Abstract:This study establishes wave equation of simple three semi-infinite beams coupled at arbitrary angles based on the theory of Euler-Bernoulli beam with internal damping taken into account. According to the equilibrium and continuity conditions of the junction, near-field amplitude subjected to flexural wave and longitudinal wave excitations is derived. Due to the introduction of internal damping coefficient, the near-field terms will be attenuated. Near-field dissipation power coefficients are obtained from the relationship between the vibration amplitude and the vibration power. An example of three semi-infinite beam junctions coupled at arbitrary angles is studied to reveal the effects of internal damping coefficient, coupled angles and excitation frequency on near-field dissipation power coefficient. Numerical results show some interesting phenomena and this study can provide references and guidelines for the design of vibration of coupled beams.