UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Spherical indentation analysis of stress relaxation for thin film viscoelastic materials

Cheneler, D; Mehrban, N; Bowen, J; (2013) Spherical indentation analysis of stress relaxation for thin film viscoelastic materials. Rheologica Acta , 52 (7) pp. 695-706. 10.1007/s00397-013-0707-5. Green open access

[thumbnail of Mehrban_Spherical indentation analysis.pdf]
Preview
Text
Mehrban_Spherical indentation analysis.pdf - Accepted version

Download (737kB) | Preview

Abstract

The mechanical testing of thin layers of soft materials is an important but difficult task. Spherical indentation provides a convenient method to ascertain material properties whilst minimising damage to the material by allowing testing to take place in situ. However, measurement of the viscoelastic properties of these soft materials is hindered by the absence of a convenient yet accurate model which takes into account the thickness of the material and the effects of the underlying substrate. To this end, the spherical indentation of a thin layer of viscoelastic solid material is analysed. It is assumed that the transient mechanical properties of the material can be described by the generalised standard linear solid model. This model is incorporated into the theory and then solved for the special case of a stress relaxation experiment taking into account the finite ramp time experienced in real experiments. An expression for the force as a function of the viscoelastic properties, layer thickness and indentation depth is given. The theory is then fitted to experimental data for the spherical indentation of poly(dimethyl)siloxane mixed with its curing agent to the ratios of 5:1, 10:1 and 20:1 in order to ascertain its transient shear moduli and relaxation time constants. It is shown that the theory correctly accounts for the effect of the underlying substrate and allows for the accurate measurement of the viscoelastic properties of thin layers of soft materials.

Type: Article
Title: Spherical indentation analysis of stress relaxation for thin film viscoelastic materials
Open access status: An open access version is available from UCL Discovery
DOI: 10.1007/s00397-013-0707-5
Publisher version: https://doi.org/10.1007/s00397-013-0707-5
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Transient shear moduli, Generalised standard linear solid model, Stress relaxation, Spherical indentation, Soft solids
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > The Ear Institute
URI: https://discovery.ucl.ac.uk/id/eprint/10088257
Downloads since deposit
14Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item