Working principle of resonant testing machines Resonant testing machines stress specimens or components with a dynamic load superimposed to a static load. The machines are equipped with a digital controller for each kind of load. The dynamic load is generated by an oscillating system (resonator) which runs in its natural frequency. The oscillating system consists of masses and springs wheras the test piece is also an important part of it. The masses can be varied to change the operating frequency in steps.

Two-masses-system (simplified view)

The static load is made by a spindle and is coupled to the system by a spring.

The machines discussed here are operating at full resonance, that means the operating point is on the peak of the resonant curve. The resonantor is excited by an electromagnet which has to supply the energy to maintain the required loadamplitude.

Due to the resonant effect the power consumption is very low (typical 20 to 1000 Watts), that means 3% to 10% in comparison to a servohydraulic testing machine. The operating frequency is in a range of 40 to 300 Hz on standard machines.

CO2.pdf