Question

I. 20% Consider the undamped vibration absorber discussed in class. The excitation frequency is w. Re-derive the forced response magnitudes of the main mass and the absorber mass Xa(t) FO)-Fo sin o f tx( as well as the vibration absorber design criterion ma Discuss the effect of absorber mass selection. What if the excitation frequency is equal to the original resonance frequency »,m

Answer 1

Ka rm assuming hamoníc Scluhon Fc mtoZeno ไท erdv-to make amplifudz

ka ma 9f the machine before addihon of nomic v,'bration abimben冲erates

machine operah'ng at its resoont FG Ka and ω Ma.

2 St La - (ni) St Co

Without absorber With absorber With absorber 16 m2 1l m 20 12 4 21 0.6 0.7 0.8 0.91.0 1.2 1.3 ωί

St -Te's shows that force ex eted bǎauxil'e 3E can be seen fro m毛 Eliminat,na Vibmhon a the impre , ed uency uo introduces uo

fue m a different mass (ma ahsorbers effeets Shown be louo

2.6 122 for 02-0,5 2.2 112 for ω2 for 1.2 1.0 0.8 0.6 0.4 0.2 0.0 for -0.5 g1 for n 20 0 0.2 0.4 0.6 0.8