Finite element modeling in the design and optimization of portable instrumentation

Abstract

Finite element modeling method (FEM) is a powerful numerical analysis method that is widely used in various engineering and scientific domains. In this thesis, we have utilized FEM to study structural analysis, heat transfer, and fluid flow in the instrumentation design and optimization. In particular, we have designed and optimized a portable micro-dispenser for bio-medical applications and a portable enclosure device for industrial applications. In the micro-dispenser study, our proposed model is comprised of a permanent mainframe and a disposable main tank, which can hold a bulk volume of sample fluid as an off-chip reservoir. The height of the micro-dispenser and the diameter of the passive valve have been analytically designed upon the physical properties of the fluid sample. A Peltier thermoelectric device supported by a fuzzy logic controller is dedicated to controlling the temperature within the micro-dispenser. As an extension, we have also explored another piezoelectric-based actuator, which is further optimized by genetic algorithm and verified by FEM simulations. Furthermore, in the enclosure study, we have proposed a design and optimization methodology for the self-heating portable enclosures, which can warm up the inner space from -55°C for encasing the low-cost industrial-class electronic devices instead of expensive military-class ones to work reliably within their allowed operating temperature limit. By considering various factors (including hardness, thermal conductivity, cost, and lifetime), we have determined to mainly use polycarbonate as the manufacturing material of the enclosure. The placement of the thermal resistors is studied with the aid of FEM-based thermal modeling. In summary, despite the distinct specialties and diverse applications in this multi-disciplinary research, we have proposed our design methodologies based on FEM. The design efficacy has been not only demonstrated by the FEM simulations, but also validated by our experimental measurements of the corresponding prototypes fabricated with a 3D printer.