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Energy Harvesting & Design Optimization Lab. |
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University
of Maryland Baltimore County, Dept. of Mechanical Engineering |
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Current Topics
3. Reliability-based Design Optimization:
Reliability-based design optimization (RBDO) search for a design of consistent system performance regardless of various uncertain factors including material properties, loading conditions, geometry tolerances. Two recent studies on RBDO is introduced in this page:
3.1. Sensor layout design for maximum detectability: Multifunctional
structural materials possess attractive attributes that can be designed to
realize smart system functionalities such as integrated sensing systems for
failure diagnostics and prognostics. With the integrated sensing
capabilities, real-time monitoring of potentially damaging structural
responses becomes possible. However, due to various uncertainties introduced
by structural material properties, manufacturing processes, as well as
operating conditions, ensuring the robustness of sensing performance is of
vital importance for smart sensing system development. This research presents
a reliability-based robust design approach to develop piezoelectric materials
based structural sensing systems for failure diagnostics and prognostics. In
the proposed approach, a detectability measure is defined to evaluate the
performance of any given sensing system, and the sensoring system design problem can be formulated to maximize the detectability for
different failure modes by optimally allocating piezoelectric materials into
a target structure. This formulation can be conveniently solved using
reliability-based robust design framework to ensure design robustness while
considering the uncertainties. A rectangular plate is employed in this study
to demonstrate the efficacy of the proposed methodology in developing
multifunctional material sensing systems.
3.2. RBDO for vibrational energy harvesting device: The power output of a vibration energy harvesting device is highly sensitive to uncertainties in materials, manufacturing, and operating conditions. Although the use of a nonlinear spring (e.g., snap-through mechanism) in energy harvesting device has been reported to reduce the sensitivity of power output with respect to the excitation frequency, the nonlinear spring characteristic remains significantly sensitive and it causes unreliable power generation. In this paper, we present a reliability-based design optimization (RBDO) study of vibration energy harvesters. For a nonlinear harvester, a purely mechanical nonlinear spring design implemented in the middle of cantilever beam harvester is considered in the study. This design has the curved section in the center of beam that causes bi-stable configuration. When vibrating, the inertia of the tip mass activates the curved shell to cause snap-through buckling and make the nature of vibration nonlinear. In this paper, deterministic optimization (DO) is performed to obtain deterministic optimum of linear and nonlinear energy harvester configuration. As a result of the deterministic optimization, an optimum bi-stable vibration configuration of nonlinear harvester can be obtained for reliable power generation despite uncertainty on input vibration condition. For the linear harvester, RBDO is additionally performed to find the optimum design that satisfies a target reliability on power generation, while accounting for uncertainty in material properties and geometric parameters.
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Energy Harvesting & Design Optimization
Lab. University of Maryland Baltimore County,
Dept. of Mechanical Engineering 1000 Hilltop Circle, Baltimore, MD, 21250 © 2013 |
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