###### Abstract  
In order to investigate the vibration characteristics of a composite sleeper-ballasted track and provide a basis for further popularization, a vehicle-track dynamic coupling model is established and the viscoelastic properties of the composite sleeper are considered. The power flow method is employed to reveal the power flow distribution characteristics of the composite sleeper. The results show that the viscoelastic properties of the composite sleeper have little influence on the rail power and have a greater influence on the power flow of the sleeper and ballast bed in some frequency ranges. The viscoelastic properties of the composite sleeper can effectively improve the calculation accuracy of the track structure's power flow. Compared with the type-III pre-stressed concrete sleepers widely used in China, composite sleepers consume more energy in the vibration process due to their own physical characteristics, which reduces the power flow transmitted downward and relieves vibration on the ballast bed, especially in the ranges of 80-125 Hz and 250-400 Hz. The temperature change mainly affects the power flow of the composite sleeper in the frequency range above 50 Hz. As the temperature increases, the modulus of the composite sleeper decreases and the vibration reduction effect of the ballast bed is improved. composite sleeper; power flow; ballasted track; vibration energy; viscoelastic properties +
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[PERSON] [2], [PERSON] [4], and [PERSON] [5] have discussed the effects of employing composite materials to repair sleepers or of developing composite sleepers to replace timber sleepers. [PERSON] et al. [6] classified composite sleepers into three categories according to the length, number, and direction of fibers in composite sleepers at present, and analyzed the challenges that composite sleeper technology will overcome. [PERSON] et al. [7] studied the optimum parameters for making composite sleepers using wood and bamboo composite hybrid materials. [PERSON] et al. [8] developed a composite sleeper using sandwich panels, which is suitable for narrow-gauge railways. [PERSON] et al. [9; 10; 11; 12] systematically tested the mechanical properties of high-density polyethylene composite sleepers. The assembly fatigue performance, bending behavior, and spike pullout behavior of the sleepers were tested. In the spike pullout tests, the effects of different spike types, reserved hole diameters, depths, and temperatures were tested, and the test results were relatively satisfactory. [PERSON] [13] compared and analyzed the influences of composite sleepers and concrete sleepers on the mechanical properties of track structures. It was found that composite sleepers can increase the contact area between the ballast bed and sleepers and can reduce the maximum contact forces. [PERSON] et al. [14] studied the influence of composite sleepers (fiber-reinforced foamed urethane (FFU)) on track geometry, dynamic performance, and noise in the turnout area. It was found that FFU sleepers and timber sleepers have equivalent dynamic and static performance, and that the former have a longer service life. [PERSON] [15] optimized composite sleepers of different structural types to increase their lateral resistance, tested the lateral resistance, and recommended the best design. [PERSON] [16] investigated the dynamic performance of a composite sleeper-ballasted track by conducting wheel drop tests and calculated the damping parameters and dynamic stiffness of the track structure. Most research works have mainly focused on the material compositions and mechanical properties of composite sleepers. Few studies have focused on the vibration energy of composite sleepers. The mechanical parameters of composite sleepers are usually considered as constants in the whole frequency range [17; 18]; however, composite sleepers are composed of rubber, plastic, and other polymers, which have viscoelastic properties.