Tuned Mass Damper Design for Attenuating Vibration
Introduction
A mass-spring-damper is disturbed by a force that resonates at the natural frequency of the system. This application calculates the optimum spring and damping constant of a parasitic tuned-mass damper that the minimizes the vibration of the system. The vibration of system with and without the tuned mass-spring-damper is viewed as a frequency response, time-domain simulation and power spectrum.
restart:withDynamicSystems:withColorTools:
Derive Expressions for the Optimum Spring and Damping Constant of the Tuned Mass Damper
Natural frequency of the tuned mass damper:
ω__2≔k__2m__2:
Natural frequency of the main system:
ω__1≔k__1m__1:
Ratio of the natural frequencies:
α≔ω__2ω__1
α≔k__2m__2k__1m__1
Optimum ratio of natural frequencies:
α__opt≔11+m__2m__1:
Hence the optimum spring constant of the tuned mass-spring-damper:
k__2_opt≔solve⁡α=α__opt,k__2
k__2_opt≔m__1⁢k__1⁢m__2m__1+m__22
Damping ratio:
z≔b__22 m__2 ω__2:
Optimum damping ratio:
z__opt≔3 m__2m__18 1+m__2m__13:
Hence the optimum damping constant of the tuned mass-spring-damper:
b__2_opt≔subsk__2=k__2_opt,solvez=z__opt,b__2
b__2_opt≔6⁢m__2m__1⁢1+m__2m__13⁢m__1⁢k__1m__1+m__22⁢m__22
System Parameters
Main spring mass damper parameters:
params__main≔m__1=1.764 105,k__1=3.45 107,b__1=1.531 105:
Mass of the tuned mass damper:
m__TMD≔8165:
Optimum spring and damping constants of the tuned mass damper are:
k__2_calc≔evalk__2_opt,params__main,m__2=m__TMD;
k__2_calc≔1.458730861×106
b__2_calc≔evalfevalb__2_opt,params__main,m__2=m__TMD;
b__2_calc≔26869.77096
Parameters for the system with and without a tuned mass damper:
params__TMD≔params__main,m__2=m__TMD,k__2=k__2_calc,b__2=b__2_calc:params__noTMD≔params__main,m__2=0,k__2=0,b__2=0:
Equations of Motion for the Entire System
de:=m__2⁢ⅆ2ⅆt2⁢x__2t=−k__2 x__2t−x__1t−b__2 ⅆⅆt⁢x__2t−ⅆⅆt⁢x__1t, m__1 ⅆ2ⅆt2⁢x__1t=−k__1 x__1t−b__1 ⅆⅆt⁢x__1t−k__2 x__1t−x__2t−b__2 ⅆⅆt⁢x__1t−ⅆⅆt⁢x__2t+Ft:ic:=x__10=0,D⁡x__1⁡0=0,x__20=0,D⁡x__2⁡0=0:
sys:=DiffEquation⁡de,F⁡t,x__1t:
Frequency Response
Response with tuned mass damper:
p1:=MagnitudePlot⁡sys,range=5..30,parameters=params__TMD,color=ColorRGB,0/255,79/255,121/255,legend=Tuned:
Response with no tuned mass damper:
p2≔MagnitudePlotsys,range=5..30,parameters=params__noTMD,color=ColorRGB,150/255,40/255,27/255,legend=Not Tuned:
plots:-displayp1,p2,size=800,400,thickness=2,axesfont=Calibri,labelfont=Calibri,background=ColorRGB,218/255,223/255,225/255,legendstyle=font=Calibri
Dynamic Response
Assume that the system is perturbed at the natural frequency of the system.
f__nat≔evalω__1,params__main
f__nat≔13.98492872
p3≔ResponsePlotsys,7500⁢sinf__nat⋅t,parameters=params__TMD,color=ColorRGB,0/255.,79/255,121/255,legend=Tuned:
p4≔ResponsePlotsys,7500⁢sinf__nat t,parameters=params__noTMD,color=ColorRGB,150/255,40/255,27/255,legend=Not Tuned:
plots:- displayp3,p4,axesfont=Calibri,thickness=2,size=800,400,gridlines,axesfont=Calibri,labelfont=Calibri,background=ColorRGB,218/255,223/255,225/255,legendstyle=font=Calibri
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