Abstract

The Tribomechadynamics Research Challenge (TRC) was a blind prediction of the vibration behavior of a thin plate clamped on two sides using bolted joints.

Specifically, the natural frequency and damping ratio of the fundamental bending mode were requested as function of the amplitude, starting from the linear regime until high levels, where both frictional contact and nonlinear bending-stretching coupling become relevant.

The predictions were confronted with experimental results in a companion paper; the present article addresses the experimental analysis of this benchmark system.

Amplitude-dependent modal data was obtained from phase resonance and response controlled tests.

In the phase resonance test, a resonant phase lag between response and excitation was ensured via feedback control, and the excitation level was step-wise in-/decreased.

In the response controlled test, the response level was kept fixed via feedback control.

An original variant of response controlled testing is proposed:

Instead of a fixed frequency interval, a fixed phase interval is analyzed.

This way, the high excitation levels required outside resonance, which could activate unwanted exciter nonlinearity, are avoided.

The consistency of the nonlinear modal testing methods, with each other, and with conventional linear tests at low amplitudes, is carefully analyzed.

Comparisons of nonlinear-mode based predictions with direct frequency response curve measurements (at fixed excitation level) serve as additional cross-validation.

Overall, these measures have enabled a high confidence in the acquired modal data.

The different sources of the remaining uncertainty were further analyzed.

A low reassembly-variability but a moderate time-variability were identified.

The latter is attributed to some thermal sensitivity of the system.

Two nominally identical plates were analyzed, which both have an appreciable initial curvature, and a significant effect on the vibration behavior was found depending on whether the plate is aligned/misaligned with the support structure.

Further, a 1:2 nonlinear modal interaction with the first torsion mode was observed, which only occurs in the aligned configurations.

All data (time series of nonlinear tests; linear modal properties) and post-processing methods are publicly available.

To cite this article