Adhesion and rupture

Maugis, D., Contact, Adhesion and Rupture of Elastic Solids. Solid State Sciences. Springer, Berlin, 2000. 

Johnson, K.L., Contact Mechanics, Cambridge University Press, Cambridge, UK 1985 see also Johnson, K.L. and Greenwood, J.A., J, Colloid Int. Sci. 192, 326-33 (1997) see also Maugis, D., Contact, Adhesion and Rupture of Elastic Solids, Springer, Berlin (1999) 284-296. 

The theory that we have developed does not demand that all fibrils and their bases be the same size, or that their mechanical properties be identical. Chain entanglement is a statistical property, and (as already noted) the number of chains per fibril is small enough that serious fluctuations in local properties are to be expected. Even if, in a particular case, the vast majority of fibrils detach cleanly and without leaving any polymer on the solid, a small fraction of the fibrils may rupture, in an experiment of "adhesive" separation. Likewise in a frictional experiment even when, at the majority of points of adhesional attachment, detachment occurs without appreciable fibril drawing, there may be fibrildrawing and rupture at a few sites and consequently, wear will occur. 

The tensile standard uses the tensile dumbbells standardized in ISO 527-2 and requires that the load applied be maintained within I % of the desired load. The loading mt chan-ism must be designed both to apply the load smoothly and without overshoot and to do this consistently. In creep testing it is essential to avoid any shocks at any time during the test. The strain must be measured to an accuracy of 0.01mm, and the elapsed lime to 0.1 %. Contactless optical extensometers are recommended, e.spccially for creep rupture tests. The standard slates that strain gauges are only suitable w-here they can be attached by adhesive, and only when the adhesion quality is constant throughout the lest. 

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