The low noise levels of vehicles with electrified powertrains has resulted in drivers demanding improved levels of NVH from the suspension and driveline, which in turn means that vehicle manufacturers wish to ascertain NVH issues earlier in the design process and over a greater operating range. In response to these changing OEM engineering needs, automotive test system supplier, AB Dynamics has launched an axle-level NVH rig, the ANVH 250, which measures NVH transmission from a vehicle’s wheel hubs, through the suspension components, to the suspension mounting points. The rig accurately measures the transmission of vibration, up to 250Hz, from the suspension springs, dampers, linkages, anti-roll bars, and elastomeric bushes.
The test rig features a stiff frame design in combination with AB Dynamics’ high-frequency linear actuators, which have been specifically designed for this application. The direct-acting electric linear actuators enable what the company claims is a unique range of frequency, displacement and load, as well as being safer than hydraulic systems because there is less stored energy in the system.
With an axle installed, two sets of three actuators apply precise motion to each hub at frequencies from 0-250Hz and displacements from +/-0.01 to +/-50mm, while tri-axial load cells measure the forces transmitted to each vehicle attachment point. The ANVH 250 can apply a range of sinusoidal, random input and road load data displacements to the axle system. Displacements can be applied to the wheel hubs in pairs or individually in the vertical (Z), longitudinal (X) or lateral (Y) directions, and the paired displacements at the hubs can be in phase or in anti-phase.
The user can navigate between different parts of the system to control the machine and configure the test procedure via the graphical user interface. All data relating to the axles tested and the tests performed, as well as system configuration and instrumentation settings, are stored in a relational database system, and key axle data is entered via the interface screen. The ANVH 250 is also supplied with ANVH Grapher, a screen-plotting program that enables results to be viewed as soon as a test is completed so the user can check the test has run successfully.
Edward Haynes, chief engineer for electric actuators at AB Dynamics explained, “The ability to assess the suspension at the early design stage over such a large frequency range helps avoid expensive NVH fixes at later stages of a vehicle program. This reduces overall vehicle cost and accelerates product time-to-market.”
As an option, the ANVH rig can be supplied with the Dynamic Arm Wheel Position Measurement System (WPMS) from AB Dynamics for accurate measurement of the wheel hub motion in all six degrees of freedom. The Dynamic Arm WPMS was specifically developed for use on AB Dynamics’ SPMM 5000E Kinematics and Compliance test machine.