Mechanical Engineering - Masters by Research Theses
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Item Development of a 3D-printed hybrid compliant revolute joint for modular continuum robots(University College Cork, 2025) Wang, Zhengyao; Hao, Guangbo; Kavanagh, RichardThis thesis presents a novel hybrid compliant revolute joint (CRJ) design, developed for modular integration into a compliant continuum robot (CCR). The joint features a hybrid structure in which stiff polylactic acid (PLA) provides structural reinforcement, while flexible thermoplastic polyurethane (TPU) enables rotational compliance. These materials are spatially distributed to achieve directional stiffness control, and the joints can be monolithically manufactured using dual-material Fused Deposition Modelling (FDM) 3D printing. To support the development of this design, a systematic methodology is proposed that includes mechanical design principles, material selection, and the experimental characterisation of material properties and interfacial bonding parameters, which provides the necessary input for accurate finite element modelling in the commercial software ABAQUS. Simulation results show that the hybrid joint exhibits a higher ratio of off-axis to on-axis rotational stiffness compared to single-material joints made entirely of PLA or TPU. Furthermore, the design offers potential for programmable joint-level stiffness through local adjustment of the soft-to-stiff material ratio. When further assembled with an anti-buckling support frame, the joint becomes suitable for serial integration into a compliant-joint CCR, where the frame ensures structural stability while task-specific compliance is achieved through joint-level tuning.Item A drifter-based self-powered piezoelectric sensor for ocean wave measurements(University College Cork, 2022-07-01) Kargar, Seyyed Masoud; Hao, Guangbo; Kavanagh, Richard; European Regional Development FundIn the present research, a drifter-based piezoelectric sensor is proposed to measure ocean waves’ height and period. To analyze the motion principle and the working performance of the proposed drifter-based piezoelectric sensor, a dynamic model is developed. The developed dynamic model investigates the system’s response to an input of ocean waves and provides design insights into the geometrical and material parameters. Next, finite element analysis (FEA) simulations using the commercial software COMSOL-Multiphysics have been carried out with the help of a coupled physics analysis of Solid Mechanics and Electrostatics Modules to achieve the output voltages. An experimental prototype has been fabricated and tested to validate the results of the dynamic model and the FEA simulation. A slider-crank mechanism is used to mimic ocean waves throughout the experiment, and the results show a close match between the proposed dynamic modeling, FEA simulations, and experimental testing. In the end, a short discussion is devoted to interpreting the output results; comparing the results of the simulations and the experimental testing; the sensor’s resolution; and the self-powering functionality of the proposed drifter-based piezoelectric sensor.