Charles Lu - US grants

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The objective of this Major Research Instrumentation (MRI-R2) award is to acquire several complementary instruments to establish a strong capability in micro- and nano-characterization of mechanical behavior of materials in controlled environments and under external stimuli. Specifically, a nanoindenter and a nano-impact/fatigue tester will be acquired that are capable of operating in controlled temperature, atmosphere, and liquid environment while under thermal, electrical, electrochemical, and biological stimuli. The instruments will enable and enhance several research and education activities, including understanding and developing: (1) new materials for electrochemical energy storage; (2) lightweight materials for aerospace and automotive applications; (3) lead-free soldering for electronic interconnects, micro-electromechanical devices (MEMS), and micro-fluidic devices; and (4) biomaterials and multi-functional, smart materials for biomedical applications. Advancing these technologies requires measuring, at the micro- and nano-meter scale, mechanical behavior of functional and structural materials in application environments.

In the coming decade, coupled mechanical-X (where X can be thermal, electrical, electrochemical, or biological stimuli) will emerge as an active field of scientific pursuit with a broad range of applications. In situ nanomechanical measurements at application conditions will accelerate materials research in many critical technology areas, including more powerful and longer lasting batteries, lighter and stronger materials for automobiles and airplanes, and more robust bio-compatible and bio-degradable implants. Graduate and undergraduate students will benefit through hands-on laboratory training and participation in the research using the in situ nanomechanical systems. The instruments will be accessible to faculty members, students, and industrial partners from multiple disciplines who have a shared interest and a common need for nanomechanical characterization. The research activities enabled by the instruments will impact critical areas such as automotive, aerospace, electronics, medicine, and energy conversion and storage.

This grant provides financial funding to design, fabricate and model the behavior of structurally stable and strong shape memory composites that could recover large deformations with temperature and/or magnetic field. Novel shape memory composites will be composed of (conventional and magnetic) shape memory alloys and shape memory polymers. A deeper understanding of temperature, stress and magnetic field-dependent properties and reversible actuation mechanisms of shape memory composites will be attained by systematic investigations of the effects of pre-straining, mixture ratio, surface finish, volume ratio, size and shape of alloys on the strength, ductility, recovery stress and strain, interfacial strength, damping and stiffness properties of shape memory composites. Moreover, a micromechanics-based analytical model will be founded to explain and predict the behavior of shape memory composites and then calibrated through the achieved experimental findings.

If successful, novel composites that could demonstrate large reversible actuation with tunable functional properties such as stiffness and damping as functions of temperature and magnetic field will be fabricated. Fabricated composites can be employed as high endurance, lightweight, higher strength, low cost and functionally tunable composites to result in more efficient systems and mechanisms in actuator applications. They can utilize their i) self-sensing ability to sense the changes in environmental conditions (e.g. temperature, humidity) and adapt their behavior accordingly; ii) high strength with reversible actuation capability to be used as stents and drug delivery systems; iii) temperature and magnetic field dependent damping properties for vibration isolation, iv) force generation capability for self-healing in structures. Given the interdisciplinary nature of the proposed research, this project will contribute significantly to the scientific education of graduate/undergraduate university students, K-12 students, high school teachers and the public at large in the emerging field of intelligent materials.