Shape optimization of structures with cutouts by an efficient approach based on XIGA and chaotic particle swarm optimization

in European Journal of Mechanics. A, Solids (2019), 74

Structural shape optimization is one important and crucial step in the design and analysis of many engineering applications as it aims to improve structural characteristics, i.e., reducing stress ... [more ▼]

Structural shape optimization is one important and crucial step in the design and analysis of many engineering applications as it aims to improve structural characteristics, i.e., reducing stress concentration and structural weight, or improving the stiffness, by changing the structural boundary geometries. The goal of this paper is to present an efficient approach, which goes beyond limitations of conventional methods, by combining extended isogeometric analysis (XIGA) and chaotic particle swarm optimization algorithm for shape optimization of structures with cutouts. In this setting, mechanical response of structures with cutouts is derived by the non-uniform rational B-spline (NURBS) and enrichment techniques. The computational mesh is hence independent of the cutout geometry, irrelevant to the cutout shape during the optimization process, representing one of the key features of the present work over classical methods. The control points describing the boundary geometries are defined as design variables in this study. The design model, analysis model, and optimization model are uniformly described with the NURBS, providing easy communication among the three aforementioned models, resulting in a smooth optimized boundary. The chaotic particle swarm optimization (CPSO) algorithm is employed for conducting the optimization analysis. Apart from that, the CPSO has some advantages as it includes: (i) its structure is simple and easy to implement; (ii) without the need for the complicated sensitivity analysis as compared with the traditional gradient-based optimization methods; and (iii) effectively escaping from the local optimum. The accuracy and performance of the developed method are underlined by means of several representative 2-D shape optimization examples. [less ▲]

Experimental and numerical analysis of early age behavior in non-reinforced concrete

in Construction and Building Materials (2019), 210

An approach combining numerical simulations and experimental techniques is proposed to investigate the early-age properties of non-reinforced concrete. Both thermo-mechanical and fracture behaviors are ... [more ▼]

An approach combining numerical simulations and experimental techniques is proposed to investigate the early-age properties of non-reinforced concrete. Both thermo-mechanical and fracture behaviors are studied, providing a deep insight into the hydration process. This work makes an important step in understanding the effects of hydration on the performance of cement-based materials. More specifically, in the first part, the shrinkage and fracture properties of a non-reinforced concrete have been experimentally considered, along with the characterization of several material parameters. The experimental results exhibit a high risk of early-age cracking for this kind of concrete. Especially, the fracture phenomena are complex, including multi-evolution-stages, initiation, propagation, stop-growing, and re-growing. In the second part, the computational modeling based on the phase field method of failure mechanism is applied to simulate the thermal, mechanical and fracture behavior due to early-age hydration. A detailed discussion on the identification of model/material parameters and the construction of numerical model including the boundary conditions is given. We provide the following comparison between predictions of the numerical simulation with the experimental observations. An excellent predictive capability of the computational model is noted. More importantly, this work demonstrates the performance of the proposed approach, which requires only a few tests to identify the model inputs. Most of the chemo-thermal parameters can be theoretically determined based on the concrete mix and the chemical/mineral compositions of the cement. [less ▲]

Phase field modeling of interfacial damage in heterogeneous media with stiff and soft interphases

in Engineering Fracture Mechanics (2019), 218

Phase field modeling of interfacial crack propagation in quasi-brittle heterogeneous materials

in International Conference on Computational Modeling of Fracture and Failure of Materials and Structures (2019)

Structural shape optimization by IGABEM and particle swarm optimization algorithm

in Engineering Analysis with Boundary Elements (2018), 88

Modeling of Complex Microcracking in Quasi-Brittle Materials: Numerical Methods and Experimental Validations

in Advances in Multi-Physics and Multi-Scale Couplings in Geo-Environmental Mechanics (2018)

Modelling of early-age complex crack propagation in cement-based materials using phase field method

in 6th European Conference on Computational Mechanics (2018)

Modelling of inter- and transgranular stress corrosion crack propagation in polycrystalline material by using phase field method

in Journal of the Mechanical Behavior of Materials (2018), 26

Adaptive multi-patch isogeometric analysis based on locally refined B-splines

in Computer Methods in Applied Mechanics and Engineering (2018), 339

Phase field modelling of anisotropic crack propagation

in European Journal of Mechanics. A, Solids (2017), 65