MIL-STD 810, Method 501 High Temperature Testing is used to evaluate the effects of high temperature conditions on performance, materials, and integrity.  Method 501 is applicable for temperature testing products that are deployed in areas where temperatures (ambient or induced) are higher than standard ambient.  Note, the latest revision of this method is 501.7 from MIL-STD-810H.

Method 501 is limited to evaluating the effects of relatively short-term (months, as opposed to years), even distributions of heat throughout the test item. This method is not typically practical for evaluating materials where solar radiation produces thermal gradients or photochemical effects.  Method 505 is used to test the effects of solar radiation.  It is also not practical to evaluate degradation that occurs from continuous long-term exposure to high temperatures where synergetic effects may be involved.

The following are typical failures that could occur from products used in high temperature environments.

• Parts bind from the differential expansion of dissimilar materials.
• Lubricants become less viscous; joints lose lubrication by the outward flow of lubricants.
• Materials change in dimension.
• Packing, gaskets, seals, bearings, and shafts become distorted, bind, and fail causing mechanical failures.
• Gaskets display permanent sets.
• Closure and sealing strips deteriorate.
• Fixed-resistance resistors change in values.
• Electronic circuit stability varies with differences in temperature gradients and differential expansion of dissimilar materials.
• Transformers and electromechanical components overheat.
• Operating/release margins of relays and magnetic or thermally activated devices alter.
• Shortened operating lifetimes.
• High pressures are created within sealed cases (batteries, etc.).
• Discoloration, cracking, or crazing of organic materials.
• Out-gassing of composite materials or coatings.
• Failure of adhesives.

MIL-STD-810 Method 501 Tests: High Temperature Procedures

1. Procedure I – Storage.  Procedure I is for testing products that are stored at high temperatures.  After the high temperature storage test is completed, an operational test at ambient conditions is performed.  Procedure I can be either a cyclic temperature test or a constant temperature test. 
2. Procedure II – Operation.  Procedure II is used to investigate how high temperatures could affect the performance of items while they are operating.  Temperature Procedure II can be performed as either a cyclic temperature test or a constant temperature test. 
3. Procedure III – Tactical-Standby to Operational.  This temperature procedure evaluates the material’s performance at normal operating temperatures after being presoaked at high non-operational temperatures.  An example of Procedure III is a product that is stored in an enclosed environment that develops high internal temperatures before being removed and then operated in a relatively short period of time.

What is the procedure for MIL-STD-810 High Temperature Testing? 

First, identify the high temperature levels, test conditions, and applicable procedures. DES can help determine the appropriate temperature ramp rates and durations of the tests based on the equipment’s intended use and the operating environmental conditions.  Consider the following climatic temperatures from Table 501.7-I. (MIL-STD-810H):

Next, determine whether a constant temperature test or a cyclic temperature test is appropriate.  Constant temperature testing is used only for items situated near heat-producing equipment or when it is necessary to verify the operation of an item at a specified constant temperature.  The duration for constant temperature test temperature is at least two hours following test specimen stabilization.

For cyclic exposure, there are two 24-hour cyclic profiles contained in Tables 501.7-II and 501.7-III.  The number of cycles for the Procedure I storage test is a minimum of seven to coincide with the one percent frequency of occurrence of the hours of extreme temperatures during the most severe month in an average year at the most severe location.   The minimum number of cycles for the Procedure II operational testing is three. This number is normally sufficient for the test item to reach its maximum response temperature.

You can trust the DES MIL-STD-810 High Temperature Testing lab

Advantages with DES : 

• DES is A2LA accredited to MIL-STD-810, Method 501 High Temperature Testing
• DES has extensive experience running MIL-STD-810 Method 501.7 high temperature Tests
• DES has multiple temperature chambers capable of performing MIL-STD-810 high temperature compliance testing

Contact us today to to discuss testing your product in our MIL-STD-810 accredited Test Laboratory. 

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In the demanding realms of aerospace and defense, ensuring that products can withstand the rigors of high-altitude environments is paramount. MIL-STD 810 is a Department of Defense Test Standard for environmental engineering considerations and laboratory tests.  Method 500 in MIL-STD-810 defines procedures for low-pressure (altitude) testing.  The latest revision of this method is 500.6 from MIL-STD-810H.

Altitude Testing Services at Delserro Engineering Solutions

At Delserro Engineering Solutions, our altitude testing services are designed to meet the rigorous demands of the aerospace and defense industries. By employing the comprehensive procedures outlined in MIL-STD-810H Method 500.6, we ensure that every product undergoes thorough low pressure testing under simulated high-altitude conditions. The altitude test chambers at Delserro Engineering Solutions (DES) can meet the requirements of MIL-STD-810H (and previous revisions) accurately ensuring that products are not just compliant but are primed for operational excellence.

MIL-STD-810 altitude testing services are tailored to products that:

1. Operate or are stored at significant elevations.
2. Experience pressurized or unpressurized conditions in aircraft.
3. Could undergo rapid or explosive decompression.
4. Are externally mounted on aircraft and exposed to extreme conditions.

Method 500 is not intended for items that are installed or operated in space vehicles, aircraft, or missiles that fly at altitudes above 21,300 m (70,000 ft). 

The following are typical failures that could occur from products used in a high altitude (low pressure) environment:

1. Leakage of gases or fluids from gasket-sealed enclosures
2. Deformation, rupture, or explosion of sealed containers
3. Change in physical and chemical properties of low-density materials
4. Overheating of materiel due to reduced heat transfer
5. Evaporation of lubricants
6. Erratic starting and operation of engines
7. Failure of hermetic seals
8. Erratic operation or malfunction of materiel resulting from arcing or corona

MIL-STD-810 Method 500.6 Insights for Low Pressure Testing

MIL-STD-810 Method 500.6 has four procedures:

1. Procedure I – Storage/Air Transport. Procedure I is for testing material that is transported or stored at high ground elevations or transported by air in its shipping/storage configuration.
2. Procedure II – Operation/Air Carriage. Procedure II is used to test the performance of products operated at high altitudes.  It may be preceded by Procedure I.
3. Procedure III – Rapid Decompression.  Procedure III is for determining if a rapid decrease in cabin pressure will cause a failure or malfunction that would endanger nearby personnel the ground vehicle or the aircraft in which it is being transported.
4. Procedure IV – Explosive Decompression. Procedure IV is similar to Procedure III except that it involves an instantaneous decrease in pressure.

How is MIL-STD-810 Low Pressure Testing performed?  First, it is necessary to determine the test parameters such as test altitude (pressure) and temperature, rate of change of pressure (and temperature if appropriate), duration of exposure, and test item configuration based upon the Life Cycle Environmental Profile.  Once the parameters are defined, low pressure testing is performed by placing the specimen in a specialized chamber that simulates altitude by controlling pressure and temperature.  Upon completion of the altitude test, DES will promptly deliver a detailed test report that includes the customer’s name and address, the test dates, a summary of the test procedure, equipment & measuring system calibration information, plots of altitude and temperature, test observations & results, color pictures of the altitude test setup and color pictures of any failures. 

Why Choose DES for MIL-STD-810 Low Pressure (Altitude) Testing

• A2LA Accreditation: Our laboratory’s accreditation is a testament to our commitment to quality and excellence in environmental testing.  DES is A2LA accredited to MIL-STD-810 Low Pressure (Altitude) Testing.
• Trusted by Industry Leaders: Our state-of-the-art testing facilities, experienced engineering team, and track record of success has made us the number one choice of top defense contractors.
• Advanced Testing Capabilities: With equipment capable of simulating altitudes from below sea level to as high as 1,000,000 feet and temperatures ranging from -75°C to +150°C, we can accommodate a wide variety of testing requirements.

Contact us today to discuss how our altitude testing services can contribute to the success and reliability of your next project.

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

Procedure III is used to determine what shock conditions will cause a product to stop operating, degrade or fail.  The shock magnitudes are systematically increased until a problem occurs.  This procedure can be also performed using environmental temperature conditioning.

This article will assume that the fragility shocks expected to be encountered by the product are not complex transients.  Therefore, the trapezoidal classical shock pulse, as defined in Figure 516.7-11 and Table 516.7-V from MIL-STD-810, Method 516 would be used for Fragility testing.

Figure 516.7-11. Trapezoidal shock pulse configuration and tolerance limits (for use when shock response spectrum analysis capability is not available in Procedure III – Fragility)

Note 1: Am is dependent upon drop height “h.”

Note 2: “h” is the drop height in SI: m (in) and g=9.81 m/s2(386.09 in/sec2)

Table 516.7-V. Trapezoidal pulse parameters

T_D corresponds to the period of the first mounted natural frequency of the item.  During fragility testing, T_D is held constant.  Determination of the fragility level is accomplished by starting at low levels of shock magnitude (A_m) and then proceeding to increase the shock magnitude until:

1. Failure or degradation of the unit occurs.
2. A predefined test goal is reached without failure of the unit under test.
3. A critical level of shock is reached whereby increasing the magnitude will cause a failure at a higher level of shock.

An analysis of the product should be performed prior to testing to:

• estimate its anticipated fragility level
• establish a low starting shock level
• estimate the first mode mounted frequency of the materiel in order to specify the pulse duration T_D.

The product is normally tested in an un packaged, non-operational condition.  The typical procedure when using the trapezoidal classical shock pulse is to first perform calibration shocks using a mass similar in size, weight and center of gravity (CG) of the unit 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.

Operation of the test item and inspection for visual damage is performed before/after each shock.  If testing along more than one axis is required, then testing in the next axis should be completed before proceeding to the next higher shock magnitude.

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

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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MIL-STD 810, Method 516, Shock Testing Overview

Shock testing according to Procedure I of MIL-STD 810, Method 516 is intended to test products while they are operating to see if any functional problems occur and to determine if they survive without damage.  The applied shocks usually represent those that may be encountered during operational service.  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 I -Functional Test.  In limited cases a half sine shock impulse is specified.  Its shape and tolerance limits are shown in Figure 516.7-12.

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.

The typical shock testing procedure is to first perform calibration shocks using a mass similar in size, weight and center of gravity (CG) of the product to be tested.  Most commonly a non-working mechanical product is used for this purpose.  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.  Since this is a functional shock, the product must be operating and monitored for anomalies.   Therefore, before the shock is applied, the product must be energized and the monitoring equipment should be operating.  After each shock, operation of the test item is verified and it is inspected for visual damage.

The most common requirement is to perform 3 shocks along both the positive and negative directions along 3 orthogonal axes.  This is a total of 6 directions and 18 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 is a public military test standard that is designed to assist in the environmental engineering considerations for product design and testing.  For the purposes of this blog series we will focus on Method 516.7, Shock Testing.

The purpose of shock testing is to:

1. Evaluate if a product can withstand shocks encountered in handling, transportation, and service environments
2. Determine the product’s fragility level
3. Test the strength of devices during a crash situation to verify that parts do not break apart, eject and become a safety hazard

Shock testing failures are a function of the amplitude, velocity, and the duration of the impulse.  If a product has a resonance frequency that corresponds with the frequency of the shock, the effects of the shock will be magnified.

Typically shocks in Method 516.7 are limited to a frequency range not to exceed 10,000 Hz, and a duration of not more than 1.0 second.  Method 516.7 contains eight test procedures which are summarized in Table 516.7-I.

Table 516.7-I from MIL-STD-810G w/Change 1

The differences among procedures is briefly defined below:

1. Procedure I – Functional Shock. Procedure I is intended to test products while they are operating to see if any functional problems occur and to determine if they survive without damage. The applied shocks usually represent those that may be encountered during operational service.
2. Procedure II – Transportation Shock. Procedure II is used to evaluate products for repetitive shocks from transportation environments. This procedure typically uses a classical terminal peak sawtooth impulse to simulate transportation shocks.
3. Procedure III – Fragility. Procedure III is used to determine what shock conditions will cause a product to stop operating, degrade or fail. The shock magnitudes are systematically increased until a problem occurs.  This procedure can be also performed at environmental temperature extremes.
4. Procedure IV – Transit Drop. This procedure is used to test items that could be accidentally dropped such as when they are removed from a shelve or dropped when handling. The test item is physically dropped onto a hard surface during Procedure IV.  The items can be tested inside their transit case or unpackaged.
5. Procedure V – Crash Hazard Shock Test. Procedure V is used to test materiel mounted in air or ground vehicles. This procedure is intended to verify that parts do not beak loose which would cause a hazard to occupants or create significant damage to the vehicle.
6. Procedure VI – Bench Handling. This procedure is used to test products that may experience shocks on a work bench. Bench handling shocks could occur when items are being repaired or when they are in the process of being packaged.  The products are tested in an unpackaged configuration.  The drop heights are less than Procedure IV.

Procedures VII and VII are very specialized shock tests.  They are briefly mentioned because they are part of Method 516.7, Shock Testing.

1. Procedure VII – Pendulum Impact. Procedure VII is intended to test the ability of large shipping containers and their internal contents to resist horizontal impacts from accidental handling.
2. Procedure VIII – Catapult Launch/Arrested Landing. Procedure VIII is intended for materiel mounted in or on fixed-wing aircraft that is subject to catapult launches and arrested landings.

The laboratory shock test options are summarized below in Table 516.7-II.  The shock test options are divided according to the use of Time Waveform Replication (TWR), drop tests, classical shock pulses, or SRS shocks.  TWR is considered to be superior and the most realistic as it is based upon direct replication of field measured data, however it is not usually available.  Classical shock pulses are used when TWR data is unavailable.  Shock Response Spectra (SRS) refers to cases in which an SRS curve is used for the test specification.

Table 516.7-II – Laboratory Shock Test Options from MIL-STD-810G w/Change 1

TWR – Time Waveform Replication

Drop = free fall drop event

SRS = Shock Response Spectra

X_tp – terminal peak sawtooth classical shock

X_trap – symmetric trapezoidal classical shock

X_sin – two-second damped (Q=20) sine burst

Note (1)- Horizontal Impact

It is important that the shock data acquisition instrumentation is adequate to capture the shock impulse.  Method 516.7 provides guidelines for the shock test data acquisition system.

To learn more about our shock testing services, please feel free to contact us with your inquiry. Feel free to explore our site to learn about our full line of product testing services, and the test standards that we can help our clients with.

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Mixed Mode Vibration Testing is less common than Sinusoidal and Random Vibration Testing.  However, it does have a special purpose for simulating specialized helicopter vibration or vibration from tracked vehicles such as tanks.

The three mixed modes of vibration testing are:

• Sine-on-Random (SoR)
• Random-on-Random (RoR)
• Sine-on-Random-on-Random (SoRoR)

Some common test standards that have specifications for Mixed Mode Vibration Testing are:

• MIL-STD-810 Department of Defense Test Method Standard for Environmental Engineering Considerations and Laboratory Tests
• RTCA DO-160 Environmental Conditions and Test Procedures for Airborne Equipment

Sine-on-Random (SoR) Vibration Testing

Sine-on-Random (SoR) vibration testing contains sine tones that are superimposed on a low level of broadband random vibration.  The sine tones can be fixed frequency or sweeping.  If they are sweeping, they are normally very narrow frequency bands.  Some examples of SoR vibration are from helicopters, propeller driven airplanes and aircraft rapid gun-fire events.

All aircraft have some levels of random vibration.  In helicopters and propeller driven airplanes, the sine tones are produced by the main rotary components.  In addition, sine tones can come from rapid gun fire events.  Figure 1 shows a typical SoR helicopter vibration test profile from MIL-STD-810G.

Random-on-Random (RoR) Vibration Testing

Random-on-Random (RoR) vibration testing has narrow band random peaks that are superimposed on a low level of broadband random vibration.  Typical applications that contain RoR vibration are tracked vehicles such as tanks or a truck changing speed while driving over a rough road.  For example, the pitch of the tracks produces rhythmic random vibration peaks at specific frequencies versus speed of the vehicle.  Figure 2 shows a typical tracked vehicle vibration test profile from MIL-STD-810G.

Sine-on-Random-on-Random (SoRoR) Vibration Testing

Sine-on-Random-on-Random (SoRoR) vibration testing contains both sine tones and narrow band random peaks superimposed on broadband random vibration.  Applications that contain SoRoR vibration could be a rapid gun-fire event on a tracked vehicle or components mounted near a turbine engine with various rotating machinery elements and background random vibration produced by air turbulence.

Whether your vibration testing needs are complex or simple, DES has the experience and knowledge to perform your test.  For more information on Vibration Testing or other testing services contact DES or call 610.253.6637.

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