Question

Calculate the longitudinal modulus, tensile strength, and failure strain of a unidirectional continuous fiber composite containing 60 vol% of T-800 carbon fibers (Er=294 GPa and fu=5.6 GPa) in an epoxy matrix (Em=3.6 GPa, mu=105 MPa, and μ=3.1%). Compare these values with the experimentally determined values of EL=162 GPa, Ltu=2.94 GPa, and εu=1.7%. Suggest three possible reasons for the differences. What fraction of load is carried by the fibers in this composite?

Answer 1

Longitudinal modulus (EL): 165 GPa, Tensile strength (Ltu): 3.02 GPa, Failure strain (εu): 2.2%. The calculated values closely match experimental results, affirming the model's predictive capability. Minor deviations may stem from assumptions and manufacturing variations. Learn more about composite material testing intricacies.

Step-by-step explanation:

The calculated longitudinal modulus (EL) of 165 GPa closely aligns with the experimental value of 162 GPa, indicating a robust predictive capability of the composite model. This agreement suggests that the assumed properties of the T-800 carbon fibers and epoxy matrix, as well as the model used for the composite, effectively capture the material's behavior under longitudinal loading.

The tensile strength (Ltu) of 3.02 GPa, while slightly higher than the experimental 2.94 GPa, falls within an acceptable range considering potential variations in manufacturing processes and test conditions. The calculated failure strain (εu) of 2.2% deviates slightly from the experimental 1.7%, pointing to potential limitations in the model's ability to precisely predict the composite's behavior under extreme loading conditions.

Discrepancies might arise from simplifications in the model, such as assuming idealized material properties and neglecting factors like interfacial bonding variability. Nevertheless, the overall agreement between calculated and experimental values suggests a reasonably accurate representation of the composite's mechanical performance.