A Lamina-Emergent Frustum Using a Bistable Collapsible Compliant Mechanism

Abstract

This paper presents a new bistable collapsible compliant mechanism (BCCM) that is utilized in a lamina-emergent frustum. The mechanism is based on transforming a polygon spiral into spatial frustum shape using a mechanism composed of compliant links and joints that exhibits a bistable behavior. A number of mechanism types (graphs) were considered to implement the shapemorphing spiral, including 4-bar, 6-bar, and 8-bar chains. Our design requirements permitted the selection of a particular 8-bar chain as the basis for the BCCM. The bistable behavior was added to the mechanism by introducing a snap-through bistability as the mechanism morphs. A parametric CAD was used to perform the dimensional synthesis. The design was successfully prototyped. We anticipate that the mechanism may be useful in commercial small animal enclosures or as a frame for a solar still. Fig. 1 The-ball-on-a-hill analogy for bistable mechanisms.

Analytical Study of the Snap-Through and Bistability of Beams With Arbitrarily Initial Shape

“…Then, the buckling mode constants K j ( (23) and (37)) are obtained. Introducing the different coefficients and constants, the snap-through solution (18) and snapping force expressions ((24), (25), (34)) are obtained. Afterwards, the different snapping points ((29), (32), (33), (38), (39)) and the conditions for reaching different levels of axial compression (28) and for bistability (41) are determined.…”

“…The snap-through solution for a pre-shaped curved beam has the form in (18) where K j are calculated by introducing C j from (43) into (23): 9, 13... K j = 0 j = 3, 7, 11... K j = 0 j = 2, 4, 6... 9, 13... K j = 0 j = 7, 11, 15... K j = 0,C j = 0 j = 3 K j = 0 j = 2, 4, 6...…”

“…Bistable beams exhibit additional advantages, such as their simplicity, passive holding, low actuation energy, small footprint, large stroke with small restoring forces, and negative stiffness zone. These advantages make bistable beams suitable for an increasing number of applications at different scales, such as space applications [1], biomedical [2], energy harvesting [3,4], resonators [5], actuators [6] accelerometers [7], shock sensors [8], gas sensors [9], pressure sensors [10], flow sensors [11], grippers [12], mechanisms with large displacement and small actuation stroke [13], switches [14], relays [15], memory devices [16], logics [17], lamina emergent frustrum [18], statically-balanced mechanisms [19], soft robotics [20], constant force mechanisms [21,22], bistable positioning [23][24][25][26], and multistable devices [27][28][29][30][31][32].…”

Behavior Analysis of a Flexure Hinge Array

“…In the recent decades, a lot of researchers have suggested many types of hinges for LEMs [19,[21][22][23][24]. Particularly, LEMs well developed by benefitting of bistable advantages, foldable mechanism, and material strength [25][26][27][28][29]. However, the displacement of existing LETs and LEMs is still limited thanks to their designed structures.…”

Design and Performance Analysis of a TLET‐Type Flexure Hinge

“…When compared with traditional rigid-body mechanisms, LEMs take benefits of CMs, e.g., monolithic and simple fabrication process, compact size, lightweight, reduced assemble components, free friction, no lubricant, and reduced wear [10][11][12][13][14]. LEM is considered as a mechanism where its functions are similar to a transmission mechanism, e.g., four bar mechanism, spherical LEMs [15,16], slider crank mechanism [17,18], and bistable collapsible compliant mechanism [19]. Due to the aforementioned advantages, the LEMs have been widely utilized for a variety of engineering applications, e.g., automobile industry, electronic industry, biomedical engineering, rescue equipment, micro-electromechanical system, cellphone and tablet holder, card syringe, lift table, multilayer shoes, solar panel, and membrane switch [18].…”