University of Twente Student Theses


Optimization of flexure mechanisms using gradient-based methods

Hagen, Jason ten (2023) Optimization of flexure mechanisms using gradient-based methods.

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Abstract:In this thesis, a method for optimizing SPACAR modeled flexure mechanisms is developed, using gradient-based algorithms. The finite differences of the objective and constraint functions were analyzed to find a suitable step size. The importance of scaling the objective function, constraints, and design space was analyzed. Using the maximum stress over the entire mechanism as constraint results in a discontinuous differentiable function, which is solved by using specific stresses as separate constraints. A similar issue can potentially occur for the objective natural frequency, when different modes catch up with each other. A reinforced cartwheel hinge was successfully and robustly optimized, using 25 design variables, showing the merit of the developed method. The proposed algorithms are sequential quadratic programming included in the MATLAB function fmincon, which is the most efficient and robust algorithm tested, and a basic quasi-Newton method implementation that can potentially handle different frequency modes in the objective function.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
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