主講人：宣辰 西交利物浦大學(xué)副教授
時(shí)間：2024年4月7日9：30
地點(diǎn)：三號(hào)樓332室
舉辦單位：數(shù)理學(xué)院
主講人介紹：宣辰，西交利物浦大學(xué)副教授，荷蘭烏得勒支大學(xué)的客座教授。主要從事多物理場(chǎng)下連續(xù)體的本構(gòu)理論，固體應(yīng)力誘導(dǎo)相變，智能材料力學(xué)和軟體機(jī)器人等領(lǐng)域的研究，在相關(guān)課題上取得了重要研究成果，目前已在 American Physical Society, International Liquid Crystal Elastomer Conference, British Liquid Crystal Society, ICTAM等國(guó)際重要學(xué)術(shù)期刊上發(fā)表論文多篇。
內(nèi)容介紹：Certain hydrogel is light sensitive, since light provides heat and hydrogel shrinks under high temperature thus making the hydrogel photosensitive. When light shines on the hydrogel, the hydrogel shrinks and as light propagates through the hydrogel shrinks less thus bending towards the light. This hydrogel beam undergoes a vibration, governed by a wave PDE with a second derivative in time and 4th derivative in space coupled with a diffusion equation, a result of a competition between the elasticity of the beam and the photo induced bending. This photo induced vibration enables the hydrogel beam to swim in water. Based on dimensional energy analysis, we determine the stable vibration amplitude and construct phase diagrams for the increase and decrease of the oscillation amplitude, which are further confirmed experimentally. It is found that resonance can occur and damping plays an important role in determining the conditions for resonance. A mass-spring-damper ODE system subjected to a displacement dependent excitation force is developed to investigate the features in generalized self-excited oscillating systems. The prototypical PDEs can be well understood by the above simplified ODE model. This work lays a solid foundation for understanding self-excited oscillation and provides design guidelines for self-sustainable soft robots. It also puts forth another interesting question of whether chaos is involved in future work.