A Comparison of Experimental and Computation Results of Finding Effective Characteristics of Elastic Properties of Polymer Layered Composites from Carbon and Glass Fabrics

Anisotropy of mechanical properties of the entire material and each of its layers is characteristic for polymer layered composite materials, as well as the fact that production processes of the composite material and parts from it are often combined in time. In this case, the elastic properties and strength of the material will be different not only in the thickness of the part, but also at each point. All this leads to a complication of the design process, which is due to the need to determine the elastic properties and strength of the polymer layered composite materials, taking into account the structure of the entire material and each of its layers. This work aims at evaluating the existing computational methods of finding effective characteristics of elastic properties by comparing computation results obtained by various methods with each other, as well as with the experimental results related to elastic properties of polymer layered composite materials from carbon and glass fabrics. We estimated the computational methods of finding effective characteristics of the elastic properties of composites based on the experimental results of finding the characteristics of the elastic properties of polymer layered composite materials made of carbon and glass fabrics, differing in density and type of weaving. The experimental values of the effective characteristics of elastic properties were determined as a result of standard tensile tests of laboratory specimens. As a result of the study, it was found that all the considered models and methods give consistent results when calculating the longitudinal modulus of elasticity E 11, the results of calculating shear modulus E 33 and shear moduli G 12 and G 23 are less consistent for all the considered materials. The comparison of the results of the experimental studies and computations showed that the Chamis model and the bridge model are better than other models to predict the values of the longitudinal elastic modulus.

Preliminary Studies for One-Step Fabrication of Metallic Iron-Based Coatings on Magnesium as Temporary Protection in Biodegradable Medical Application

Iron and magnesium are being considered as promising candidates for biodegradable materials in medical applications, both materials having their specific advantages and challenges. A hybrid of metallic iron and magnesium in a layered composite is studied in the present work, to combine the merits of both metals. A single-step dip-coating method was employed to prepare the layered composite material. Morphology, composition, crystal structure and corrosion behavior of the Mg/Fe sheet were assessed by SEM, EDX, XRD, and electrochemical measurements. The Mg/Fe layered composite sheet is composed of the magnesium substrate, a 1–2 µm metallic iron coating, and a pompon-like Mg(OH)2/MgO top layer. Long-term open-circuit potential measurements revealed that the Mg/Fe sheet samples exhibit a “self-healing” effect in Dulbecco’s modified Eagle’s medium.