Silencers are used in vehicles to reduce the noise in the engine system. However,silencers themselves may produce break-out noise due to the interactionwith the exhaust gas ow and structure. In this Master thesis project, thenumerical simulation of vibrational behavior of housing plates of silencers isdeveloped.The housing plate is composed of two steel plates and a brous materiallayer. Measurement results show that the brous material has good dampingeect to decrease the vibration and radiated sound of steel plates. Steel platesare connected by spot welding. Modeling of spot welds can improve themodal assurance criterion between simulation and measurements. Interfacedamping is introduced into the simulation models to simulate the contacteect between two steel plates so that the simulated amplitude can have agood agreement with measurement result.Several numerical models of brous material are investigated. The Mikimodel is not chosen for the nal result due to the limit of range of frequencies.The rigid frame model can simulate the sound absorption but is unfeasible forthe simulation of vibration. The limp frame model can simulate the vibrationof light glass wool but cannot simulate the vibration of heavy glass wool.Finally, the Biot-Allard model which is a poro-elastic model is investigatedfor the nal result. The simulation results show good agreement with themeasurement result. / Ljuddampare anvands i fordon for att anvands for att minska buller i motorsystemet. Ljuddampare kan emellertid sjalva producera utbrottsbuller pagrund av samspelet mellan avgassodet och ljuddampare. I detta examensarbeteutvecklas den numeriska simuleringen av vibrationsbeteende hos husplaterfor ljuddampare.Husplaten bestar av tva Platar av stal och ett brost materiallager. Resultatenav matningen visar att det brosa materialet har god dampningseektfor att minska det utstralade ljudet och vibrationen hos platerna. platernaansluts med punktsvetsning. Modellering av punktsvetsar kan forbattra kriterietfor modal forsakring mellan simulering och matning. Dampning avgranssnitt infors i simuleringsmodellerna for att simulera kontakteektenmellan tva platar sa att simuleringsamplituden kan ha ett bra overensstammelse med matresultatet. Flera numeriska modeller av brost material undersoks i detta projekt. Miki-modellen anvands inte for slutresultatet pa grund av gransen for frekvensomraden. Stiv modell kan simulera ljudabsorptionen men ar omojligfor simulering av vibrationer. Limpmodell kan simulera vibrationer av lattglasull men kan inte simulera vibrationer av tung glasull. Slutligen undersoksBiot-Allard-modellen som ar en poro-elastisk modell for slutresultatet. Simuleringsresultatenvisar bra overensstammelse med matresultatet.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-280544 |
| Date | January 2020 |
| Creators | Cao, Da |
| Publisher | KTH, Marcus Wallenberg Laboratoriet MWL |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | TRITA-SCI-GRU ; 2020:007 |
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