The rheological characterization of jetting fluids at high shear rates using a piezo axial vibrator.

Sammanfattning: This thesis covers the design, manufacturing and testing of a Piezo Axial Vibrator type rheome-ter, with the goal of characterizing jetting fluids at high shear rates. The project was carried out at Micronic Mydata AB and is associated with jet printing for the production of electronics. A literature study is conducted on the field of rheology prior to the realization of the prototype. The working principle of the PAV is based on the deformation of a fluid sample using a piezo ele-ment, while simultaneously measuring the response. Improvements are made on this proposed design and a thorough analysis with respect to structural resonance is conducted before manufac-turing the device. Electronics tailored for this application is developed along with a GUI for controlling the meas-urements and sensors. By using the stress and strain components of the vibration, the phase and amplitude response is studied for a broad frequency range. This device is tested with Newtonian fluids of different viscosities, as well as viscoelastic fluids with shear thinning properties. The result is compared to what can be obtained using conventional rheometers. It is concluded that the developed rheometer shows great potential in characterizing complex fluids. Great repeata-bility and accuracy is achieved along with the ability to adapt the device for measurements on a wide variety of fluids. Finally, possible future work is described involving rework of the electronics as well as the pro-cessing of the measured data into a more useful representation.