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/VISC/PRONY

/VISC/PRONY

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/VISC/PRONY

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/VISC/PRONY - Visco-Elastic Law

Description

This is an isotropic visco-elastic Maxwell model that can be used to add visco-elasticity to certain shell and solid element material models. The visco-elasticity is input using a Prony series.

Format

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/VISC/PRONY/mat_ID/unit_ID

M

 

Kv

 

 

 

 

 

 

 

Read only if M > 0. Read M card

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Gi

 

 

 

 

 

 
hmtoggle_plus1Flag Definition

Field

Contents

SI Unit Example

mat_ID

Material identifier which refers to the viscosity card

(Integer, maximum 10 digits)

 

unit_ID

Optional unit identifier

(Integer, maximum 10 digits)

 

M

Maxwell model order (number of Prony coefficients)

Default = 0  (Integer)

 

Kv

Optional viscous bulk modulus

Default = 0.  (Real)

Gi

Shear relaxation for ith term (i=1, M)

(Real)

Shear decay for ith term (i=1, M)

(Real)

hmtoggle_plus1Comments
1.For shell elements this model is available with /MAT/LAW66 and /MAT/LAW25. For solid elements it is available with hyperelastic material laws /MAT/LAW42, /MAT/LAW69, and /MAT/LAW82.
2.The viscosity effect is taken into account by using a Prony series. The deviatoric viscous stress is given by the convolution integral of the form:

with

and denotes the deviatoric part of strain tensor.

Shear decay:

where is a relaxation time.

3.The viscous pressure is given by:

4.Starting with RADIOSS version 2017, identical results are obtained using the same Prony coefficents Gi in /VISC/PRONY and viscoelastic materials /MAT/LAW34, /MAT/LAW40, and /MAT/LAW42.  In previous RADIOSS versions, 2 Gi had to be input into /VISC/PRONY to get equivalent results.

See Also:

Material Compatibility