TRaC extends vibration testing with low-frequency test rig
TRaC, the environmental and standards-compliance test house, has extended its capabilities in low-frequency mechanical vibration testing by commissioning a new low-frequency test rig at its Warwick laboratory. The new rig is one of the few commercially available systems that can apply a wide range of vibration tests, such as the demanding European Naval specifications, to large and/or heavy products and systems.
The test system comprises a vibration platform measuring 1.3 x 1.3m, that can carry a test-piece load of up to 2 tonnes. The system is single-axis; that is, the platform's actuator moves it back-and-forth in one plane or direction, subjecting a unit-under-test (UUT) to vibration over a calibrated frequency range that extends as low as 0.1Hz, and up to 150Hz. UUTs can be subjected to a maximum acceleration of 5g at a frequency of 150Hz, and maximum displacement is 150 mm full-scale.
Movement of the table is under the control of a closed-loop system that employs electro-hydraulic actuators to generate the motion, and a combination of displacement transducers and capacitance-type accelerometers to give high-accuracy feedback in position and acceleration, respectively. The level of precision of which the control system is capable means that it can apply either sinusoidal or random vibration, or pre-defined profiles of shock and vibration over specified intervals. These scenarios include the marine and sub-sea low-frequency environments that the original specification set out to meet.
Existing test facilities that generate low-frequency mechanical vibration use electromagnetic actuation ("electrodynamic" systems) which creates stray magnetic fields, meaning that UUTs sensitive to such fields cannot be tested. TRaC's electro-hydraulic system completely avoids this limitation, as well as going far beyond the lower frequency limit of electrodynamic systems.
Robust construction also means that TRaC's test platform can carry