Maximum Dynamic Factor Research Articles

Prestressed Continuous Bridge Evaluation using Structural Health Monitoring System

Dorim Goh is a prestressed concrete (PSC) continuous bridge in Seuol, Korea. The structural health monitoring is used to assess the behavior of this bridge. 12 strain, 6 displacement and two accelerometer sensors are used to collect the behavior of the bridge under static and dynamic loads. The low-pass filter is used to estimate the static behavior of bridge and extract the accurate values for the bridge performances. Six’s cases of static loads and truck’s speeds from 10 to 60 Km/h are evaluated. The maximum strain and deflection collect during static loads are 60 με and 1.8 mm, respectively. Moreover, the distribution of stress on the bridge deck is assessed, and we find that the bridge status is safe under static loads. The dynamic factor (DF) is calculated during dynamic test, and the results show that the maximum DF is 0.228. In addition, Fast Fourier Transformation (FFT) is used to estimate the dominant frequency of bridge. The dominant frequency is estimated from acceleration measurements after filtering the collection data; the results show that the dominant frequency of bridge girder is 4.94 Hz. The results are compared with the design simulation model results and we find that the bridge is safe under applied loads.

Excitation prediction by dynamic transmission error under sliding friction in helical gear system

Monte Carlo method was adopted to calculate the meshing error considering the manufacture error and assembly error of the meshing point along the time-varying contact line for helical gear pair. The flexural-torsion-axis dynamic model coupled was established under the tooth friction force and solved by the perturbation method to compute real dynamic tooth load. The change laws of the friction force and friction torque were obtained in a meshing period. The transmission error formulation was analyzed to introduce meshing excitations. The maximum dynamic transmission error, the maximum meshing force and the maximum dynamic factor were calculated under different speeds, external loads and damping factors. The conclusions can provide theoretical basis for the gear design especially in tooth profile correction.