粘弹性

Viscoelastic behavior is a consequence of the time-dependent rearrangement of a material’s microstructure. When a stress is applied, some of the energy is stored elastically in the stretching or bending of molecular bonds, while some is dissipated as heat through the viscous sliding of molecules past one another. This dual behavior leads to several characteristic phenomena. One is creep, where the material continues to deform slowly over time under a constant load. Another is stress relaxation, where the stress required to maintain a constant strain decreases over time as the material’s internal structure rearranges.

This time-dependent response is often modeled using combinations of ideal springs (representing the elastic component, following Hooke’s Law) and dashpots (representing the viscous component, following Newton’s Law of Viscosity). Simple models like the Maxwell model (spring and dashpot in series) and the Kelvin-Voigt model (spring and dashpot in parallel) capture the basic features of stress relaxation and creep, respectively. More complex models, such as the Standard Linear Solid model, combine these elements to provide a more accurate description of real materials.

粘弹性材料的行为也高度依赖于温度和施加的应变率。在低温或高应变率下，它们的行为更像弹性固体；而在高温或低应变率下，它们的行为更像粘性流体。这被称为时间-温度叠加原理。