Perception and sense of touch are extremely important factors in design, but until
recently, the exploration of skin tribology related to tactility has been relatively
untouched. In this emergence, skin-on-polymer interactions are becoming more widely
investigated due to the prevalence of polymers in everyday life, and the ability to define
these interactions in terms of tactility would be hugely beneficial to the engineering and
design process.
Previous work has investigated polymer textiles concerning tactility, examining
environmental and material properties that affect skin on fabric coefficient of friction. In
this study, similar friction procedure was used to compare coefficients of friction of a
fingerpad across varying polymer fabrics. Forces were applied in both longitudinal and
lateral directions, and it was discovered that force directionality greatly affects
coefficient of friction. Specific causes have yet to be determined, but it is suspected that
material weave and microscopic surface properties play a major role in this directional
behavior. To complement these studies and relate them to tactility, trained human
evaluators rated the samples against four tactile attributes: abrasiveness, slipperiness, sensible texture, and fuzziness. These ballots were then analyzed with Quantitative Data
Analysis and shown to be repeatable among the participants, and each of the attributes
were shown to be statistically independent of coefficient of friction. It should be noted,
however, that fuzziness showed the greatest correlation coefficient of R^2=0.27.
Material selection plays an integral role in frictional behavior, and researchers
have been studying contact theory on both microscopic and macroscopic levels to
determine how surface topography affects skin-polymer tribology. To negate material
effects discussed in the Greenwood-Williamson contact model, frictional tests were
performed on identical polypropylene plaques with textured grooves of varying
dimensions. Both geometry and directionality proved to be major frictional contributors;
as groove size increased, finger friction in the longitudinal direction decreased, but
friction increased laterally. In addition to testing a fingerpad, friction was measured with
a silicone wand to simulate a finger with different material properties. The silicone
exhibited the opposite trend as skin; as groove width decreased, frictional forces
increased longitudinally and decreased laterally. While topography affects frictional
behavior, counterface stiffness, and intrinsic material properties may cause the trend
shift between skin and silicone.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2010-12-8993 |
| Date | 2010 December 1900 |
| Creators | Darden, Matthew Aguirre |
| Contributors | Schwartz, Christian J. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | thesis, text |
| Format | application/pdf |
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