Axle level vibration test rig helps automotive manufacturers detect NVH issues earlier in the design cycle.
Automotive testing specialist, AB Dynamics has developed an axle level NVH (Noise, Vibration, Harshness) rig, the ANVH 250. The development of the new rig follows demand from manufacturers to ascertain NVH issues earlier in the design process and over a greater operating range. Electrified powertrains have significantly reduced the acceptable level of NVH for vehicle manufacturers.
According to Edward Haynes, Chief Engineer for Electric Actuators at AB Dynamics, the ANVH 250 enables manufacturers to measure and optimise the NVH characteristics of suspension systems during the vehicle design process, helping to produce a cost-effective suspension design that delivers high levels of cabin refinement.
“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, reduces the overall vehicle cost and accelerates product time-to-market,” explains Haynes.
The ANVH 250 measures NVH transmission from wheel hubs, through suspension components, to the suspension mounting points. It accurately measures the transmission of vibration up to 250Hz from the suspension springs, dampers, linkages, anti-roll bars and elastomeric bushes.
High frequency actuators
The test rig makes use of an exceptionally stiff frame design in combination with AB Dynamics’ own high frequency linear actuators, specifically designed for this application. The direct acting electric linear actuators deliver motion over a frequency, displacement and load range not achievable with any available hydraulic actuator. They are also inherently safer than hydraulics because there is less stored energy in the system.
With the growing popularity of hybrid and electric vehicles leading to reductions in typical cabin background noise levels, it has never been more important to control or eliminate NVH sources from the vehicle suspension and driveline. With the ANVH 250, AB Dynamics has produced an accurate, cost effective, easy to use and reliable test machine that allows fine-tuning to be done at a much earlier stage in the design process, providing manufacturers with an invaluable head start.
Not just a vibration table
The test rig goes beyond traditional vibration testing methods by employing a testing environment that has been specifically designed for its chosen purpose.
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. The paired displacements at the hubs can be in phase or in anti-phase.
A graphical user interface allows the operator to easily navigate between different parts of the system to control the machine and configure the test procedure. All data relating to the axles tested and the tests performed are stored in an easy to use relational database system. Key axle data is entered via the interface screen. The ANVH 250 is supplied with ANVH Grapher. This is 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.
The rig is suitable for testing the majority of passenger and light commercial vehicles. As an option, the ANVH rig can be supplied with the Dynamic Arm Wheel Position Measurement System (WPMS) for high accuracy measurement of the wheel hub motion in all six degrees of freedom.