Testing method for rotor blades
IABG developed a new and improved concept for dynamic fatigue tests on rotor blades that offers significant advantages over traditional testing methods. In general, the proof of fatigue strength for rotor blades is obtained in dynamic fatigue tests endured over several millions of stress cycles, i.e., by vibration tests in line with the resonance principle.
The test frequency is hereby limited by the initial natural bending frequency of the item under test. For current blades, this lies clearly below one Hertz, which leads to long testing times and thus, in the end, to high costs. The blade deflection curve appearing in resonance tests often varies from the real-operation deflection curve due to aerodynamic loads. Here, exceedingly high or low stress levels can appear locally that negatively impact testing quality.
The patented test method of IABG can significantly reduce or avoid these deficiencies.
The new method allows for increasing the natural bending frequency, improved simulation of the deflection curve, setting a medium load during the text cycle, as well as for doubling the testing frequency.