Microplane model M4 - Microplane_M4

Model M4 covers inelastic behavior of concrete under complex triaxial stress states. It is based on the microplane concept and can describe softening. However, objectivity with respect to element size is not ensured - the parameters need to be manually adjusted to the element size. Since the tangent stiffness matrix is not available, elastic stiffness is used. This can lead to a very slow convergence when used within an implicit approach. The model parameters are summarized in Tab. 39.

Table 39: Microplane model M4 - summary.

Description	M4 material model
Record Format	Microplane_M4 nmp(in) # c3(rn) # c20(rn) # k1(rn) # k2(rn) # k3(rn) # k4(rn) # E(rn) # n(rn) #
Parameters	- nmp number of microplanes, supported values are 21, 28 and 61
	- n Poisson ratio
	- E Young modulus
	- c3,c20, k1, k2, k3, k4 model parameters
Supported modes	3dMat