MIL-STD 810 is a Department of Defense Test Method Standard for environmental engineering considerations and laboratory tests.  It is the most popular Military specification used to conduct environmental testing of military products.  It exists so as to ensure that products used for defense-related purposes meet very specific requirements with regard to ruggedness, durability, and performance.  Given the fact that these products may be exposed to harsh or even extreme conditions, their reliability under stress is essential

MIL-STD 810 is jointly maintained by the Army, Navy, and Air Force, while being enforced by the Department of Defense.  There have been a number of iterations of MIL-STD 810, and the current version is MIL-STD 810H.  This military standard is periodically updated to reflect emerging technologies, as well as to amend any deficiencies which have become apparent with experience.  The updates are made by a MIL-STD 810 Working Group comprised of experts from the Army, Navy, Air Force and private industry.  

MIL-STD 810 is a standard which has now reached over 1,000 pages in length, and is comprised of three major sections: Environmental Engineering Program Guidelines, Laboratory Test Methods, and World Climatic Regions.  The second of these, the Laboratory Test Methods, is the one which many manufacturers focus on the most, because it’s the one which contains test procedures.

Purpose of Mil Std 810

The purpose of Mil-Std 810 is to ensure products will survive in harsh military applications.  Additionally, it helps achieve the objective of developing products that will perform adequately under the environmental conditions likely to be found throughout their life-cycle in the regions of intended use.

Part One’s, Environmental Engineering Program Guidelines, purpose is to describe management, engineering, and technical roles in the environmental design and testing process.  It focuses on the process of tailoring materiel design and test criteria to the specific environmental conditions an item is likely to encounter during its service life.

Part Two’s, Laboratory Test Methods, objective is to define test methods that can be consistently performed by any laboratory.  This section also defines requirements for equipment used to perform testing.  It contains environmental data and references, and identifies possible tailoring opportunities for the test methods.  Some methods afford a wide latitude for tailoring; while some have relatively few tailoring options.  There is also background information to help determine the appropriate level of tailoring.

Part Three, contains a compendium of climatic data from World Regions.  Its purpose is to provide climatic data to aid in the research, development, test, and evaluation of items used throughout their life cycles in various regions throughout the world.   

Product testing with MIL-STD 810

Products that are sold to the Military have to undergo extensive reliability testing, usually to a Military standard.  MIL-STD 810 is the most popular standard used for this application.   Testing must be conducted in specially equipped laboratories capable of subjecting products to harsh test conditions.  There are numerous types of tests which can be conducted on a given product, checking conditions such as low pressure, high & low temperatures, rain, sand or dust, vibration, shock, icing and freezing, acceleration, and acoustic noise.  The list of specific methods in MIL-STD 810 is as follows:

• Method 500  Low Pressure (Altitude)
• Method 501 High Temperature
• Method 502 Low Temperature
• Method 503 Temperature Shock
• Method 504 Contamination by Fluids
• Method 505 Solar Radiation (Sunshine)
• Method 506 Rain
• Method 507 Humidity
• Method 508 Fungus
• Method 509 Salt Fog
• Method 510.Sand and Dust
• Method 511 Explosive Atmosphere
• Method 512 Immersion
• Method 513 Acceleration
• Method 514 Vibration
• Method 515 Acoustic Noise
• Method 516.Shock
• Method 517 Pyroshock
• Method 518 Acidic Atmosphere
• Method 519 Gunfire Shock
• Method 520 Combined Environments, Temperature, Humidity, Vibration, and Altitude
• Method 521 Icing/Freezing Rain
• Method 522 Ballistic Shock
• Method 523 Vibro-Acoustic/Temperature
• Method 524 Freeze / Thaw
• Method 525 Time Waveform Replication
• Method 526 Rail Impact
• Method 527 Multi-Exciter
• Method 528 Mechanical Vibrations of Shipboard Equipment

Conclusion

Over the years, MIL-STD 810 has been developed as a means to ensure that products used by the armed forces perform optimally, even under extreme conditions such as might be encountered in harsh climates or under combat conditions.  Because these test conditions are so thorough, they have also been adopted by some civilian manufacturers who wish to claim that their products have been designed and engineered to the same exacting standards required by the Military. You can therefore expect that any product that is tested to MIL-STD-810 requirements will perform well, even when exposed to severe conditions.

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MIL-STD 810, Method 516, Shock Testing Overview

MIL-STD 810, Method 516, Shock Testing Procedure I – Functional Shock

MIL-STD 810, Method 516, Shock Testing Procedure II – Transportation Shock

MIL-STD 810, Method 516, Shock Testing Procedure III – Fragility

MIL-STD 810, Method 516, Shock Testing Procedure IV – Transit Drop

Crash hazard shocks apply to materiel mounted in air or ground vehicles.  Shock testing according to Procedure V of MIL-STD 810, Method 516 is intended to test the strength of products during a crash situation to verify that parts do not break apart, eject and become a safety hazard.  Failures of this nature could cause dangerous projectiles that could impact occupants or create significant damage to the vehicle.

This article will focus on the shock test condition when measured field data is not available and the testing will use classical shock impulses.  The terminal peak sawtooth is the default classical shock pulse to be used for this condition.  Figure 516.7-10 from MIL-STD-810 shows its shape and tolerance limits.  Table 516.7-IV contains the terminal peak sawtooth default test parameters for Procedure V – Crash Hazard Shock.  In limited cases a half sine shock impulse is specified.  Its shape and tolerance limits are shown in Figure 516.7-12.

Figure 516.7-10. Terminal peak sawtooth shock pulse configuration and its tolerance limits

Table 516.7-IV. Terminal peak sawtooth default test parameters for Procedure V – Crash Hazard Shock

Figure 516.7-12. Half-Sine shock pulse configuration and tolerance limits

The product should be mounted to the machine or fixture as it would in normal use.  So if it is bolted using a flange, then it should be attached to a fixture using this flange with the same size and number of bolts.

Typically, calibration shocks are performed first using a mass similar in size, weight and center of gravity (CG) of the product to be tested.  Once the desired shock requirements are met with the calibration mass, the mass is removed and the product to be tested is installed on the shock test machine or fixture.  The units under test do not have to be operating during crash hazard shocks.  After each shock, the test sample is inspected for visual damage.  Minor permanent deformations are usually acceptable as long as the product stays intact.  Significant damage such as large cracks may be cause for failure if they pose a risk of structural failure.

The most common requirement is to perform 2 shocks along both the positive and negative directions along 3 orthogonal axes.  This is a total of 6 directions and 12 total shocks.  When setting up to perform shocks in each direction, calibration shocks with the mass simulant are performed first because the weight, CG and product response could require different settings on the shock machine.  The shocks are performed along both the positive and negative directions of each axis because classical shocks are single polarity.

For more information on Shock Testing or other testing services, contact DES or call 610.253.6637.

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MIL-STD 810, Method 516, Shock Testing Overview

MIL-STD 810, Method 516, Shock Testing Procedure I – Functional Shock

MIL-STD 810, Method 516, Shock Testing Procedure II – Transportation Shock

MIL-STD 810, Method 516, Shock Testing Procedure III – Fragility

Method 516, Procedure IV is for testing products that could be accidently dropped such as when they are removed from a shelve or dropped when handling.  The test item is physically dropped onto a hard surface to produce the shock.  Products can be tested inside their transit case or unpackaged.  Typically, they would be tested in the configuration that is normally used for transportation, handling, or a combat situation.

The default drop test conditions are contained in Tables 516.7-VII through 516.7-IX from MIL-STD-810G w/Change 1.  They are meant to represent typical drop events that an item might experience from the time it is shipped from its manufacturer to the end of its service life.  Table 516.7-X and Figure 516.7-15 from MIL-STD-810G w/Change 1 show the standard drop orientations.  Figure 516.7-16 shows typical edge and corner drop configurations for large packages as discussed in Notes 2-4 of Table 516.7-VII.

If practical, the product should be periodically visually inspected and/or operationally checked during the drop test.  After completion of all of the drop events, typically a full visual inspection and operational check is performed.

DES has performed many product or package drop tests.  For more information on Shock Testing or other testing services, contact DES or call 610.253.6637.

Table 516.7-VII. Logistic transit drop test¹

Table 516.7-VIII. Tactical transport drop test

Table 516.7-IX. Severe tactical transport drop test

Table 516.7-X. Five standard drop test orientations

Figure 516.7-15. Standard drop orientations for rectangular and cylindrical packages

Figure 516.7-16. Illustration of edge drop configuration

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MIL-STD 810, Method 516, Shock Testing Overview

MIL-STD 810, Method 516, Shock Testing Procedure I – Functional Shock

Procedure II of Method 516 is used to evaluate the response of products to transportation environments that cause a repetitive shock load such as those occurring from ground vehicle shipping. This procedure uses the classical terminal peak sawtooth to characterize the transportation scenario.  Transportation shocks are typically repetitive low amplitude shock impulses. This procedure would be used in addition to shipping vibration testing and is not meant to be a substitute.

The items are usually tested in a packaged or unpackaged configuration in a non-operational state.  The shock test sequence is defined in Table 516.7-VI in Procedure II.  Normally, either the On-Road or Off-Road shock sequence is performed, not both.  The sequence in Table 516.7-VI is repeated along each applicable axis and direction as specified in the test plan.  After the shock testing is complete, operation of the product is verified and it is inspected for visual damage.

Table 516.7-VI Transportation shock test sequence^1,2,3

Note 1: The shocks set out in Table 516.7-VI must always be carried out together with ground transportation vibration testing as specified in Method 514.7, Category 4 and/or Category 20.

Note 2: The above tabulated values may be considered for both restrained cargo and installed materiel on wheeled and tracked vehicles. Transportation shock associated with two-wheeled trailers may exceed off-road levels as defined.

Note 3: The shock test schedule set out in Table 516.7-VI can be undertaken using either terminal peak sawtooth pulses applied in each sense of each orthogonal axis, or a synthesis based on the corresponding SRS that encompasses both senses of each axis.

Note 4: The above number of shocks is equivalent to the following distances: a) On-road vehicles: 5000 km; b) Off-road vehicles: 1000 km. If greater distances are required, more shocks must be applied in multiples of the figures above.

For more information on Shock Testing or other testing services, contact DES or call 610.253.6637.

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