Multi-Axis Vibration Control

Testing two or more axes in parallel reduces traditional test times considerably and reproduces the true environment more closely than with classical single-axis, single-shaker excitation.

m+p VibControl provides coupled and uncoupled multi-axis vibration testing (MIMO) in a closed control loop. Test modes include random, sine, shock and time domain replication (road load simulation). Multi-axis motions are characteristic of field environments. The more a vibration test can replicate the field environment, the more realistically it can induce a vibration stress loading equivalent to that experienced by the product in the field.

Whereas a single-axis random or sine test can be defined by a single value at each frequency, a multi-axis test requires the definition of a complex matrix at each frequency representing all the demand levels, as well as the coherence and cross-phases between each pair. The flexible display arrangements allow tailoring to show just the required information for maximum clarity during test operation, while all measured data is recorded and available for later analysis. Where the cross-phases and coherences are defined, m+p VibControl will verify that the demanded control values are feasible and also within the capabilities of the system.

Applications of the m+p VibControl multi-axis controller include vehicle road load simulations for durability tests, testing of large and complicated structures for operational loading as well as earthquake simulation as per IEEE 344. Components and sub-assemblies are tested on specially designed shaker tables with motion in several degrees of freedom. For seismic qualification the test specimen is fixed to a multi-axis earth­quake shake table. Large structures such as complete automobiles, aircraft, rockets and railroad cars are excited on multiple shakers each directly attached to a load input point.

The m+p PCU4 phase and amplitude control unit ensures that up to four shakers are reliably synchronized and coupled together to act as one system. It processes sine, random and shock data in a frequency range from 5 Hz to ca. 3 kHz. This specialist phase and amplitude control unit is used for optimization of the effective shaker force in the special application case where shakers are rigidly coupled via a head expander or slip table.