Hui-Ru Shih

Photonic Control of Cylindrical Shells with Electro-Optic Photostrictive Actuators

Photostrictive actuator, which can directly turn light energy into mechanical energy, is a new promising photoactuation technique for active vibration control of flexible structures. It offers the advantage of generating distributed actuation strain without connecting any electric lead wires. Photonic control of flexible cylindrical shells using discrete photostrictive actuators is investigated, and the photoactuation effectiveness is evaluated. A coupled optopiezothermoelastic shell theory is presented that incorporates photovoltaic, pyroelectric, piezoelectric, and thermal effects and has the capability to accurately predict the response of a shell to a command illumination applied to the photostrictive actuators. Expressions for the photogenerated forces and moments have been developed. Governing equations are formulated. Solution procedures based on the modal analysis technique are outlined. The detailed actuator control effectiveness is evaluated with respect to actuator placements. It is shown that by properly positioned the actuators the system performance can be improved. Numerical simulation results also show that the membrane control action is more significant than the bending control action. The circumferential membrane control action dominates, and the photonic control effectiveness is only slightly reduced by the removal of all of the actuator patches along the longitudinal direction.

Photostrictive actuators for photonic control of shallow spherical shells

Photostrictive materials, exhibiting light-induced strain, are of interest for the future generation of wireless remote control photo-actuators. Photostrictive actuators are expected to be used as the driving component in optically controlled flexible structures. In this paper, the photonic control of flexible spherical shells using discrete photostrictive actuators is investigated. This paper presents a coupled opto-piezothermoelastic shell theory that incorporates photovoltaic, pyroelectric and piezoelectric effects, and has the capability to predict the response of a spherical shell driven by the photostrictive actuators. In this study, the effects of actuator location as well as membrane and bending components on the control action have been analyzed. The results obtained indicate that the control forces are mode and location dependent. Analysis also shows that the membrane control action is much more significant than the bending control action.

Distributed vibration sensing and control of a piezoelectric laminated curved beam

The distributed vibration sensing and control of a piezoelectric laminated curved beam are studied. The mathematical model of a curved beam with a distributed piezoelectric sensor and actuator is formulated first, followed by vibration analysis. This model provides estimates of the sensor signal, actuator-induced membrane force, and actuator-induced bending moment, as well as predicting the controlled damping ratio and dynamic response. The sensor sensitivity with various sensor thicknesses is studied and compared. The effectiveness of active damping controls is evaluated with respect to different beam thickness, and sensor/actuator thickness. Numerical examples are provided and simulation results are discussed.

Displacement Control of a Beam using Photostrictive Optical Actuators

Photostrictive materials are emerging as a new actuation medium. In contrast to the traditional transducers, photostrictive materials can produce actuation strains as a result of irradiation from incident light, having neither electric lead wires nor electric circuits. In this study, a static analytical model is derived for a flexural beam with surface bonded photostrictive optical actuators. An analysis of the proposed model is carried out by considering the induced force and bending moment produced on the beam by the patched actuator. Analytical solutions of the transverse deflection, induced by the photostrictive actuators, are derived for different boundary conditions. Those solutions are explicitly expressed in terms of the geometry and position of the actuators patched on the beam. To support the validity of the developed model, a finite element verification is presented. This research work investigates the application of photostrictive actuators for optimum displacement control of a flexible beam structure. Studies are performed to examine the effects of various actuator locations and lengths on photostrictive actuation.

Photonic control of flexible structures?application to a free-floating parabolic membrane shell

In this paper, the photonic control of free-floating flexible parabolic shells using photostrictive actuators is investigated. The parabolic shell of revolution is considered to be one of the most difficult geometries among all shell and non-shell structures. Because of this, an approximate way to estimate the dynamic behavior and light-induced control forces for a photostrictive coupled parabolic shell is presented. On the basis of the approximate spherical model, the effects of actuator locations as well as membrane and bending components on the control action are analyzed. The analysis results presented show that the control forces are location dependent. It is also shown that the membrane control action is much more significant than the bending control action. The validation of the approximate model is done by comparing the light-induced control forces of the photostrictive coupled shells obtained using the approximate equivalent spherical shell model and those obtained using the parabolic shell model. From the comparison, it can be concluded that there is only a slight difference between a spherical shell and a parabola for a surface with a focal length to diameter ratio of 1.00 or larger.

Impact of Nanotechnology on Future Civil Engineering Practice and Its Reflection in Current Civil Engineering Education

Current civil engineering education should address the need to provide a broad vision, develop the higher-order skills of future civil engineers, enable them to adopt emerging technologies, and formulate innovative solutions to complex problems. This paper introduces relevant nanotechnology developments to convey the new vision and inspire creativity in civil engineering. It also presents a pedagogical framework for integrating nanotechnology education into a civil engineering curriculum and cultivating self-regulated learning and creativity skills for civil engineering students. The pedagogical framework includes the introduction of nanotechnology innovations and other relevant innovative technologies, and explicit instructions on cognitive strategies for facilitating and inspiring self-regulated learning and creativity. It is implemented with problem/project-based learning for a cocurricular project that requires self-regulated learning and creativity. This pedagogical framework provides a model for int...

Wireless Control of Parabolic Shells Using Photostrictive Actuators

Photostrictive actuator, which can turn light energy into mechanical energy, is a new promising photoactuation technique for non-contact wireless active control of flexible structures. Optical mirrors, communication antennas, solar/optical reflectors, nozzles, rocket fairings, etc. often have the shape of parabolic shells or shells of revolution, due to their required focusing, aiming, or reflecting performance. In this paper, the active control of flexible parabolic shells using discrete photostrictive actuators is investigated. Parabolic shell of revolution is considered one of the most difficult geometry among all shell and non-shell structures. Because of this, an approximate way to estimate the dynamic behavior and light-induced control forces of a photostrictive coupled parabolic shell is presented. Based on the approximate model, the effects of actuator locations as well as membrane and bending components on the control action are analyzed. The results obtained indicate that the control forces are mode and location dependent. It is also shown by analysis that the membrane control action is much more significant than the bending control action. The validation of the approximate model is done by comparing the light-induced control forces of the photostrictive coupled shells obtained by the approximate equivalent spherical shell model and those obtained by the parabolic shell model.Copyright

An innovative certification program that prepares undergraduate students for engineering research

Faculty at Jackson State University have developed an In-House Certification program focused on introducing students to scientific and engineering research through hands-on learning experiences. This program is innovative as it is designed specifically for undergraduate research experiences and details a very structured and strategic plan to teach students effective research principles with a measureable incentive. This program is a result of positive results from initiatives funded through the National Science Foundation Nanotechnology for Undergraduate Education program. Students participate in learning characterization techniques, scientific principles and research methods associated with various characterization tools. The program is planned so that students will engage in an analysis technique for 3–6 week duration and then receive a certification for proficiency. Upon completion of the program students participate in mini-projects that are focused in the areas of materials research. The program is a hands-on introduction to materials research that spurs the growth of undergraduates who will continue in meaningful research projects, external internships and ultimately graduate school.

Photonic Control of a Free-Floating Parabolic Membrane Shell

Communication antennas, optical mirrors, solar/optical reflectors, etc. often have the shape of parabolic shells or shells of revolution, due to their required focusing, aiming, or reflecting performance. In this paper, the wireless control of free-floating flexible parabolic shells using discrete photostrictive actuators is investigated. Parabolic shell of revolution is considered to be one of the most difficult geometry among all shell and non-shell structures. Because of this, an approximate way to estimate the dynamic behavior and light-induced control forces of a photostrictive coupled parabolic shell is presented. Based on the approximate spherical model, the effects of actuator locations as well as membrane and bending components on the control action are analyzed. The results obtained indicate that the control forces are location dependent. It is also shown by analysis that the membrane control action is much more significant than the bending control action. The validation of the approximate model is done by comparing the light-induced control forces of the photostrictive coupled shells obtained by the approximate equivalent spherical shell model and those obtained by the parabolic shell model. From the comparison, it can be concluded that there is only a slight difference between a spherical shell and a parabola for surface with an F/D (focal length to diameter ratio) of 1.00 or larger.Copyright

Course Module on Precision Control of Piezoelectric Actuators

Conventional mechanical actuation mechanisms, which have been used to drive nanoscale devices, have the drawback of requiring high power for operation. However, the piezoelectric actuation mechanism offers the advantages of extremely low power consumption. As piezoelectric materials change the practice of engineering and technology, providing undergraduate students with experiences with these materials has become necessary. This paper presents the design of a course module on precision control of piezoelectric actuators for undergraduate students. The course module incorporates lecture, experiment, and problem-based learning as pedagogical tools. Students are given opportunities to work directly with piezoelectric actuators to gain hands-on experience. Students can learn about actuation advantages of the piezoelectric materials along with their control problems. This course module can improve the knowledge of the students on how to design and analyze piezoelectric devices.Copyright