Hardness, Abrasion and Friction

Abrasion is measured by the depletion in mass of a body after being in 

FIGURE 4-37 Creep and stress relaxation profiles (three-dimensionaD 

Creep appears in the 7-t plane (iso stress), while the stress-strain relationship (at a fixed time) is described by the S-7 plane. Stress relaxation (at constant strain) is described by the S-t plane. Premium engineering polymers or reinforced thermosets illustrate a relatively low creep. Fiber reinforcement usually decreases the creep. 

Stress relaxation, another viscoelastic feature, may be expressed for the simple case (a Maxwell model) by a decay function, as mentioned in Section 4.1  

While stress relaxation does not control material fracture, it is frequently measured while following the environmental resistance of elastomers. Thermosets show very low relaxation. 

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