Minh Ngoc Nguyen

Geometrically nonlinear analysis of functionally graded plates using isogeometric analysis

Purpose – The purpose of this paper is to propose an efficient and accurate numerical model that employs isogeometric analysis (IGA) for the geometrically nonlinear analysis of functionally graded plates (FGPs). This model is utilized to investigate the effects of boundary conditions, gradient index, and geometric shape on the nonlinear responses of FGPs. Design/methodology/approach – A geometrically nonlinear analysis of thin and moderately thick functionally graded ceramic-metal plates based on IGA in conjunction with first-order shear deformation theory and von Karman strains is presented. The displacement fields and geometric description are approximated with nonuniform rational B-splines (NURBS) basis functions. The Newton-Raphson iterative scheme is employed to solve the nonlinear equation system. Material properties are assumed to vary along the thickness direction with a power law distribution of the volume fraction of the constituents. Findings – The present model for analysis of the geometricall...

An efficient meshfree method for analysis of two-dimensional piezoelectric structures

Further application of an efficient novel meshfree technique based on the moving kriging (MK) interpolation for static and dynamic analyses of two-dimensional piezoelectric structures is presented. The MK scheme is used for constructing the shape functions which satisfy the Kronecker delta property. Hence, the burdensome task of enforcing the essential boundary conditions as in the moving least-squares approximation is avoided. The mechanical displacements, electric potential and natural frequencies of structures are investigated in detail through a series of numerical examples that are to demonstrate the applicability and the efficiency of the proposed method. The results obtained are then compared with those of other available reference solutions with very good agreement.

Computational Modeling of Concrete Degradation Due to Alkali Silica Reaction

This paper presents a computational multi-level model for the description of alkali and moisture transport in concrete structures coupled to a macroscopic alkali silicate reaction (ASR) induced phase-field damage model. Concrete is modeled as a heterogeneous material consisting of a partially saturated pore space with diffusively distributed microcracks and the solid skeleton (cement paste and potentially reactive and inert aggregates). The influence of the topology of the pore space and the presence of oriented microcracks on ion diffusion and moisture transport is taken into account through a novel continuum micromechanics homogenization model. The transport model is connected to a phenomenological reaction kinetics model to account for the ASR induced volume expansion of the affected aggregates. At the macroscopic scale, crack propagation and effects of induced topological changes on the fluid and ion transport are taken into account using a phase-field model.

A novel numerical approach for fracture analysis in orthotropic media

This paper presents a novel approach for fracture analysis in two-dimensional orthotropic domain. The proposed method is based on consecutive-interpolation procedure (CIP) and enrichment functions. The CIP were recently introduced as an improvement for standard Finite Element method, such that higher-accurate and higher-continuous solution can be obtained without smoothing operation and without increasing the number of degrees of freedom. To avoid re-meshing, the enrichment functions are employed to mathematically describe the jump in displacement fields and the singularity of stress near crack tip. The accuracy of the method for analysis of cracked body made of orthotropic materials is studied. For that purpose, various examples with different geometries and boundary conditions are considered. The results of stress intensity factors, a key quantity in fracture analysis, are validated by comparing with analytical solutions and numerical solutions available in literatures.