Due to the importance of collecting rapping system in electrostatic precipitators (ESP) and controlling the relevant damage under impact loading, fatigue durability of this system is analyzed in the present study based on the numerical and experimental results considering fatigue damage growth and vibration acceleration in the collecting system because of the successive impact of rapping hammers. By microscopic examination of the fracture surface of rapping hammer, beach marks obviously show typical fatigue failure in the rapping hammer arm. In addition, the microscopic examination of the cross section of the collecting plates indicates the corrosion voids which cause crack and eventually fatigue failure. The finite element method is applied to determine both the stress and concentration positions of dynamic stress on the rapping system under impact loading. The paper results can be utilized in system optimization and new material selection for the system by evaluating rapping system durability. 1. Introduction Dust particles of combustion gases produced in various industries such as cement industry, copper melting, and iron melting play a significant role in environmental pollution [1, 2]. Therefore, to prevent emitting the dust into the environment, electrostatic precipitators (Figure 1) have been utilized in which a strong electrostatic field is applied to migrate dust particles and produced gas through the plates and electrodes. Then the gas and particles become ionized in the field (corona formation) and charged dust particles immigrate toward the collecting plates [3–5]. Finally by depositing a portion of dust particles on the discharge electrodes and according to the viscosity and the dust type of different industries a rapping system will be needed to make a vibration with proper acceleration and amplitude on the collecting plates (Figure 2) [6]. Figure 1: Electrostatic precipitator, collecting plates, and rapping system. Figure 2: Rapping system of collecting plates and the amount of acceleration in different points of the collecting plates. According to the investigations, the minimum acceleration to separate a dust cake of deposited dust particles on the collecting plates from these plates is 100？g (980？m/s2) (g is gravitational acceleration). The minimum and maximum accelerations caused by rapping on the collecting plates are illustrated in Figure 2. So, with the parameters like thickness, frame dimension, and material of collecting plates, the sufficient energy obtained by rapping should be provided in order to make such an acceleration
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