BilinearOilDamper Material: Difference between revisions
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| [[File:Fig1_OilDampers.jpg| | | [[File:Fig1_OilDampers.jpg|550px|thumb|left| Oil Damper with various input parameter variations]] | ||
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| [[File:Fig2_OilDampers. | | [[File:Fig2_OilDampers.jpg|550px|thumb|left| Oil Damper with various input parameter variations]] | ||
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Revision as of 15:07, 1 June 2015
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This command is used to construct a BilinearOilDamper material, which simulates the hysteretic response of bilinear oil dampers with a valve relief. Two adaptive iterative algorithms have been implemented and validated to solve numerically the constitutive equations within a bilinear oil damper with a high-precision accuracy.
| uniaxialMaterial BilinearOilDamper $matTag $K $Cd $alpha <$Fr $p> <$LGap> < $NM $RelTol $AbsTol $MaxHalf> |
| $matTag | integer tag identifying material |
| $K | Elastic stiffness of linear spring (to model the axial flexibility of an oil damper (brace and damper portion) |
| $Cd | Viscous parameter of oil damper |
| $alpha | Viscocity exponent |
| $Fr | Damper relief force (Damper property) |
| $p | Post-relief damping coefficient ratio (Damper property) |
| $LGap | gap length to simulate the gap length due to the pin tolerance |
| $NM | Employed adaptive numerical algorithm (default value NM = 1; 1 = Dormand-Prince54, 2=adaptive finite difference) |
| $RelTol | Tolerance for absolute relative error control of the adaptive iterative algorithm (default value 10^-6) |
| $AbsTol | Tolerance for absolute error control of adaptive iterative algorithm (default value 10^-6) |
| $MaxHalf | Maximum number of sub-step iterations within an integration step (default value 15) |
Examples:
| 1. Input parameters: | |
| Assume a bilinear oil damper with axial stiffness K=200.0kN/mm, viscous damping coefficient C=6.0KN/(mm/s), relief load Fr=1000.0KN, p=0.1. | The input parameters for the material should be as follows: |
| uniaxialMaterial BilinearOilDamper 1 200.0 6.0 1000 0.1 | |
| Using these properties, Figure 1c shows the hysteretic response of this damper for sinusoidal displacement increments of 12, 24 and 36mm and a frequency f = 1.0Hz. Figures 1a-1d show the damper hysteresis with varying post-relief viscous damping coefficient ratio (p=1.0, 0.5, 0.1, 0.0). | |
| Assume a bilinear oil damper with axial stiffness K=200.0kN/mm, viscous damping coefficient C=6.0KN/(mm/s), relief load Fr=1000.0KN, p=0.1 and LGap = 0.5mm due to the pin tolerance at the damper ends. | The input parameters for the material should be as follows: |
| uniaxialMaterial BilinearOilDamper 1 200.0 6.0 1000 0.1 0.5 | |
| Using these properties, Figure 2c shows the hysteretic response of this damper for sinusoidal displacement increments of 0.5, 1 and 1.5mm and a frequency f = 1.0Hz. Figures 2a-2d show the damper hysteresis with varying gap length (LGap = 0.0, 0.2. 0.5. 1.0 mm) | |
References:
| [1] | Akcelyan, S., and Lignos, D.G. (2015), “Adaptive Numerical Method Algorithms for Nonlinear Viscous and Bilinear Oil Damper Models Under Random Vibrations”, ASCE Journal of Engineering Mechanics, (under review). |
Code Developed and Implemented by : Sarven Akcelyan & Prof. Dimitrios G. Lignos, (McGill University)