In this paper a measurement method for the analysis of the structural behavior of heart valves is presented by the use of the thermoelasticity and laser Doppler vibrometry. A special experimental test bench has been realized with the purpose to fix the body of the valve and to excite the parts of remarkable importance from the structural point of view by means of a shaker. The vibrational measurements have been adopted as boundary condition for the FEM simulations and the relative maps in terms of stress have subsequently been validate through the employment of the thermoelasticity.
The goal of this work is the development of a new application of fiber Bragg gratings sensors (FBG), in order to measure the pre-load transmitted to a couple of roll bearings, inside a high speed electro-mandrel. FBG sensors has been preferred to classical electrical strain gauges because of their intrinsic immunity to electromagnetic fields. This last are very strong in the application here considered, and moreover its effect cannot be easily filtered because it occur at the same frequency of the phenomena to observe. The mechanical component design, used to convert the preloading forces in measurable strain, is also illustrated. On this component the fiber optic sensor is installed and the load cell obtained is calibrated. An uncertainty value equal to 1% of the full scale, is obtained. The effective pre-load value induced by the tightening system on the rolling bearings has been measured with the system developed.
In this work a system for static and dynamic calibration of in-fibre Bragg grating sensors (FBG), is described. Our idea starts from the calibration procedure of strain gauges that is done by applying a pure bending on the sample. The aim of this work is to develop a system that allows as to apply an analogous experimental technique. In this case we use as reference a Laser Vibrometer, and therefore to the sample a dynamic excitation by an electrodynamic actuator. The test bench is used to apply a sinusoidal force in a symmetrical way in order to obtain an alternate pure bending in the area where the sensor is glued on the structure. The greatest excitation frequency, limited by the characteristics of FBG interrogation system, is about 20 Hz.