Calculating incompressibility parameter for Ogden Material Model

- January 16, 2019 at 5:04 pm
  
  zjuv9021
  Subscriber
  
  Hi all,
  
  I have Silicone rubber (mu1= 140 psi, alpha1 = 1.6), and two polyurethanes (mat 1: mu1= 2000 psi, alpha1 = 1.4; mat 2: mu1 = 855 psi, alpha =1.04), and am required to have an Incompressibility Parameter D1 for all 3. Do you know how to calculate this/get a ballpark estimate for Ogden 1st Order Materials?
  
  Also, what does this number do and how significant is it for convergence behavior? For instance, If I say my D1 is 1E-08, am I going to have more convergence difficulties in comparison to if I chose D1 to be 1E-05, three orders of magnitude larger?
  
  Kind Regards,
  
  Zach
- January 16, 2019 at 6:21 pm
  
  jj77
  Subscriber
  
  In the software I mostly use (Strand7), there is no such parameter.
  
  From a couple of examples seen on the internet this parameter (d1), is related to the incompressibillity of the material and is taken (at least for other hyp. el. models, and Ogden), as 2/K, where K is the bulk modulus of the material.
- January 16, 2019 at 6:23 pm
  
  peteroznewman
  Subscriber
  
  Hi Zach,
  
  Here is one way to obtain a value for D1. Though that link shows Yeoh, the same formula is used for Ogen if you check the material reference in ANSYS help.