Aditya Sukma Nugraha

Rotor-Dynamic Characteristic Evaluation of Generator Geothermal Power Plant Using Finite Element Method

Dynamic characteristics of a critical speed of the rotor components at generator geothermal power plant is evaluated using finite element method. In this study, the critical speed is evaluated based on the over speed scenario at 100%, 120% and 150% of rated speed. The critical speed of the rotor is investigated in the Campbell diagram, which shows the relationship between natural frequency and rotational velocity of the system. Based on the rotordynamic evaluation using finite element, the critical speed at 100% and 120% of the operating speed occurs in the rotational speed of 2750 and 2837 rpm, while at 150%, the critical rotation occurs in the rotational speed of 2750, 2762 and 4051 rpm. It can be concluded that the speed ranges are the critical speed or the resonance region which can be as a direct cause of the component damage, therefore the operating speed should not work too long on that critical speed.

Tow eye failure analysis using energy strain release

The crack initiation of tow eye is doing research on crack propagation. Finite element method simulation used in the tow eye crack growth analysis. This simulation used ANSYS software to study about characteristic during loading time based on load history. The static approach is chosen in this research to purposes failure mode on the tow eye sample. Testing for the material of tow eye to determine the simulation, such as tensile test, and Optical Emission Spectroscopy test to determine the chemical composition of tow eye. On the end of test, noted that tow eye material is manganese steel, the input data from material properties is using with finite element method (FEM) based on fracture mechanic theory. The simulation with ANSYS also using Strain Energy Release (j-Integral) approach to calculate mode shape of failure. The result of simulation gives representation about the contour of crack. Finally, the conclusion of research, FEM method can be the prediction of Stress Intensity Factor and j-Integral in all of contour of crack to determine width of crack.

Analysis of electric wheelchair passanger comfort with a half car model approach

Numerical simulation of vibration amplitude used in this research to calculate dislocation human neck during driving with the wheelchair. To improve riding comfortability, a half car bond graph model used. Firstly, free body diagram with lumped mass simplification used in this paper which parameters has been specified such as 60 kg of human weight, the shock suspension are used, the dimension of wheelchair and other various component like tire of wheels are used. Then, motion equation derivation with six degree of freedom has been made to solve by numerical methods. Fourth order numerical algorithm are used in this analysis adapted by Rung Kutta approach. To calculate calculation use 0,01 second to get precision result. The result with randomness parameter on the wheelchair value is the amplitude of head/neck value is 0.85 mm on flat road and 17 mm on sinusoidal excitation road, that show the amplitude characteristic of wheelchair comforts at human neck.

Magnetic Evaluation for Uprating 400 mW Coal Fired Generator

One of the considerations many power plants today is whether they can get more power out of their existing equipment especially generator. However, it is required design review and feasibility study in order to extend the operating life and increase the capability and reliability. In this study, analysis of magnetic field was performed due to power uprating in order to prevent a saturation of the magnetic field in the core laminate which can lead to the emergence of heat concentration. Based on the results of magnetic analysis using finite element, there are no saturation of the magnetic field in the core lamination which can lead to the magnetic saturation and heat concentration, both for existing and uprating conditions.Therefore, the increasing a design margin on the generators from the current design of the margin of 471,000 kVA to 494,550 kVA with the 0.85 power factor will not pose a problem as long as all of the following recommendations can be implemented. Although it is predicted, there will be no saturation and hotspots on the generator, but the risk of temperature rise due to the uprating should be reduced by replacing the stator winding using the Full Class F Insulation which is resistant to temperatures up to 155 °C.

Evaluation of Critical Speed of the Rotor Generator System Based on ANSYS

Critical speed rotor phenomenon characteristics at gas turbine generator is evaluated using finite element method. In this study, the critical speed is evaluated based on the over speed of 4500 rpm. The critical speed of the rotor is investigated in the Campbell diagram, which shows the relationship between natural frequency and rotational velocity of the system Dynamic characteristic in this paper simulated with ANSYS rotor dynamic software. The Finite Element simulation results will be known forms of vibration at each critical speed. Finally the results od simulation can be a reference for dynamic analysis and optimized the design of rotor generator.