Ultrasonic fatigue allows 1 billion mechanical stress in 14h.
 stress frequency: 20kHz
 10^{9} cycles in less than 14h
 Tests in economically viable time
 15min Installation on conventional system
 Ease of use
 Ease of calibration
Main characteristics :
 Select the biasing amplitude and the number of cycles to reach
 Automatic completion of several rounds of solicitations at different amplitudes
 Automatic stop once the broken
 Ease of Use
Provided materials :
 steel structure
 Signal generator
 Converter
GF20TC : Turkey machine
Tests in TensionCompression

GF20KB : Turkey machine
Tests in CompressionCompression

GF20KT
Tests in TensionTension or TensionCompression

Reliable and robust, our Ultrasonic fatigue machines test materials in TensionTension, TensionCompression and CompressionCompression on more than one billion cycles in less than 14h..
Automobile 
Wind Power 

Aerospace 

Train 
Research 
State of the art
When Wöhler proposed his fatigue endurance curve, the leading applications of the time were steam engines for railway locomotives and ships. These were slow machines, operating at a few tens of cycles per minute and with lifespans of between 10^{6} and 10^{7} cycles. It was perfectly justified in practical terms to consider a megacycle limit on fatigue, especially as the fatigue testing machines of the time could not exceed 10 Hertz or so. To give a few currentday examples, the rotation speed of today’s engines is measured in thousands of cycles per minute, the service life of an internal combustion engine in hundreds of millions of cycles and that of a turbine in billions of cycles. Nevertheless, fatigue tests exceeding 10^{7} cycles remain relatively rare due to the operating costs of conventional testing machines. It is also of note that accelerated fatigue tests using resonance testing machines have not been sufficiently successful to date. The main criticism of such machines has been the lack of control over test parameters. Computercontrolled machines and sensors with fast response times have rendered this criticism obsolete. Reliable fatigue testing machines are now in use that can perform 10^{10} cycles in less than a week where conventional systems would have taken over three years to achieve the same number of cycles for a single test piece.
Accordingly, one may ask whether it is sufficient to apply the current standards (Fig. 1) to determine a safe fatigue limit beyond 10^{7} cycles using a statistical approach, or whether a SN curve should be extended to 10^{10} cycles and beyond. To summarise the current situation, we accept that the concept of a fatigue limit is bound to the assumption that there is a horizontal asymptote on the SN curve above 10^{6} or 10^{7} cycles. Accordingly, a test piece that has not ruptured at 10^{7} cycles is considered to have an infinite service life, which may actually be a practical and economical approximation but is not particularly rigorous.
It is important to understand that the staircase method is popular today for determining an assumed fatigue only because of the convenience of this approximation. A fatigue limit determined by rupture of a test piece at 10^{7} cycles requires around 30 hours of testing on a machine operating at 100 Hertz. Extending the test to 10^{8} cycles would take 300 hours and increase the cost tenfold, explaining why the possibility of accelerated testing on a piezoelectric testing machine is so advantageous.
Principle of piezoelectric fatigue testing
Numerous articles have been published on the overall principle of vibration fatigue; this article will therefore simply summarise the fundamental theory. A detailed explanation can be found in “Gigacycle Fatigue In Mechanical Practice” by C. Bathias and P.C. Paris, published by Dekker/CRC (2005).
The key principle of vibration fatigue testing machines (Fig. 2) is to produce stationary resonant vibrations in a test piece. This requires a converter capable of converting the sinusoidal signal supplied by the electrical generator into mechanical vibrations. In commerciallyavailable units the converter and generator generally operate at a fixed frequency (20 kHz).
The vibration from the converter is in principle too weak to damage the test piece. A horn is required to amplify the vibrational travel. If the vibration system (converter, horn and sample) has the same intrinsic frequency (20 kHz) a high vibration amplitude can be achieved with a low energy level and a stationary wave in the system.
The following underlying assumptions apply to the theoretical analysis of fatigue vibration testing:
– The metal studied is uniform and isotropic.
– The material is elastic (the plastic domain is considered as negligible compared to the elastic domain for fatigue at particularly long service life times).
– As the vibration is longitudinal, the theoretical analysis can be simplified to one dimension.
Under these conditions, piezoelectric fatigue testing machines can only give results after 106 cycles in elastic operation; clearly they cannot replace hydraulic testing machines.
History of piezoelectric fatigue testing machines
Vibration fatigue testing at 33 Hz was first discussed in scientific publications by Hopkinson in 1911, then by Jenkin and Lemann; the first machine to reach 20 kHz was developed by Mason in 1950. Below this frequency the wave is audible. Girard conducted tests in 1959 and Vidal in 1965 to increase the frequency to 92 and 199 kHz respectively. However, the computers of the day were not powerful enough to control the tests correctly and the results were not convincing. Successful numerical control of piezoelectric testing machines was not achieved until recently by C. Bathias and his team.
This technique, at an unofficial standard of approximately 20 kHz, is used for fatigue testing of particularly longlasting materials and rupture mechanics.
Experimental vibration fatigue testing resources have been significantly improved since the 1970s, and new systems and more extensive test possibilities have been developed. In 1996, S. Stanzl summarized the development and the various aspects of ultrasound fatigue testing. The first international congress entitled “Fatigue Life In the Gigacycle Regime” was held in France in 1998, organized by Euromech. Three subsequent congresses at Vienna (2001), Kyoto (2004) and Ann Arbor (2007) have confirmed the increasing attention paid to very long cycle fatigue testing.
The hightech vibration fatigue testing system marketed by LASUR was developed in C. Bathias’s laboratory.
Book :
Gigacycle Fatigue in Mechanical Practice, Claude BATHIAS & Paul C. PARIS. 2004