.. function:: uniaxialMaterial('ViscousDamper', matTag, K_el, Cd, alpha, LGap=0.0, NM=1, RelTol=1e-6, AbsTol=1e-10, MaxHalf=15)
:noindex:
This command is used to construct a ViscousDamper material, which represents the Maxwell Model (linear spring and nonlinear dashpot in series). The ViscousDamper material simulates the hysteretic response of nonlinear viscous dampers. An adaptive iterative algorithm has been implemented and validated to solve numerically the constitutive equations within a nonlinear viscous damper with a high-precision accuracy.
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``matTag`` |int| integer tag identifying material
``K_el`` |float| Elastic stiffness of linear spring to model the axial
flexibility of a
viscous damper (e.g. combined stiffness of the
supporting brace and
internal damper portion)
``Cd`` |float| Damping coefficient
``alpha`` |float| Velocity exponent
``LGap`` |float| Gap length to simulate the gap length due to the
pin tolerance
``NM`` |int| Employed adaptive numerical algorithm (default
value NM = 1;
* ``1`` = Dormand-Prince54,
* ``2`` = 6th order Adams-Bashforth-Moulton,
* ``3`` = modified Rosenbrock Triple)
``RelTol`` |float| Tolerance for absolute relative error control of the adaptive
iterative algorithm (default value 10^-6)
``AbsTol`` |float| Tolerance for absolute error control of adaptive iterative
algorithm (default value 10^-10)
``MaxHalf`` |int| Maximum number of sub-step iterations within an
integration step (default value 15)
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.. seealso::
`Notes <http://opensees.berkeley.edu/wiki/index.php/ViscousDamper_Material>`_