MIL-STD-167-1A
a. Measurements shall be made at locations corresponding to components or areas on the equipment of particular concern for operation of the equipment, whose failure would impair the ability of the equipment to perform its principal function. Such locations shall be determined prior to test.
b. A sufficient number of measurement locations should be selected such that the response of the equipment is measured at locations near the base, top, and center of the equipment to measure response prominences associated with global motion of the equipment. These transducers should be attached to rigid areas of the equipment representing major structural components such as the housing, shell, or body of the equipment.
c. The transducers shall be oriented to measure vibration in the direction of the vibration excitation provided for any given test. Transducers may be re-oriented between tests to accomplish this.
d. If the testing machine rigidity has not been demonstrated by analysis, a sufficient number of transducers shall be located on the testing machine to demonstrate that the testing machine is rigid over the frequency range of the test. At a minimum, these transducers should be located at the point of force application to the table and at the equipment attachment interface(s) to the testing machine.
5.1.2.3 Methods of attachment.
5.1.2.3.1 Shipboard equipment. For all tests, the equipment shall be secured to the testing machine at the same points or areas of attachment that it will be secured shipboard. In case alternate attachment points or areas are specified, tests shall be performed using each attachment configuration. Equipment that is hard mounted (i.e., not isolation mounted) aboard ship shall be hard mounted to the testing machine. For equipment designed to be secured to a deck and a head brace support, a vertical bracket shall be used to simulate a bulkhead. The bracket shall be sufficiently rigid to ensure that its motion will be essentially the same as the motion of the platform on the testing machine. For isolation mounted shipboard equipment, see 5.1.2.3.4.
5.1.2.3.2 Shipboard portable and test equipment. Portable and test equipment that is designed for permanent or semi-permanent attachment to ship structure shall be attached to the vibration testing machines in the same manner
it is attached to the ship. Equipment that is not designed for permanent or semi-permanent attachment shall be secured to the testing machine by suitable means.
5.1.2.3.3 Orientation for vibration test. Equipment shall be installed on vibration testing machines in such a manner that the direction of vibration will be in turn along each of the three rectilinear orientation axes of the equipment as installed on shipboard - vertical, athwartship, and fore and aft. On a horizontal vibration-testing machine, the equipment may be turned 90 degrees in the horizontal plane in order to vibrate it in each of the two horizontal orientations. At no time shall the equipment be installed in any other way than its normal shipboard orientation.
5.1.2.3.4 Isolation mountings. For Type I testing of equipment to be installed shipboard on isolation mounts, the testing shall be performed on isolation mounts or hard mounted to the testing machine or as specified (see
6.2.f(4)). Type I testing of a particular piece of equipment on isolation mounts is valid only for the isolation mount type and configuration used during testing. Type I vibration testing may be performed hard mounted at some
frequencies and isolation mounted at others. For example, the isolation mounts can be removed during the variable
frequency and/or the endurance test at resilient mount resonance frequencies determined during the exploratory test, and the equipment can be tested hard mounted at these frequencies. If equipment is tested for Type I vibrations hard mounted to the test fixture throughout the duration of the test, the test is valid for either hard mounted or isolation mounted shipboard installations provided the isolation mounts are Navy standard mounts contained in MIL-M-
17191, MIL-M-17508, MIL-M-19379, MIL-M-19863, MIL-M-21649, MIL-M-24476 (see 2.2.1), or distributed isolation material (DIM).
5.1.2.3.5 Internal isolation or shock mountings. Equipment that incorporates other isolation mountings integrally within the equipment box (such as electronic cabinets) shall be tested with the internal mountings in the normal shipboard configuration or as specified (see 6.2.f(5)).
5.1.2.4 Vibration tests. Each of the tests specified herein shall be conducted separately in each of the three principal directions of vibration. All tests in one direction shall be completed before proceeding to tests in another direction. The equipment shall be secured to the vibration table as specified in 5.1.2.3. If major damage (see 5.1.1) occurs, the test shall be discontinued and the entire test shall be repeated following repairs or correction of deficiencies.
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