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MI L - S TD - 202 - 207 4.4 Hamm ers . The te s t ap par at us i s equ i ppe d w i t h t w o 400 - pound ha m m e r s . O n e ha m m er renders a blow by a vertical drop . The ot her h am m er app l i e s a f or c e i n …

MIL-STD-202-207

METHOD 207

HIGH IMPACT SHOCK

1. SCOPE

1.1 Purpose. This test is performed for the purpose of determining the ability of various parts to withstand shock of

the same severity as that produced by underwater explosions, collision impacts, near-miss gunfire, blasts caused by

air explosions, and field conditions. Exact simulation of some of the severe shock motions experienced in the field is

difficult to reproduce; however, parts that successfully complete the test of this method have been found to possess

the necessary ruggedness for this use. The test apparatus utilized in this method is the same as that designated as

Shock Testing Machine for Lightweight Equipment in

MIL-S-901, Shock Tests, HI (High-Impact), Shipboard

Machinery, Equipment and Systems, Requirements for. The purpose of this apparatus is to determine the ability of

equipment installed aboard naval ships to withstand shock and still continue to perform its operational function. This

test method is limited to testing of parts weighing not more than 300 pounds.

2. APPLICABLE DOCUMENTS

2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a

part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are

those cited in the solicitation or contract.

DEPARTMENT OF DEFENSE SPECIFICATIONS

MIL-S-901 - Shock Tests, H.I. (High Impact), Shipboard Machinery, Equipment, and Systems,

Requirements For

MIL-DTL-1222 - Studs, Bolts, Screws and Nuts for Applications Where a High Degree Of Reliability Is

Required; General Specification For

MIL-I-24768/14 - Insulation, Plastic, Laminated, Thermosetting, Cotton-Fabric-Base, Phenolic-Resin (FBG)

(Copies of these documents are available online at http://quicksearch.dla.mil)

3. DEFINTIONS

This section not applicable to this standard.

4. GENERAL REQUIREMENTS

4.1. Precautions. The apparatus shall be examined periodically for damage. Any hardware that has become

defective by being deformed or cracked shall be replaced. Particular attention shall be given to the anvil plate which

shall not be bowed more than 1 inch at the center. Proper safeguards shall be taken to protect personnel from

objects that may become loosened and act as projectiles as a result of this test. A sound-warning arrangement shall

be made, for use in alerting personnel in the vicinity of the test of the impending drop of the hammer.

4.2. Apparatus. The apparatus used in this test method shall be as shown on figure 1 and the associated detail

drawings. The parts shall be installed on a mounting fixture which is attached to the anvil plate of the shock-testing

apparatus. A 400-pound hammer shall be dropped from a specified height (see 4.6.4) onto a shock pad located on

the anvil plate. The shock motion is then transmitted by the anvil plate to the parts attached on the mounting fixture.

4.3 Anvil plate. The test apparatus of this method is so constructed that the anvil plate (see figure 3) can be

installed, in sequence, in two positions. By utilizing these two installation positions and separately employing both

hammers of the apparatus shock is applied through the three principal mutually perpendicular axes of the part being

subjected to test. One position is to locate the anvil in such a manner that it will receive blows through the back of the

anvil plate by contact from the horizontal hammer, and blows on the top shock pad of the anvil plate by a drop of the

vertical hammer as shown on figure 2. The other position is as shown on figure 1, whereby the end shock pad is

contacted by the horizontal hammer.

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MIL-STD-202-207

4.4 Hammers. The test apparatus is equipped with two 400-pound hammers. One hammer renders a blow by a

vertical drop. The other hammer applies a force in a horizontal direction. In this manner, and by changing the

orientation of the anvil plate, blows may be delivered to the anvil and the parts in three directions.

4.5 Mounting fixtures. Figure 4A, figure 4B, figure 5, and figure 6 show standard mounting fixtures that shall be

used when testing parts with this test apparatus. These mounting fixtures simulate platform and panel mountings.

The applicable mounting fixture shall be as specified. When one of the standard mounting fixtures shown on figure

4A, figure 4B, figure 5, and figure 6 cannot be used, the individual specification shall specify a mounting fixture or

adapter which approximates the actual rigidity encountered in service.

4.6. Procedure.

4.6.1 Mounting method. The specimens shall be installed by their normal mounting means on the mounting fixture

in their normal operating position. Bolts for mounting the parts shall conform to type I, type II, or type III, grade 2, of

MIL-DTL-1222, Studs, Bolts, Hex Cap Screws, Socket Head Cap Screws and Nuts. Mounting bolts shall be checked

for tightness before each blow. Care shall be taken in the mounting procedure to prevent initial stresses being

applied to the specimens prior to shock.

4.6.2 Anvil-plate bolts and positioning springs. Due to the severity of the shock applied to the anvil plate by a

series of three blows, the anvil-plate bolts shall be checked for tightness before each series of blows. The spacing

between stops of the positioning springs (1.5 inches) shall also be corrected before each succession of blows.

4.6.3 Direction of shock. A total of nine blows, three through each of the three principal mutually perpendicular

axes for the heights indicated in 4.6.4, shall be delivered to the anvil plate supporting the specimens under test.

Direction of the shock shall be, in order, to the back, top, and side. Back and top blows shall be applied with the anvil

plate located to receive blows from the horizontal and vertical hammers. Side blows are delivered by the horizontal

hammer contacting the end shock pad of the anvil plate (see 4.3).

4.6.4 Height of hammer drops. The hammer shall strike the shock pad on the anvil plate, in sequence, from

heights of 1 foot, 3 feet, and 5 feet.

4.6.5 Hammer supports. During the test, the hammer not in use shall be disengaged from the lifting cable and

supported so that the hammer and its support are not in contact with the anvil plate.

4.6.6 Electrical load and operating conditions. The electrical load and operating conditions applied to the

specimens shall be as specified.

4.6.7 External resilient mountings. Unless otherwise specified, no external resilient mountings associated with the

specimen being tested shall be used. Integral mounting devices and external resilient mountings (if specified)

associated with the specimen shall remain unblocked during tests.

北测（上海）电子科技有限公司

联系方式：xuyj@beice-sh.com 13917165676

MIL-STD-202-207

FIGURE 1. High-impact shock-testing apparatus.

北测（上海）电子科技有限公司

联系方式：xuyj@beice-sh.com 13917165676