Solid solution additives elastic strain

In many practical systems, polymers are added to solutions to conttol their flow characteristics. The attractive feature of polymeric additives is that even in rather low concenttations they can dramatically affect the rheology of a fluid, imparting to a solution properties intermediate between those of elastic solids and those of viscous fluids. The elastic behavior is dominant in solids. It is described by Hooke s law (a = Ey, Eq. 19, see above). Viscous behavior is dominant in simple liquids. It is described by Newton s law (Eq. 43), which states that the applied stress a is proportional to the rate of strain dyidt, with a proportionality constant ii, the viscosity. 

The structural solution computes the full 3D elastic-plastic deformation and stress fields for the solid components of the stack. The primary stress-generation mechanism in the SOFC is thermal strain, which is calculated using the coefficient of thermal expansion (CTE) and the local temperature difference from the material s stress-free temperature. These thermal strains and mismatches in thermal strains between different joined materials cause the components to deform and generate stresses. In addition to the thermal load, the stack will have boundary conditions simulating the mechanical constraints from the rest of the system and may also have external mechanical preloading. The stress solution is obtained based on the imposed mechanical constraints and the predicted thermal field. Figure 26.6 shows... 

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