Meeting & Exceeding Standards: Shock and Vibration

Part of military standard MIL-STD-810G outlines testing for a device’s ability to withstand general vibration and shock. Previously, we reviewed resistance testing guidelines for water, temperature and environmental contaminants.

Vibration

General Vibration: For equipment transported as cargo or operated on a vehicle
The test equipment is mounted onto a vibration table. Low level vibration is applied and increased in stages for lengths of time as representative of the expected environment. Test steps are repeated for each axis.

Loose Cargo Transportation: For equipment transported as unsecured cargo
The test equipment is placed in a package tester. Frequency and length of vibration is adjusted according to the expected environment. Testing is repeated for each package orientation.

Large Assembly Transportation: For large assemblies of equipment installed or transported on vehicles
The test equipment is mounted in a vehicle or on a surface designed to simulate transport. The vehicle is driven through the expected environment or the simulation is conducted to match the expected environment. Additional test runs may be completed.

Aircraft Carriage and Free Flight: For fixed wing carriage and free flight aircraft storage and missiles
The test equipment is suspended from a structural support frame and attached to suspension equipment such as a bomb rack, launcher or pylon. Low level vibration is applied and increased in stages for lengths of time as representative of the expected environment. Additional test runs may be completed.

Shock

Functional Shock: For equipment required to function during and after shock exposure in the field
Equipment is subjected to three to six shocks along each axis at a strength according to the expected environment.

Material to be Packaged: For equipment that may be dropped before, during or after packaging
Equipment is subjected to three to six drop shocks along each axis at a height according to package weight.

Fragility: For fragile equipment
Pre-testing is conducted to determine stress thresholds to prevent damage to equipment during testing. Drop height is set at varying levels according to expected shipping environment. Equipment is dropped on each axis at the lowest level it is expected to survive and continually dropped in increasing increments until reaching the highest threshold.

Transit Drop: For equipment likely to experience shock while in transit due to loading and unloading
Equipment is dropped from a height and a number of times dependent on the weight of the equipment while in its shipping case.

Crash Hazard: For equipment mounted in air or ground vehicles that could become unsecured during a crash and present a hazard
For ground vehicle equipment, the shock duration must be between 8 and 13 milliseconds and peak at a g factor of 75. Aircraft equipment shock duration must be between 15 and 23 milliseconds and peak at a g factor of 40. Two shocks are given in both directions on each axis for a total of 12 shocks.

Bench Handling: For equipment exposed to bench handling or maintenance
One edge of the equipment is raised 100 millimeters (4 inches) or until reaching a 45° angle, whichever is less. The equipment is dropped on all four edges of the same horizontal face and then repeated on each other face.

Pendulum Impact: For large shipping containers likely to experience horizontal impacts
The pendulum consists of a platform large enough to support the container with its top surface 23 centimeters (9.1 inches) above the floor. A concrete or masonry bumper is constructed at least 8 centimeters (3.1 inches) from the platform. The bumper must be at least 46 centimeters (18.1 inches) high, wide enough to make full contact with the container, and of sufficient mass to withstand impacts.

The shipping container is loaded with its actual or dummy contents and placed on the platform with its front end extended to touch the bumper. The pendulum is pulled back to simulate a drop of 23 centimeters (9 inches). The container is rotated and “dropped” on each side and end.

Catapult Launch/Arrested Landing: For aircraft equipment intended for catapult launches and arrested landings
If possible, tests should be conducted with measured data from the aircraft. If measured data is not available, the amplitude and frequency of shock should be determined by a structural analysis of the aircraft. The equipment is placed in its operational mode on a shock table and subjected to 30 shocks in a longitudinal axis, each followed by a 10-second rest. Testing is repeated in the vertical axis.

Sealevel MIL-STD-810G Testing

Sealevel designs and manufactures equipment with rigorous in-house testing, including the use of vibration tables and shock chambers.