Article
Engineering, Mechanical
Mohammad R. Mehraban, Majid R. Ayatollahi, Bahador Bahrami, Filippo Berto
Summary: This study investigates the effects of higher order terms on the stress and displacement fields around sharp V-notched components under pure antiplane shear loading. The use of nonsingular terms is necessary only when seeking stress distribution far from the notch tip and with small notch angles. Parameters affecting accurate determination of unknown coefficients and convergence of the numerical results were also studied to check the stability of the results.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2022)
Article
Engineering, Mechanical
Alberto Visentin, Alberto Campagnolo, Giovanni Meneghetti
Summary: The Peak Stress Method (PSM) allows for a quick estimation of the notch stress intensity factors (NSIFs) for the fatigue strength assessment of sharp V-notches and welded joints by utilizing properly calibrated coefficients. This study calibrated the coefficients for the full range of notch opening angles using Ansys (R) FE code and implemented polynomial expressions to generalize the application of PSM.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2023)
Article
Engineering, Mechanical
Giovanni Meneghetti, Alberto Campagnolo, Alberto Visentin, Massimiliano Avalle, Matteo Benedetti, Andrea Bighelli, Davide Castagnetti, Andrea Chiocca, Luca Collini, Massimiliano De Agostinis, Alessandro De Luca, Eugenio Dragoni, Stefano Fini, Vigilio Fontanari, Francesco Frendo, Alessandro Greco, Giuseppe Marannano, Fabrizio Moroni, Antonio Pantano, Alessandro Pirondi, Alessandro Rebora, Alessandro Scattina, Raffaele Sepe, Andrea Spaggiari, Bernardo Zuccarello
Summary: This paper presents a Round Robin study among eleven Italian Universities to calibrate the peak stress method (PSM) using seven different commercial FE software packages. The study found that most of the FE software packages had similar PSM parameter values, with the main source of discrepancy being the stress extrapolation method at FE nodes.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2022)
Article
Mechanics
Yongyu Yang, Wei Pan, Shanlong Yao, Changzheng Cheng, Qiaoguo Wu
Summary: This paper analyzes the role of non-singular stresses near the apex of anti-plane sharp notches, finding that taking into account only the singular stress term is insufficient when describing the complete stress field of the notch. By coupling singular characteristic analysis with the finite element method, the authors show that including the first two non-singular stress terms can accurately characterize the stress field far from the notch tip with a maximum error below 2%.
ENGINEERING FRACTURE MECHANICS
(2021)
Article
Materials Science, Multidisciplinary
Mirzaul Karim Hussain, S. R. K. Murthy
Summary: This study surveys and compares finite element based methods for extracting NSIFs, evaluating their accuracy. The results indicate that displacement-based methods consistently provide the most accurate NSIFs relative to the number of sampling points.
JOURNAL OF MECHANICS OF MATERIALS AND STRUCTURES
(2022)
Article
Mechanics
Weichen Kong, Yanwei Dai, Yinghua Liu
Summary: This paper extends the notch stress intensity factor (NSIF) and strain energy rate density (SERD) rule to the three-dimensional (3D) sharp V-notch tip under creeping conditions. The out-of-plane factor T-z is introduced to describe the 3D NSIF, and the out-of-plane effect on SERD is studied. A method to evaluate the 3D sharp V-notch NSIF based on the concept of SERD is proposed. The link between NSIF and SERD of the 3D sharp V-notch is established and discussed.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Engineering, Mechanical
Zhongwen Yue, Linzhi Peng, Yaxu Qiao, Wei Liu, Shengnan Xu, Yanan Yuan
Summary: This study investigates the dynamic fracture behavior of rock specimens with a sharp V-notch through experiments and numerical simulations. Ultra-high speed photography and digital image correlation are used to observe the fracture process and extract relevant fracture parameters. The experimental results validate the applicability of digital image correlation in studying the dynamic brittle fracture in sharp V-notched rock specimens.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Engineering, Mechanical
S. Karen Alavi, M. R. Ayatollahi, Jamaloddin Jamali, Michal Petru
Summary: This article experimentally investigates the stress field around various blunt notches using the digital image correlation method. The effects of geometry parameters on stress distribution are discussed, and the accuracy of calculated notch stress intensity factors and HOTs coefficients are studied by comparing with finite element analysis results.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Kamau Kingora, Hamid Sadat-Hosseini
Summary: This paper presents a novel 2nd order direct forcing immersed boundary method for simulating incompressible flow problems with complex immersed boundaries. The method reshapes the cells cut by the immersed boundary to conform to its shape, eliminating spatial pressure oscillations and improving the resolution of the boundary layer. It enforces boundary conditions directly at the exact location of the immersed boundary, ensuring accurate simulations even on grids with high aspect ratio and enabling simulations with multiple immersed boundaries in close proximity.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Engineering, Multidisciplinary
Heinrich Kraus, Joerg Kuhnert, Andreas Meister, Pratik Suchde
Summary: This paper presents a meshfree generalized finite difference method for solving Poisson's equation with a diffusion coefficient that contains jump discontinuities. The diffusion operator is discretized using a strong form method and a conservative formulation based on locally computed Voronoi cells. Additionally, a novel conservative formulation for enforcing Neumann boundary conditions is proposed, and a switching method from the strong form to the conservative formulation is introduced. The results of benchmark tests show that the new hybrid method produces better results compared to the classical generalized finite difference approach for high jumps in diffusivity.
APPLIED MATHEMATICAL MODELLING
(2023)
Article
Engineering, Civil
Wei Shen, Guiming Liang, Jiajing Lei, Chunmei Li
Summary: This study derived a simplified formula for calculating the notch stress distribution and N-SIF of double edge V-notch plate based on linear elastic fracture mechanics and singular strength theory. The evaluation formula of notch stress field was simplified by introducing the singular intensity factor 'as' and extended to arbitrary opening angles. The simple formula proposed showed high accuracy in calculating N-SIF across a wide range of opening angles and geometric sizes, making it convenient for engineering applications.
THIN-WALLED STRUCTURES
(2021)
Article
Engineering, Multidisciplinary
Francesco Calabro, Gianluca Fabiani, Constantinos Siettos
Summary: This study introduces a numerical method based on machine learning, using Extreme Learning Machines to approximate solutions to linear elliptic partial differential equations. By utilizing a feedforward neural network to compute matched solutions, the method avoids the cumbersome training phase of other machine learning approaches. Numerical results demonstrate high accuracy, outperforming traditional central Finite Differences methods.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Engineering, Marine
Chun-Hsien Wu, Ming-Chung Fang
Summary: This paper presents an improved frequency-domain Rankine source method based on a biquadratic B-spline scheme with an improved radiation mechanism. The method accurately solves unsteady flows produced by an oscillating, translationally moving submerged singularity and simulates the radiation of generated waves at various tau conditions.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2022)
Article
Acoustics
E. Atroshchenko, C. Anitescu, T. Khajah, A. Calderon Hurtado
Summary: In this study, a numerical framework based on isogeometric collocation is developed to solve boundary value problems (BVPs) with absorbing boundary conditions (ABCs). The approach offers advantages such as lower computational cost, reduced pollution error, and the ability to evaluate higher order derivatives. The accuracy of the ABCs is analyzed through comparison with analytical solutions, and a detailed parametric study is conducted.
Article
Engineering, Mechanical
Chung-Gang Li, Rahul Bale, WeiHsiang Wang, Makoto Tsubokura
Summary: In this study, a sharp interface immersed boundary method (IBM) for low Mach number viscous compressible flows is developed. The IBM utilizes a robust interpolation scheme to ensure stability for complex geometries with zero-thickness walls. By gradually reducing the order of interpolation near the wall, the method eliminates interaction between opposite sides in high order schemes. It also efficiently handles moving objects in compressible flows without requiring any special treatment. The method has been successfully applied to aerodynamic simulations, compression and expansion processes, and aeroacoustics simulations.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Engineering, Geological
Bahador Bahrami, Morteza Nejati, Majid Reza Ayatollahi, Thomas Driesner
Summary: This paper proposes a new test called ANBD to measure true mode III fracture toughness of rock materials. The test performance was evaluated through experiments on granite samples and the effects of test parameters were investigated. The results demonstrate the effectiveness of the ANBD test and provide insights into the fracture behavior of rock materials.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Mechanical
Ali Aminzadeh, Bahador Bahrami, Majid Reza Ayatollahi, Morteza Nejati
Summary: The study shows a tension-based fracturing type prevailing in the DNBD samples of polymethyl-methacrylate (PMMA). A comparison between PMMA and rock samples demonstrates the main reason for the different observed fracturing types.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Materials Science, Multidisciplinary
Seyed Karen Alavi, Majid R. Ayatollahi, Bahador Bahrami, Morteza Nejati
Summary: This study presents an analytical stress solution for bi-material V-notches with an end hole. The stress field is derived as an asymptotic series solution using the Kolosov-Muskhelishvili approach, with the constant coefficients computed using the least square method. The accuracy of the solution is verified through benchmarking with finite element method results.
MATHEMATICS AND MECHANICS OF SOLIDS
(2023)
Article
Engineering, Mechanical
Bahador Bahrami, Majid R. Ayatollahi, Mohammad R. Mehraban, Morteza Nejati, Filippo Berto
Summary: In this study, the effects of higher order terms (HOTs) on the stress distribution near the sharp corner of two bonded dissimilar materials were investigated. The numerical results show that ignoring HOTs can lead to considerable errors in the stress field estimation.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2022)
Article
Materials Science, Multidisciplinary
S. M. Javad Razavi, Amir Nabavi-Kivi, Majid R. Ayatollahi
Summary: Fused deposition modeling is an additive manufacturing technique used for rapid manufacturing and prototyping. However, the layer-wise fabrication process often leads to anisotropic behavior in the final products. This research aims to determine whether the isotropic assumption of material using maximum tangential stress and mean stress criteria can predict the mixed-mode fracture resistance of 3D-printed parts. The results show that both criteria can accurately predict the fracture loads of the fused deposition modeling parts.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART L-JOURNAL OF MATERIALS-DESIGN AND APPLICATIONS
(2023)
Article
Engineering, Mechanical
S. Karen Alavi, M. R. Ayatollahi, Jamaloddin Jamali, Michal Petru
Summary: This article experimentally investigates the stress field around various blunt notches using the digital image correlation method. The effects of geometry parameters on stress distribution are discussed, and the accuracy of calculated notch stress intensity factors and HOTs coefficients are studied by comparing with finite element analysis results.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Engineering, Mechanical
Majid R. R. Ayatollahi, Parham Rezaeian, Amir Nabavi-Kivi, Mohammad Reza Khosravani
Summary: This study investigates the effect of heat treatment on the tensile, flexural, and fracture strength of PLA specimens made by the FDM technique. Annealing at different temperatures (80℃, 100℃, 120℃) was conducted on dog bone and ECT specimens to evaluate the mechanical and fracture performance of the FDM-PLA parts. Fracture behavior was assessed using EMC, J-integral, ASED, and MTS criteria, and compared with experimental results. Heat treatment significantly improved the structural integrity of FDM specimens, with a 57% increase in fracture resistance.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2023)
Article
Chemistry, Physical
Alireza Akhavan-Safar, Ghasem Eisaabadi Bozchaloei, Shahin Jalali, Reza Beygi, Majid R. Ayatollahi, Lucas F. M. da Silva
Summary: Repeated impact is a common loading condition for bonded joints. However, the behavior of metal-composite bonded joints under repeated impact loads has not been widely studied. This study proposes the use of bi-adhesive technique to improve the durability of composite-metal joints under impact fatigue. Experimental and numerical analyses reveal that the double adhesives technique significantly enhances the impact fatigue life of the joints.
Article
Mechanics
A. Nabavi-Kivi, Majid R. Ayatollahi, Nima Razavi
Summary: This study investigates the fracture behavior of FDM specimens made of ABS under mixed-mode I/III loading conditions. Four different raster configurations and five loading angles were used, and the failure loads were predicted using the Equivalent Material Concept coupled with J-integral and Maximum Tangential Stress criteria. Both criteria were able to accurately predict the experimental failure loads, and SEM analysis confirmed the presence of three failure features.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2023)
Article
Engineering, Mechanical
Reza Jalayer, Behnam Saboori, Majid Reza Ayatollahi
Summary: A new test specimen is proposed for investigating mixed mode I/II/III fracture of materials. This test specimen creates mixed mode I/III loading conditions by displacing the position of an inclined crack from the middle of the rectangular specimen, in addition to mode II loading under anti-symmetric four-point bending. The experimental fracture loads of PMMA specimens are compared with theoretical predictions, showing satisfactory consistency.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2023)
Article
Engineering, Mechanical
Bahador Bahrami, Hossein Talebi, Majid R. Ayatollahi, Mohammad Reza Khosravani
Summary: This research demonstrates the application of artificial neural network (ANN) in predicting fracture under mixed-mode I/II loadings. By analyzing the importance of different input factors, crack parameters and material properties are selected as input data. Multiple ANN models are trained and optimized using different algorithms. The optimized models show low errors and high accuracy in predicting fracture, indicating the effectiveness and potential wide range application of data-driven fracture predictions compared to traditional physics-based criteria.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Materials Science, Composites
Mostafa Moazzami, M. R. Ayatollahi, Alireza Akhavan-Safar, Sofia Teixeira de Freitas, Lucas F. M. da Silva
Summary: Moisture diffusion occurs in composite laminates when exposed to humidity, leading to a reduction in their mechanical properties, especially flexural stiffness, which is important in design. This research investigates the mechanical properties of CFRP and GFRP composites as a substrate in adhesive joints under cyclic wet/dry aging conditions for long-term structural applications. The results show that the reduction in flexural stiffness is more severe in CFRP laminates compared to GFRP laminates, indicating the suitability of GFRP laminates for ocean applications.
JOURNAL OF COMPOSITE MATERIALS
(2023)
Article
Engineering, Civil
S. Karen Alavi, Majid R. Ayatollahi, Mohd Yazid Yahya, S. S. R. Koloor
Summary: This work presents an analytical investigation of the damped forced vibration behavior of viscoelastic annular sector plates made of porous polymer foam. The motion equations are derived using the first-order shear deformation theory (FSDT) in conjunction with the energy method and calculus of variations. Three types of pore distribution in the plate thickness are explored, and the obtained relations are extended to constitutive equations using the standard linear solid (SLS) viscoelastic model. The system of equations with variable coefficients is solved using perturbation technique and Fourier series, and the asymmetrically dynamic response is computed analytically in a closed-form solution. Transient dynamic behavior of viscoelastic functionally graded porous (VFGP) annular sector plates is then analyzed for various loadings, and a user-defined field code is developed for reliability evaluation.
THIN-WALLED STRUCTURES
(2023)
Article
Polymer Science
Hossein Talebi, Mohsen Askari, Majid Reza Ayatollahi, Sergio Cicero
Summary: The research investigates the fracture behavior of brittle specimens weakened by V-shaped notches with end holes (VO-notches). Experimental investigation is conducted, and it is found that the size of the notch end-hole has an effect on the fracture resistance. Two stress-based criteria, the maximum tangential stress (MTS) criterion and the mean stress (MS) criterion, are developed for VO-shaped notches under mixed-mode I/III loading, and they accurately predict the fracture resistance of VO-notched samples with about 92% and 90% accuracy, respectively.
Article
Engineering, Chemical
A. Akhavan-Safar, Sh. Jalali, L. F. M. da Silva, M. R. Ayatollahi
Summary: Cyclic loading significantly affects the durability of adhesively bonded joints, especially under cyclic impact loads. Low-energy cyclic impacts decrease the fracture energy of the joints, challenging the assumption of infinite life under cyclic impacts. The stress concentration caused by cyclic impact stress waves leads to a higher density of cracks at the specimen edges. Comprehensive inspections for bonded structures exposed to low-energy cyclic impacts are important to maintain joint strength and safe design and inspection practices.
INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES
(2023)
Article
Engineering, Mechanical
Rosaria Del Toro, Maria Laura De Bellis, Marcello Vasta, Andrea Bacigalupo
Summary: This article presents a multifield asymptotic homogenization scheme for analyzing Bloch wave propagation in non-standard thermoelastic periodic materials. The proposed method derives microscale field equations, solves recursive differential problems within the unit cell, establishes a down-scaling relation, and obtains average field equations. The effectiveness of this approach is validated by comparing dispersion curves with those from the Floquet-Bloch theory.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Yue Bao, Zhengcheng Yao, Yue Zhang, Xueman Hu, Xiandong Liu, Yingchun Shan, Tian He
Summary: This paper proposes a novel triple-gradient phononic acoustic black hole (ABH) beam that strategically manipulates multiple gradients to enhance its performance. The study reveals that the ABH effect is not solely brought about by the thickness gradient, but also extends to the power-law gradients in density and modulus. The synergistic development of three different gradient effects leads to more pronounced and broader bandgaps in PCs.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Matthias Ryser, Jason Steffen, Bekim Berisha, Markus Bambach
Summary: This study investigates the feasibility of replacing complex experiments with multiple simpler ones to determine the anisotropic yielding behavior of sheet metal. The results show that parameter identifiability and accuracy can be achieved by combining multiple specimen geometries and orientations, enhancing the understanding of the yield behavior.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Wenjun Li, Pengfei Zhang, Siyong Yang, Shenling Cai, Kai Feng
Summary: This study presents a novel two-dimensional non-contact platform based on Near-field Acoustic Levitation (NFAL), which can realize both one-dimensional and two-dimensional transportation. Numerical and experimental results prove the feasibility and ease of this method.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Shuo Liu, Lu Che, Guodong Fang, Jun Liang
Summary: This study presents a novel lamina conjugated bond-based peridynamic (BB-PD) model that overcomes the limitations of material properties and is applicable to composite laminates with different stacking sequences. The accuracy and applicability of the model are validated through simulations of elastic deformation and progressive damage behavior, providing an explanation of the damage modes and failure mechanisms of laminated composite materials subjected to uniaxial loading.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Omar El-Khatib, S. Kumar, Wesley J. Cantwell, Andreas Schiffer
Summary: Sandwich-structured honeycombs (SSHCs) are hierarchical structures with enhanced mass-specific properties. A model capable of predicting the elastic properties of hexagonal SSHCs is presented, showing superior in-plane elastic and shear moduli compared to traditional honeycombs, while the out-of-plane shear moduli are reduced.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Zhi-Jian Li, Hong-Liang Dai, Yuan Yao, Jing-Ling Liu
Summary: This paper proposes a process-performance prediction model for estimating the yield strength and ultimate tensile strength of metallic parts fabricated by powder bed fusion additive manufacturing. The effect of main process variables on the mechanical performance of printed metallic parts is analyzed and the results can serve as a guideline for improvement. The accuracy of the proposed model is validated by comparison with literature.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
Saman A. Bapir, Kawa M. A. Manmi, Rostam K. Saeed, Abdolrahman Dadvand
Summary: This study numerically investigates the behavior of an ultrasonically driven gas bubble between two parallel rigid circular walls with a cylindrical micro-indentation in one wall. The primary objective is to determine the conditions that facilitate the removal of particulate contamination from the indentation using the bubble jet. The study found that the bubble jet can effectively remove contamination from the indentation for certain ranges of indentation diameter, but becomes less effective for larger indentation diameters.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
Article
Engineering, Mechanical
E. Polyzos, E. Vereroudakis, S. Malefaki, D. Vlassopoulos, D. Van Hemelrijck, L. Pyl
Summary: This research investigates the elastic and damage characteristics of individual composite beads used in 3D printed composites. A new analytical probabilistic progressive damage model (PPDM) is introduced to capture the elastic and damage attributes of these beads. Experimental results show strong agreement with the model in terms of elastic behavior and ultimate strength and strain.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2024)
