Fig. 5

The first four linear mode shapes of a (SS) beam subjected to a partially variable foundation \(k_r^{2f*} = \eta (1 + \sin (\alpha x_r^*))\), analyzed for various values of \(\eta\), with \(\alpha = 3\) and \(\chi = 0.7\).

The first four linear mode shapes of a (SS) beam subjected to a partially variable foundation \(k_r^{2f*} = \eta (1 + \sin (\alpha x_r^*))\), analyzed for various values of \(\eta\), with \(\alpha = 3\) and \(\chi = 0.7\).