A universal defining equation of ultrasonic vibration system is derived,with its definite solution ascertained involving both linear and nonlinear boundary conditions.Then,based on the wave theory,universal defining equation of composite radius-changing horn is given in exponential form,and the linear boundary condition is set to solve the sectionalized nonlinear equation to derive the general expressions of wave node position and amplification coefficient relevant to the horn.Furthermore,the nonlinear boun...