MIL-STD-810G – Part 27 – (Rail Impact) Method 526

MIL-STD-810G covers Rail Impact in Method 526.  Method 526 is new to 810G and 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, and the tiedown arrangements during the specified logistic conditions.  Method 526 is short at 7 pages.

Method 526 is also not intended for testing small, individually packaged material that would normally be shipped when mounted on a pallet or as part of a larger shipment.  It is intended for testing items such as tanks, trucks, etc., that are transported by rail.

The rail impact test is intended to test materiel that will be transported by rail; to determine the effect of railroad car impacts that may occur during rail shipment, to verify the structural integrity of the materiel, to evaluate the adequacy of the tiedown system and the tiedown procedures, and to assess transportability1 by the Military Surface Deployment and Distribution Command Transportation Engineering Agency (SDDCTEA). All items are to be tested at their maximum gross weight (fully loaded) rating unless otherwise specified in the transportability requirements for the materiel. 

Subjecting materiel to a lab shock test or performing an analytical simulation does not eliminate the requirement to conduct a rail impact test.

Method 526 is not intended for railcar crash conditions. 

Effects of Rail Impact

Rail impact shock has the potential for producing adverse effects on the physical and functional integrity of transported materiel. The following are examples of problems that could occur when materiel is exposed to the rail impact environment.

1. Loosening of tiedown straps.


2. Failure of attachments, creating a safety hazard.


3. Shifting of materiel on the railcar.


4. Failure of materiel.


5. Structural failure.


6. Fuel spills.

Testing

Tests are performed with rail cars. 

Loaded cars are preferred for use as the buffer or struck cars. However, empty cars may also be used. In either case, the total weight of the buffer cars is to be at least 113,400kg (250,000 lb). The first buffer car must be a standard draft gear car. The remaining buffer cars should have standard draft gear, if possible.  Draft gear is the shock absorber which is part of the coupler.

The test railcar is equipped with chain tiedowns and end-of-car cushioned draft gear, unless other railcar types are approved by Director, SDDCTEA. SDDCTEA is the designated DoD agent for land transportation. Some materiel may require other types of railcars for testing to be representative of the intended shipping methods.

A locomotive and at least 200 feet of dry, level track is used to get the rail cars up to the required speed as below.  At the desired speed, the test load car is released so it rolls freely into the buffer cars with the couplings open.  An alternative method of testing is to use an inclined track of sufficient length and gradient to achieve the test speeds.

The test item secured to the test railcar should be at gross weight with the fuel tanks at least 3/4 full.

Subject the test item to four impacts, the first three of which are in the same direction and at speeds of 4, 6, and 8 mph respectively. Perform the fourth impact at 8 mph (+0.5, -0.0 mph) impacting the opposite end of the test car from the first three impacts. If it is not possible to turn the test car because of track layout, this may be accomplished by running the test item car to the opposite end of the buffer cars and impacting as above.

Analysis

1. The test item fails this test if the test item, or any item that is attached to it, or that is included as an integral part of the test item, breaks free, loosens, or shows any sign of permanent deformation beyond specification tolerances.


2. The test item and its subassemblies must be operationally effective after the test.


3. f tiedown securement items break or displace substantially, photograph and document the problem areas for evaluation of the procedures and materials used. The test director and SDDCTEA jointly decide if any failed securement items require reconfiguring and, if so, whether a complete retest is required.


4. Additional considerations:
   (1) Loosening of tiedown straps.
   (2) Failure of attachments, creating a safety hazard.
   (3) Shifting of materiel on the railcar.
   (4) Failure of materiel.
   (5) Structural failure.
   (6) Fuel spills.

MIL-STD-810G – Part 27 – (Rail Impact) Method 526

MIL-STD-810G – Part 27 – (Rail Impact) Method 526

MIL-STD-810G covers Rail Impact in Method 526.  Method 526 is new to 810G and 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, and the tiedown arrangements during the specified logistic conditions.  Method 526 is short at 7 pages.

Method 526 is also not intended for testing small, individually packaged material that would normally be shipped when mounted on a pallet or as part of a larger shipment.  It is intended for testing items such as tanks, trucks, etc., that are transported by rail.

The rail impact test is intended to test materiel that will be transported by rail; to determine the effect of railroad car impacts that may occur during rail shipment, to verify the structural integrity of the materiel, to evaluate the adequacy of the tiedown system and the tiedown procedures, and to assess transportability1 by the Military Surface Deployment and Distribution Command Transportation Engineering Agency (SDDCTEA). All items are to be tested at their maximum gross weight (fully loaded) rating unless otherwise specified in the transportability requirements for the materiel. 

Subjecting materiel to a lab shock test or performing an analytical simulation does not eliminate the requirement to conduct a rail impact test.

Method 526 is not intended for railcar crash conditions. 

Effects of Rail Impact

Rail impact shock has the potential for producing adverse effects on the physical and functional integrity of transported materiel. The following are examples of problems that could occur when materiel is exposed to the rail impact environment.

1. Loosening of tiedown straps.


2. Failure of attachments, creating a safety hazard.


3. Shifting of materiel on the railcar.


4. Failure of materiel.


5. Structural failure.


6. Fuel spills.

Testing

Tests are performed with rail cars. 

Loaded cars are preferred for use as the buffer or struck cars. However, empty cars may also be used. In either case, the total weight of the buffer cars is to be at least 113,400kg (250,000 lb). The first buffer car must be a standard draft gear car. The remaining buffer cars should have standard draft gear, if possible.  Draft gear is the shock absorber which is part of the coupler.

The test railcar is equipped with chain tiedowns and end-of-car cushioned draft gear, unless other railcar types are approved by Director, SDDCTEA. SDDCTEA is the designated DoD agent for land transportation. Some materiel may require other types of railcars for testing to be representative of the intended shipping methods.

A locomotive and at least 200 feet of dry, level track is used to get the rail cars up to the required speed as below.  At the desired speed, the test load car is released so it rolls freely into the buffer cars with the couplings open.  An alternative method of testing is to use an inclined track of sufficient length and gradient to achieve the test speeds.

The test item secured to the test railcar should be at gross weight with the fuel tanks at least 3/4 full.

Subject the test item to four impacts, the first three of which are in the same direction and at speeds of 4, 6, and 8 mph respectively. Perform the fourth impact at 8 mph (+0.5, -0.0 mph) impacting the opposite end of the test car from the first three impacts. If it is not possible to turn the test car because of track layout, this may be accomplished by running the test item car to the opposite end of the buffer cars and impacting as above.

Analysis

1. The test item fails this test if the test item, or any item that is attached to it, or that is included as an integral part of the test item, breaks free, loosens, or shows any sign of permanent deformation beyond specification tolerances.


2. The test item and its subassemblies must be operationally effective after the test.


3. f tiedown securement items break or displace substantially, photograph and document the problem areas for evaluation of the procedures and materials used. The test director and SDDCTEA jointly decide if any failed securement items require reconfiguring and, if so, whether a complete retest is required.


4. Additional considerations:
   (1) Loosening of tiedown straps.
   (2) Failure of attachments, creating a safety hazard.
   (3) Shifting of materiel on the railcar.
   (4) Failure of materiel.
   (5) Structural failure.
   (6) Fuel spills.

MIL-STD-810G – Part 27 – (Rail Impact) Method 526

MIL-STD-810G – Part 27 – (Rail Impact) Method 526

MIL-STD-810G covers Rail Impact in Method 526.  Method 526 is new to 810G and 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, and the tiedown arrangements during the specified logistic conditions.  Method 526 is short at 7 pages.

Method 526 is also not intended for testing small, individually packaged material that would normally be shipped when mounted on a pallet or as part of a larger shipment.  It is intended for testing items such as tanks, trucks, etc., that are transported by rail.

The rail impact test is intended to test materiel that will be transported by rail; to determine the effect of railroad car impacts that may occur during rail shipment, to verify the structural integrity of the materiel, to evaluate the adequacy of the tiedown system and the tiedown procedures, and to assess transportability1 by the Military Surface Deployment and Distribution Command Transportation Engineering Agency (SDDCTEA). All items are to be tested at their maximum gross weight (fully loaded) rating unless otherwise specified in the transportability requirements for the materiel. 

Subjecting materiel to a lab shock test or performing an analytical simulation does not eliminate the requirement to conduct a rail impact test.

Method 526 is not intended for railcar crash conditions. 

Effects of Rail Impact

Rail impact shock has the potential for producing adverse effects on the physical and functional integrity of transported materiel. The following are examples of problems that could occur when materiel is exposed to the rail impact environment.

1. Loosening of tiedown straps.


2. Failure of attachments, creating a safety hazard.


3. Shifting of materiel on the railcar.


4. Failure of materiel.


5. Structural failure.


6. Fuel spills.

Testing

Tests are performed with rail cars. 

Loaded cars are preferred for use as the buffer or struck cars. However, empty cars may also be used. In either case, the total weight of the buffer cars is to be at least 113,400kg (250,000 lb). The first buffer car must be a standard draft gear car. The remaining buffer cars should have standard draft gear, if possible.  Draft gear is the shock absorber which is part of the coupler.

The test railcar is equipped with chain tiedowns and end-of-car cushioned draft gear, unless other railcar types are approved by Director, SDDCTEA. SDDCTEA is the designated DoD agent for land transportation. Some materiel may require other types of railcars for testing to be representative of the intended shipping methods.

A locomotive and at least 200 feet of dry, level track is used to get the rail cars up to the required speed as below.  At the desired speed, the test load car is released so it rolls freely into the buffer cars with the couplings open.  An alternative method of testing is to use an inclined track of sufficient length and gradient to achieve the test speeds.

The test item secured to the test railcar should be at gross weight with the fuel tanks at least 3/4 full.

Subject the test item to four impacts, the first three of which are in the same direction and at speeds of 4, 6, and 8 mph respectively. Perform the fourth impact at 8 mph (+0.5, -0.0 mph) impacting the opposite end of the test car from the first three impacts. If it is not possible to turn the test car because of track layout, this may be accomplished by running the test item car to the opposite end of the buffer cars and impacting as above.

Analysis

1. The test item fails this test if the test item, or any item that is attached to it, or that is included as an integral part of the test item, breaks free, loosens, or shows any sign of permanent deformation beyond specification tolerances.


2. The test item and its subassemblies must be operationally effective after the test.


3. f tiedown securement items break or displace substantially, photograph and document the problem areas for evaluation of the procedures and materials used. The test director and SDDCTEA jointly decide if any failed securement items require reconfiguring and, if so, whether a complete retest is required.


4. Additional considerations:
   (1) Loosening of tiedown straps.
   (2) Failure of attachments, creating a safety hazard.
   (3) Shifting of materiel on the railcar.
   (4) Failure of materiel.
   (5) Structural failure.
   (6) Fuel spills.

MIL-STD-810G – Part 27 – (Rail Impact) Method 526

Editor"s Choice in Military Embedded Systems Magazine

SAN DIEGO, CA, December 11, 2015 — Chassis Plans’ (www.chassis-plans.com) TFX rackmount LCD Display was added to the Editor’s Choice Products in the November edition of Military Embedded Systems magazine.

Editorial Director John McHales describes the TFX1-19 as “a rugged military-grade 2U rackmount LCD panel display [that] features three 19-inch TFT LCD displays with per-panel resolution of 1,280×1,024.” Display options include a bonded anti-reflective glass cover and a bonded ITO EMI filter. The system is built to meet Military Standards and includes a high-end military-grade wide temperature range LCD controller and other rugged components. Electrical systems are specified for long-term reliability and multi-year program availability.

Please click here for the full article.

About Chassis Plans

Chassis Plans is a design and manufacturer of servers, LCD displays, storage arrays designed and assembled in the USA for Military and Industrial applications.

For further information, call +1 800.787.4913 or email sales [at] chassisplans.com.

Editor"s Choice in Military Embedded Systems Magazine

MIL-STD-810G – Part 27 – (Rail Impact) Method 526

MIL-STD-810G covers Rail Impact in Method 526.  Method 526 is new to 810G and 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, and the tiedown arrangements during the specified logistic conditions.  Method 526 is short at 7 pages.

Method 526 is also not intended for testing small, individually packaged material that would normally be shipped when mounted on a pallet or as part of a larger shipment.  It is intended for testing items such as tanks, trucks, etc., that are transported by rail.

The rail impact test is intended to test materiel that will be transported by rail; to determine the effect of railroad car impacts that may occur during rail shipment, to verify the structural integrity of the materiel, to evaluate the adequacy of the tiedown system and the tiedown procedures, and to assess transportability1 by the Military Surface Deployment and Distribution Command Transportation Engineering Agency (SDDCTEA). All items are to be tested at their maximum gross weight (fully loaded) rating unless otherwise specified in the transportability requirements for the materiel. 

Subjecting materiel to a lab shock test or performing an analytical simulation does not eliminate the requirement to conduct a rail impact test.

Method 526 is not intended for railcar crash conditions. 

Effects of Rail Impact

Rail impact shock has the potential for producing adverse effects on the physical and functional integrity of transported materiel. The following are examples of problems that could occur when materiel is exposed to the rail impact environment.

1. Loosening of tiedown straps.


2. Failure of attachments, creating a safety hazard.


3. Shifting of materiel on the railcar.


4. Failure of materiel.


5. Structural failure.


6. Fuel spills.

Testing

Tests are performed with rail cars. 

Loaded cars are preferred for use as the buffer or struck cars. However, empty cars may also be used. In either case, the total weight of the buffer cars is to be at least 113,400kg (250,000 lb). The first buffer car must be a standard draft gear car. The remaining buffer cars should have standard draft gear, if possible.  Draft gear is the shock absorber which is part of the coupler.

The test railcar is equipped with chain tiedowns and end-of-car cushioned draft gear, unless other railcar types are approved by Director, SDDCTEA. SDDCTEA is the designated DoD agent for land transportation. Some materiel may require other types of railcars for testing to be representative of the intended shipping methods.

A locomotive and at least 200 feet of dry, level track is used to get the rail cars up to the required speed as below.  At the desired speed, the test load car is released so it rolls freely into the buffer cars with the couplings open.  An alternative method of testing is to use an inclined track of sufficient length and gradient to achieve the test speeds.

The test item secured to the test railcar should be at gross weight with the fuel tanks at least 3/4 full.

Subject the test item to four impacts, the first three of which are in the same direction and at speeds of 4, 6, and 8 mph respectively. Perform the fourth impact at 8 mph (+0.5, -0.0 mph) impacting the opposite end of the test car from the first three impacts. If it is not possible to turn the test car because of track layout, this may be accomplished by running the test item car to the opposite end of the buffer cars and impacting as above.

Analysis

1. The test item fails this test if the test item, or any item that is attached to it, or that is included as an integral part of the test item, breaks free, loosens, or shows any sign of permanent deformation beyond specification tolerances.


2. The test item and its subassemblies must be operationally effective after the test.


3. f tiedown securement items break or displace substantially, photograph and document the problem areas for evaluation of the procedures and materials used. The test director and SDDCTEA jointly decide if any failed securement items require reconfiguring and, if so, whether a complete retest is required.


4. Additional considerations:
   (1) Loosening of tiedown straps.
   (2) Failure of attachments, creating a safety hazard.
   (3) Shifting of materiel on the railcar.
   (4) Failure of materiel.
   (5) Structural failure.
   (6) Fuel spills.

MIL-STD-810G – Part 27 – (Rail Impact) Method 526

MIL-STD-810G – Part 26 – (Freeze/Thaw) Method 524

MIL-STD-810G covers Freeze/Thaw in Method 524.  Method 524 is new to 810G and was adopted from NATO STANAG 4370, AECTP 300, Method 315. The purpose of the test is to determine the ability of material to withstand the effects of moisture phase changes between liquid and solid (freezing) and the effects of moisture induced by transfer from a cold-to-warm or warm-to-cold environment.  It is a short 6 pages. This test is applicable to materiel that will experience one or more excursions through the freeze point while wet or in the presence of moisture (free water or vapor).

This test is not intended to evaluate the effects of low temperature, thermal shock, rain, or icing. These may be determined using Methods 502.5, 503.5, 506.5, and 521.3, respectively.

Effects of the Environment

This test induces physical changes in or on the materiel that is not stationary. Examples of problems that could occur during this test are as follows:

1. Distortion or binding of moving parts.


2. Failure of bonding materials.


3. Failure of seals.


4. Failure of materials due to freezing/re-freezing of absorbed, adjacent, or free water.


5. Changes in characteristics of electrical components.


6. Electrical flashover/reduced insulation resistance.


7. Fogging of optical systems during freeze-thaw transitions.


8. Inability to function correctly due to ice adhesion and interference or blockage of moving parts.

Test Procedures

Method 524 provides three test procedures:

Procedure I, Diurnal Cycling Effects – To simulate the effects of diurnal cycling on materiel exposed to temperatures varying slightly above and below the freeze point that is typical of daytime warming and freezing at night when deposits of ice or condensation, or high relative humidity exist.  Test for 20 cycles.

Procedure II, Fogging – For materiel transported directly from a cold to a warm environment such as from an unheated aircraft, missile or rocket, to a warm ground area, or from a cold environment to a warm enclosure, and resulting in free water or fogging.  Test for 3 cycles.

Procedure III, Rapid Temperature Change – For materiel that is to be moved from a warm environment to a cold environment (freeze) and then back to the warm environment, inducing condensation (free water).  Test for 3 cycles.

Because this is a freezing cycle test, the required temperature range is narrow with cycle ranges between +5 deg C and-10 deg C.  Use moisture from local, clean sources and apply as water vapor or free water spray.

 

 

 

MIL-STD-810G – Part 26 – (Freeze/Thaw) Method 524

MIL-STD-810G – Part 25 – (Vibro-Acoustic/Temperature) Method 523.3

MIL-STD-810G covers Vibro-Acoustic/Temperature in Method 523.3.  Method 523.3 is performed to determine the synergistic effects of vibration, acoustic noise, and temperature on externally carried aircraft stores such as bombs, missiles and sensor pods during captive carry flight.  It is 16 pages plus one 9-page Annex.

This method would apply to rugged embedded computer systems as installed in externally mounted sensor pods.

Application

For captively-carried stores, this method is intended primarily to test electronics and other electro-mechanical assemblies within the store for functionality in a vibro-acoustic/temperature environment.

Limitations

This method is not intended to provide for:

1. An environmental design qualification test of a store or any of its individual components for functionality. (For such testing see Method 500.5, Altitude; Method 501.5, High Temperature; Method 502.5, Low Temperature; Method 503.5, Temperature Shock; Method 507.5, Humidity; Method 513.6, Acceleration; Method 514.6, Vibration; Method 515.6, Acoustic Noise; Method 516.6, Shock; Method 517.1, Pyroshock; and Method 520.3, Temperature, Humidity, Vibration, Altitude).


2. An environmental design qualification test of a store air frame or other structural components for structural integrity.


3. Any test to satisfy the requirements of the Life Cycle Profile except that for the combined vibration, acoustic, and temperature environments related to reliability testing.

Tailoring Guidance

Possible effects of a combination of vibration, acoustic noise, and temperature include all effects that these factors can cause separately (see Methods 514.6, 515.6, and 520.3). In addition, increased stress as a result of moisture from thermal change may produce possible effects seen in Methods 501.5, 502.5, 503.5, and 507.5. The combined vibration, acoustic noise, and temperature environments may interact to produce effects that would not occur in any single environment or a lesser combination of environments.

Not all environmental stresses contribute equally to materiel deterioration or failure. Analysis of service-use failures caused by aircraft environmental stress on the store (paragraph 6.1, reference a) has identified the following four most important causes of failure:

1. loading of the store through captive carriage,


2. temperature,


3. vibration, and


4. moisture.

Operating any materiel item produces stress that can cause failure. In the case of external aircraft stores, operation generally means providing full electrical power, that produces thermal, electromagnetic, and electrochemical stress.

Temperature

The most severe temperature shock to internal components may come from powering the materiel when it is cold. In order to induce all the stresses related to temperature in their proper proportion, use a thermal model of the store to predict the temperatures and rates of change at several internal points under service mission profiles.  Temperature is constrained by the following:

1. Ambient Temperature
   The greatest variations in ambient temperature occur near the surface of the Earth. The low temperature extreme experience by a store is, in many cases, due to low ambient temperatures immediately preceding flight.


2. Aerodynamic Heating
   During captive flight, the high convective heat transfer rate will cause the surface temperature of an external store to be near that of the boundary layer.


3. Power Dissipation
   Although the high heat transfer rate will tend to keep the surface of a store at the boundary layer recovery temperature, internal temperatures may be considerably higher due to power dissipation of electronic equipment.


4. Temperature Gradients
   The strongest temperature gradients will usually be those associated with powering the materiel when it is cold. Temperature gradients will also occur due to changes in flight speed and altitude that change the surface temperature more rapidly than internal temperatures.

Vibration

Vibration may cause mechanical fatigue failure of parts, abrasion due to relative motion, dislodging of loose particles that can cause electrical shorts, and degradation of electronic functions through microphonics and triboelectric noise.

Moisture

Moisture, in conjunction with soluble contaminants, can result in corrosion. In conjunction with electrical power it may result in shorts. Freezing of water in confined spaces may produce mechanical stress. The test cycle should provide for diffusion of water vapor and condensation.

Shock

Shock can cause failure through mechanical stress similar to that induced by vibration. Shocks that are more nearly transient vibrations (many zero crossings), such as aircraft catapult and arrested landing shock, may be included in this test. Short duration shocks such as pyrotechnic shocks associated with store or sub-munition launch, flight surface deployment, etc., are generally too difficult to reproduce at the store level. Ensure that these events that are potentially destructive to electronics are accounted for in other analyses and tests.

Altitude

Barometric pressure is generally not a stress for external stores. However, variation in pressure may enhance the penetration by moisture. Reduced pressure may increase the temperature due to reduced power dissipation and there may be increased electrical arcing.

Testing

Testing for Method 523.3 is very difficult and requires highly specialized test facilities.  The test item is subjected, simultaneously, to high energy acoustic noise up to 165dB over the range of 150 to 2500 Hz, vibration by electrodynamic or electrohydraulic exciters and temperature in the range of -40 deg C to +85 deg C with a rate of change as high as 4 deg C.  The test item is power cycled to induce electrical stress.  The test item is instrumented for acceleration, acoustic pressure, and temperature plus other measurements as required by the particular store.

Typical Arrangement of MIL-STD-810G Method 523.3 Test Apparatus

MIL-STD-810G – Part 25 – (Vibro-Acoustic/Temperature) Method 523.3

Chassis Plans Launches Rugged Portable Computer

SAN DIEGO, CA, December 4, 2015 — Chassis Plans (www.chassis-plans.com) has launched a rugged light weight portable computer, which is a purpose built customized solution used for ground based communications, weapons and radar systems testing.

This rugged light weight portable computer provides a 17” 1280×1024 LCD, NEMA class keyboard, and is configured with pre-qualified, high-quality, and long-life revision controlled components. This system is designed with high speed data recording through the use of 120GB solid state drives (SSD) disks. The system incorporates a Core i5 Intel Xeon processor and 13 slot PCI backplane.

The computer’s rugged aluminum alloy construction provides improved rigidity and ruggedness and is designed to meet MIL-STD’s 810 and 461. It is designed to operate in extreme temperatures and is built to withstand the harshest environments for deployed operations.

 

About Chassis Plans

Chassis Plans is a design and manufacturer of servers, LCD displays, storage arrays designed and assembled in the USA for Military and Industrial applications.

For further information, call +1 800.787.4913 or email sales@chassisplans.com.

Downlaod as PDF

Chassis Plans Launches Rugged Portable Computer

MIL-STD-810G – Part 24 – (Ballistic Shock) Method 522

MIL-STD-810G covers Ballistic Shock in Method 522.  Method 522 is somewhat lengthy at 13 pages and covers the momentum exchange between two or more bodies or momentum exchange between a liquid or gas and a solid.  The method is used to assure components mounted in, for example, an armored vehicle continue to operate after that vehicle has been hit buy non-penetrating enemy fire or a nearby mine.

Ballistic Shock Defined

Ballistic Shock is a high-level shock that generally results from the impact of projectiles or ordnance on armored combat vehicles.  Armored combat vehicles must survive the shocks resulting from large caliber non-perforating projectile impacts, mine blasts, and overhead artillery attacks, while still retaining their combat mission capabilities.  This is a very complex subject given actual shock levels vary with the type of vehicle, the specific munition used, the impact location or proximity, and where on the vehicle the shock is measured.  No good computational simulation has yet been  developed.  That is, the prediction of response to ballistic shock is, in general, not possible except in the simplest configurations. When an armored vehicle is subjected to a non-perforating large caliber munition impact or blast, the structure locally experiences a force loading of very high intensity and of relatively short duration. Though the force loading is localized, the entire vehicle is subjected to stress waves traveling over the surface and through the structure.

General characteristics of ballistic shock environments are as follows:

1. near-the-source stress waves in the structure caused by high material strain rates (nonlinear material region) that propagate into the near field and beyond;


2. combined low and high frequency (10 Hz – 1,000,000 Hz) and very broadband frequency input;


3. high acceleration (300g – 1,000,000g) with comparatively high structural velocity and displacement response;


4. short-time duration (<180 msec);


5. high residual structure displacement, velocity, and acceleration response (after the event);


6. caused by (1) an inelastic collision of two elastic bodies, or (2) an extremely high fluid pressure applied for a short period of time to an elastic body surface coupled directly into the structure, and with point source input, i.e., input is either highly localized as in the case of collision, or area source input, i.e., widely dispersed as in the case of a pressure wave;


7. comparatively high structural driving point impedance (P/v, where P is the collision force or pressure, and v the structural velocity). At the source, the impedance could be substantially less if the material particle velocity is high;


8. measurement response time histories that are very highly random in nature, i.e., little  repeatability and very dependent on the configuration details;
   i. shock response at points on the structure is somewhat affected by structural discontinuities;


9. structural response may be accompanied by heat generated by the inelastic impact or the fluid blast wave;


10. the nature of the structural response to ballistic shock does not suggest that the materiel or its components may be easily classified as being in the “near field” or “far field” of the ballistic shock device. In general, materiel close to the source experiences high accelerations at high frequencies, whereas materiel far from the source will, in general, experience high acceleration at low frequencies as a result of the filtering of the intervening structural configuration.

Effects of Ballistic Shock

1. a. materiel failure as a result of destruction of the structural integrity of micro electronic chips including their mounting configuration;


2. materiel failure as a result of relay chatter;


3. materiel failure as a result of circuit card malfunction, circuit card damage, and electronic connector failure. On occasion, circuit card contaminants having the potential to cause short circuits may be dislodged under ballistic shock. Circuit card mounts may be subject to damage from substantial velocity changes and large displacements.


4. materiel failure as a result of cracks and fracture in crystals, ceramics, epoxies or glass envelopes.


5. materiel failure as a result of sudden velocity change of the structural support of the materiel or the internal structural configuration of the mechanical or electro-mechanical materiel.

Selecting a Test Procedure

Method 22 provides for five ballistic shock tests:

Procedure I – Ballistic Hull and Turret
Procure an actual vehicle or prototype and fire appropriate threat projectiles at it.  This is a very expensive test.

Procedure II – Large Scale Ballistic Shock Simulator
Shock testing of complete components, with assemblies weighing up to 1100 lbs, can be accomplished using devices such as a Large Scale Ballistic Shock Simulator. For large items, the Large Scale Ballistic Shock Simulator (LSBSS) utilizes an explosive charge to drive a plate to which the materiel is mounted. This is considerably less expensive than Procedure I. 

Procedure III – Light Weight Shock Machine
For assemblies weighing less that 250 lbs, a Light Weight Shock Machine from MIL-S-901D can be used.

Procedure IV – Medium Weight Shock Machine
For assemblies weighing less that 5000 lbs, a Medium Weight Shock Machine from MIL-S-901D can be used.

Procedure V – Drop Table
Light weight components, usually weighing less than 40 lbs, can be tested using a drop table.  The commonly available drop test machine is the least expensive and most accessible test technique.

Test Evaluation

After the testing, evaluate the components for damage and proper operation.

MIL-STD-810G – Part 24 – (Ballistic Shock) Method 522