Investigation of the Noise and Thermal Response When the Material of a Control Box Is Modified

Abstract

Dette projekt er et udspring fra et tidligere projekt. Derfor er grundelementerne og motivationen for projektet først beskrevet. Efterfølgende er det numeriske system omhandlende vibrationer af det anvendte software, ANSYS, beskrevet. For at reducere beregningstiden, anvendes equivalent radiated power til at estimere støjen. Efterfølgende udføres benchmark, mesh og retningsvirknings studier. Ydermere, er et materialestudie af emnet inkluderet. Materialestudiet undersøger tre tilfælde af materialekombinationer af emnet: Komplet polycarbonat, blandet aluminium og polycarbonat og komplet aluminium. Dette studie inkluderer modal og harmoniske analyser med Mode Superposition metoden. Studiet afslørede at modellen med komplet polycarbonat emne har den laveste egenfrekvens og en større støj ved en lav frekvens sammenlignet med modellen med komplet aluminium. Det skal dog bemærkes, at resultatet kan være påvirket af den valgte dæmpningsfaktor. Ydermere er ændringen af materialet undersøgt i forhold til en termisk analyse. Temperaturen falder når emnet er lavet i komplet aluminium. Konklusionen er dog at emnet kan modstå temperaturen uanset om det er lavet i aluminium eller polycarbonat. Slutligt er der udført et manuelt parametrisk studie. Studiet viser en stærk negative sammenhæng mellem tykkelsen af emnet og den maksimale equivalent radiated power. Yderligere, viser studiet at positionen af det ene af skruetårnene i emnet har en medium positiv sammenhæng med den maksimale temperatur. Hvorfor det er muligt at minimere begge responser med parametrene.

This project is the spin-off of a previous one thus, the bases and motivations are defined first. Then, the numerical scheme of the software used, ANSYS, is included, in terms of vibrations. To decrease computational time, the equivalent radiated power is used to estimate the noise instead. Afterwards, benchmark, mesh and directivity studies are done. Moreover, a material study of the case is included, considering three cases: full polycarbonate, mixed aluminium and polycarbonate, and full aluminium. This study incorporates modal and harmonic analyses, with the Mode Superposition method. The study revealed that the model with the full polycarbonate case has lower natural frequencies and a greater noise at low frequencies, than when aluminium is present. However, results may be affected by the chosen damping ratio. Later, the material change is studied in terms of thermal analysis. The temperature decreases with the presence of aluminium on the case. The model can withstand temperatures with no issues regardless of the material. Finally, a manual parametric study is done. It shows a strong negative correlation between the thickness of the case and the maximum equivalent radiated power. Additionally, the position of one of the screws has a medium positive correlation with the maximum temperature. Therefore, it is possible to minimize both responses with the parameters.

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A master thesis from Aalborg University

Investigation of the Noise and Thermal Response When the Material of a Control Box Is Modified