Abstract
Mechanisms that consist of many elements and are potentially small sized, benefit from kinematic elementary units like revolute joints that are compliant and monolithic, and therefore could be produced without need for assembly. We present a novel concept of a compliant revolute joint that features low axis drift, high support stiffness and a large range of motion. The concept is based on a helicoidal shell of which a portion reverses its twist direction upon application of a rotation. The reversed region increases gradually, resulting in a constant reaction moment. Analytical, numerical, and experimental analyses are presented to reveal and quantify the constant-moment behaviour. Prototypes of the concept are employed in exemplary linkages to demonstrate the ability to create a large variety of neutrally stable compliant linkages, which require extremely low actuation forces and exhibit large ranges of motion.
Highlights
With the desire to create mechanical devices that are ever smaller and cheaper, engineers have been working on so-called compliant mechanisms for the past couple of decades[1]
Mechanisms that consist of many elements and are potentially small sized, benefit from kinematic elementary units like revolute joints that are compliant and monolithic, and could be produced without need for assembly
We present a novel concept of a compliant revolute joint that features low axis drift, high support stiffness and a large range of motion
Summary
With the desire to create mechanical devices that are ever smaller and cheaper, engineers have been working on so-called compliant mechanisms for the past couple of decades[1]. A significant part of the investigations on compliant mechanisms has been directed towards realising revolute joints [21,22,23,24,25] that mimic as much as possible the behaviour of classical joints, and that take advantage of the typical strengths of compliant mechanism: the absence of friction, play, wear, needed assembly and needed lubrication [26] The availability of such units would make it possible to apply the well-established paradigms in classical mechanism design to the design of compliant mechanisms. The cross-spring pivot has been described, modelled, applied and optimized extensively for a long time [30,31,32,33,34,35,36] This concept significantly increases the range of motion with respect to the notch-type joints, not being as critical for stress concentrations. The butterfly joint [37], the infinity joint [22], and similar joints that are essentially based on planar bending deformation, are successfully
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