Abstract
Polymer-based three-dimensional (3D) printing—such as the UV-assisted layer-by-layer polymerization technique—enables fabrication of deformable microstructured materials with pre-designed properties. However, the properties of such materials require careful characterization. Thus, for example, in the polymerization process, a new interphase zone is formed at the boundary between two constituents. This article presents a study of the interphasial transition zone effect on the elastic instability phenomenon in hyperelastic layered composites. In this study, three different types of the shear modulus distribution through the thickness of the interphasial layer were considered. Numerical Bloch-Floquet analysis was employed, superimposed on finite deformations to detect the onset of instabilities and the associated critical wavelength. Significant changes in the buckling behavior of the composites were observed because of the existence of the interphasial inhomogeneous layers. Interphase properties influence the onset of instabilities and the buckling patterns. Numerical simulations showed that interlayer inhomogeneity may result in higher stability of composites with respect to classical layup constructions of identical shear stiffness. Moreover, we found that the critical wavelength of the buckling mode can be regulated by the inhomogeneous interphase properties. Finally, a qualitative illustration of the effect is presented for 3D-printed deformable composites with varying thickness of the stiff phase.
Highlights
Composite materials are deeply integrated in the modern life, due to their excellent mechanical and functional properties, which until recently were unachievable
We assumed that the interphasial layers, stiffer homogenous layer, and t is the period of the unit cell
Before considering non-ideal composites with interphasial layers, let us firstly make some on the instability in ideal hyperelastic composites without interphases
Summary
Composite materials are deeply integrated in the modern life, due to their excellent mechanical and functional properties, which until recently were unachievable. In contrast with delamination, when composites lose the integrity catastrophically, the loss of stability can be considered as reversible microstructure transformation mode; once the external loads are removed, the initial undeformed state is restored thanks to the stored elastic energy This phenomenon of instability-induced microstructure transformation has been employed to design materials with the switchable properties and functions [1,2,3,4,5,6,7,8]. The onset of macroscopic instabilities in fibrous and layered composites were analytically studied with the help of loss of ellipticity analysis [16,17], when the required tensor of effective elastic moduli is obtained based on phenomenological models, or by means of micromechanics based homogenization approaches [18,19,20]. Some qualitative comparison with the experimentally observed instability modes in 3D printed layered composites is discussed
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