# 4.14.5.3. ViscousDamper Material¶

uniaxialMaterial('ViscousDamper', matTag, K_el, Cd, alpha, LGap=0.0, NM=1, RelTol=1e-6, AbsTol=1e-10, MaxHalf=15)

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.

 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)