Composite materials with enhanced dimensionless Young’s modulus and desired Poisson’s ratio

Abstract

We have designed a new type of composite materials which not only has a Young’s modulus much larger than the Voigt limit, but also is always nearly isotropic. Moreover, its Poisson’s ratio can be designed at a desired value, e.g. positive, or negative, or zero. We have also demonstrated that structural hierarchy can help to enhance the stiffness of this type of composite materials. The results obtained in this paper provide a very useful insight into the development of new functional materials and structures.

Nano-structured interpenetrating composites with enhanced Young’s modulus and desired Poisson’s ratio

“…As can be seen, the analytical results for the Young's modulus of the interpenetrating composites obtained from Equations (2) - (20) are constantly smaller than the simulation results, indicating that the analytical results always underestimate the Young's modulus of the composites. This is consistent with the mechanics principle because the restraints inside the RVE in the finite element analysis are much stronger than those in the simplified analytical model, and any additional restraint always tends to make a material or structure stiffer [16]. One primary objective of this paper is to demonstrate that interpenetrating composites have a much larger Young's modulus than that of their conventional isotropic particle or fibre counterparts.…”

“…In addition, not only the Young's modulus of a composite could be much larger than the Voigt limit, but also the Poisson's ratio could be designed to have a desired value (e.g. positive, negative or zero) [16]. It has been generally recognised that for conventional particle or fibre composites at the nanometer scale, the smaller the filler (e.g.…”

Composite Materials with Enhanced Conductivities

“…Moreover, the geometrical structures in Figure 1a and b can not only significantly enhance the conductivity of isotropic composites, but also, by combination with the different Poisson's ratios of the two constituent materials, enable the Young's modulus of the composites to be much greater than the Voigt limit. [34,35] It is noted that other types of composites, e.g., laminate materials, could also have a Young's modulus greater than the Voigt limit because of the effects of the Poisson's ratios. [36][37][38][39][40] Thus, we could conclude that the type-I structure in Figure 1a can maximize the isotropic conductivity of two-phase composites, and that the type-II structure shown in Figure 1b can μ [23] μ [24] μ [25] μ [26] μ [27] Fig .…”

“…Both types of composites have cubic symmetry [32,33] and their thermal/electrical conductivities and mechanical properties [34,35] are obviously the same in the x, y, and z directions.…”

Homogenized out-of-plane shear response of three-scale fiber-reinforced composites

“…We then aim at obtaining the effective elastic coefficients related to relationships (30) and (31), to characterize the outof-plane shear mechanical response. This can be done by performing a standard decomposition of the problems (26) and (27) into in-plane and antiplane problems.…”