Design optimization of viscoelastic discharge pump pipe with nonlinear finite element analysis

Pressure fluctuations in pipelines transmitted from pumps or other sources are known to be sources of vibration and noise. Pressure fluctuation is the cause of vibrations on pipe system components. Apart from the vibration transmitted by the pressure fluctuation, the vibration that is cause of pump and electric motor rotation and pump blade passing frequency can also be transmitted through pipelines and other elements of the system. For this reason, appropriate steps should be taken in the design phase to minimize vibration amplitude and optimize noise level for the piping in the conduit of vibration transmission. The damping ratio of the material in vibration transmission is an important parameter. Rubber based viscoelastic materials with high damping ratio are used in hydraulic systems and pipe designs in order to minimize vibration amplitude. Choosing the most suitable design and viscoelastic material is usually made by experimenting, which leads to significant amounts of time and monetary costs. In the scope of this thesis, mechanical properties of viscoelastic pump discharge pipe were obtained experimentally and the studies of pipe vibrations in literature were researched. In the study, the mechanical properties of the viscoelastic material were obtained from the DMA tests, by sweeping excitation frequencies (0.1Hz-100Hz) and material temperatures (35°C-80°C). Neo-Hookean hyperelastic model were used according to the storage and the loss modulus of the material. The material master curve was fitted by using experimental data fit in MSC Marc software. The material coefficients obtained from the curve and the FFT measurements taken from the pump were provided as inputs to the nonlinear finite element package program MSC Marc software. The analysis results and the vibration measurements which were taken the point where thepipe was connected to the system were compared. After comparing the model and the experiment results, nonlinear finite element analysis was performed with design of experiments consisting of varying parameters depending on geometry. Design optimization has been carried out to minimize vibration amplitude according to the results obtained from the analyzes. The effect of sound power level on the optimized dishwasher was investigated experimentally.