MIL-STD-810 Ballistic Shock Testing:
This Method includes a set of ballistic shock tests. In general, these involve momentum exchange between two or more bodies, or between a liquid or gas and a solid. Military ballistic testing ensures that material can structurally and functionally withstand infrequent shock effects. These result from high levels of momentum exchange on a structural configuration that the material is mounted to.
Ballistic Shock Testing experimentally estimates the material’s fragility level relative to ballistic shock. This is so that shock mitigation procedures may be employed to protect the material. This testing should be performed in a ballistic shock testing lab.
Keystone Compliance is a ballistic shock lab with significant experience in MIL-810 ballistic shock testing. Our test engineers have an in-depth knowledge of military ballistic testing standards. This includes MIL-810G ballistic shock and MIL-810H ballistic shock. This makes Keystone Compliance uniquely qualified to provide ballistic shock certifications for all you commercial, military, and aerospace products.
The following information is extremely technical in nature. It provides a summary of Method 519.8, as derived from the MIL-STD 810 ballistic shock section. The following derives from all previous versions of the standard. This includes MIL-STD 810G ballistic shock and MIL-STD 810H ballistic shock.
What is the Definition for Ballistic Shock According to MIL-STD 810 ?
Ballistic shock is a high-level shock, usually a result of the impact of projectiles or ordnance on armored combat vehicles. Armored combat vehicles must survive the shocks from large caliber non-perforating projectile impacts, mine blasts, and overhead artillery attacks. Actual shock levels vary with the type of vehicle and the specific munition used. Other variation factors include impact location or proximity, and where on the vehicle the shock is measured.
There is no intent here to define the actual shock environment for specific vehicles. Furthermore, the ballistic shock technology is still limited in its ability to define and quantify the actual shock phenomenon. Though considerable progress has been made in the development of measurement techniques, currently used instrumentation is still bulky and cumbersome.
The development of analytical methods to determine shock levels, shock propagation, and mitigation is lagging behind the measurement technology. The analytical methods under development and in use are not reliable enough to warrant not testing.
Generally, the prediction of response to ballistic shock is not possible, except in the simplest configurations. An armored vehicle may be subjected to a non-perforating large caliber munition impact or blast. In this case, the structure experiences a force loading of high intensity and short duration. Though the force loading is localized, the entire vehicle is subjected to stress waves traveling.
What are the Effects of Ballistic Shock Testing on Materials?
Ballistic shock has the potential for producing adverse effects on all electronic, mechanical, and electro-mechanical systems. Generally, the level of adverse effects increases with the level and duration of the shock. But it decreases with distance from the source. Adverse effects are enhanced when material stress waves correspond with the natural frequency wavelengths of micro electronic components.
When structure response movements correspond with the low frequency resonances of mechanical and electro-mechanical systems adverse effects are enhanced.
Examples of problems associated with ballistic shock include:
- System failure due to destruction of the structural integrity of micro electronic chips including their mounting configuration.
- System component failure due to relay chatter.
- System component failure due to circuit card malfunction, circuit card damage, and electronic connector failure. On occasion, circuit card contaminants able to cause short circuits are dislodged under ballistic shock. Circuit card mounts may be subject to damage from substantial velocity changes and large displacements.
- Material failure due to cracks and fractures in crystals, ceramics, epoxies or glass envelopes.
- System component due to sudden velocity change of the structural support of the system component. Or due to the internal structural configuration of the mechanical or electro-mechanical system.
What is the Appropriate Procedure for Best Ballistic Shock Testing?
This method includes six ballistic shock test procedures for ballistic shock compliance.
Procedure I – Ballistic Hull and Turret (BH&T), Full Spectrum, Ballistic Shock Qualification. Projectiles are fired at a BH&T with the test material mounted inside. This replicates the shock of ballistic impacts on armored vehicles.
This procedure is very expensive and requires that an actual vehicle or prototype be available, as well as appropriate threat munitions. Because of these limitations, a variety of other approaches are often pursued.
Procedure II – Large Scale Ballistic Shock Simulator (LSBSS). This procedure includes ballistic shock testing of complete components over the entire spectrum (10 Hz to 100 kHz). It is done using devices like the Large Scale Ballistic Shock Simulator (LSBSS). This approach is used for components weighing up to 500 Kg (1100 lbs), and is considerably less expensive than Procedure I.
Procedure III – Limited Spectrum, Light Weight Shock Machine (LWSM). This is for components weighing less than 113.6 kg and shock mounted to eliminate sensitivity to frequencies above 3 kHz. This procedures tests over the spectrum of 10Hz to 3 Hz using a Light Weight Shock Machine (LWSM). The LWSM is adjusted for 15 mm displacement limits.
Use of the LWSM is less expensive than full spectrum simulation. It may be appropriate if the test item does not respond to high frequency shock. And if it cannot withstand the excessive low frequency response of the drop table.
Procedure IV – Limited Spectrum, Mechanical Shock Simulator. Mechanical shock simulators have been constructed to test very light weight components. These machines produce a shock that lies within the envelope of the default shock response spectrum. Shock content is present above 10 kHz, but it is not well defined.
Use of a Mechanical Shock Simulator is less expensive than full spectrum simulation. It may be appropriate for lightweight items that are sensitive to shock up to 10 kHz.
Procedure V – Limited Spectrum, Medium Weight Shock Machine (MWSM). This is for components weighing less than 2273 kg and not sensitive to frequencies above 1 kHz. They can be tested over the spectrum from 10 Hz to 1 kHz using a Medium Weight Shock Machine (MWSM). The MWSM is adjusted for 15 mm displacement limits.
Use of the MWSW may be appropriate for heavy components and subsystems that are shock mounted. An that are not sensitive to high frequencies.
Procedure VI – Drop Table. Light weight components, which are shock mounted can be evaluated at frequencies up to 500 Hz using a drop table. This technique often results in overtest at the low frequencies. The vast majority of components that need shock protection on an armored vehicle can be readily shock mounted.
The commonly available drop test machine is the least expensive and most accessible test technique. The shock table produces a half-sine acceleration pulse that differs significantly from ballistic shock. The response of material on shock mounts can be enveloped quite well with a half-sine acceleration pulse. That is if an overtest at low frequencies and an under test at high frequencies is acceptable.
What Ballistic Shock Laboratory Is Most Trusted for the Best Ballistic Shock Testing?
Looking for the best ballistic shock lab in your area? Contact Keystone Compliance today to work with an
expert who understands the requirements of ballistic shock compliance. Keystone has a military ballistic lab, and experienced test engineers. Talk to our experts to develop a streamlined test plan and receive a professional and affordable quote.
As an expert in shock certification, Keystone Compliance has been recognized for their superior testing services. Our capabilities include testing commercial, aerospace, and military ballistic shock testing standards. Contact us to learn why so many manufacturers rely on Keystone Compliance to meet their mechanical and aerospace shock testing needs.
There have been several versions of the ballistic shock testing procedures in MIL-STD-810 vibration testing. Below is a list of each version and the appropriate method number: