Topology optimization of Stable and Adjustable Mechanisms for Optical Instruments and Implants

Stijn Koppen (PhD candidate) and Matthijs Langelaar (supervisor)

Keywords

Compliant mechanisms, Alignment, Additive manufacturing, Topology optimization

Description

Throughout the high tech engineering field, instrumentation and high-performance equipment rely on adjustable mounts for fine alignment of optical components. However, current manual or actuated adjustable mounts and mechanisms typically consist of many parts, are voluminous, lack crosstalk-free control of individual degrees of freedom, and are sensitive to mechanical and thermal disturbances. Radical technological innovation is needed to overcome these limitations without a severe penalty in terms of engineering costs. This project develops a design methodology that uses computational topology optimization methods in order to generate multi-degrees of freedom monolithic compliant mechanisms with fully decoupled kinematic adjustment modes. The latter is optimized for dynamic aspects as well as mechanical and thermal stability and can be readily manufactured by additive manufacturing.

Topology optimization of planar multi-input-multi-output compliant mechanism with decoupled kinematic adjustment modes. This mechanism consists of two adjustment modes: left to right and bottom to top. If actuated in the first mode (transmission ratio of -0.5), the displacement of the input and output of the second mode (transmission ratio of -0.6) is close to zero (transmission ratio of 0.01-0.1), and vice versa. Due to the interaction between the two modes, only a highly complex topology can achieve the required decoupling.
Topology optimization of stress-constrained short-range precision flexure insensitive to manufacturing errors. This mechanism is compliant in rotation, though stiff in shear motion. Most importantly, the deformation stiffnesses and maximum Von Mises stress in the obtained design are insensitive to manufacturing uncertainties. The colors represent the stress distribution in rotation mode (low stress - black, high stress - pink).
The design evolution of the topology optimization of a stress-constrained short-range precision compliant mechanism (inverter) insensitive to manufacturing errors. This mechanism transfers an input displacement into an output displacement with a transmission ratio of -2. Most importantly, the transmission ratio and maximum Von Mises stress in the obtained design are insensitive to manufacturing uncertainties.
Efficient topology optimization of multi-partition structural optimization problems, such as multi-input-multi-output compliant mechanisms. This is an example of the topology optimization of a complex network of heat loads and heat sinks. The resulting topology efficiently transfers heat between 200 different points in the domain. To this end, the problem consists of 200 different finite element analyses per optimization iteration. Using a novel method, such multi-partition structural optimization problems can now be solved up to 100 times faster and with only a fraction of memory usage.

 

Partners

  • Fontys University of Applied Sciences
  • TNO Optomechatronics
  • Airbus Defense and Space
  • BAAT Medical
  • ASML
  • Nexperia-ITEC
  • VDL Enabling Technologies Group

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