Article
Engineering, Mechanical
S. H. Sajjadi, A. R. Khorshidvand, M. Jabbari, M. Javadi
Summary: A new brittle fracture criterion was proposed for sharp V-shaped notches, taking into account the effect of shear stress and showing strong correlation with experimental results. This criterion has broad applicability and is capable of predicting fracture in various loading conditions.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2021)
Article
Engineering, Mechanical
M. Jabbari, J. Akbardoost, A. R. Torabi
Summary: This research investigates the size effects on the mode I notch fracture toughness of polymeric specimens weakened by a rounded-tip V-shaped notch through experimental and theoretical methods. The results show that the notch fracture toughness is significantly dependent on the sample size, with larger sample size leading to higher fracture toughness. A modified point stress criterion is proposed to justify the size dependency and a semiempirical relation is used to describe this dependency accurately. The findings demonstrate the importance of considering size effects in predicting notch fracture toughness of polymeric materials with RV-shaped notches.
JOURNAL OF ENGINEERING MECHANICS
(2022)
Article
Polymer Science
Ali Reza Torabi, Mahdi Jabbari, Javad Akbardoost, Sergio Cicero
Summary: The aim of this study is to assess the impact of size and geometry on the mode I notch fracture toughness of polymeric samples with rounded-tip V-shaped notches. The experiments show that the modified mean stress criterion provides accurate estimations of the size-dependent notch fracture toughness in these samples.
Article
Mechanics
Wei Liu, Yulong Li, Zhiqian Zhang, Liyun Yang, Yi Luo, Zhongwen Yue
Summary: This study investigates the mixed-mode I+II fracture characteristics of V-notched rock specimens under impact loads, considering the effects of loading rate, notch angle, and loading angle. Experimental and numerical analysis results show that loading rate has a significant positive effect on the fracture toughness value, but has a negative effect on the crack initiation angle.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Engineering, Geological
J. Justo, J. Castro, S. Cicero
Summary: This study evaluates the fracture of U-notched limestone samples under mixed mode I + II loading conditions at varying temperatures. The Theory of Critical Distances is applied successfully to analyze the experimental results, providing accurate assessments for both pure mode I and mixed mode fracture conditions. The results show a certain influence of notch radius on the critical distance, with relatively constant values observed for different mode mixities.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Construction & Building Technology
Sreekumaran Sreenath, Kaliyaperumal Saravana Raja Mohan, Gunasekaran Murali
Summary: This study investigates the effect of GGBS on the fracture toughness of RPCs under different fracture modes, and finds that incorporating GGBS and fibers can significantly improve the fracture toughness of RPCs.
Article
Construction & Building Technology
B. Bahrami, A. Bahadori, M. Petru, M. Nejati, M. R. Ayatollahi
Summary: This study conducted fracture tests on marble specimens and found that the traditional fracture criteria could not predict crack formation accurately. By introducing the first non-singular term of the notch stress field, new fracture criteria that can accurately predict fracture strength and crack initiation angle were developed.
CONSTRUCTION AND BUILDING MATERIALS
(2022)
Article
Mechanics
F. Hatami, M. R. Ayatollahi, A. R. Torabi
Summary: The study developed fracture limit curves for key-hole notched components made of brittle materials, and conducted fracture tests to evaluate the influence of notch tip radius on fracture toughness. The results showed good consistency between the experimental data and fracture limit curves, indicating reliable estimation of notch fracture toughness under different loading conditions.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2021)
Article
Mechanics
Xiangqiao Yan
Summary: Using the concepts of critical stress and critical distance by Taylor, this study proposes a local approach for fracture analysis of V-notch specimens based on the linear-elastic stress field. The local approach has been verified to be simple and accurate for V-notched specimens made of both brittle and ductile materials.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Mechanics
S. H. Sajjadi, A. R. Khorshidvand, M. Jabbari, M. Javadi
Summary: This study evaluated the effectiveness of two criteria for sharp V-shaped notches, showing that they can provide satisfactory results under various mixed-mode loading conditions and are in good agreement with experimental results.
PHYSICAL MESOMECHANICS
(2021)
Article
Engineering, Mechanical
A. R. Torabi, Hossein Talebi, M. R. Ayatollahi, Michal Petru
Summary: The notch fracture resistance of stainless steel 316L under mixed-mode I/III loading is investigated. Modified test fixture and combination of Fictitious Material Concept with maximum tangential stress and mean stress criteria are used to predict the notch fracture toughness values determined experimentally. The combined criteria, FMC-MTS and FMC-MS, show approximately 87% and 86% accuracy in estimation of the mean experimental results, respectively.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Mechanics
Edouard Sorin, Jean-Luc Coureau, Cedric Perez
Summary: This study provides detailed data on the quasi-brittle behavior of maritime pine and spruce using R-curves. The method used in this study for R-curve characterization is an improved version of the method presented by Lespine (2007), which is automated and based on measurement errors. The study investigates the influence of crack plane orientation and density on fracture mechanisms and highlights the differences between spruce and maritime pine.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Materials Science, Multidisciplinary
V. D. Kurguzov, A. V. Shutov
Summary: The study investigates Mode I fracture of plate specimens with sharp V-shaped notches through analytical and numerical methods. Results indicate that under small-scale yielding conditions, accurate simulation of crack propagation and opening process can be achieved using predefined coupled fracture criteria and strain-based fracture criteria. Additionally, assessment of the plastic zone near the notch tip and calculation of the stress intensity factor for cracks growing from V-shaped notches are crucial aspects.
INTERNATIONAL JOURNAL OF FRACTURE
(2021)
Article
Mechanics
Weichen Kong, Shuaifeng Ma, Yanwei Dai, Yinghua Liu
Summary: This paper studies the tip stress field of a plane stress sharp V-notch and provides an analytical solution. By comparing it with the finite element solution, the asymptotic solution shows good agreement. The research results have significance in evaluating the plane stress sharp V-notch tip field under creeping conditions.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Materials Science, Multidisciplinary
Chenzhuo Li, Xinyue Wei, Meng Wang, Mokhtar Adda-Bedia, John M. Kolinski
Summary: When brittle hydrogels fail, it is challenging to identify the dominant mechanism that alters the state of stress near the crack tip. This study uses hydrogels as a model to probe the small-scale yielding region and understand the loss mechanisms in brittle material failure. Through microscopy methods, the researchers identify a process zone where most of the energy is dissipated through the loss of cohesion, providing insights into the scale and structure of this zone.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Engineering, Mechanical
Ali Reza Torabi, Behnam Saboori, Moslem Mirzavand
Summary: This research investigates the fracture of notched friction-stir welded aluminum alloys (AA2024-T3 and AA7075-T6). Experimental fracture tests are conducted on U-notched diagonally loaded square plates made of the welded alloys under different loading conditions. The theoretical part uses the equivalent material concept (EMC) combined with two brittle fracture criteria to predict the load-bearing capacity (LBC) of the samples. The experimental and theoretical results show that the combination of the criteria and EMC can accurately predict the LBC of the notched samples.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(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
M. Bakhshizadeh, S. Pirmohammad, M. R. Ayatollahi
Summary: This paper investigates the impact of supports on fracture mode of loading using semicircular bending specimen through finite element analysis and experiments. The results show that parameters like support type and crack angle can influence the values of geometry factors, and the friction coefficient can significantly change the loading mode at the crack tip.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(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
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
Pedram Bagheri, Ali Reza Torabi, Bahador Bahrami
Summary: This research focuses on the numerical investigation of fracture loads of U-notched specimens made of Al-6061-T6 and Al-5083 under pure opening mode and mixed mode I/II loading conditions. A new methodology is introduced to assess the notch fracture loads and crack growth path using the combination of the equivalent material concept (EMC) and extended finite element method (XFEM). The results are compared with a conventional elastic-plastic damage model, and the EMC-XFEM model is found to be more efficient and accurate in predicting fracture of ductile aluminum notches.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(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
Chemistry, Physical
Ali Reza Torabi, Moslem Mirzavand, Behnam Saboori, Sergio Cicero
Summary: The purpose of this study is to predict the load-bearing capacity of fracture specimens containing V-notched friction-stir welded joints. Elastic-plastic fracture criteria are complex and time-consuming for the fracture analysis of FSWed alloys. In this study, the equivalent material concept (EMC) is applied, and two brittle fracture criteria are utilized to accurately predict the load-bearing capacity.
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)
