Page 74 - libroRicercaIinnovazione_2016

Department of Engineering, ICT and Technologies for Energy and Transport Patent Title Radial force transducer, in particular for rotating shaf’s. Ref. CNR 10305 Assignee(s): CNR CNR Institute: INSEAN Main Inventor: Fabrizio Ortolani Countries: IT Priority date: 28/03/2014 Abstract Radial forces measurement on rotating shaf is ofen a challenge. The use of strain gauges mounted directly on the shaf requires the use of slip rings or a radio link in order to power the system and acquire data. Moreover underwater applications or into a dirty environment are even more difficult to achieve. A customer pass thru­hole, strain gauges based, biaxial force transducer has being. Developed to quantify radial forces acting on a rotating shaf It is designed to be mounted as shaf’s frame and it converts shaf’s deflections into forces measure using sensitive plates equipped with strain gauges. Moreover, scalability and sensitivity can be changed in a wide range just modifying main body dimensions or sensitive parts’ thickness. Background The first purpose of the transducer is going to be the measure of lateral forces acting on propellers during model test. Usually the measure of propeller’s transversal loads are performed using dedicated instruments, that allow to study only the propeller, in so called “open water“ tests. Thus, the propeller is separated from the vehicle so hull’s contributions or interactions are modeled only in theoretical mathematical simulations. Technology The transducer’s operating principle is the conversion of the deflection of sensitive beams, caused by forces on the shaf, into a voltage signal using strain gauges sensors. The transducer is composed of independent structures, machined in order to decouple the force’s components and eliminate effects due to bending moments. Advantages and Applications Using this transducer is possible to perform measurements in a real operative condition, working both as a frame and as measuring device. Other applications would be turbine or airfoil test into wind/cavitation tunnel, measurements of loads on structures/equipments that foresee the use of loaded rods or shafs, as automation and control system, automotive monitoring or R&D preliminary and prototyping measurements. Development stage A prototype has been already developed. A test session on full experimental setup, that is the transducer mounted on vessel model’s shaf line, in order to measure bearing loads during free running maneuvering tests, has been performed. Those tests, besides validating the correct behavior of the transducer, showed some new phenomenological aspects that have been presented on several published paper. Further 65 experimental applications are foreseen on sea flow turbines.