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Linear viscoelastic materials creep with adhesion

Nanometer-scale contacts to compliant linear viscoelastic materials can be studied experimentally with the scanning force microscope (SFM). Creep significantly modifies the formation and rupture of these contacts compared to contacts to elastic materials. Not only does the maximum contact area depend on the loading history but, unlike elastic materials, it reaches its maximum value well after the maximum load is applied. Effects due to creep are distinct firom those induced at the periphery of the contact by adhesion. Creep effects dominate adhesion effects in SFM-scale contacts for a wide range of compliant viscoelastic materials. Strategies are presented to optimize experimental parameters for creep studies in SFM-scale contacts to linear viscoelastic materials. [Pg.66]

We also show that the time dependent response of SFM-scale contacts to linear viscoelastic materials should be dominated by creep response in the bulk, rather than adhesion effects at the contact periphery even for materials with effective moduli as large as 10-100 MPa. [Pg.81]

Typical examples of tensile (isochronous) linear and nonlinear stress-strain diagrams for elastic and viscoelastic materials are shown in Fig, 10.1. For elastic materials, the response is time independent, so there is a single curve for multiple times and the nonlinearity is apparent as a deviation of the stress-strain response from linear. For linear viscoelastic materials, the isochronous response is linear, but the effective modulus decreases with time so that the stress-strain curves at different times are separated from one another. When a viscoelastic material behaves nonlinearly, the isochronous stress-strain curves begin to deviate from linearity at a certain stress level. Fig. 10.2 shows creep compliance data for an epoxy adhesive as a function of stress level for various time intervals after initial loading. [Pg.328]

Creep in Viscoelastic Contacts in the Absence of Adhesion. Viscoelastic effects are important whenever contact dimensions change in a time interval that is comparable to a characteristic relaxation time rof the viscoelastic material. Ting (5), following earlier work by Lee and Radok (26), Ting obtained a general solution to the Hertz contact problem for the case of a rigid axisymmetric probe and a substrate with linear viscoelastic response. He used the boundary conditions... [Pg.71]


See other pages where Linear viscoelastic materials creep with adhesion is mentioned: [Pg.363]    [Pg.67]    [Pg.876]   
See also in sourсe #XX -- [ Pg.77 , Pg.78 , Pg.79 ]




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