{"id":162063,"date":"2023-01-25T07:34:13","date_gmt":"2023-01-25T07:34:13","guid":{"rendered":"\/knowledge\/forums\/topic\/how-to-deal-with-the-workbench-error-elasticity-is-required-but-is-currently-undefined-while-using-a-visco-elastic-material\/"},"modified":"2023-07-31T12:36:20","modified_gmt":"2023-07-31T12:36:20","slug":"how-to-deal-with-the-workbench-error-elasticity-is-required-but-is-currently-undefined-while-using-a-visco-elastic-material","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/how-to-deal-with-the-workbench-error-elasticity-is-required-but-is-currently-undefined-while-using-a-visco-elastic-material\/","title":{"rendered":"How to deal with the workbench error: &#8220;Elasticity is required, but is currently undefined&#8221; while using a visco-elastic material?"},"content":{"rendered":"<p>Viscoelastic behavior has a viscous (time-dependent) component acting upon the elastic (time independent) component. The elastic component can either linear (linear elasticity) or nonlinear elastic (hyperelastic). The viscous component is usually modeled using Prony series which uses the normalized shear moduli and the characteristic time constants (they come in pairs) as the material properties.  When viscoelastic shear data is being inputted, curve fitting needs to be performed to calculate the Prony series constants to complete the definition. Once this is done, the normalized shear moduli and their corresponding time constants are obtained. Since the moduli are normalized there is still a need to define an elastic component for the viscous component to act upon.  When the isotropic elasticity is not defined the material has no stiffness behavior associated with it and it throws the above-mentioned error. On the other hand, even when the isotropic elasticity is defined along with the &#8216;shear data &#8211; viscoelasticity&#8217; if the Prony constants are missing due to the lack of curve-fitting, there is no viscous behavior associated with it and the behavior observed would be just elastic.<\/p>\n","protected":false},"template":"","class_list":["post-162063","topic","type-topic","status-publish","hentry","topic-tag-4391","topic-tag-engineering-data","topic-tag-general","topic-tag-structural-mechanics"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Viscoelastic behavior has a viscous (time-dependent) component acting upon the elastic (time independent) component. The elastic component can either linear (linear elasticity) or nonlinear elastic (hyperelastic). The viscous component is usually modeled using Prony series which uses the normalized shear moduli and the characteristic time constants (they come in pairs) as the material properties. 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