A two-step computational homogenization approach for determination of elastic constants of hybrid composites

Date

2023-9-08

Author

Batır, Musa

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Carbon-fiber-reinforced polymer composites consist of carbon as a reinforcement element and polymer as a matrix. This kind of material shows unique mechanical properties. Because of the deficiency of adhesion properties, transverse mechanical properties are not as good as longitudinal properties. This restricts the use of carbon-reinforced polymer composites. Carbon Nanotubes can be grown on the surface of carbon fiber as an interphase to increase the transverse properties of the material. This material is called fuzzy fiber composites (FFC) or hybrid composites. Both the manufacturing and the characterization of the produced material are very challenging.\\ The study's main aim is to characterize the fuzzy fiber composite with the help of homogenization techniques. By using micromechanical and numerical methods, a new two-step homogenization method is proposed to calculate the effective mechanical properties of this hybrid composite. At first, a micromechanical method, i.e., Mori-Tanaka, is followed to obtain the mechanical properties of the graded interphase region. FEM analyses are conducted for a representative volume element (RVE) after determining the interphase's homogenized properties.\\ This study conducts several parametric studies using the proposed two-step homogenization approach. The effects of CNT length, CNT volume fraction, and fiber volume fraction are investigated. Parametric studies are performed via engineering material constants. Engineering material constants are calculated from the effective elasticity tensor of the constitutive model obtained by the two-step homogenization approach.

Subject Keywords

Homogenization, Interphase, Hybrid composites, Fuzzy fiber composites, Carbon nanotubes, Finite element method, Effective modulus, Micromechanics

URI

https://hdl.handle.net/11511/105437

Collections

Graduate School of Natural and Applied Sciences, Thesis