F2010C066
Application of Cross-Correlation Techniques in Four-poster Rig Durability Tests
Durability tests in laboratory conditions try to emulate real loads encountered by vehicles in realistic service conditions. In particular, road loads tend to be the dominant excitation that explains the majority of body and suspension fatigue problems and for that reason test rigs capable of reproducing these input forces or displacements have been developed and are currently used as a standard tool in the vehicle development process.
The simplest form of a test rig for complete vehicle durability analysis is based on four independently driven cylinders that reproduce the vertical displacement exhibited by the wheel hubs during driving conditions on severe tracks. The four cylinders are driven by a MIMO system that adjust the oil flow into each cylinder so that the time domain acceleration (or displacement) signal of each wheel, as measured during real driving conditions, is reproduced.
Although the reproduction of in-service acceleration time histories measured in the wheel hubs (and some other body points) is a common practice when performing durability test in four-poster rigs, additional processing of the road load data can reveal fundamental information about the nature of the road excitation as a bending and torsion inducer and the associated vehicle response in terms of its dynamic behaviour.
This paper presents a case study based on the application of cross-correlation techniques in the frequency domain in order to explore the dominant relationship between the excitation applied to the vehicle wheels, the spatial structure of road characteristics and the structural response of the vehicle body.
This abstract is supplemented by a PDF, which can be viewed here.