
25~100
Displacement amplitude
Note: ①The test is carried out in three axes: ②The sweep rate is one octave per minute. Additional instructions:
Acceleration amplitude
Test method
1. Initial vibration response test: Carry out 5 sweep frequency cycles! 2. Carry out a total endurance test of 2h at the dangerous rate. If there is no dangerous frequency, test at 30Hz frequency
3. Final vibration response test: Carry out 5 sweep frequency cycles after the endurance test.
Each frequency band shall be scanned at least
! 1. Each frequency band shall be scanned 1~
This standard was proposed by the 603rd Institute of China State Shipbuilding Corporation. This standard is managed by the Marine Environmental Conditions Management Group.
2. Vibrate at the dangerous frequency for 2h. If there is no relief frequency
, vibrate at 30Hz for 2h.
This standard was drafted by the Standardization Office of the Seventh Institute of China State Shipbuilding Corporation. The main drafter of this standard: Huang Shufu.
Application examples
Equipment in the main area of surface ships and submarines
Equipment in the main area of high-speed oil-engine speedboats
Equipment in the stable area of various ships
Equipment on various types of reciprocating engines and directly connected to reciprocating engines
General communication and navigation equipment for ships
Electrical, electronic and automation equipment for ships
Other compasses on ships except the main compass
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