Synthesis of PR-/RP-chain-based compliant mechanisms – design of applications exploiting fibre reinforced material characteristics

Abstract. Compliant mechanisms have several advantages, especially their smaller number of elements and therefore less movable joints. The flexural members furthermore allow an integration of special functions like balancing or locking. Synthesis methods based on the rigid body model (Howell, 2001; Sönmezv, 2008) or topology optimisation (Zhou and Mandala, 2012) provide practical applications from the advantages of compliant elements. Beside these methods, a much simpler approach is the geometric-based synthesis (Ehlig et al., 2013) which is focused on solving guidance tasks by using RR-chain¹-based compliant linkages. More compact compliant linkages can be build up by using only PR² or RP³ chains. Therefore a tool is needed to extend the RR-chain-based approach. The necessary analysis of the compliant beam element can be done by numerical analysis and through experiments. Due to the validity of the Bernoulli beam model the elastic similitude can be specialised and a more general synthesis of compliant beam elements can be created. Altogether a generalised synthesis method can be created for handling different linkage structures as well integrating beam elements derived numerically or by measurement. The advances in this method are applied in the synthesis for a cupholder mechanism made of fiber reinforced material.

¹ one link with two rotational joints (R)
² one link with one frame fixed prismatic joint (P) and one moving rotational joint (R)
³ one link with one frame fixed rotational joint (R) and one moving prismatic joint (P)