Resonance dwell test & sine dwell test

Description

In a resonance dwell test, the shaker generates a harmonic sinusoidal oscillation with a fixed frequency, in contrast to the sliding frequency of the sinusoidal oscillation in the sine sweep test. The test frequency of the resonance dwell test corresponds to the natural frequency of the test specimen. The natural frequencies of the test specimen are usually determined before the endurance test in a resonance search test on the shaker.

In case the natural frequency of the device under test changes during the resonance dwell test (as a result of a change in its mechanical structure), the test frequency is automatically tracked to the natural frequency. This ensures that the device under test always oscillates in its resonance and is exposed to the correct load.

Resonance dwell tests are often fatigue strength tests. The test duration is determined by the number of cycles required to demonstrate fatigue strength.

Pictures: Test profile of a resonance duration test with tracking of the test frequency (recognizable by the cross)

Application using the example of motors

During operation, motor components and parts are often excited to resonance vibrations by the motor orders. This can lead to increased mechanical stress and failure of a component. The resonance dwell test is used to demonstrate that motor components have sufficient durability against the natural vibrations excited by the motor.

Description

During the sine dwell test, the devices under test are exposed to a harmonic sinusoidal oscillation with a fixed frequency. In contrast to the resonance dwell test, the test frequency does not correspond to the natural frequency of the test specimen. The test frequency depends on the vibration excitation at the mounting location of the product, e.g. the excitation by a neighboring power unit with a fixed rotational speed.

Application using the example of shipbuilding