Frame17 – Vibration of a String Under Tension!

Example Description

A flexible string is attached to two supports and tensioned to 0.5 kips. The first three modes of the tensioned string are calculated and compared with independent results derived using formulas presented in Kreyszig 1983.
The string is modeled using a single frame object. Two different models are created for the comparison. The first has the frame object discretized into 10 elements and the second has it discretized into 100 elements.
The initial tension force is applied in this model through a static nonlinear analysis that is specified to consider P-Delta effects. The modal analysis to obtain the frequencies is performed in a second load case. The modal load case is specified to use the stiffness at the end of the static nonlinear case.

Tested Features

•  Static nonlinear analysis using the P-Delta option to provide tension stiffening
•  Modal analysis of frame for eigenvalues