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m. m. 2m. 2m. Chap 5. Multi DOF. Normal Mode Analysis Ex 5.1-1 Undamped 2DOF. To have non-trivial Soln. 1. 1. 0.731. -2.73. In - phase. Out – of - phase. Initial Conditions. In general , undamped 2DOF are coupled.
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m m 2m 2m Chap 5. Multi DOF Normal Mode Analysis Ex 5.1-1 Undamped 2DOF
1 1 0.731 -2.73 In - phase Out – of - phase
Initial Conditions In general , undamped 2DOF are coupled Using principal coords (normal coords) , two eqns are decoupled
m2 m1 5.4 Forced Harmonic Vibration
Chap 7. Lagrange’s Equation Hamilton’s Principle W.R.Hamilton (1805-1865) : Irish Mathematician
Explicit : Central Difference , Runge-Kunta Implicit : Houbolt , Newmark β , wilson θ , Hughes α • Direct Integration MDM MAM LDRV , Lanczos , Krylov • Superposition Chap 11. Mode-Summation Procedures for Continuous Systems • Superposition & Direct Integration
Mode Superposition Method Mode Displacement Method (MDM)
Krylov Sequence Krylov Sequence
Load Dependent Ritz Vectors (LDRV) Load Dependent Ritz Vectors (LDRV)
References Lanczos Algorithm Nour-Omid, B. and Clough, K.W.,”Dynamic Analysis of Structure using Lanczos Co-ordinates”, Earthquake Eng. And structure Dyn.Vol. 12, pp 565-577 ,1984 Load Dependent Ritz Vectors (LDRV) Kline, K.A., ”Dynamic Analysis Using a Reduced Basis of Exact Modes and Ritz Vectors”, AIAA J, Vol. 24, pp2022-2029, 1986 Wang, S. and Choi, K.K. ,”Continuum Design Sensitivity of Transient Response Using Ritz and Mode Acceleration Methods”, AIAA J ,Vol. 30, pp1099-1109, 1992. Iterative Solution