Article
Engineering, Manufacturing
Zhengtong Shan, Minh Tien Tran, Wanchuck Woo, Sun-Kwang Hwang, Huai Wang, Vladimir Luzin, Ed. J. Kingston, Michael R. Hill, Adrian DeWald, Dong-Kyu Kim
Summary: This study proposes a multiscale framework based on the inherent strain method to accurately predict residual stress distribution in functionally graded materials (FGMs) processed via additive manufacturing (AM) using directed energy deposition (DED). The results indicate that the proposed model predicts the residual stress distribution in FGMs consistent with experimental measurements and allows for the investigation of the effects of interlayers and scanning strategies on residual stress and distortion.
ADDITIVE MANUFACTURING
(2023)
Article
Materials Science, Multidisciplinary
F. Hajializadeh, A. Ince
Summary: The DMD process is efficient for manufacturing complex parts, but results in significant residual stresses which require accurate assessment methods. A novel artificial neural network-based modeling approach improves the prediction of residual stresses for different geometric structures and enhances computational efficiency.
MATERIALS TODAY COMMUNICATIONS
(2021)
Article
Computer Science, Interdisciplinary Applications
Xiaoxi Zhao, Birendra Jha
Summary: This study presents a computational framework to understand the impact of plastic deformation on induced fault slip events. Results show that a poroplastic reservoir exhibits larger vertical deformation and delayed slip compared to a poroelastic reservoir, and a reservoir with a smaller modulus than the caprock displays a larger vertical displacement and an earlier onset of both plastic failure and fault slip.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Chuanfeng Wu, Junmei Chen, Zhiyuan Yu, Chun Yu, Jijin Xu, Hao Lu
Summary: This study thoroughly investigated the heterogeneous mechanical properties along the building direction in a direct laser deposited 17-4 PH part by conducting tensile tests. The results showed significant variations in yield strength and elongation at different positions within the as-built cuboid. The microstructure analysis revealed differences in chemical composition and dislocation density among samples, attributed to heat accumulation during the building process. Additionally, the varying reduction in austenite fractions after tensile tests indicated diverse extents of strain-induced phase transformation.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Kyeongsik Ha, Young Hoon Moon, Tae Hwan Kim, Gyeong Yun Baek, Ki Yong Lee, Do-sik Shim, Wookjin Lee
Summary: This study aimed to develop a computational methodology to estimate the residual stress formation behavior followed by direct energy deposition of high-speed tool steel hard materials. Through experiments and finite element simulations, it was found that the proposed method is effective in controlling distortions and analyzing the evolution of residual stress.
METALS AND MATERIALS INTERNATIONAL
(2023)
Article
Engineering, Mechanical
Ritin Mathews, Kishore Mysore Nagaraja, Runyu Zhang, Sumair Sunny, Haoliang Yu, Deon Marais, Andrew Venter, Wei Li, Hongbing Lu, Arif Malik
Summary: Additive manufacturing generates residual stresses due to thermal gradients, and heat treatments are commonly used to reduce these stresses. Computational fluid dynamics (CFD) and finite element analysis (FEA) models are often used to improve the understanding of residual stress distributions. However, CFD cannot predict structural response, while FEA lacks the ability to predict geometric and fluid behavior. An integrated CFD-FEA framework is proposed to overcome these limitations and provide accurate predictions for additive manufacturing processes.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Engineering, Manufacturing
Shaun Cook, Greg Sweet, Keivan Ahmadi, Paul Bishop, Rodney Herring
Summary: In this study, a sequentially coupled thermo-mechanical-metallurgical finite element model for directed energy deposition process was developed and validated.
JOURNAL OF MANUFACTURING PROCESSES
(2022)
Article
Thermodynamics
Guiru Meng, Yadong Gong, Jingdong Zhang, Lida Zhu, Hualong Xie, Jibin Zhao
Summary: Laser deposition manufacturing is a promising technology for high performance metal parts and has broad applications in aerospace and other fields. A multi-scale modeling approach is used to simulate the microstructure evolution during the process, and the effects of different process parameters are investigated. The simulated results are consistent with experimental observations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Metallurgy & Metallurgical Engineering
Chuanfeng Wu, Junmei Chen, Zhiyuan Yu, Hao Lu, Chun Yu, Jijin Xu
Summary: The anisotropic ductility of a direct laser deposited 17-4 PH cubic part was investigated, revealing different elongations and orientations of ferrite in various samples. The orientation of ferrite was found to impact the ductility of the part due to its effects on plastic deformability and deformation compatibility between phases during loading.
ACTA METALLURGICA SINICA-ENGLISH LETTERS
(2021)
Article
Mechanics
Shengnan Zhang, Yingjie Xu, Weihong Zhang
Summary: This study proposes a novel micromechanical model to investigate the effects of curing on the tensile properties and failure mechanisms of carbon/epoxy laminates reinforced with z-pins. The microstructures caused by z-pins, such as fiber distortion and resin-rich pockets, are characterized. The results show that increasing z-pin density leads to the presence of cure-induced residual stresses. The high stress concentration is attributed to the thermal expansion and volume shrinkage mismatch between z-pins and resin-rich regions. The existence of interfacial stress concentration and resin-rich channels results in a loss of tensile strength and provides an initial pathway for crack growth under tension. Moreover, the failure mode changes from interfacial cracking to softening and damages of both interface and resin-rich regions with increasing z-pin density.
COMPOSITE STRUCTURES
(2022)
Article
Engineering, Civil
Mohammad Amin Hariri-Ardebili, Victor E. Saouma, Nolan W. Hayes
Summary: The paper proposes an integrative framework linking test results with finite element analyses to predict future response, further enhanced through a probabilistic framework. This methodology could be expanded as a prognosis tool to other applications seeking future responses of ASR affected structures.
ENGINEERING STRUCTURES
(2021)
Article
Engineering, Mechanical
Vishal Singh, Rakesh Kumar, Yann Charles, Dhiraj K. Mahajan
Summary: Modeling the coupled diffusion-mechanics response is essential for understanding the multifaceted hydrogen-assisted damage evolution in metallic materials. This study utilizes a dislocation density-based crystal plasticity model coupled with a hydrogen diffusion/trapping model to simulate the deformation and failure under the HELP mechanism of hydrogen embrittlement. The findings highlight the significant role of hydrogen in influencing dislocation interactions and density, leading to macroscopic softening or hardening.
INTERNATIONAL JOURNAL OF PLASTICITY
(2022)
Article
Engineering, Multidisciplinary
Zhanfeng Li, Chennakesava Kadapa, Mokarram Hossain, Jiong Wang
Summary: This paper establishes a finite element framework to study the electro-mechanical response in growing materials such as biological tissues and hydrogels. By understanding the coupled effects of growth and electric fields on deformation behavior, it is possible to precisely control the bending angle by adjusting growth parameters and external voltage, as well as simulate pattern formation and transition behavior. This method provides an accurate, efficient, and stable tool for numerical simulation of electro-elastic solids incorporating growth effect, which can be used for understanding coupled growth phenomenon in biological soft matter and developing smart devices for medical treatment.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Engineering, Industrial
Feijie Cui, Minghui Yang, Ben Deng, Fangyu Peng, Rong Yan, Aodi Yan
Summary: This paper investigates the cutting mechanism of TiBw/TA15 composites by establishing multiscale finite element cutting models and validating the model with experiments. The results show that cutting speed and cutting depth have an impact on the hardened layer depth.
JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Jiaxuan Chi, Zhongyi Cai, Hepeng Zhang, Hongqiang Zhang, Wei Guo, Zhandong Wan, Guofeng Han, Peng Peng, Zhi Zeng
Summary: The combined manufacturing of direct energy deposition (DED) and laser shock peening (LSP) shows great potential in repairing titanium alloy components and improving their mechanical properties. This study evaluated the effects of LSP on microstructures, residual stress, and tensile properties of DEDed samples, finding that LSP induces a high-level compressive residual stress state and microstructure refinement, leading to an improvement in ultimate tensile strength.
MATERIALS & DESIGN
(2021)
Article
Engineering, Multidisciplinary
Yang Li, Jianbing Sang, Xinyu Wei, Zijian Wan, G. R. Liu
Summary: This study presents a novel approach to predict the hyperelastic material parameters of skeletal muscles using nonlinear finite element method, neural networks, and experiments. The study establishes FEM models to simulate the deformation of skeletal muscles and create a dataset of the nonlinear relationship between stress and stretch. Two-way neural networks are then trained using this dataset to predict the material parameters, and experiments are conducted to validate the predictions.
INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS
(2022)
Article
Robotics
Shuyong Duan, Ningning Lu, Zhongwei Lyu, Guirong Liu, Bin Cao
Summary: The novel technique OC-Anchors is proposed to improve the accuracy of real-time single-stage object detectors by creating anchors based on the categories of foreground objects. The performance of OC-Anchors in the YOLOv2 framework with COCO dataset shows significant improvement in detection accuracy without affecting prediction speed.
INTERNATIONAL JOURNAL OF INTELLIGENT ROBOTICS AND APPLICATIONS
(2022)
Article
Water Resources
Wen Li, Blossom Nwedo Nzeribe, G. R. Liu, Guangming Yao, Michelle Crimi, Kalani Rubasinghe, Craig Divine, Jeff Mcdonough, Jack Wang
Summary: The Horizontal Reactive Media Treatment (HRX) well is a novel technology for in situ treatment of contaminated groundwater. Groundwater capture simulation plays a crucial role in the design of the HRX well.
ADVANCES IN WATER RESOURCES
(2022)
Article
Engineering, Multidisciplinary
Shuyong Duan, Chunlu Li, Pengfei Xu, Guirong Liu
Summary: A novel method for mitigating the jittering of a robot arm-tip is proposed, which involves transmitting the jittering to a vibration of a mass block inside a jittering mitigator. This method only requires the frequency of the jittering at the arm-tip. The feasibility of the method is verified through simulations and physical experiments with a practical robot, resulting in a significant reduction in the amplitude of the jittering vibration at the arm-tip.
INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS
(2022)
Article
Thermodynamics
Xueming Yang, Fanxing Meng, Xinyao Zhang, Bingyang Cao, Yao Fu
Summary: The study systematically investigated the thermal conductivities of 3D carbon nanotubes and graphene fillers using SPH and DPD simulations, revealing that introducing both CNT and graphene fillers simultaneously can most effectively improve the thermal conductivity of the composites. The coupled DPD and SPH model was demonstrated as a viable approach for understanding the thermal conductivities of nanocomposites with reduced computational cost compared to full atomistic simulation.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
Article
Engineering, Multidisciplinary
J. G. Zhao, G. R. Liu, S. H. Huo, Z. R. Li
Summary: This paper explores the unique feature of smoothed finite element methods (S-FEMs) to obtain accurate modes for both free and forced vibration analysis. A 3D code has been developed and compared with the commercial finite element analysis software ABAQUS.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2022)
Article
Engineering, Multidisciplinary
G. R. Liu
Summary: Artificial neural networks, such as MLP, CNNs, and RNNs, have been widely used for practical problems. The paper focuses on studying the theoretical foundation of NNs and proposes a novel Universal Prediction Theory (UPT) based on intensive study of affine transformations and their role as prediction functions. The effects of network architecture and nonlinear activation functions are also investigated.
INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS
(2023)
Article
Engineering, Multidisciplinary
G. R. Liu
Summary: This paper presents a Neurons-Samples Theorem which provides an answer to the question of how many neurons or layers of neurons should be used for a given dataset, stating that the number of neurons should be equal or less than the number of samples used to train the NN.
INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS
(2022)
Article
Engineering, Multidisciplinary
Shao-Wei Wu, G. R. Liu, Chao Jiang, Xin Liu, Kai Liu, De-Tao Wan, Jun-Hong Yue
Summary: This study extends the smoothed finite elements method (S-FEM) to arbitrarily complicated meshes, including nonconvex polygonal meshes. A novel formulation based on S-FEM is presented for analyzing elastic and elastoplastic problems using arbitrarily polygonal elements. The method utilizes the unique features of S-FEM to ensure stability, accommodation to mesh distortion, and differentiation-free strain field computation. It effectively handles general non-convex elements with good accuracy and robustness, making it an effective tool for dealing with polycrystalline metallic materials of arbitrary shapes.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Engineering, Multidisciplinary
Sandeep Kshirsagar, H. Nguyen-Xuan, G. R. Liu, Sundararajan Natarajan
Summary: In this paper, three different smoothed finite element methods, NS-FEM, FS-FEM, and a-FEM, are used for 3D solids with large deformation. The common feature of these techniques is the introduction of smoothed strain as a weighted average of the compatible strain field over smoothing domains. The implementation of SFEM in Abaqus software is challenging due to the interconnected SFEM elements at the elemental level. However, this work effectively addresses the challenges and provides a validated implementation for benchmark examples and real-life problems.
INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS
(2023)
Article
Engineering, Multidisciplinary
X. Cui, G. R. Liu, Z. R. Li
Summary: In this paper, a high-order edge-based smoothed finite element method (ES-FEM) using special triangular elements with four nodes (T4) is proposed. The strain field in each smoothing domain is expressed by polynomials of complete order and can be expressed in the form of first-order and second-order shape functions for T4 elements. Two types of ES-FEM models, constant-strain ES-FEM-T4 and linear-strain ES-FEM-T4, are developed and found to have high calculation accuracy and the ability to remove volumetric locking in incompressible or nearly incompressible solids.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2023)
Article
Engineering, Mechanical
Shao-Wei Wu, De-Tao Wan, Chen Jiang, Xin Liu, Kai Liu, G. R. Liu
Summary: This paper presents a Unified-Implementation of smoothed finite element method (UI-SFEM) for analyzing large deformations of complex biological tissues. The method utilizes automatically generated linear triangles and tetrahedrons to construct the numerical integration domain, and can combine arbitrary forms of smoothing domains based on the numerical characteristics of materials or components. It also considers the instantaneous hyperelasticity and time-dependent viscous behaviors commonly observed in biological tissues. Numerical experiments demonstrate that the UI-SFEM possesses high flexibility, accuracy, computational efficiency, and is insensitive to mesh distortion when simulating multi-material and multi-component biological tissues.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Computer Science, Interdisciplinary Applications
Parikshit Boregowda, Gui-Rong Liu
Summary: Handling boundaries in smoothed particle hydrodynamics (SPH) is a critical problem and significant progress has been made in exploring boundary integral terms to improve accuracy. However, formulation consistency is difficult due to fundamental difficulties, affecting solution accuracy. This study investigates the order of accuracy of SPH approximation with boundary integral terms, examining both kernel consistent and particle consistent formulations. The results show that particle consistent formulation significantly outperforms traditional correction factors in terms of accuracy.
MATHEMATICS AND COMPUTERS IN SIMULATION
(2023)
Article
Engineering, Civil
Leonardo Leonetti, H. Nguyen-Xuan, Gui-Rong Liu
Summary: This paper investigates a new solid-shell finite element formulation, which introduces new stress variables and an extra smoothing region to improve the accuracy of the approximate solutions. The assumed natural strain and discrete shear gap techniques are employed to alleviate trapezoidal and shear locking. The proposed method successfully solves popular benchmark tests and avoids cross-diagonal meshes.
THIN-WALLED STRUCTURES
(2023)
Article
Engineering, Multidisciplinary
F. T. Xu, S. Y. Duan, F. Wang, G. R. Liu
Summary: This study developed an inverse procedure to predict and monitor contact wire wear of trains, regardless of whether the pantograph passes. A three-dimensional finite element model was used to simulate static and dynamic contact processes, and the wear-level was found to strongly relate to displacement variation of the collector head. Simple formulae were derived for estimating wear-level based on either static or dynamic measurements, making the results easily applicable in real-time.
APPLIED MATHEMATICS IN SCIENCE AND ENGINEERING
(2022)
