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1. ### I Elastic Constants for Natural Rubber

Hi, Looking for the Elastic Constants for any rubber-like material such as Natural Rubber. It can be inorganic or organic. The constants I am looking for take the form of a fourth-rank tensor. I only need the first order elasticities, not the zeroth or higher (not Cij or Cijklmn.. just Cijkl)...
2. ### I Usage of First Order Elastic Constants in Soft Body Equations

Yeah, yeah, you're totally right.. where is my mind at! So, C2132 = C1232 = C1223 and Eijmn also equals Ejinm. Since Ejinm wasn't specified, just wanted to double check. And sorry for the delay, want to be thorough in proving these symmetries check out, but my mind is super full trying to...
3. ### I Usage of First Order Elastic Constants in Soft Body Equations

Hi, I have some soft body equations that require first order elasticity constants. Just trying to figure out the proper indexing. From Finite Elements of Nonlinear Continua by J.T. Oden, the elastic constants I am trying to obtain are the first order, circled below: My particular constitutive...
4. ### Tetrahedron Simplex Shape Functions in FEA

Hi, I've bought several books on this and related topics including "Peter I. Kattan MATLAB Guide to Finite Elements An Interactive Approach" which I just found out has a download link here https://extras.springer.com/2008/978-3-540-70697-7.zip Does the book you mention cover details on 3D shape...
5. ### Tetrahedron Simplex Shape Functions in FEA

Hi, 2 part question trying to get tetrahedron Finite Element shape functions working: 1) How do I properly setup the shape coefficient matrix and 2) How do I build the coefficient quantities in the shape functions properly? ANY tips or corrections may unblock me and would be of much value...