With the advent of hybrids and electric vehicles, the need for lightweight and highperformancematerials is growing. Sheet molding compound (SMC) is a compositemade of short and randomized bers that o ers a substantial weight reduction andgood mechanical properties while meeting the demand for large volume production.This thesis aims to develop a constitutive FE model of the SMC used in the bodyin black of an autonomous vehicle.To extract its properties, several physical tests were performed on specimens madeof the above-mentioned material. Both the tensile and three point bending testsresults show that the material is not homogeneous and that its properties vary fordi erent directions. The damping ratio extracted from the vibration test is muchlower than in conventional structural materials like aluminum and steel.In the FE analysis, the material was modeled both as isotropic and orthotropic.After adjusting the Young's modulus, the isotropic model shows accurate resultsuntil 1200 Hz. On the other hand, without knowing in which directions the propertiesoccur, the orthotropic model is very limited.In conclusion, even though the properties were tailored speci cally for the specimen,the model might not correctly represent the material's behavior, being itsproperties not the same for di erent components. Therefore, it is more reasonableto use average data instead. / Tack vare en okad efterfragan av hybrid och eldrivna fordon, kommer ett storrebehov av lattvikts-och hogpresterande material. Sheet Molding Compound (SMC)ar en komposit av korta, randomiserade brer som ger en vasentlig viktreduktion,liksom goda mekaniska egenskaper, samtidigt som det moter kraven fran hogvolymsproduktioner. Malet med detta examensarbete ar att utveckla en FE-modell for detSMC material som anvands for chassit pa ett sjalvkorande, eldrivet fordon.For att ta reda pa dess egenskaper, har era fysiska tester utforts pa prover gjort avovannamnda material. Bade dragprov och bojprov visar att materialet inte ar homogentoch att materialets egenskaper varierar i olika riktningar. Dampningsfaktornsom ar extraherad fran vibrationstesterna ar mycket lagre an for konventionella material,sa som aluminium och stal.I FE-analysen, var materialet modellerat som bade isotropt och ortotropt. Efteratt ha justerat E-modulen, visade den isotropa modellen mer korrekta resultat, upptill 1200 Hz. Dock ar den ortotropa modellen valdigt begransad, eftersom riktningarnafor de olika egenskaperna ar okanda.Som slutsats, aven om egenskaperna var justerade speci kt for detta prov, kan dethanda att modellen inte representerar materialets beteende korrekt, eftersom egenskapernainte kommer vara samma for alla komponenter. Darfor ar det mer rimligtatt anvanda genomsnittliga data istallet.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-290039 |
| Date | January 2020 |
| Creators | Ambrogio, Simone |
| Publisher | KTH, Lättkonstruktioner |
| 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 ; 2020:229 |
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