Activities per year
Abstract
The design of audio related microelectromechanicalsystems (MEMS) such as transducers, hearing aid receivers/transmitters, sensors, mobile phone components, etc. is becoming more and more difficult due to the increasing demands for additional functionality, decreasing size of the components and the desire for lower power consumption. This makes an already complicated and multi physical engineering design task ever more complicated. Thus, a fundamental need for new insight and design methodologies are needed, and one such tool that can provide insight intoboth physics and geometric layout is systematic structural optimization. The physics governing the investigated design problem includes the coupling between mechanical stresses and the intensity of an electric field through Maxwell’s stress tensor. This relation dictates that the deformation of the mechanical structures, which also acts as electrodes, influences the intensity of the electric field. Hence, the modelling of the electric field must be conducted in the deformed configuration, which even for very small deformations can lead to a substantial change in electric field. It is worth noting that the interaction between elasticity and electromagnetics only takes place on the interface between the conductor and insulator. This fact is especially important when choosing the structural optimization tool to be applied later. Having determined the deformed equilibrium of the conductor/structure makes it possible to evaluate the acousticmechanical coupling and subsequent frequency response of the timeharmonic vibro acoustic system. Again, we emphasize that the acousticmechanical interaction occurs on the interface between the mechanical structure and the surrounding fluid (air). To summarize, the numerical modelling consists of first solving astatic, nonlinear mechanicalelectrical system. This is followed by a linearization of the dynamic equations about the deformed equilibrium, which is then perturbed by a mechanical, timeharmonic load to obtain the frequency response.The modelling  and subsequent optimization  problem can be investigated using several numerical approaches where the most interesting for structural optimization are 1) a monolithic PDE formulation with varying material parameters to be used with topology optimization and 2) immersed boundary methods such as CutFEM or xFEM to be used for generalized shape optimization. Due to the highly localized coupling at the interface, the desired resonance phenomena under operation and the nonlinearity of the model problem, the authors have chosen to apply the CutFEM approach together with shape optimization. The optimization problem is solved by gradient based methods, i.e. the Method of Moving Asymptotes, and we apply adjoint analysis to obtain the sensitivities. The viability of the design methodology is demonstrated on problems in which the goal is to maximize the acoustic output, e.g. the soundpressurelevel, by modifying the shape of the mechanical structure and electrodes, subject to different input voltages and harmonic, mechanical loads.
Original language  English 

Publication date  2019 
Number of pages  1 
Publication status  Published  2019 
Event  13th World Congress of Structural and Multidisciplinary Optimization  China National Convention Center, Beijing, China Duration: 20 May 2019 → 24 May 2019 Conference number: 13 http://www.wcsmo13.org/ 
Conference
Conference  13th World Congress of Structural and Multidisciplinary Optimization 

Number  13 
Location  China National Convention Center 
Country  China 
City  Beijing 
Period  20/05/2019 → 24/05/2019 
Internet address 
Fingerprint Dive into the research topics of 'Shape optimization for electroacousticmechanical micro systems'. Together they form a unique fingerprint.
Activities
 1 Conference presentations

Shape optimization for electroacousticmechanical micro systems
Niels Aage (Guest lecturer)
20 May 2019 → 24 May 2019Activity: Talks and presentations › Conference presentations
File