Tinh Quoc Bui

• Associate Professor, Dr. techn.
• Tokyo Institute of Technology

This paper presents a computationally effective approach for crack propagation under mechanical and thermal loads based on an adaptive mesh refinement (AMR) approach tailored for our recently developed enhanced local damage model. The mesh-dependent issue encountered in the classical local theories is effectively mitigated by incorporation of fract...

The work focuses on the numerical investigation of compressive mechanical behaviors and energy absorption properties of high entropy alloys (HEAs) with stochastic bicontinuous nanostructures (SBNs) and octet nanostructures (ONs). The study reveals a strong correlation between mechanical behaviors and the relative density of the nanostructures. The...

An improved naturally stabilized nodal integration (NSNI) is presented for resolving displacement locking concerned with highly orthotropic and nearly incompressible materials in the linear setting. It is recognized that the original NSNI is susceptible to the locking when dealing with these types of materials. The proposed method utilizes spectral...

This article is devoted to extension of the recently developed enhanced local damage model for failure prediction in bi-material structures. Compared to non-local models, the enhanced local model offers lower computational cost while the inherent mesh-dependency issue is treated. By defining equivalent strain based on the bi-energy norm concept and...

A size-dependent post buckling analysis of functionally graded (FG) microbeams is conducted by using an analytical solution based on a reformulated strain gradient elasticity theory (RSGET). The nonlinear behavior of post buckling is considered by employing the von-Karman nonlinear strain–displacement relation. The microstructure-dependent behavior...

In this paper, an adaptive mesh refinement scheme is utilized to further enhance the local damage model (shortly as the local model) for quasi-brittle materials, for e.g., concrete or limestone. The novelty here is twofold: (i) introduction of an alternative equivalent strain for a local damage model and (ii) incorporation of the proposed model wit...

Modeling failure mechanisms in solids by using sharp crack discontinuities suffers various shortcomings that can be diminished by diffusive crack conception or phase-field method. The phase-field method describes sharp crack surfaces with a continuous field variable evaluated through a differential evolution equation. This study deals with the disc...

Compositionally graded materials have emerged at the frontier of science involving material science, engineering, physics, and chemistry due to their unusual and tunable material properties derived from spatial variations in compositions. However, achieving a comprehensive understanding of the mechanical and failure behavior of compositionally grad...

The singular integral equation method is applied to present analytical solutions for modified electric-magnetic-polarization saturation (EMPS) models subjected to semipermeable center cracked magneto-electro-elastic (MEE) materials. A generalized methodology is presented to explicitly solve the EMPS model under any arbitrary saturated electric and...

This paper is devoted to numerical investigation of quasi-brittle fracture under thermal-elastic loading condition using a novel thermal-mechanical local damage model associated with the enhanced bi-energy norm based equivalent strain. In contrast to the non-local or gradient-enhanced damage models, a local damage counterpart generally requires les...

This paper presents the analytical closed‐form solutions of moving two equal collinear semipermeable cracks in magneto‐electro‐elastic material considering the strip electric‐magnetic polarization saturation (EMPS) model. To simulate the dynamic/moving cracks problem, two equal collinear Yoffe type cracks moving with a constant subsonic velocity al...

Isogeometric analysis (IGA) is known to show advanced features compared to traditional finite element approaches. Using IGA one may accurately obtain the geometrically nonlinear bending behavior of plates with functional grading (FG). However, the procedure is usually complex and often is time-consuming. We thus put forward a deep learning method t...

We present a dynamic modeling technique for brittle fracture based on a novel nonlocal damage model. The formulation of our developed damage theory is based on the earlier published one, i.e., Tran et al. CMAME 2023, 413:116123, but has an important ingredient that renders the enhanced theory more effective with respect to the time-dependent loadin...

This paper presents an improved non-sensitivity structural topology optimization method incorporating virtual elements with unstructured polygonal meshes. Specifically, we employ the recently developed gradient-free proportional topology optimization (PTO) approach, for the first time, together with a new material distribution formula suitable for...

In this paper, we present the distributed dislocation technique (DDT) based numerical algorithms to study the generalized strip saturated (GSS) models for two equal collinear cracks in 2‐D finite and infinite piezoelectric media. Numerical studies for particular cases such as linear, quadratic and cubic strip saturated models are simulated by consi...

This paper proposes a general strain-gradient and shear-deformable isogeometric microshell formulation based on the complete Mindlin’s form II strain gradient theory (SGT) and Reissner–Mindlin shell model for the static and dynamic analyses of in-plane functionally graded (IFG) microshell structures. The material properties are assumed to vary alon...

Compositionally graded ferroelectrics (CGFEs) have attracted great interest due to their exceptional and tunable electromechanical properties, which are anticipated to be superior to traditional ferroelectrics. However, an effective design of CGFEs with desired properties from a huge compositional space remains an enormous challenge. In this study,...

In this paper, the Proportional Topology Optimization (PTO) algorithm is extended for the two-scale concurrent topology optimization, in which both the structure and material cellular micro-structure are subject to design. PTO was originally developed on the concept that the amount of material being distributed to an element would be proportional t...

This study presents the incorporation of the effective gradient-free proportional topology optimization algorithm into the framework of isogeometric analysis. The minimization of the compliance is considered, and the solid isotropic material with penalization method is used. The geometry, displacements, and density are all described by non-uniform...

The failure process in a thermal barrier coating (TBC) system can be complicated due to complex microstructure, material property mismatch, high temperature change, chemical reactions during the failure process, etc. It brings considerable difficulties to the modelling technique. A complete failure process in TBC contains multiple failure types, eg...

This paper presents a novel framework combining the state-based peridynamics (SBPD) with the extended finite element method (XFEM) for crack propagation in two-dimensional solids. Numerical examination is conducted fulfilling both the quasi-static and time-dependent loading conditions. The computational domain is partitioned into two regions: (a) S...

Composite materials inherently own desirable properties including high strength, high stiffness and good toughness. The macroscopic mechanical properties of composite materials are generally anisotropic. Fracture in anisotropic or orthotropic materials has been widely concerned by researchers in the fields of computational mechanics, aviation, aero...

In finite element analysis, adaptive mesh refinement (AMR) has become a common practice to improve the accuracy of the numerical solution in sensitive or disturbed regions without having to refine the mesh in the entire domain. It is important to determine when, where, how much, and how the element size should be adjusted during the phase field fra...

This paper presents an improved local continuum damage model for quasi-brittle fracture analysis. A local damage model, as compared to its non-local damage counterpart, owns the advantages of simple implementation and low computational cost. However, it is in general suffered from the mesh-size dependency. In this work, this drawback is mitigated b...

In this paper, an enriched reproducing kernel particle method combined with stabilized conforming nodal integration (SCNI) is proposed to tackle material interface problems. Regarding the domain integration, the use of SCNI offers an effective NI technique and eliminates the zero-energy modes which occurs to direct NI. To model material interfaces,...

Phase field models have become a promising tool in modelling failure processes for various engineering applications. However, their computational inefficiency has posed challenges for a wider application which is desired in engineering. While most papers present implicit phase field models, only a few studies devoted to explicit phase field models...

Although robust in handling different fracture processes such as nucleation, branching and coalescence, the phase-field method (PFM) is computationally very expensive because it requires extremely fine meshes to resolve the necessary physics. This paper presents a hybrid adaptive PFM discretized by using finite element method to model quasi-static...

This study presents an efficient and robust isogeometric gradient-free proportional topology optimization (IGA-PTO) algorithm to address the multi-material optimization problems. More precisely, non-uniform rational B-spline basis functions are used for the descriptions of geometry, displacement field, and density fields of material phases. The mat...

In this work, novel four-unknown refined theories were used to evaluate the free vibration of rotating stiffened toroidal shell segments subjected to varying boundary conditions in thermal environments. The shell segments consist of a functionally graded graphene-platelet-reinforced composite (FG-GPLRC). The effective material properties of the com...

Potential damage in composite structures caused by hail ice impact is an essential safety threat to the aircraft in flight. In this study, a nonlinear finite element (FE) model is developed to investigate the dynamic response and damage behavior of hybrid corrugated sandwich structures subjected to high velocity hail ice impact. The impact and brea...

In this paper, we report numerical simulations for dynamic fracture and fragmentation problems in brittle materials using a recently developed split strain energy diffusive mass-field damage model in terms of standard finite element method (FEM). The enhanced constitutive laws for mass source and mass flux by means of strain energy decomposition ar...

This paper presents closed-form solutions for exploring size-dependent postbuckling of Euler–Bernoulli and Timoshenko microbeams using a novel strain gradient elasticity theory. To capture the size effects of microbeams, a reformulated strain gradient elasticity theory incorporating strain gradient and couple stress effects simultaneously with only...

This study presents the incorporation of the effective gradient-free proportional topology optimization algorithm into the framework of isogeometric analysis. The minimization of the compliance is considered, and the solid isotropic material with penalization method is used. The geometry, displacements, and density are all described by non-uniform...

This paper presents a hybrid approach for multiscale topology optimization of structures. The topological shape of both macro-structure and micro-structure are concurrently optimized, based on the solid isotropic material with penalization (SIMP) technique in combination with finite element method (FEM). The material is assumed to have periodically...

Elastocapillarity of high-aspect-ratio structures (HAR) has been emerging as an enabling technique for many applications including smart actuators, three-dimensional self-assembly, and anti-counterfeiting. However, most existing works only show the elastocapillarity phenomena at micrometer or sub-micrometer scales. In this study, we fill out the ga...

In linear isogeometric analysis of beams, the success of selective reduced integration and ̅ projection methods in mitigating the locking phenomenon has been proved. This study further extends these methods to the geometrically nonlinear analysis with two isogeometric Timoshenko-Ehrenfest beam formulations, i.e., 0-continuous NURBS selective reduce...

The objective of this work is to study dynamic crack propagation in brittle materials under time-dependent loading conditions by using the recently developed adaptive isogeometric phase-field approach. The current approach owns several ingredients including the advantages of the phase-field method (PFM), which can be used to model complex crack mor...

The yarn/yarn and yarn/matrix interface debonding has been recognized as a vital failure mode of 3 D braided composites. We present in this paper a meso-scale finite element (FE) model, which considers yarn/yarn and yarn/matrix interface debonding, for modeling progressive damage evolution of 3 D braided composites under typical tensile and shear l...

This paper aims at presenting numerical simulation of dynamic failure process of Duran 50 glass plates subjected to high-velocity impact loads using a bond-based peridynamics (PD). In simulation, several affecting parameters including impact velocity, impact angle, impact contact area, glass plate thickness, and porosity percentage in glass plate a...

Dynamic fracture deals with the degradation and failure of materials and structures under conditions where the inertia effect must be included in the analysis. In this contribution, a dynamic description of a simple local damage approach and its detailed finite element implementation is presented towards brittle and quasi-brittle localization failu...

In the phase field model (PFM), fracture timing and direction are determined automatically by the stationary condition of the system’s potential, it is normally considered an advantage since not a failure initiation criterion is required to be appointed. However, it may become an obstacle when a specific failure criterion is required to calculate t...

The nature of fracture in most engineering materials exhibits the inherent anisotropy. Assuming isotropic evolution of fracture in such anisotropic materials is no longer consistent. It is because that the principles and fundamental issues that behind the directional-dependent fracture mechanism are still interrogative. In this paper, the recently...

We present a novel smeared gradient-enhanced damage model which takes into account directional-dependent damage evolution in two-dimensional brittle materials (e.g., uniaxial fiber-reinforced composites and polycrystalline materials). The recently developed smoothing gradient damage model for isotropic localized failure analysis is revisited by int...

This paper presents a novel topology optimization approach without calculation of sensitivity for the minimum compliance problems, based on the meshfree Radial Point Interpolation Method (RPIM). Relying on the algorithm of Proportional Topology Optimization (PTO), material is distributed using only information of the objective function (which is th...

This study elaborates the invariance of spatial Timoshenko-Ehrenfest beam formulations in the context of isogeometric analysis. Such invariance confirms that zero strain measures are always generated by rigid transformations, i.e., rigid translations and rotations. The violation of this property can degrade the performance of the formulations in pr...

This paper presents numerical simulations of transient dynamic fracture behaviors and quasi-static crack growth in cracked functionally graded composites using the enhanced extended consecutive-interpolation quadrilateral element (XCQ4). The mechanical properties of functional composites are assumed to vary continuously in spatial coordinates. In t...

In this paper, we present for the first time a multi-material topology optimization scheme based on the gradient-free proportional topology optimization algorithm for plates, using Reissner–Mindlin plate theory. For finite element analysis of plates, treatment of the common shear-locking is crucial. To this end, the four-node quadrilateral element...

A first-order shear deformation (FOSD) free-form microshell model described in general curvilinear coordinates was developed within the complete framework of Mindlin’s form II linear isotropic strain-gradient theory (SGT), considering both strain-gradient and micro-inertia effects. The high-order governing equations of motion and consistent boundar...

The objective of this technical note is to illustrate twofold. The first issue is devoted to the ability of the recently developed smoothing gradient-enhanced damage model (SGDM), which is associated with the modified von Mises equivalent strain in modelling mixed-mode fracture problems, in particular the common Nooru–Mohamed's test. We show that t...

We present a new scalar damage model for dynamic brittle fracture. In contrast to existing damage theories, the internal damage variable is alternatively derived based on energy limiter theory, directly tightening to its physical meaning. Finite element implementation for the developed approach at small strain towards localized brittle failure is g...

This paper presents a numerical investigation of single and multiple cracks in hyperelastic solids by using an extended moving Kriging meshfree method. The behavior of crack such as jump of displacement field across crack surface is mathematically captured by enriched functions, which are selected based on asymptotic solution. For meshless numerica...

Large piezoelectric effect in nonlinearly graded lead‐free ferroelectric thin films In article number 2100370, using extended phase field simulations, Le Van Lich and co‐workers demonstrate that a large piezoelectric effect can be obtained in nonlinearly graded lead‐free ferroelectric thin film. The enhancement of piezoelectric property originates...

Shakedown analysis plays a substantial role in safety assessment, especially in nuclear plant industry, chemical industry and civil engineering. This paper presents numerical investigations of shakedown problems with holes using the adaptive extended isogeometric analysis (XIGA). An adaptive strategy performed in the discretized framework of a kine...

In this study, the nondeterministic linear static response of planar microbeams accounting for the influence of material microstructures and material uncertainty is investigated by the method of spectral stochastic isogeometric analysis (SSIGA). The beam formulation is developed based upon Timoshenko hypothesis and modified couple stress theory. Th...

This paper aims at presenting a hybrid computational strategy and its detailed implementation for simulation of crack propagation problems in three-dimensional (3D) solids. The key idea of the hybrid approach lies in the combination of extended finite element method (XFEM) and bond-based peridynamics (PD), which takes excellent features of the high...

Plate structures suffering thermal environments are often encountered in practice. In this paper, thermal buckling behavior of complex-shaped plates by an adaptive multi-patch isogeometric analysis (IGA) based on locally refined NURBS and Nitsche’s method is studied. Kinematic equations are derived using Reissner–Mindlin plate theory, while complex...

Limit analysis can be used to directly calculate the ultimate load of structures without considering cumbersome elastic–plastic analysis. We present an adaptive mesh refinement strategy by mean of extended isogeometric analysis (XIGA) in association with second-order cone programming (SOCP) for kinematic limit analysis of hole and inclusion problem...

In this article, we present a new computational damage approach based on localized mass loss concept and its detailed finite element implementation for brittle fracture under quasi-static loading condition. Formulation of this approach is derived in a general way by means of finite deformation regime and nonlinear isotropic materials. The underlyin...

This study commences the application of the modified couple stress theory in the analysis of spatial arbitrarily curved microbeams. The kinematic assumptions of the Timoshenko beam theory are employed. The moving trihedron of the beam axis are used to form a local Cartesian coordinate system. Displacements of the beam axis and cross-sectional rotat...

The simultaneous influence of surface and couple stresses on the nonsymmetrical frictionless indentation of a linearly elastic, homogenous, and isotropic half plane under a tilted, rigid, flat-ended indenter with sharp, square corners was investigated by adopting existing continuum-based models. The half plane was mathematically constituted by the...

A phase field model for nonlinearly graded ferroelectric thin films is developed based on the Ginzburg–Landau theory. The developed phase field model is validated by comparing simulated results and available experiment data. Via phase field simulations, effects of gradient index on polarization field and electromechanical response are systematicall...

Unlike two-dimensional (2D) crack problems of which the analytical symplectic eigensolutions are available, the analytical symplectic solution of three-dimensional (3D) planar and axial dynamic cracks has not been derived yet. We thus propose a trial displacement field for the 3D planar and axial crack problem using the existing solutions of the 2D...