MIL-STD-167 Vibration Test Systems For Shipboard Equipment

MIL-STD-167 vibration test systems for shipboard equipment standard specifies procedures and requirements for environmental and internal excitation vibration tests for naval shipboard equipment installed on ships with conventional axial propulsion. Suitable for shipboard equipment subject to mechanical vibration from the environment and internal excitation caused by unbalanced rotating components of naval shipboard equipment.

Vibration type

Type1：Environmental vibration
Type2：Internally excited vibration

Environmental vibration

A. For Type I vibration testing, this standard applies to the vibration environment experienced by equipment using conventional axial propeller propulsion on naval ships. The Type I vibration test is not suitable for high-speed or surface effect ships subject to high speed wave beating vibrations, which produce vibrations that exceed the amplitude and frequency of conventional naval ships

B. This standard applies to Type I vibration testing of equipment used on ships with conventional axial propeller propulsion and does not necessarily apply to water jet propellers, pod propellers or other types of propellers, including those designed for blade rate forces

Test procedure

Vibration magnitudes in prescribed frequency and amplitude ranges to reveal any critical response prominences or potential deficiencies.
A 2-hour minimum endurance test at the response prominence frequency or frequencies most seriously affecting its functional and/or structural integrity.

Shipboard Equipment

For all tests, the equipment shall be fixed to the same connection point or area as the test machine, which will be fixed to the ship. If alternative attachment points or regions are specified, each attachment configuration should be used for testing. Hard-mounted (i.e. non-isolated) equipment on board shall be hard-mounted to the test machine. For equipment designed to be fixed to deck and head support supports, vertical supports should be used to simulate bulkheads. The bracket should be rigid enough to ensure that its movement is essentially the same as that of the platform on the test machine.

Vibration test direction

When installing the equipment on the vibration test machine, the vibration direction should be sequentially along the three linear direction axes of the equipment installed on the ship - vertical direction, transverse direction and forward and backward direction. On the horizontal vibration test machine, the equipment can be rotated 90 degrees on the horizontal plane in order to vibrate in each of the two horizontal directions. At no time shall the equipment be installed in any other way than in its normal shipborne direction.

Internal isolation or shock absorption installation

Other isolated installations integrated into the equipment housing (such as electronic boxes) should be tested in the normal onboard configuration or as required using internal installations

Endurance test

Endurance test frequencies are selected from the candidate list of endurance test frequencies developed during exploratory and variable frequency testing . When specified selection of these frequencies is subject to approval.  The equipment shall be vibrated for a total period of at least 2 hours at the frequency determined to most seriously affect the functional or structural integrity of the equipment. Guidance for selecting response prominences from exploratory or variable frequency testing, for determining whether a response prominence is significant, and if the more serious response prominences can be identified, is given in Appendix A. In cases where there are multiple response prominence frequencies selected, the duration of vibration testing at each frequency shall be in accordance with Table II.  If neither response prominences nor effects on equipment structural/functional performance are observed, this test shall be performed at 33 Hz or at the upper frequency as specified in 5.1.2.4.4.  The amplitudes of vibration shall be in accordance with Table I, unless otherwise specified (see 5.1.2.4.5).  See Figure 1 for a graphical representation of the amplitudes in Table I.


Vibration test
Each test specified herein shall be carried out separately in three main vibration directions. All tests in one direction must be completed before tests in the other direction can be carried out.
To determine the presence of response prominenees in the equipment under test, the equipment shall be secured to the vibration test systems and vibrated at frequencies from 4 Hz to 33 Hz, at a table vibratory single amplitude of 0.0100.002 inch . The change in frequeney shall be made in diserete frequeney intervals of 1 Hz and maintained at each frequeney for about 15 seconds.  Alternately, a continuous frequeney sweep with a rate of change of frequeney not to exeeed 0.067 Hz/second can be used.  The frequencies at which functional or structural requirements are affected or violated and frequencies and locations at which response prominences oceur shall be recorded, and these frequencies (rounded to the nearest integer frequeney if diserete frequeney intervals were not used) shall be considered as eandidates for endurance testing .