Functional buckling behavior of silicone rubber shells for biomedical use

The use of soft elastic biomaterials in medical devices enables substantial function integration. The consequent increased simplification in design can improve reliability at a lower cost in comparison to traditional (hard) biomaterials. Functional bi-stable buckling is one of the many new mechanism...

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Bibliographic Details
Published in:Journal of the mechanical behavior of biomedical materials 2013-12, Vol.28, p.47-54
Main Authors: van der Houwen, E.B., Kuiper, L.H., Burgerhof, J.G.M., van der Laan, B.F.A.M., Verkerke, G.J.
Format: Article
Language:English
Subjects:
Biocompatible Materials - chemistry
Biomaterials
Biomedical materials
Buckling
Elasticity
Humans
Mechanical testing
Rubber - chemistry
Rubber shells and membranes
Shells
Silicone rubber
Silicones - chemistry
Simplification
Snap-through buckling
Soft materials
Stability
Structural failure
Surgical implants
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Summary:The use of soft elastic biomaterials in medical devices enables substantial function integration. The consequent increased simplification in design can improve reliability at a lower cost in comparison to traditional (hard) biomaterials. Functional bi-stable buckling is one of the many new mechanisms made possible by soft materials. The buckling behavior of shells, however, is typically described from a structural failure point of view: the collapse of arches or rupture of steam vessels, for example. There is little or no literature about the functional elastic buckling of small-sized silicone rubber shells, and it is unknown whether or not theory can predict their behavior. Is functional buckling possible within the scale, material and pressure normally associated with physiological applications? An automatic speech valve is used as an example application. Silicone rubber spherical shells (diameter 30mm) with hinged and double-hinged boundaries were subjected to air pressure loading. Twelve different geometrical configurations were tested for buckling and reverse buckling pressures. Data were compared with the theory. Buckling pressure increases linearly with shell thickness and shell height. Reverse buckling shows these same relations, with pressures always below normal buckling pressure. Secondary hinges change normal/reverse buckling pressure ratios and promote symmetrical buckling. All tested configurations buckled within or closely around physiological pressures. Functional bi-stable buckling of silicone rubber shells is possible with adjustable properties in the physiological pressure range. Results can be predicted using the proposed relations and equations. Small rubber shells (top) can be used in medical devices to perform switching operations, like in a tracheostoma valve (below). Their behavior can now be estimated using buckling theory and limited experiments. [Display omitted] . •Functional snap through buckling pressures of small rubber shells can now be estimated using buckling theory and limited experiments.•Small rubber shells can be designed to buckle and buckle back under physiological pressures.•Small rubber shells can be used in medical device designs to perform switching or check valve operations.
ISSN:1751-6161
1878-0180
DOI:10.1016/j.jmbbm.2013.07.002