Material Property ElementMAT2 lets you define a hyper-elastic material model for NLFE elements that follows the incompressible Neo-Hookean material law.


       id       = "integer"
       mu       = "real"       
       nu       = "real"
       rho      = "real"
       YS       = "real"


Unique material property identification number.
Shear modulus for the element.
Poisson's ratio for the element. Default is 0.49.
Element density.
An elastic limit for strain. Default is 0.0.
YS >= 0.0


The example demonstrates the definition of a MAT2 element.

<MAT2 id="1" mu="1.906036" nu="0.499" rho="2.150e-6" YS="0.125"/>


  1. This material element defines a hyper-elastic material that obeys the incompressible Neo-Hookean law for the strain energy density function:

    U = μ 2 ( I ¯ 1 3 ) + k 2 ( J 1 ) 2


    μ is the shear modulus; μ = N K T , where N is the number of polymer chains per unit volume, K is the Boltzmann constant, and T is temperature

    k = 2 μ ( 1 + v ) 3 ( 1 2 v ) is the bulk modulus

    v is the Poisson's ratio

    I ¯ 1 = J 2 3 I 1 , I 1 = t r ( C ) = r x T r x + r y T r y + r z T r z

    J = det ( J ) = r x T ( r y × r z )

    Each element must have a unique material identification number.

  2. This material model can only be used with a fully parameterized element (BEAM12, QUAD12, TRIA12 and solid elements).
  3. YS lets you specify a maximum limit on the elastic strain that the component is allowed. If, during the simulation, the component strain (at any element in the component) exceeds this value, MotionSolve issues a warning message.