Materials & Testing
Categories
Advantages of large piezo actuators and high power drivers for fatigue and fretting test
19 June 2023
Constant expansion of new materials requires fretting or fatigue machines in order to test their failure. In many cases tests must be performed in severe conditions and at high frequency. These requirements come from the use of the materials in highly demanding applications. At the same time it is expected to reduce the time required to characterise such materials. Piezoelectric actuators are more and more common in testing machines, but they still reach limitations in terms of maximum displacement, cycling frequency or power. In order to cope with these issues, Cedrat Technologies has been investigating solutions. In this paper long stroke and high frequency actuators, coupled with powerful driving control are introduced. These actuators are based on piezoelectric materials and can be easily integrated into the fatigue machines. In order to improve precision of these tests, two of the most common displacement sensors used in smart actuators are also presented in this paper.
M2EMS Miniature magnetic rotating motor
19 June 2023
Thanks to the help of intensive modelling, the two first prototypes realised in the framework of the M2 EMS project are functional. It consists of prototypes of single-phase stepper motor whose structure has been transformed from the Lavet motor so as to take into account collective production of the magnet film layers, which are developed in the M2 EMS project.
Testing of amplified piezoelectric actuator in a combined vibration and acceleration
19 June 2023
Sandia National Laboratories has previously tested a capability to impose a 7.5 g-rms (30 g peak) radial vibration load up to 2 kHz on a 25 lb object with superimposed 50 g acceleration at its centrifuge facility. This was accomplished by attaching a 3,000 lb Unholtz-Dickie mechanical shaker at the end of the centrifuge arm to create a “Vibrafuge”. However, the combination of non-radial vibration directions, and linear accelerations higher than 50g’s are currently not possible because of the load capabilities of the shaker and the stresses on the internal shaker components due to the combined centrifuge acceleration.
Characterisation of magneto-rheological fluids for actuators applications
19 June 2023
Magnetorheological fluids (MRF) are magnetically controlled fluids and they find more and more industrial applications in actuation functions. These include shock absorbers, semi-active dampers, clutches, brakes, haptic actuators & devices. Several of these applications have been studied by Cedrat Technologies for its industrial customers, and a device-oriented test bench has been developed in order to characterise the magneto-mechanical properties of MRF such as the magnetisation curve, the yield stress ….
Upgrade of miniature outrunner brushless DC motors
19 June 2023
Miniature Brushless DC motors (less than 5gr) offer some challenges both in the design and the manufacturing. They are used in several mass volume applications, such as hard disk drive, gyroscopes, and more recently in some unnamed aircraft vehicles (UAVs), where Cedrat is involved. For this last application, the efficiency is of upmost importance. Cedrat has used its Flux software solution to optimize the Brushless motor design: Some materials and dimensions have been changed in the motor to improve its efficiency.
