Acceleration Testing (sometimes called Constant Acceleration Testing) applies a constant or steady inertial load to a product. Constant acceleration testing is performed to verify that components can withstand exposure from inertial stresses such as would be experienced in aircraft, missiles, etc.
DES has a large Centrifuge for this type of testing with an 8 Foot Diameter Arm that can apply up to 100G’s of acceleration. The centrifuge generates acceleration by rotating about a drive shaft. Products are typically mounted near the end of the centrifuge arm which exposes them to inertial G forces. The acceleration loads are directly proportional to the distance from the center of rotation.
Products can be non-operating or operating during acceleration testing. Non-operational acceleration tests are typically used to verify that material will not break apart and become hazardous during crash inertial loads. For operating tests, wires are connected to terminals mounted on the centrifuge arm. The terminals are connected to slip rings mounted on the rotating drive shaft. The slip rings transmit electrical loads, power and data, while the centrifuge is spinning, to stationary equipment located outside of the perimeter of the centrifuge. DES has many slip ring lines for power, data transmission and for RF transmission.
Typical test specifications are:
- MIL-STD-202, Method 212
- MIL-STD-810G, Method 513
- RTCA/DO-160, Section 7.0
- IEC 60068-2-7
Typical failures from acceleration testing are:
- Permanent deformation, broken parts and fasteners
- Deflections that interfere with product operation
- Opens or shorts in circuit boards
- Relays that open or close when they are not supposed to
- Fluids leaking
Acceleration testing is different than shock testing. Shock is a dynamic impulse that excites resonant frequencies in a product. Acceleration loading is held steady for an extended period of time (typically 1 to 5 minutes). Constant acceleration testing is a quasi-static force. Both shock and acceleration are typically measured as a G force which can be confusing. Shock testing is not a substitute for acceleration testing and vice versa.
DES has performed many acceleration tests on products used in military, aircraft, helicopter and aerospace applications. For more information on Acceleration Testing or other testing services, contact DES or call 610.253.6637.