MIL-STD-810: Environmental Engineering Considerations and Laboratory Tests
MIL-STD-810, Environmental Engineering Considerations and Laboratory Tests, is a United States Military Standard that emphasizes tailoring an equipment’s environmental design and test limits to the conditions that it will experience throughout its service life, and establishing chamber test methods that replicate the effects of environments on the equipment rather than imitating the environments themselves. Although prepared specifically for military applications, the standard is often used for commercial products as well.
The standard’s guidance and test methods are intended to:
• define environmental stress sequences, durations, and levels of equipment life cycles;
• be used to develop analysis and test criteria tailored to the equipment and its environmental life cycle;
• valuate equipment’s performance when exposed to a life cycle of environmental stresses
• identify deficiencies, shortcomings, and defects in equipment design, materials, manufacturing processes, packaging techniques, and maintenance methods; and
• demonstrate compliance with contractual requirements.
Scope and purpose of MIL-STD-810:
- MIL-STD-810 addresses a broad range of environmental conditions that include: low pressure for altitude testing; exposure to high and low temperatures plus temperature shock (both operating and in storage); rain (including wind blown and freezing rain); humidity, fungus, salt fog for rust testing; sand and dust exposure; explosive atmosphere; leakage; acceleration; shock and transport shock; gunfire vibration; and random vibration. The standard describes environmental management and engineering processes that can be of enormous value to generate confidence in the environmental worthiness and overall durability of a system design. The standard contains military acquisition program planning and engineering direction to consider the influences that environmental stresses have on equipment throughout all phases of its service life. The document does not impose design or test specifications. Rather, it describes the environmental tailoring process that results in realistic materiel designs and test methods based on materiel system performance requirements.
- Finally, there are limitations inherent in laboratory testing that make it imperative to use proper engineering judgment to extrapolate laboratory results to results that may be obtained under actual service conditions. In many cases, real-world environmental stresses (singularly or in combination) cannot be duplicated in test laboratories. Therefore, users should not assume that an item that passes laboratory testing also will pass field/fleet verification tests.
MIL-STD-810 Test Methods:
Specific examples of Test Methods called out in MIL-STD-810 are listed below:
| Method | Test | Description |
|---|---|---|
|
500.6 |
Low Pressure (Altitude) | These tests check the effects (in terms of performance) of altitude, including loss of cabin pressure on the device/system/equipment. Factors tested include dielectric strength, cooling under low pressure, and resilience to rapid change in air pressure. The norm defines the different temperature profiles under which the equipment must be tested. Due to the variety of aircraft, the equipment is classified in categories. |
|
501.6 |
High Temperature | These tests exercise the assemblies' capability of surviving extreme temperature changes and the effects of differing coefficients of thermal expansion. |
|
502.6 |
Low Temperature | These tests exercise the assemblies' capability of surviving extreme temperature changes and the effects of differing coefficients of thermal expansion. |
| 503.6 | Temperature Shock | These tests exercise the assemblies' capability of surviving extreme temperature changes and the effects of differing coefficients of thermal expansion. |
| 504.2 | Contamination by Fluids | Aviation related fluids susceptibility including a variety of fluids ranging from carbonated sugared beverages to various cleaners and solvents. |
| 505.6 | Solar Radiation (Sunshine) | This method has two purposes: a. To determine the heating effects of direct solar radiation on materiel. b. To help identify the actinic (photodegradation) effects of direct solar radiation. |
| 506.6 | Rain | The purpose of this method is to help determine the resistance of protective covers, seals and other items with respect to rain, water spray, or dripping water. |
| 507.6 | Humidity | These tests under humidity check the effects of high concentrations of humidity and the article's ability to withstand moisture effects. Typically moisture sensitive devices have issues with this test and require a conformal coat or other types of protection. |
| 508.7 | Fungus | This test determines whether equipment material is adversely affected by fungi under conditions favorable for their development, namely, high humidity, warm atmosphere and presence of inorganic salts |
| 509.6 | Salt Fog | This test verifies the test article's ability to survive multiple exposures of salt fog and drying and the environment's ability to cause accelerated corrosion. |
| 510.6 | Sand and Dust | These tests subject the unit to an environment of blowing sand and dust of specific particle sizes in which the unit must operate at the end of exposures. |
| 511.6 | Explosive Atmosphere | The explosive atmosphere test is performed to demonstrate the ability of materiel to operate in fuel-air explosive atmospheres without causing ignition and/or demonstrate that an explosive or burning reaction occurring within encased material will be contained, and will not propagate outside the test item |
| 512.6 | Immersion | The immersion test is performed to determine if materiel can withstand immersion or partial immersion in water (e.g., fording), and operate as required during or following immersion. |
| 513.7 | Acceleration | The acceleration test is performed to assure that materiel can structurally withstand the steady-state inertia loads that are induced by platform acceleration, deceleration, and maneuver in the service environment, and function without degradation during and following exposure to these forces. Acceleration tests are also used to assure that materiel does not become hazardous after exposure to crash inertia loads. |
| 514.7 | Vibration | Vibration tests are performed to develop materiel to function in and withstand the vibration exposures of a life cycle including synergistic effects of other environmental factors, materiel duty cycle, and maintenance. This method is limited to consideration of one mechanical degree-of-freedom at a time. Refer to Method 527 for further guidance on multiple exciter testing. |
| 515.7 | Acoustic Noise | The acoustic noise test is performed to determine the adequacy of materiel to resist the specified acoustic environment without unacceptable degradation of its functional performance and/or structural integrity. |
| 516.7 | Shock | Shock tests are performed to provide a degree of confidence that materiel can physically and functionally withstand the relatively infrequent, non-repetitive shocks encountered in handling, transportation, and service environments. This may include an assessment of the overall materiel system integrity for safety purposes in any one or all of the handling, transportation, and service environments. |
| 517.2 | Pyroshock | Pyroshock tests involving pyrotechnic (explosive- or propellant-activated) devices are performed to provide a degree of confidence that materiel can structurally and functionally withstand the infrequent shock effects caused by the detonation of a pyrotechnic device on a structural configuration to which the material is mounted and experimentally estimate the materiel's fragility level in relation to pyroshock in order that shock mitigation procedures may be employed to protect the materiel’s structural and functional integrity. |
| 518.2 | Acidic Atmosphere | Use the acidic atmosphere test to determine the resistance of materials and protective coatings to corrosive atmospheres, and when necessary, to determine its effect on operational capabilities. |
| 519.7 | Gunfire Shock | Gunfire shock tests are performed to provide a degree of confidence that materiel can structurally and functionally withstand the relatively infrequent, short-duration transient high rate repetitive shock input encountered in operational environments during the firing of guns. |
| 520.4 | Temperature, Humidity, Vibration, and Altitude | The purpose of this test is to help determine the combined effects of temperature, humidity, vibration, and altitude on airborne electronic and electro-mechanical material with regard to safety, integrity, and performance during ground and flight operations. Some portions of this test may apply to ground vehicles, as well. In such cases, references to altitude considerations do not apply. |
| 521.4 | Icing/Freezing Rain | This test determines performance characteristics for equipment that must operate when exposed to icing conditions that would be encountered under conditions of rapid changes in temperature, altitude and humidity. |
| 522.2 | Ballistic Shock | This method includes a set of ballistic shock tests generally involving momentum exchange between two or more bodies, or momentum exchange between a liquid or gas and a solid performed to provide a degree of confidence that material can structurally and functionally withstand the infrequent shock effects caused by high levels of momentum exchange on a structural configuration to which the material is mounted and experimentally estimate the materiel's fragility level relative to ballistic shock in order that shock mitigation procedures may be employed to protect the materiel’s structural and functional integrity. |
| 523.4 | Vibro-Acoustic/Temperature | The vibro-acoustic/temperature procedure is performed to determine the synergistic effects of vibration, acoustic noise, and temperature on externally carried aircraft stores during captive carry flight. |
| 523.4 | Fire and Flammability Testing | This analysis and test verify the assembly will not provide a source to fire. |
| 524.1 | Freeze / Thaw | The purpose of this test is to determine the ability of materiel to withstand the effects of moisture phase changes between liquid and solid, in or on materiel, as the ambient temperature cycles through the freezing point and the effects of moisture-induced by transfer from a cold-to-warm or warm-to-cold environment. |
| 525.1 | Time Waveform Replication | Replication of a time trace under Time Waveform Replication (TWR) methodology in the laboratory is performed to provide a degree of confidence that the materiel can structurally and functionally withstand the measured or analytically specified test time trace(s) to which the materiel is likely to be exposed in the operational field environment and to experimentally estimate the material’s fragility level in relation to form, level, duration, or repeated application of the test time trace(s). |
| 526.1 | Rail Impact | The purpose of this test method is to replicate the railroad car impact conditions that occur during the life of transport of systems, subsystems and units, hereafter called materiel and the tiedown arrangements during the specified logistic conditions |
| 527.1 | Multi-Exciter | Multi-exciter test methodology is performed to provide a degree of confidence that the materiel can structurally and functionally withstand a specified environment, e.g., stationary, non-stationary, or of a shock nature, that must be replicated on the test item in the laboratory with more than one motion degree-of-freedom consideration. The laboratory test environment may be derived from field measurements on materiel, or may be based on an analytically generated specification. |
| 528.1 | Mechanical Vibrations of Shipboard Equipment | This method specifies procedures and establishes requirements for environmental and internally excited vibration testing of Naval shipboard equipment installed on ships. |
The user of the standard must also decide interdependently of the standard, how much additional test margin to allow for the uncertainty of test conditions and measurement in each test. Source: Wikipedia
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