Select Page

military helicopter

MIL-STD-202 Vibration Testing

The purpose of MIL-STD-202 vibration testing is to determine the effects of vibration on component parts, within the predominant frequency ranges and magnitudes encountered during field service. Most vibration encountered in field service is not of a simple harmonic nature. However, tests based on vibrations of this type have proved sufficiently useful for determining critical frequencies, and modes of vibration. This and other determined data are necessary for planning protective steps against the effects of undue vibration.

During the life cycle, vibration can cause loosening of parts or relative motion between parts in the specimen. This can produce operating characteristics, noise, wear, and physical distortion that are objectionable. Such things often result in fatigue and failure of mechanical parts.

Keystone Compliance is a vibration test lab with significant mil-std-202 vibration test experience. Our vibration laboratory and test engineers understand the nuances of the vibration profiles and vibe testing.

The following information is extremely technical in nature. It was derived from test method 201 of version G of Mil-202 vibration section. Even though the language is from mil-202g vibration, it applies to previous versions of the standard.

What is the Procedure For Mil-Std 202 Vibration Tests?

Prior to vibration testing, the specified tests or measurements shall be made. The specimens shall be mounted as specified using suitable mounting apparatus and testing fixtures. This ensures that mounting is free from resonances over the test frequency range.

The specimens shall be subjected to a simple harmonic motion having an amplitude of 0.03 inch. This results in an 0.06 inch maximum total excursion. The frequency must be varied uniformly between the approximate limits of 10 and 55 hertz (Hz). The entire frequency range, from 10 to 55 Hz and back to 10 Hz, shall be traversed in approximately 1 minute.

Unless otherwise specified, this motion shall be applied for a period of 2 hours in each of 3 mutually perpendicular directions. This results in a total of 6 hours of motion application. If applicable, this test shall be made under electrical-load conditions.

In the previous Mil-202H vibration issue of this method test certain conditions required shorter test lengths. Test conditions A and B refer to a test length of 5 hours and 2.5. This procedure language is taken directly from MIL-STD 202G. The procedure is similar to other versions of the standard including MIL-STD 202H. It complies with the prescriptions of MIL STD-810.

What are the Detailed Requirements of Mil-202G Vibration Testing?

Measurements: According to Mil-202 vibration, the specified measurements shall be made both during and after vibration. There should be details regarding tests and measurements prior to vibration included in the individual specification. The specification should also include tests and measurements that occurred during and after vibration.

If the duration of vibration is different than what was already specified it should be detailed. The direction of motion should also be detailed, if it is different than what was already specified. The method of mounting should be included in the individual specification. Lastly, if applicable, a note should be made of the electrical-load conditions.

What are the Effects of the Environment?

It is important that all tests take place in an appropriate vibration laboratory environment utilizing the proper test equipment. Vibration results in dynamic deflections of and within material. Such dynamic deflections coupled with their associated velocities and accelerations may cause or be a contributing factor to structural fatigue. It may also lead to mechanical wear of structures, assemblies, and parts.

In addition, dynamic deflections may result in impacting of elements and/or disruption of function. Some typical symptoms of problems caused by these dynamic deflections include:

  • Electrical shortages
  • Chafed wiring
  • Excessive electrical noise
  • Intermittent electrical contacts
  • The loosening of fasteners and components
  • The failure of components
  • The migration of particles and failed components
  • Particles and failed components may lodge in circuitry or mechanisms
  • Optical or mechanical misalignment
  • Cracked and/or broken structures
  • The deformation of seals
  • Fretting corrosion in bearings

This list is not intended to be comprehensive. It demonstrates a few possible problems that may arise when a component fails to meet vibration compliance standards. MIL-STD 202G and MIL-STD 202H vibration provided the appropriate guidelines for meeting these compliance test standards.

Keystone Compliance has been recognized as one of the best vibration testing labs in the country. Our capabilities include testing to commercial and military vibration testing standards. With one of the best vibration labs we use only state of the art vibration test systems. Our vibration laboratory and test engineers understand the nuances of the vibration profiles and vibe testing.

Looking to get a vibration certification for your product? Talk to our experts to develop a streamlined test plan and receive a professional and affordable quote. Work with certified vibration analysts that understand the requirements of military vibration testing standards. Contact us to learn why so many manufacturers rely on Keystone Compliance to meet their vibration testing needs.

Looking for other MIL-STD-202 compliance tests? Click on a link below to learn more about the other test methods.