Development of a shape memory polymer fastening system

Cable, K.; Hermiller, Jason; Kirby, Brandon D.; Sunday, Matthew

doi:10.1117/12.815376

Cited by 2 publications

(1 citation statement)

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“…Only a few studies, however, have attempted to use SMPs to manufacture releasable fasteners. Cornerstone Research Group Inc. developed shape memory 'smart' fasteners [2]. When two sides of the group's mushroom-shaped SMP fasteners were heated, they became flexible, thus enabling snap-on attachment.…”

Section: Introductionmentioning

confidence: 99%

Component assembly with shape memory polymer fastener for microrobots

Kim¹,

Lee²,

Koh³

et al. 2013

Smart Mater. Struct.

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Adhesives are generally used for the assembly of microrobots, whereas bolts, screws, or rivets are used for larger robots. Although adhesives are easy to apply, lightweight, and small, they cannot be used for repeated assembly and disassembly of parts. In this paper, we present a novel microfastener composed of a polyurethane-based shape memory polymer (SMP) that is lightweight and small but that is easily detached for disassembly. This was achieved by using the shape recovery and modulus change of the SMP. A sheet of macromolded SMP was laser machined into an I-beam-shaped rivet, and notches were added to the structure to prevent stress concentration. Pull-off tests showed that, as the notch radius increased, the disengagement strength of the rivet fastener decreased and the reusability increased. Through the elastoplastic model, a single SMP rivet was calculated to have maximum disengagement strength of 150 N cm−2 in the elastic range, depending on the notch radius. The fasteners were applied to a jumping microrobot. The legs and body were assembled with ten fasteners, which showed no permanent deformation after impact during jumping movements. The legs were easily replaced with ones of different stiffness by heating the engaged sites to make the fasteners compliant and detachable. The proposed detachable SMP microfasteners are particularly useful for testing the isolated performance of microrobot components to determine the optimal designs for these components.

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Section: Introductionmentioning

confidence: 99%

Component assembly with shape memory polymer fastener for microrobots

Kim¹,

Lee²,

Koh³

et al. 2013

Smart Mater. Struct.

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Time and Temperature Dependent Recovery of Epoxy-Based Shape Memory Polymers

Castro

Westbrook

Hermiller

et al. 2011

Journal of Engineering Materials and Technology

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Shape memory polymers (SMPs) are a group of adaptive polymers that can recover the permanent shape from a temporary shape by external stimuli on demand. Among a variety of external stimuli for polymer actuation, temperature is the most extensively used. In SMP applications, one of the major design considerations is the time necessary to recover the shape without external deformation constraints, or free recovery, and the amount of the recoverable strain. This paper investigates the amount of the recoverable strain and the recovery rate of an epoxy-based SMP (Veriflex® E, VFE1-62 (CRG, Dayton, OH)) under different thermal conditions. In particular, the free recovery behaviors of the SMPs under two experimental protocols, isothermal and shape memory (SM) cycle, are studied. It is found that free recovery in isothermal experiments is much faster than that in a SM cycle at the same recovering temperature and the material is fully recoverable at the temperature above differential scanning calorimetry Tg. Furthermore, for the recovery in SM cycle experiments, reshaping the sample at a low temperature and recovering from the deformation at a high temperature yield the fastest recovery rate, while reshaping at a high temperature and recovering at a low temperature cannot recover the original shape within this work’s experimental time frame. The possible mechanism for these observations is discussed.

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Development of a shape memory polymer fastening system

Cited by 2 publications

References 0 publications

Component assembly with shape memory polymer fastener for microrobots

Component assembly with shape memory polymer fastener for microrobots

Time and Temperature Dependent Recovery of Epoxy-Based Shape Memory Polymers

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