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Seminar. Reporter : Chine-Feng Wu Advisor : Jeng-Tzong Chen Date : October 22, 2019 Space : HR1 104. Outline. Continuous system Discrete system SDOF MDOF. Question :.
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Seminar Reporter:Chine-Feng Wu Advisor:Jeng-Tzong Chen Date:October 22, 2019 Space:HR1 104 Department of Harbor and River Engineering
Outline • Continuous system • Discrete system • SDOF • MDOF Department of Harbor and River Engineering
Question : Consider a straight bar for which the axial stiffness EA and mass per unit length vary along its length as indicated in Fig. Department of Harbor and River Engineering
Notation • : Displacement in the axial direction • : Mass per unit length • : Modulus of elasticity • : Area • : Length • : Wave number • : Mass • : Spring constant • : Eigenvalues • : Eigenvetors Department of Harbor and River Engineering
The governing equation Department of Harbor and River Engineering
Dynamic equilibrium relationship • Where • The governing equations , Department of Harbor and River Engineering
The method of separation of variables The wave equation The boundary condition Department of Harbor and River Engineering
trivial trivial Department of Harbor and River Engineering
Eigenvalue & Eigenvector Department of Harbor and River Engineering
Eigenvalue Continuous system Department of Harbor and River Engineering
Eigenvetors Department of Harbor and River Engineering
Mode one of continuous system n=1 • Mode one of discrete System (詹雅馨) • Mode one of continuous system Department of Harbor and River Engineering
Mode two of continuous system n=2 • Mode two of discrete system (詹雅馨) • Mode two of continuous system Department of Harbor and River Engineering
Mode three of continuous system (n=3) • Mode threeof discrete system (詹雅馨) • Mode 3 of continuous system Department of Harbor and River Engineering
Discrete system Department of Harbor and River Engineering
Eigenvalue Department of Harbor and River Engineering
Eigenvetors Department of Harbor and River Engineering
Continuous system Department of Harbor and River Engineering
x t=10 t=0 y SDOF Department of Harbor and River Engineering
t=0 t=10 Department of Harbor and River Engineering
Rigid body G Example (1) Motorcycle frame Department of Harbor and River Engineering
G = Department of Harbor and River Engineering
G Example (2) Motorcycle frame Department of Harbor and River Engineering
Transform back to obtain the physical response. Solve the free vibration problem (eigenvalue problem) to obtain the natural frequencies and modal vectors. Solve the uncoupled equations to obtain the modal response. Evaluate the transformed mass, stiffness and force matrices. Form the modal matrix. Identify the generalized coordinates that will be used to describe the motion of the system. Derive the equations of motion for the system. Department of Harbor and River Engineering
where Department of Harbor and River Engineering
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