MIL-STD-167-1A
5. DETAILED REQUIREMENTS
5.1 Type I - environmental vibration. When Type I vibration requirements are specified (see 6.2.e), the equipment shall be subjected to a simulated environmental vibration as may be encountered aboard naval ships. This standard provides an amplitude sufficiently large within the selected frequency range to obtain a reasonably high degree of confidence that equipment will not malfunction during service operation.
a. For Type I vibration testing, this standard shall be used for equipment subjected to the vibration environment found on Navy ships with conventionally shafted propeller propulsion. Type I vibration testing shall not be applicable to high-speed or surface-effect ships that are subject to vibrations from high- speed wave slap, which produce vibration amplitudes and frequencies in excess of the levels on conventional Navy ships.
b. This standard applies to Type I vibration testing for equipment used in Navy ships with conventionally shafted propeller propulsion, and is not necessarily applicable to waterjet, podded, or other propulsor types, including those that have been designed to minimize blade-rate forces.
c. For equipment installed on ships with propulsion systems with frequency ranges not covered by Table I, this standard shall not apply.
5.1.1 Basis of acceptability. For equipment that can be vibration tested, acceptability shall be contingent upon the ability of the equipment to withstand tests specified in 5.1.2 and the ability to perform its principal functions during and after vibration tests. Minor damage or distortion will be permitted during the test providing such damage or distortion does not in any way impair the ability of the equipment to perform its principal functions (see 6.2.f(1) and 6.2.f(6)). Because of the numerous types of equipment covered by this standard, a definite demarcation between major and minor failures cannot be specified. Therefore, during testing a determination shall be made whether a failure is minor or major to determine whether testing should continue (see 6.2.f(2)). In general, a major failure is one that would cause maloperation or malfunction of the item of equipment for a long period. Non-repetitive
failures of such parts as connectors, knobs/buttons, certain fasteners, and wiring, which can be easily replaced or repaired, are generally considered minor failures. As such, the repair could be made and the test continued with no penalty to the remainder of the equipment. The critical use of the equipment shall be considered when determining
the category of failure; that is, a failure of a part in a lighting circuit may be considered minor. The same failure in a
control circuit may be major.
5.1.2 Test procedures. The tests specified herein are intended to expose equipment to:
a. Vibration magnitudes in prescribed frequency and amplitude ranges to reveal any critical response prominences (see 3.19) or potential deficiencies.
b. A 2-hour minimum endurance test at the response prominence frequency or frequencies most seriously affecting its functional and/or structural integrity.
5.1.2.1 Testing machine. Vibration tests shall be made by means of any testing machine capable of meeting the conditions specified in 5.1.2.4, and the additional requirements contained herein. Means shall be provided for controlling the direction of vibration of the testing machine and for adjusting and measuring its frequencies and amplitude of vibration to keep them within prescribed limits. It is acceptable to utilize different machines for the vertical and horizontal directions. The testing machine, including table, actuator, and attachment fixtures, shall be rigid within the frequency range to be tested. This includes test fixture resonances that may result from interaction between the table and mounted equipment. Testing machine rigidity shall be demonstrated by analysis or by measuring transmissibility in accordance with 5.1.2.2.d.
5.1.2.2 Additional test instrumentation. Vibration measurement transducers, such as accelerometers, shall be installed on the test equipment to aid in the determination of response prominences during the exploratory and variable frequency vibration tests of 5.1.2.4.2 and 5.1.2.4.3. The number, orientation, and placement of vibration transducers will depend upon the equipment under test and should be sufficient to provide a suitable survey for identifying response prominences of the tested equipment and testing machine. When required, approval of transducer locations shall be obtained from the procuring activity (see 6.2.f(3)). Guidance below shall be used in selection of measurement locations:
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