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The method of reverberation-ray matrix proposed by Pao et al. is applied to analyze the transient response of a multi-span pipe conveying fluid. The pipe under transverse vibration is considered as Timoshenko beam conveying axial flow. In the process of analysis, fast Fourier transform is used to convert the partial differential equation into ordinary differential equation. The support points of the pipe are chosen as the elements’ nodes. The transient wave motions at each node are divided into incident and reflected wave. By virtue of continuity and balance condition, the scattering relation is established between the above wave motions. The transient response is obtained by inverse fast Fourier transform. In the examples, the natural frequencies are calculated for single- and multi-span pipe conveying fluid with different fluid velocity, and great agreement is shown with the published literature. And then the transient responses, such as deformation, velocity, shear force and bending moment are obtained for a two-span pipe conveying fluid under different fluid velocity.

The fatigue tests were carried out on door frame containing single-side design and double-side design to assess the effect of different designs on fatigue life. By contrast, the finite element method (FEM) was also used to analyze the stress distribution of the two frames. At last, the fracture morphologies of the specimens after fatigue test were examined by scanning electron microscopy. The results revealed that the double-side design could elevate about 18∼21 times of fatigue life. The direction of crack propagation is transverse in single-side frame, while it is longitudinal in double-side frame.