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Abstract: An asperity profile function has been proposed that describes the isotropic rough surface of a material. The function is parameterized with three new roughness parameters that control the root mean square height, the slope and the curvature of the rough surface, respectively. Unlike the roughness parameters used in the well known Greenwood–Williamson model, the three parameters introduced in this paper are independent of each other, which is an advantage as this facilitates the characterization of the isotropic random surface of the material. However, a disadvantage with this parameterization is that the roughness parameters are not linked to a contact area equation any more, like the Hertz equations that express contact with linear materials. Different asperity profiles defined by the new roughness parameters were analyzed by a 2D axial symmetric FE-model. The numerical results suggest a procedure for developing a contact area function that are parameterized with the three new roughness parameters, which is also suitable for nonlinear brittle materials. [Copyright &y& Elsevier]

Abstract: A systematic study has been carried out by using 2D axisymmetric models to understand the ductile fracture behavior of pipes with internal and external circumferential cracks. Crack growth resistance curves have been computed using the complete Gurson model. Pipes with various diameter-to-thickness ratios, internal pressure, crack depths and material properties are analyzed. The results have been compared with those of corresponding SENT and standard SENB specimens. It clearly indicates that the SENT specimen is a good representation of circumferentially flawed pipes and an alternative to the conventional standard SENB specimen for the fracture mechanics testing in engineering critical assessment of pipes. [Copyright &y& Elsevier]

Abstract: Compression behaviours of individual micron-sized acrylic particles have been studied by using a nanoindentation-based method with a flat-end tip, instead of a commonly used sharp tip. The effect of loading rate on the mechanical properties of the high monodisperse acrylic particles, such as K-value, breaking force and breaking displacement, has been investigated. A wide range of loading rate conditions has been applied to examine the sensitivity of selected mechanical properties. It has been observed that the loading rate has a significant effect on K-value and breaking force whereas breaking displacement is independent of loading rate. These results facilitate the industrial applications of acrylic particles. [Copyright &y& Elsevier]

Highlights: [•] Multi-dimensional graphitic nanostructures are constructed by spanning fullerenes with CNTs. [•] Mechanical characteristics are governed by the inter-fullerene distance. [•] Both 2D nano-mesh and 3D nano-truss exhibit a negative Poisson’s ratio. [•] Tunable Poisson’s ratio ranges from negative to positive to negative when stretched along 〈110〉 direction. [Copyright &y& Elsevier]

Abstract: This paper presents a novel three-dimensional finite element for gradient elasticity. The new finite element BR153L9 is a straightforward extension of the two-dimensional element QU34L4 developed by Shu et al. (1999) , which is based on a mixed-type formulation. Within this paper the derivation of the mixed-type finite element scheme is reviewed and details of the implementation are given. Finally, numerical results of an extended patch test and a benchmark test with the three-dimensional finite element are presented in order to validate the formulation and prove the convergence. [Copyright &y& Elsevier]