Compliant Mechanisms Re-Design based on Additive Manufacturing  and Topology Optimization   Lionel Kiener*, Hervé Saudan*, Gérald Perruchoud* and Johan Kruis* Abstract  The use of Additive Manufacturing (AM) processes for cutting-edge applications is a constantly growing  topic of interest in various sectors such as space, astrophysics, medical and watchmaking industries.  While the largest part of the research presently reported is focused on developing and optimizing designs  of what could be described as “structural or massive parts”, little work has been published up to now to  determine the limits related to the manufacturing of thin, flexible structures used in compliant  mechanisms [1].  While the common thinking is that everything can be done by AM - which is only partially true - it can be  added that it cannot be done haphazardly. The Additive Manufacturing process needs to be well  mastered as it introduces several new challenges which need to be taken into account in the design  phase. In parallel, reproducing by Additive Manufacturing the same parts that are currently produced by  traditional methods such as machining is usually of no interest. To ensure the highest added value, the  entire device - and not only the individual parts - need to be reconsidered under a process-oriented  design perspective, the whole being driven according to a system engineering mindset. CSEM is  investigating the new capabilities of AM with the aim to help industries to redesign their products  according to this holistic approach.  This paper exposes the status of the Research & Development activities carried out at CSEM with the aim  to produce novel designs of mechanisms, including compliant structures based on AM. The general  development strategy is presented, followed by material & process characterization and testing results.  The re-design, including topology optimization of space products and compliant mechanisms are  presented as well.  Introduction  CSEM is active in the design and development of very high performance flexural elements and  mechanisms for more than 30 years. Notable examples for space applications are the HAFHA flexural  pivot and the Corner Cube Mechanism which is currently operated in the IASI instrument on board MetOp  satellites, to date with more than 800 million cycles (linear stroke of ±15 mm) achieved in 10 years. Other  mechanisms (e.g. Slit Mask, tip-tilt and chopper) have been developed and produced for ground-based  telescopes as well as for the airborne SOFIA telescope.  In the same philosophy, the elaboration of new products made by additive manufacturing has been  investigated at CSEM over several years targeting the general goals of assessing the benefits and  weaknesses of the AM fabrication process for compliant mechanisms and getting a sufficient level of  expertise on AM-produced compliant mechanisms for future projects.  Development Strategy  For future development projects, CSEM tackled the challenge of producing compliant structures by  Selective Laser Melting (SLM). The first chapter of this endeavour started in 2014 with the development  *CSEM SA, Neuchâtel, Switzerland Proceedings of the 44th Aerospace Mechanisms Symposium, NASA Glenn Research Center, May 16-18, 2018 NASA/CP—2018-219887 239