Stress relief by sub-harmonic vibrations: analysis and parametrization

The worldwide industries use the sub- resonant vibration stress relief for over twenty years. In Brazil, this technic has been used for about fifteen years. In the last years, with the searching of new alternatives process aiming energy economy with consequently the Global Heating reduce, the use of this technique can be very interesting. Moreover, the time reduction between vibration and thermal stress relief processes is around 80%, allowing a faster repairing pieces, which is prime factor to make a maintenance stop in a short time. Meanwhile, the scientific literature is rare about the use and the efficacy of this system. This work has the propose of comparing the results of sub- harmonic stress relief process with conventional thermal process and correlate them to the decrease of the resonance peak frequencies, comparing before and after treatments. This work introduces some examples of successful works made at industry and presents an experimental research to measure the residual stress, before and after the treatment, comparing to the conventional heat treatment results. This work shows generally the stress relief by sub- resonant vibrations in the 0.2 mm depth, promotes stress relief on average 10% higher when compared with the results obtained by the conventional heat treatment.