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Article ; Online: Flexural properties of porcupine quill-inspired sandwich panels.

Tee, Yun Lu / Nguyen-Xuan, H / Tran, Phuong

2023 Volume 18, Issue 4

Abstract: This paper presents the bending behaviour of the porcupine quill and bioinspired Voronoi sandwich panels, aiming to explore the effect of geometrical design on the bending performance of the inspired structures. Through the x-ray micro-computed ... ...

Abstract	This paper presents the bending behaviour of the porcupine quill and bioinspired Voronoi sandwich panels, aiming to explore the effect of geometrical design on the bending performance of the inspired structures. Through the x-ray micro-computed tomography, the internal morphology of the quill is explored. The longitudinal cross-section of the porcupine quill revealed a functionally graded design in the foam structure. Based on this observation, Voronoi sandwich panels are designed by incorporating the Voronoi seed distribution strategy and gradient transition design configurations. Porcupine-inspired sandwich panels with various core designs are fabricated via material jetting technique and tested under three-point bending condition. Results show that the sample failed at the bottom face panels for uniform sandwich panels, whereas graded samples failed in the core panel. The bending behaviour developed via simulation software shows a good agreement with the experimental results. The parametric study provides insights into structural designs for engineering applications, particularly in the aerospace and automobile industries.
MeSH term(s)	X-Ray Microtomography ; Flexural Strength
Language	English
Publishing date	2023-05-09
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2235670-8
ISSN	1748-3190 ; 1748-3182
ISSN (online)	1748-3190
ISSN	1748-3182
DOI	10.1088/1748-3190/acd096
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Book ; Online: Modelling of FG-TPMS plates

Nguyen-Xuan, H. / Tran, Kim Q. / Thai, Chien H. / Lee, Jaehong

2023

Abstract: Functionally graded porous plates have been validated as remarkable lightweight structures with excellent mechanical characteristics and numerous applications. With inspiration from the high strength-to-volume ratio of triply periodic minimal surface ( ... ...

Abstract	Functionally graded porous plates have been validated as remarkable lightweight structures with excellent mechanical characteristics and numerous applications. With inspiration from the high strength-to-volume ratio of triply periodic minimal surface (TPMS) structures, a new model of porous plates, which is called a functionally graded TPMS (FG-TPMS) plate, is investigated in this paper. Three TPMS architectures including Primitive (P), Gyroid (G), and wrapped package-graph (IWP) with different graded functions are presented. To predict the mechanical responses, a new fitting technique based on a two-phase piece-wise function is employed to evaluate the effective moduli of TPMS structures, including elastic modulus, shear modulus, and bulk modulus. In addition, this function corresponds to the cellular structure formulation in the context of relative density. The separated phases of the function are divided by the different deformation behaviors. Furthermore, another crucial mechanical property of porous structure, i.e, Poisson's ratio, is also achieved by a similar fitting technique. To verify the mechanical characteristics of the FG-TPMS plate, the generalized displacement field is modeled by a seventh-order shear deformation theory (SeSDT) and isogeometric analysis (IGA). Numerical examples regarding static, buckling, and free vibration analyses of FG-TPMS plates are illustrated to confirm the reliability and accuracy of the proposed approach. Consequently, these FG-TPMS structures can provide much higher stiffness than the same-weight isotropic plate. The greater stiffness-to-weight ratio of these porous plates compared to the full-weight isotropic ones should be considered the most remarkable feature. Thus, these complex porous structures have numerous practical applications because of these high ratios and their fabrication ability through additive manufacturing (AM) technology. Comment: 27 pages (including references), 15 figures, 12 tables
Keywords	Condensed Matter - Materials Science
Subject code	620 ; 690
Publishing date	2023-03-24
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Deep learning for computational structural optimization.

Nguyen, Long C / Nguyen-Xuan, H

ISA transactions

2020 Volume 103, Page(s) 177–191

Abstract: We investigate a novel computational approach to computational structural optimization based on deep learning. After employing algorithms to solve the stiffness formulation of structures, we used their improvement to optimize the structural computation. ... ...

Abstract	We investigate a novel computational approach to computational structural optimization based on deep learning. After employing algorithms to solve the stiffness formulation of structures, we used their improvement to optimize the structural computation. A standard illustration of 10 bar-truss was revisited to illustrate the mechanism of neural networks and deep learning. Several benchmark problems of 2D and 3D truss structures were used to verify the reliability of the present approach, and its extension to other engineering structures is straightforward. To enhance computational efficiency, a constant sum technique was proposed to generate data for the input of multi-similar variables. Both displacement and stress enforcements were the constraints of the optimized problem. The optimization data for cross sections with the objective function of total weight were then employed in the context of deep learning. The stochastic gradient descent (SGD) with Nesterov's accelerated gradient (NAG), root mean square propagation (RMSProp) and adaptive moment estimation (Adam) optimizers were compared in terms of convergence. In addition, this paper devised Chebyshev polynomials for a new approach to activation functions in single-layer neural networks. As expected, its convergence was quicker than the popular learning functions, especially in a short training with a small number of epochs for tested problems. Finally, a split data technique for linear regression was proposed to deal with some sensitive data.
MeSH term(s)	Algorithms ; Deep Learning ; Image Interpretation, Computer-Assisted ; Least-Squares Analysis ; Neural Networks, Computer ; Reproducibility of Results ; Stochastic Processes ; Stress, Mechanical
Language	English
Publishing date	2020-04-10
Publishing country	United States
Document type	Journal Article
ZDB-ID	2012746-7
ISSN	1879-2022 ; 0019-0578
ISSN (online)	1879-2022
ISSN	0019-0578
DOI	10.1016/j.isatra.2020.03.033
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Book ; Online: Application of Self-Supervised Learning to MICA Model for Reconstructing Imperfect 3D Facial Structures

Nguyen, Phuong D. / Le, Thinh D. / Nguyen, Duong Q. / Nguyen, Binh / Nguyen-Xuan, H.

2023

Abstract: In this study, we emphasize the integration of a pre-trained MICA model with an imperfect face dataset, employing a self-supervised learning approach. We present an innovative method for regenerating flawed facial structures, yielding 3D printable ... ...

Abstract	In this study, we emphasize the integration of a pre-trained MICA model with an imperfect face dataset, employing a self-supervised learning approach. We present an innovative method for regenerating flawed facial structures, yielding 3D printable outputs that effectively support physicians in their patient treatment process. Our results highlight the model's capacity for concealing scars and achieving comprehensive facial reconstructions without discernible scarring. By capitalizing on pre-trained models and necessitating only a few hours of supplementary training, our methodology adeptly devises an optimal model for reconstructing damaged and imperfect facial features. Harnessing contemporary 3D printing technology, we institute a standardized protocol for fabricating realistic, camouflaging mask models for patients in a laboratory environment.
Keywords	Computer Science - Computer Vision and Pattern Recognition
Subject code	006
Publishing date	2023-04-08
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Advancing Wound Filling Extraction on 3D Faces

Nguyen, Duong Q. / Le, Thinh D. / Nguyen, Phuong D. / Le, Nga T. K. / Nguyen-Xuan, H.

Auto-Segmentation and Wound Face Regeneration Approach

2023

Abstract: Facial wound segmentation plays a crucial role in preoperative planning and optimizing patient outcomes in various medical applications. In this paper, we propose an efficient approach for automating 3D facial wound segmentation using a two-stream graph ... ...

Abstract	Facial wound segmentation plays a crucial role in preoperative planning and optimizing patient outcomes in various medical applications. In this paper, we propose an efficient approach for automating 3D facial wound segmentation using a two-stream graph convolutional network. Our method leverages the Cir3D-FaIR dataset and addresses the challenge of data imbalance through extensive experimentation with different loss functions. To achieve accurate segmentation, we conducted thorough experiments and selected a high-performing model from the trained models. The selected model demonstrates exceptional segmentation performance for complex 3D facial wounds. Furthermore, based on the segmentation model, we propose an improved approach for extracting 3D facial wound fillers and compare it to the results of the previous study. Our method achieved a remarkable accuracy of 0.9999986\% on the test suite, surpassing the performance of the previous method. From this result, we use 3D printing technology to illustrate the shape of the wound filling. The outcomes of this study have significant implications for physicians involved in preoperative planning and intervention design. By automating facial wound segmentation and improving the accuracy of wound-filling extraction, our approach can assist in carefully assessing and optimizing interventions, leading to enhanced patient outcomes. Additionally, it contributes to advancing facial reconstruction techniques by utilizing machine learning and 3D bioprinting for printing skin tissue implants. Our source code is available at \url{https://github.com/SIMOGroup/WoundFilling3D}.
Keywords	Computer Science - Computer Vision and Pattern Recognition
Subject code	006
Publishing date	2023-07-04
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: A 3D nano scale IGA for free vibration and buckling analyses of multi-directional FGM nanoshells.

Cuong-Le, Thanh / Nguyen, Khuong D / Lee, Jaehong / Rabczuk, Timon / Nguyen-Xuan, H

Nanotechnology

2021 Volume 33, Issue 6

Abstract: This article explores a three-dimensional solid isogeometric analysis (3D-IGA) approach based on a nonlocal elasticity theory to investigate size effects on natural frequency and critical buckling load for multi-directional functionally graded (FG) ... ...

Abstract	This article explores a three-dimensional solid isogeometric analysis (3D-IGA) approach based on a nonlocal elasticity theory to investigate size effects on natural frequency and critical buckling load for multi-directional functionally graded (FG) nanoshells. The multi-directional FG material uses a power law rule with three power exponent indexes concerning three parametric coordinates. Nanoshell's geometries include the square plate, cylindrical and spherical panels with the side length considered in a nanoscale with various thickness ratios. Because 3D-IGA utilizes an approximation of NURBS basic functions to integrate from geometry modeling to discretized domain, it does not require any hypotheses for deformations distribution and stress component through the plate's thickness. Therefore, the results from the 3D solution are obtained accurately with any thickness ratio of the shells. The numerical solutions are verified by those published in several pieces of literature to determine the current approach's accuracy and reliability. After a convergence solution is examined, a quartic NURBS basic function can yield ultra-converged and high-accurate results with a low computational cost. The findings show the size effect parameters which significantly impact the frequencies and the critical buckling factors of the multi-directional FG nanoshells. Generally, increases in the size effect parameters will cause declines in the frequencies and the critical buckling factors of the nanoshells.
Language	English
Publishing date	2021-11-15
Publishing country	England
Document type	Journal Article
ZDB-ID	1362365-5
ISSN	1361-6528 ; 0957-4484
ISSN (online)	1361-6528
ISSN	0957-4484
DOI	10.1088/1361-6528/ac32f9
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Book ; Online: Crack propagation in quasi-brittle materials by fourth-order phase-field cohesive zone model

Nguyen, Khuong D. / Thanh, Cuong-Le / Vogel, Frank / Nguyen-Xuan, H. / Abdel-Wahab, M.

2022

Abstract: A phase-field approach becomes a more popular candidate in modeling crack propagation. It uses a scalar auxiliary variable, namely a phase-field variable, to model a discontinuity zone in a continuity domain. Furthermore, the fourth-order phase-field ... ...

Abstract	A phase-field approach becomes a more popular candidate in modeling crack propagation. It uses a scalar auxiliary variable, namely a phase-field variable, to model a discontinuity zone in a continuity domain. Furthermore, the fourth-order phase-field approach produces a better convergence rate and more accurate solutions than the second-order one. However, it is available for modeling crack propagation in brittle material. This study addresses the fourth-order phase-field model combining the non-standard phase-field form with a cohesive zone model (CZM) to predict crack propagation in quasi-brittle material. A Cornelisson's softening law is used to capture the high precision of crack propagation prediction. The concrete material is considered as a quasi-brittle one. For computation efficiency using NURBS-based finite elements, Virtual Uncommon-Knot-Inserted Master-Slave (VUKIMS) technique is employed to derive a local refinement mesh. Numerical results are verified by the published ones from literature. It was found that the peak load and crack path are independent of the element size and insensitive to the length-scale number using the fourth-order phase-field CZM. Our proposed model shows the most significant advantage compared to the standard phase-field approach in terms of computational cost and solution accuracy. Comment: 11 pages, 11 figures
Keywords	Computer Science - Computational Engineering ; Finance ; and Science
Subject code	669
Publishing date	2022-12-14
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Non-conforming multipatches for NURBS-based finite element analysis of higher-order phase-field models for brittle fracture

Nguyen, Khuong D. / Augarde, Charles E. / Coombs, William M. / Nguyen-Xuan, H. / Abdel-Wahab, M.

2022

Abstract: This paper proposes an effective computational tool for brittle crack propagation problems based on a combination of a higher-order phase-field model and a non-conforming mesh using a NURBS-based isogeometric approach. This combination, as demonstrated ... ...

Abstract	This paper proposes an effective computational tool for brittle crack propagation problems based on a combination of a higher-order phase-field model and a non-conforming mesh using a NURBS-based isogeometric approach. This combination, as demonstrated in this paper, is of great benefit in reducing the computational cost of using a local refinement mesh and a higher-order phase-field, which needs higher derivatives of basis functions. Compared with other approaches using a local refinement mesh, the Virtual Uncommon-Knot-Inserted Master-Slave (VUKIMS) method presented here is not only simple to implement but can also reduce the variable numbers. VUKIMS is an outstanding choice in order to establish a local refinement mesh, i.e. a non-conforming mesh, in a multi-patch problem. A phase-field model is an efficient approach for various complicated crack patterns, including those with or without an initial crack path, curved cracks, crack coalescence, and crack propagation through holes. The paper demonstrates that cubic NURBS elements are ideal for balancing the computational cost and the accuracy because they can produce accurate solutions by utilising a lower degree of freedom number than an extremely fine mesh of first-order B-spline elements. Comment: 40 pages, 35 figures
Keywords	Computer Science - Computational Engineering ; Finance ; and Science
Subject code	006
Publishing date	2022-12-14
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: 3D Facial Imperfection Regeneration

Nguyen, Phuong D. / Le, Thinh D. / Nguyen, Duong Q. / Nguyen, Thanh Q. / Chou, Li-Wei / Nguyen-Xuan, H.

Deep learning approach and 3D printing prototypes

2023

Abstract: This study explores the potential of a fully convolutional mesh autoencoder model for regenerating 3D nature faces with the presence of imperfect areas. We utilize deep learning approaches in graph processing and analysis to investigate the capabilities ... ...

Abstract	This study explores the potential of a fully convolutional mesh autoencoder model for regenerating 3D nature faces with the presence of imperfect areas. We utilize deep learning approaches in graph processing and analysis to investigate the capabilities model in recreating a filling part for facial scars. Our approach in dataset creation is able to generate a facial scar rationally in a virtual space that corresponds to the unique circumstances. Especially, we propose a new method which is named 3D Facial Imperfection Regeneration(3D-FaIR) for reproducing a complete face reconstruction based on the remaining features of the patient face. To further enhance the applicable capacity of the present research, we develop an improved outlier technique to separate the wounds of patients and provide appropriate wound cover models. Also, a Cir3D-FaIR dataset of imperfect faces and open codes was released at https://github.com/SIMOGroup/3DFaIR. Our findings demonstrate the potential of the proposed approach to help patients recover more quickly and safely through convenient techniques. We hope that this research can contribute to the development of new products and innovative solutions for facial scar regeneration.
Keywords	Computer Science - Computer Vision and Pattern Recognition
Subject code	004
Publishing date	2023-03-25
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: An adaptive strategy based on conforming quadtree meshes for kinematic limit analysis

Nguyen-Xuan, H / Do, Hien V / Chau, Khanh N

2019

Abstract: We propose a simple and efficient scheme based on adaptive finite elements over conforming quadtree meshes for collapse plastic analysis of structures. Our main interest in kinematic limit analysis is concerned with both purely cohesive-frictional and ... ...

Abstract	We propose a simple and efficient scheme based on adaptive finite elements over conforming quadtree meshes for collapse plastic analysis of structures. Our main interest in kinematic limit analysis is concerned with both purely cohesive-frictional and cohesive materials. It is shown that the most computational efficiency for collapse plastic problems is to employ an adaptive mesh strategy on quadtree meshes. However, a major difficulty in finite element formulations is the appearance of hanging nodes during adaptive process. This can be resolved by a definition of conforming quadtree meshes in the context of polygonal elements. Piecewise-linear shape functions enhanced with generalized bubble functions in barycentric coordinates are used to approximate the velocity field. Numerical results prove the reliability and benefit of the present approach. Comment: arXiv admin note: text overlap with arXiv:1603.01866
Keywords	Computer Science - Computational Engineering ; Finance ; and Science
Subject code	000
Publishing date	2019-03-07
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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