Article
Engineering, Multidisciplinary
Huilong Ren, Xiaoying Zhuang, Nguyen-Thoi Trung, Timon Rabczuk
Summary: A general finite deformation higher-order gradient elasticity theory is proposed in the paper, reducing the material parameters significantly under certain simplifications. A nonlocal operator method is developed and applied to numerical examples, demonstrating the stiffness response of the high gradient solid theory and the capability of the nonlocal operator method in solving higher-order physical problems.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Astronomy & Astrophysics
Diego Saez-Chillon Gomez
Summary: In this study, a general f(R) gravitational theory is examined within the Palatini formalism. It is shown that an additional surface term in the gravitational action plays a fundamental role in calculating the entropy of black holes.
Article
Engineering, Multidisciplinary
S. Ali Faghidian, Krzysztof Kamil Zur, J. N. Reddy
Summary: The proposed higher-order unified gradient elasticity theory effectively characterizes the nanoscopic response of advanced nano-materials, as demonstrated by its application to study the torsional behavior of elastic nano-bars and determine the shear modulus of nano-sized bars in closed-form analytical formula. Additionally, a practical approach to calibrate characteristic lengths is introduced.
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
(2022)
Article
Mechanics
Saeed H. Moghtaderi, S. Ali Faghidian, Mohsen Asghari
Summary: This study examines the nonlinear vibration characteristics of elastic nano-bars with large vibration amplitudes and proposes an effective analytical method. By applying the nonlocal elasticity theory and strain gradient elasticity theory, the method considers the nano-scale effects and non-classical boundary conditions. This analytical approach can be used for optimized design of vibration-based nano-devices and addressing nonlinear dynamic phenomena.
MECHANICS BASED DESIGN OF STRUCTURES AND MACHINES
(2023)
Article
Mechanics
Xiao-Jian Xu, Jun-Miao Meng
Summary: A size-dependent elastic theory for magneto-electro-elastic (MEE) nano-materials is proposed, which includes classical and nonlocal parameters. Governing equations and boundary conditions are derived with the aid of the variational principle. General solutions for a one-dimensional beam problem are formulated, with the motion equation two orders higher than the classical model.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2021)
Article
Mathematics, Applied
Nawal Irzi, Khaled Kefi
Summary: In this paper, we study the existence of nontrivial weak solutions for the fractional p(., .)-Laplacian problem with nonlocal Neumann boundary conditions on a smooth and bounded domain. By applying the Ekeland principle and the variational method, we show the existence of such solutions under appropriate assumptions.
APPLICABLE ANALYSIS
(2023)
Article
Computer Science, Interdisciplinary Applications
Yongzheng Zhang
Summary: In this study, a nonlocal operator method (NOM) is proposed for the dynamic analysis of (thin) Kirchhoff plates. The NOM simplifies the analysis process for thin plates and derives the dynamic governing formulation and operator energy functional using a variational principle. The Verlet-velocity algorithm is used for time discretization.
ENGINEERING WITH COMPUTERS
(2023)
Article
Computer Science, Interdisciplinary Applications
Huilong Ren, Xiaoying Zhuang, Erkan Oterkus, Hehua Zhu, Timon Rabczuk
Summary: In this paper, a method based on nonlocal operator method is proposed for deriving nonlocal forms for various physical problems, such as elasticity, thin plate, gradient elasticity, electro-magneto-elasticity, and phase-field fracture method. The method is simple and general, and can efficiently convert local physical models into nonlocal forms. A criterion based on the instability of the nonlocal gradient is also proposed for fracture modeling in linear elasticity.
ENGINEERING WITH COMPUTERS
(2023)
Article
Engineering, Civil
Xiao-Jian Xu
Summary: This study addresses the paradox of abnormal frequencies in the free vibration of nonlocal cantilever beams within the framework of nonlocal strain gradient theory. By updating the inconsistencies of reported boundary conditions and proposing a method for calibrating size-effect parameters, the numerical results demonstrate the model's capability in capturing the size-dependent mechanical properties of materials, whether exhibiting stiffness-hardening or stiffness-softening effects.
THIN-WALLED STRUCTURES
(2021)
Article
Mechanics
J. Kaplunov, D. A. Prikazchikov, ab L. Prikazchikova
Summary: This paper concerns the comparative analysis of differential and integral formulations for boundary value problems in nonlocal elasticity. By studying an antiplane problem and considering a 1D exponential kernel, it is revealed that the solution to the differential model within Eringen's theory does not satisfy the equation of motion in nonlocal stresses. A more general differential setup is investigated, which shows that the transformation from the integral formulation to the differential one is only possible under certain conditions on nonlocal stresses. The proposed effective boundary condition supports an antiplane surface wave.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2023)
Article
Physics, Multidisciplinary
Didier A. Solis, Pablo Vazquez-Montejo
Summary: The paper introduces a variational framework for studying curves affected by bend and twist degrees of freedom, deriving equilibrium equations and first integrals using material curvatures. It is applied to isotropic and anisotropic Kirchhoff elastic rods to analyze twisting deformations, as well as twisting instabilities and bending anisotropy effects on deformed states.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Computer Science, Interdisciplinary Applications
Dhiraj S. Bombarde, Manish Agrawal, Sachin S. Gautam, Arup Nandy
Summary: The study introduces a novel twenty-seven node quadratic EAS element, addressing the underutilization of quadratic elements in existing 3D EAS elements. Additionally, a six-node wedge and an eighteen-node wedge EAS element are presented in the manuscript.
COMPUTERS & STRUCTURES
(2024)
Article
Thermodynamics
Vincenzo Tibullo, Martina Nunziata
Summary: This article discusses the results of the linear theory of thermopiezoelectricity. It provides a brief introduction to dielectric materials and the phenomena of direct and inverse piezoelectricity. The article then presents a general theory of thermopiezoelectricity for strain gradient materials, where the second gradient of the displacement field and electric potential are considered as independent constitutive variables. The second law of thermodynamics is formulated based on the entropy production inequality proposed by Green and Laws, and thermodynamic restrictions are obtained. The article also establishes linear constitutive equations and the mixed initial-boundary value problem. Based on this theory, uniqueness result and a variational principle are obtained.
JOURNAL OF THERMAL STRESSES
(2023)
Article
Engineering, Civil
Alaa A. Abdelrahman, Ismail Esen, Cevat Ozarpa, Ramy Shaltout, Mohamed A. Eltaher, Amr E. Assie
Summary: This study develops a nonclassical size dependent model to investigate the dynamic behavior of perforated nanobeams under moving load, considering length scale and microstructure effects. By using the virtual work principle and Navier's approach, the governing equations of motion for perforated nanobeams are derived and the impacts of perforation, moving load velocity, microstructure parameter, and nonlocal size scale effects are analyzed. The results obtained are useful for designing MEMS/NEMS structures with perforation, such as frequency filters, resonators, and accelerometers.
SMART STRUCTURES AND SYSTEMS
(2021)
Article
Mathematics, Applied
Zeyi Liu, Min Zhao, Deli Zhang, Sihua Liang
Summary: This paper utilizes Ekeland's variational principle and the mountain pass theorem to establish the existence of negative energy solution, positive energy solution, and positive ground state solution for a class of nonlocal Schrodinger-Poisson type system with sublinear term. Furthermore, the multiplicity of solutions is also demonstrated using the Clark theorem. Notably, the novelty of the equation lies in its inclusion of both nonlocal term and nonlocal coefficient.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2022)
Article
Mechanics
Rawan Aqel, Patrick Severson, Rani Elhajjar
Summary: A novel core splice joint configuration for composite sandwich structures is studied and proposed to improve the strength and toughness. Experimental and numerical efforts show that this configuration can significantly increase the ultimate strength by 13% to 51% and the toughness by 2% to 35%.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Xianheng Wang, Cong Chen, Jinsong Zhang, Xinming Qiu
Summary: In this paper, a new form-finding method based on spatial elastica model (FMSE) is proposed for elastic gridshells. The method integrates the deformations of elastic rods into the overall deformation of the gridshell, and solves a set of transcendental equations using the quasi-Newton method to ensure the deformation satisfies the given boundary conditions. The method is validated through experiments and expected to have potential applications in the investigations of elastic gridshells.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Hao Huang, Zitong Guo, Zhongde Shan, Zheng Sun, Jianhua Liu, Dong Wang, Wang Wang, Jiale Liu, Chenchen Tan
Summary: The conventional evaluation of 3D braided composites' mechanical properties through numerical and experimental methodologies hinders material application due to the expenses, time constraints, and laborious efforts involved. This study establishes a multi-scale finite element model and a surrogate model for predicting the elastic properties of 3D4D rotary braided composites with voids. By optimizing a neural network model, the results are validated and provide valuable insights into the microstructure and properties of these composites.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Xinyu Li, Hao Zhang, Haiyang Yang, Junrong Luo, Zhongmin Xiao, Hongshuai Lei
Summary: Due to their excellent mechanical properties and design flexibility, fluted-core composite sandwich structures have gained significant attention in aerospace and rail transit applications. This study investigated the free-vibration characteristics and optimized design of composite fluted-core sandwich cylinders through theoretical models and experimental tests.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Chao Li, Chunzheng Duan, Xiaodong Tian, Chao Wang
Summary: A mechanistic model considering the bottom edge cutting effect and the anisotropic characteristics of the material is proposed in this paper to accurately predict cutting forces. The model was validated through a series of milling experiments and can be used to predict the cutting force of various parts of the cutter and any feed direction.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Camila Sanches Schimidt, Leopoldo Pisanelli Rodrigues de Oliveira, Carlos De Marqui Jr
Summary: This work investigates the vibro-acoustic performance of graded piezoelectric metamaterial plates. The study shows that piezoelectric metamaterial plates with reconfigurable properties can provide enhanced vibration and sound power attenuation.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Jun Ke, Li-jie Liu, Zhen-yu Wu, Zhong-ping Le, Luo Bao, Dong-wei Luo
Summary: Compared with other green natural fibers, ramie has higher mechanical properties and lower cost. In this study, ramie and glass fiber are made into composite circular tubes. The results show that the hybrid circular tube with ramie and glass fiber has improved torsional mechanical properties and reduced weight and cost. The failure mechanisms are affected by the loading direction and the content of each fiber.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Natalia Pingaro, Gabriele Milani
Summary: This paper proposes an enhanced analytical model for predicting the behavior of FRCM samples tested under standard tensile tests. The model takes into account the interaction between fibers and matrix through the interface, and assumes different material properties at different phases. By solving a second order linear differential equation, an analytical solution can be obtained. The model is validated with experimental data and shows good predictability.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Jialiang Fan, Anastasios P. Vassilopoulos, Veronique Michaud
Summary: This article investigates the effects of voids, joint geometry, and test conditions on the fracture performance of thick adhesive Double Cantilever Beam (DCB) joints. It concludes that grooved DCB joints with low void content tested at low displacement rates showed stable crack propagation without significant crack path deviation.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Auwalu I. Mohammed, Kaarthikeyan Raghupathy, Osvaldo De Victoria Garcia Baltazar, Lawson Onokpasah, Roger Carvalho, Anders Mogensen, Farzaneh Hassani, James Njuguna
Summary: This study investigates the performance of composite pressure vessels under damaged and undamaged conditions, providing insights into their reliability and residual strength capabilities. The results demonstrate that the damage profile and its effect on compressive strength are similar between damaged and non-damaged cylinders. When subjected to quasi-static compression, the polyethylene liner absorbs enough elastic strain energy to recover without plastic deformation. Additionally, quasi-static compression has little to no influence on the axial strength of the cylinders. The damage characterization reveals fiber breakage, delamination, local buckling, and brooming failure. This study has direct implications for the safety design tolerances, manufacturing strategies, and operational failure conditions of composite overwrapped pressure vessels (COPVs).
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Muhammad Irfan Shirazi, Samir Khatir, Djilali Boutchicha, Magd Abdel Wahab
Summary: Structural health monitoring is important to ensure the safety of components and structures. This study proposes a method using finite element models and 1D-CNN network to extract and classify vibration responses for crack detection. The results show that the proposed approach is effective in real-time damage detection.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Maryam Mirsalehi, Kiarash Kianpour, Sharif Shahbeyk, Mohammad Bakhshi
Summary: This study comprehensively investigates the one-way response of 3D-woven sandwich panels (3DWSPs) and their interfering parameters, providing interpretation of elastic and failure results, failure maps, and reliable theoretical models for linear elastic response and observed failure mechanisms.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Yiming Zhao, Zhonggang Wang, Zhigang Yang, Bin Qin
Summary: The paper proposes a Ritz and statistical energy analysis (Ritz SEA) hybrid method for calculating rectangular plate acoustic vibration coupling in the mid-frequency range. This method combines the fast convergence and ability to handle arbitrary boundary conditions of the Ritz method with the power flow equation of the statistical energy analysis method. The results show that this approach effectively filters out random fluctuations in mid-frequency domains while demonstrating exceptional stability and precision.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Joao Henrique Fonseca, Woojung Jang, Dosuck Han, Naksoo Kim, Hyungyil Lee
Summary: This study addresses the enhancement of an injection-molded fiber-reinforced plastic / metal hybrid automotive structure and its plastic injection molding process through the integration of the finite element method, artificial intelligence, and evolutionary search methods. Experimental validation of finite element models, the generation of a database through orthogonal array and Latin hypercube methods, and the training of artificial neural networks are conducted. The genetic optimization algorithm is then applied to identify optimal process parameters. The results show significant reduction in product warpage and manufacturing time while maintaining structural strength, contributing to the advancement of composite automotive structures with superior quality.
COMPOSITE STRUCTURES
(2024)
Article
Mechanics
Alessandro Vescovini, Carina Xiaochen Li, Javier Paz Mendez, Bo Cheng Jin, Andrea Manes, Chiara Bisagni
Summary: This paper presents a study on six single-stringer specimens manufactured using the card-sliding technique with non-crimp fabrics and adopting a Double-Double (DD) stacking sequence. The specimens were tested under compression loading conditions to investigate post-buckling and failure in aerospace structures. Experimental results and numerical simulations were compared to analyze the behavior and failure modes of the specimens. The study found promising evidence of a viable solution to optimize aeronautical structures and enhance resistance to skin-stringer separation, particularly with the use of tapered flanges.
COMPOSITE STRUCTURES
(2024)