Frattura ed Integrità Strutturale https://www.fracturae.com/index.php/fis <p>Frattura ed Integrità Strutturale (Fracture and Structural Integrity) is the International Journal of the Italian Group of Fracture (ISSN 1971-8993). It is an open-access journal published online every three months (January, April, July, October). <br />Frattura ed Integrità Strutturale encompasses the broad topic of structural integrity, which is based on the mechanics of fatigue and fracture and is concerned with the reliability and effectiveness of structural components. The aim of the Journal is to promote works and researches on fracture phenomena, as well as the development of new materials and new standards for structural integrity assessment. The Journal is interdisciplinary and accepts contributions from engineers, metallurgists, materials scientists, physicists, chemists, and mathematicians. The Journal is completely free of charge, both for Readers and for Authors (no APC).</p> <p><strong>More details:</strong></p> <p>- The Journal is financially supported by the <a href="https://www.gruppofrattura.it/">Italian Group of Fracture (IGF)</a> and by crowdfunding. It is completely free of charge both for readers and for authors. Neither processing charges nor submission charges are required.</p> <p>- Papers can be published only after a preliminary plagiarism/autoplagiarism check and a blind peer-review process (two reviewers, at least). More than one reviewing rounds are possible.</p> <p>- The Journal is well indexed (e.g., Scopus, since 2012, and WoS, since 2015).</p> <p>- All the papers are published with their Visual Abstracts (2 minutes max videos with the "cores" of the papers). All the Visual Abstracts are available in a dedicated <a href="https://www.youtube.com/channel/UC3Ob2GNW8i0phNiiKjEVv0A">YouTube channel</a>. All the issues are also published in a browsable version (<a href="https://fis.cld.bz/Issues">LINK</a>).</p> Gruppo Italiano Frattura (IGF) en-US Frattura ed Integrità Strutturale 1971-8993 <p><strong>Copyright&nbsp;</strong><br>Authors are allowed to retain both the copyright and the publishing rights of their articles without restrictions.&nbsp;&nbsp;</p> <p><strong>Open Access Statement</strong></p> <p><em>Frattura ed Integrità Strutturale</em> <em>(Fracture and Structural Integrity, F&amp;SI</em>) is an open-access journal which means that all content is freely available without charge to the user or his/her institution. Users are allowed to read, download, copy, distribute, print, search, or link to the full texts of the articles in this journal without asking prior permission from the publisher or the author. This is in accordance with the DOAI definition of open access.</p> <p><em>F&amp;SI</em> operates under the Creative Commons Licence Attribution 4.0 International (CC-BY 4.0). This allows to copy and redistribute the material in any medium or format, to remix, transform and build upon the material for any purpose, even commercially, but giving appropriate credit and providing a link to the license and indicating if changes were made.</p> High Entropy Cantor Alloys (HEAs) modification induced by tungsten alligation, heat treatment and deep cold plastic deformation https://www.fracturae.com/index.php/fis/article/view/4047 <p>High Entropy Alloys (HEAs) is a unique class of materials that combine particular properties in a large-scale of temperatures, able to guarantee new unexplored materials and alloys with several potentially engineering applications (i.e. space and aerospace industries). As promising structural materials, HEAs consist of five or more principal elements. As a consequence of the monophasic microstructure which usually characterizes HEAs, these alloys offer an excellent combination of strength, strain hardening ability, good plasticity, ductility and fracture toughness especially at cryogenic temperatures better than the existing conventional metals and alloys. For the above reasons, the present work deals with Classic Cantor alloy, a well-known CoCrFeMnNi HEA, where mechanical properties were improved using low cost casting techniques and a combination of different metallurgical methodologies (heat treatment, cold working and adding alloying elements). A promising alloy element, tungsten, was used in the experimentation where mechanical and microstructural characterization were performed using different techniques</p> Andrea Brotzu Stefano Natali Zortea Laura De Filippo Barbara Copyright (c) 2022 Andrea Brotzu, Stefano Natali, Zortea Laura, De Filippo Barbara https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 309 320 10.3221/IGF-ESIS.63.24 Computer Vision Algorithm for the detection of fracture cracks in Oil Hardening Non-Shrinking (OHNS) die steel after machining process https://www.fracturae.com/index.php/fis/article/view/3955 <p>A variant of neural network for processing with images is a convolutional neural network (CNN). This type of neural network receives input from an image and extracts features from the image while also providing learnable parameters to effectively do the classification, detection, and many other tasks. In the present work, U-Net convolutional neural network is implemented on Jupyter platform by using Python programming for fracture surface image segmentation in Oil Hardening Non-Shrinking (OHNS) die steel after the machining process. The results showed that the fracture cracks can be validated by testing with higher accuracy.</p> Akshansh Mishra Vijaykumar S Jatti Nitin K Khedkar Rahul B. Dhabale Ashwini V Jatti Copyright (c) 2022 Akshansh Mishra, Vijaykumar S Jatti, Nitin K Khedkar, Rahul B. Dhabale, Ashwini V Jatti https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 234 245 10.3221/IGF-ESIS.63.18 The Stress Intensity Factor of convex embedded polygonal cracks https://www.fracturae.com/index.php/fis/article/view/3908 <p>In the present work, a simple formula for the evaluation of the stress intensity factor (SIF) of convex embedded polygonal cracks has been proposed. This formula is structured as a correction factor of the Oore-Burns’ equation and is based on accurate three-dimensional FE analysis. Furthermore, a precise formula for a regular polygonal crack has been given.</p> Paolo Livieri Fausto Segala Copyright (c) 2022 Paolo Livieri, Fausto Segala https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 72 79 10.3221/IGF-ESIS.63.07 Structural behavior of damaged reinforced concrete beams under static cyclic loading https://www.fracturae.com/index.php/fis/article/view/3904 <p>Bridges are regarded as one of the most important components of transportation infrastructure. More and more repairs, inspections, alterations, and construction processes are required to maintain safe usage due to increasing travel demands in addition to bridge infrastructure aging. In this paper, we will discuss the experimental investigation using five reinforced concrete beams to evaluate the effect of making damage to experimental beams under static cyclic loading to investigate their ductility and energy dissipation. The defective parameters taken into consideration in the experimental program were the gap in the concrete mold and mild steel at the middle bottom reinforcement. All tested specimens had the same cross-sectional dimensions. The concrete dimensions of the beams were 200 mm in width and 300 mm in height, and the beam's length was selected to be 2200 mm, having a clear span of 2000 mm between the supports, they were tested in positive bending using a 3-point bending load system. According to the results, when (RC) beams were subjected to any of the mentioned types of damage, they showed a significant decrease in ultimate capacities ranging from 3.03% to 19.31%. The ANSYS model shows an average difference with the experimental program within 4 % as an acceptable agreement.</p> Abdelrahman Elbaz H. Marzouk Kh. Heiza Omar Elnawawy Copyright (c) 2022 Abdelrahman Elbaz, H. Marzouk, Kh. Heiza, Omar Elnawawy https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 257 270 10.3221/IGF-ESIS.63.20 Mechanical, Wear, and Fracture Behavior of Titanium Diboride (TiB2) - Cerium Oxide (CeO2) Reinforced Al-6061 Hot-rolled Hybrid Composites https://www.fracturae.com/index.php/fis/article/view/3896 <p>Development of aluminium composites by stircasting technique is an effective method for fabrication of better quality of MMCs. Stircasting technique is one of the most commonly accepted techniques. In this research work, Al6061 / TiB<sub>2</sub>+CeO<sub>2</sub> hybrid MMCs have been fabricated with varying wt. % of TiB<sub>2</sub> (2.5%, 5%, 7.5% and 10%) particulates and constant 5% of CeO<sub>2</sub> particulates. The monolithic alloy and hybrid composite were hot-rolled at a temperature of 515°C. Whereas, both the monolithic and hot-rolled hybrid composite was subjected to micro-structural study, hardness and tensile test. Optical microscope analysis revealed uniform dispersal of hard particles with in the base matrix in case of both of ascast and hot-rolled composites. Both ascast and hotrolled hybrid composites have shown extensive enhanced mechanical behavior and high wear resistance when compared with monolithic alloy. Though, ductility of the hybrid MMCs decreased with increasing TiB<sub>2</sub> and CeO<sub>2</sub> content. A tensile and wear fractography outcome shows the internal fractured structure of a tensile and wear specimen which was analysed using a SEM analysis.</p> S. R. Sreenivasa Iyengar D. Sethuramu M. Ravikumar Copyright (c) 2022 S. R. Sreenivasa Iyengar, D. Sethuramu, M. Ravikumar https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 289 300 10.3221/IGF-ESIS.63.22 Numerical Analysis of Reinforced Concrete Circular Columns Strengthening With CFRP under Concentric and Eccentric Loadings https://www.fracturae.com/index.php/fis/article/view/3892 <p>The purpose of this study is to explore the numerical behavior of circular RC short columns with different degrees of confinement with CFRP (0%, 25%, 50%, and 100%) wraps under concentric and eccentric loading. The numerical analysis carried out by using an improved concrete plastic-damage model (CDPM) implemented in ABAQUS software for finite element (FE) analysis. The FE model simulated a total of twenty-four numerical specimens. The findings were matched to published experimental test results in the literature. The findings of the FE model and the experimental data were good similar. As a consequence, the model was found to be valid. The numerical results shows that as load eccentricity increased, the load carrying capacity of columns decreased for unconfined specimens, whereas the decline in strength for confined specimens becomes limited as the degrees of confinement ratio increased. In addition, increasing the CFRP confinement ratio improves the column's load-bearing capability at the same load eccentricity.</p> Ibrahim Harba Abdulkhalik Abdulridha Ahmed AL-Shaar Copyright (c) 2022 Ibrahim Harba , Abdulkhalik Abdulridha, Ahmed AL-Shaar https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 190 205 10.3221/IGF-ESIS.63.16 Numerical nonlinear analysis of RC beans with un-strengthened and CFRP-strengthened opening drilled under service loads within shear zones https://www.fracturae.com/index.php/fis/article/view/3857 <p>Current research paper deals with reinforced concrete (R.C.) beams numerical modeling and suggested strengthening procedure if it is required to create an opening within their shear zones. Strengthening is assumed to be achieved during different service load application conditions. Reinforced Concrete beams with rectangular or circular opening in shear zone; as critical regions; sustain two concentrated system of loads are tested till failure before and after performing suggested opening assessing technique by means of Carbon Fibers Reinforced Polymer sheets (CFRP). The main aim of this research is simulating real practice situation where the beam is subjected to service loads, supported temporary by means of hydraulic jacks, opening is created and strengthening is performed then jacking supports are released. Results of achieved numerical nonlinear modeling are introduced and influence of strengthening achieving on improving assessed beams almost structural behavior such as initial cracking loads, load deflection curves, cracking patterns, failure loads &amp; modes for reference (without opening), main un-strengthened control beams, and CFRP strengthened opening beams are introduced and analyzed in details. Some important conclusions &amp; recommendations for designer and executive engineers are stated.</p> Magdy Khalaf Louay Aboul-Nour Mahmoud Khater Marwa Ibrahim Copyright (c) 2022 Magdy Khalaf, L. Aboul-Nour, M. Khater, M. Ibrahim https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 206 233 10.3221/IGF-ESIS.63.17 Investigation on Microstructure and Tensile Fractography of RE Oxides (CeO2/Y2O3) Reinforced AZ91D Magnesium Matrix Composites https://www.fracturae.com/index.php/fis/article/view/3856 <p>The current work aims to investigate the mechanical properties of rare oxide reinforced Mg alloy based MMCs. Magnesium matrix considered in the study is AZ91D alloy, whereas rare earth oxides reinforced were CeO<sub>2</sub> and Y<sub>2</sub>O<sub>3</sub>. The Y<sub>2</sub>O<sub>3</sub> particulate reinforcement percentage was varied from 1 to 3% in the steps of 1% to study its influence on mechanical properties of MMCs. Stir casting route was adopted to fabricate sample for study. Microstructure analysis illustrated the uniform distribution of particulate in matrix alloys. The obtained results revealed the enhanced mechanical properties such as tensile strength, yield strength, elongation and hardness of MMCs due to increased percentage of reinforcement. Fractography analysis of fracture surfaces demonstrated the microcracks and cleavage were dominant in pure alloy. While particle debonding, extensive plastics deformation were prominent in-addition to microcracks in MMCs.</p> Santhosh Gotagunaki Vardhaman S. Mudakappanavar R. Suresh Copyright (c) 2022 Santhosh Gotagunaki, Vardhaman S. Mudakappanavar, R. Suresh https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 100 109 10.3221/IGF-ESIS.63.10 A simplified formula to estimate the load history due to ballistic impacts with bullet splash. Development and validation for finite element simulation of 9x21mm full metal jacket bullets https://www.fracturae.com/index.php/fis/article/view/3855 <p>An original simplified formula is proposed to estimate the load history caused by ballistic impacts characterized by the so-called bullet splash phenomenon, consisting in the complete bullet fragmentation with no penetration of the target. The formula is based on the progressive momentum variation of the mass of the bullet impacting on a planar plate normal to the impact direction. The method aims at creating a simplified approach to assess the response of structures by means of explicit finite element simulations without the need of modelling the interaction between impactor and target. The results demonstrate that the proposed method can be used to estimate the forces generated by bullet-splash phenomena of 9x21mm full metal jacket bullets and effectively applied to finite element simulations allowing significant reductions in computational cost.</p> Riccardo Andreotti Andrea Casaroli Mauro Quercia Marco V. Boniardi Copyright (c) 2022 Riccardo Andreotti, Andrea Casaroli, Mauro Quercia, Marco V. Boniardi https://creativecommons.org/licenses/by/4.0 2022-09-22 2022-09-22 17 63 602 612 10.3221/IGF-ESIS.62.41 Influence of Quenching Agents on Mechanical, Wear, and Fracture Characteristics of Al2O3 / MoS2 Reinforced Al-6061 Hybrid Metal Matrix Composite (MMCs) https://www.fracturae.com/index.php/fis/article/view/3842 <p>Aluminium (Al) based composites enhance the mechanical and wear behavior by heat treatment. The quenching factors like cooling agent, cooling rate and temperature of cooling are expected to influence the hardness, tensile, and wear behavior of the Al MMCs. This research shows the outcomes of a sequence of experiments to find the wear and mechanical behavior of the Al6061-Al<sub>2</sub>O<sub>3</sub>-MoS<sub>2</sub> hybrid composites are quenched with different quenching agents. Hardening of the developed hybrid composites was carried out at 510ºC for the time period of 2 hours. Later, the same composite samples were quenched in ice cubes and water separately. Finally, age-hardening was done at 180ºC temperature for 4 hours and then the samples were cooled under room temperature. Heat treated hybrid composites were subjected to evaluate the hardness, tensile, and wear behavior. The outcomes reveal that the heat treatment significantly enhances the wear and mechanical behavior of hybrid composites. High mechanical strength and improved wear characteristics were observed in the hybrid composites which were quenched using ice cubes. The fractured surface of the tensile test samples and the wornout surface of wear test specimens were studied using a SEM analysis.</p> K. R. Suchendra M. Sreenivasa Reddy M. Ravikumar Copyright (c) 2022 K. R. Suchendra, M. Sreenivasa Reddy; M. Ravikumar https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 122 133 10.3221/IGF-ESIS.63.12 Structural behavior of Lightweight and High strength Layered Hollow Core Slabs https://www.fracturae.com/index.php/fis/article/view/3840 <p>A new technique of Layered Hollow Core Slab (LHCS) has been used to obtain a slab with an optimum weight-to-strength ratio. Specimens with a 90 mm top layer of High Strength Concrete (HSC) and a 90 mm bottom layer of Lightweight Aggregate Concrete (LWAC) were examined. Nine full-scale slabs with dimensions of 1600* 450* 180 mm were tested under a 4-point loading test. The %core, a/d, RFT ratio, and connection method were the different studied parameters. A push-out test was conducted on triplet specimens to study the bond strength at the interface between HSC jacket and LWAC cubes using bond agent material or shear dowels, or without treatment, to determine which method of them is suitable for connecting the two layers of the tested slabs. Load, deflection, ductility, strain, crack pattern, and mode of failure were studied. The results indicate that ultimate strength is enhanced with decreasing a/d and %core and with an increasing RFT ratio of the LHCS specimens. Using shear dowels ensures an efficient bond between the two layers of the tested slabs. ANSYS program used for modelling the slab. The numerical study accepted the experimental data with a variation of less than 10% for all slabs.&nbsp;</p> Asmaa Ghamry Ahmed Esia Louay Aboul-Nour Copyright (c) 2022 Asmaa Ghamry, Ahmed Esia, Louay Aboul-Nour https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 134 152 10.3221/IGF-ESIS.63.13 Description of Fatigue Sensitivity Curves and Transition to Critical States of Polymer Composites by Cumulative Distribution Functions https://www.fracturae.com/index.php/fis/article/view/3836 <p>In this paper, a novel model is presented to describe the composite mechanical properties degradation during cyclic loading. The model is based on cumulative distribution functions using. Weibull probability distribution law and beta distribution are considered. The dependences of the fatigue sensitivity coefficient on the preliminary cyclic exposure are derived. The damage value function derivative using is proposed to define damage accumulation stages boundaries. Model parameters are obtained using experimental data. Determination coefficients are calculated. A high descriptive capability is noted. Rationality and expediency of using cumulative distribution functions as the approximation of experimental data on mechanical characteristics reduction after preliminary cyclic exposure is concluded.</p> Oleg Staroverov Artur Mugatarov Andrey Yankin Valeriy Wildemann Copyright (c) 2022 O.A. Staroverov, A.I. Mugatarov, A.S. Yankin, V.E. Wildemann https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 91 99 10.3221/IGF-ESIS.63.09 Artificial neural network based delamination prediction in composite plates using vibration signals https://www.fracturae.com/index.php/fis/article/view/3834 <p>Dynamic loading on composite components may induce damages such as cracks, delaminations, etc. and development of an early damage detection technique for delaminations is one of the most important aspects in ensuring the integrity and safety of composite components. The presence of damages such as delaminations on the composites reduces its stiffness and further changes the dynamic behaviour of the structures. As the loss in stiffness leads to changes in the natural frequencies, mode shapes, and other aspects of the structure, vibration analysis may be the ideal technique to employ in this case. In this research work, the supervised feed-forward multilayer back-propagation Artificial Neural Network (ANN) is used to determine the position and area of delaminations in GFRP plates using changes in natural frequencies as inputs. The natural frequencies were obtained by finite element analysis and results are validated by experimentation. The findings show that the suggested technique can satisfactorily estimate the location and extent of delaminations in composite plates.</p> T. G. Sreekanth M. Senthilkumar S. Manikanta Reddy Copyright (c) 2022 T. G. Sreekanth, M. Senthilkumar, S. Manikanta Reddy https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 37 45 10.3221/IGF-ESIS.63.04 Improvement of crack tip position estimation in DIC images by image processing methods https://www.fracturae.com/index.php/fis/article/view/3809 <p>The study presents and compares an application of two procedures to identify the crack tip location in PVC Sent samples under a uniaxial tensile test based on the image processing method.</p> <p>An IDS camera captures several photos of the PVC surface as part of the image analysis procedure. All relevant data on crack initiation and propagation is collected and assessed using ImageJ software using image processing methods for detecting cracks. However, the second procedure involves a developed algorithm detecting the discontinuity using digital image correlation (DIC) measurement. Although, because of the experimental conditions, the acquisition of images by the digital camera is never perfect. This noise comes from several sources, including the digital camera, image distortion due to lens magnification or lens angle, the shape and size of the pattern, and electronic noise; ... This article discusses image enhancement methods to overcome these objectionable characteristics using and comparing several filters:&nbsp; Gaussian, median, and Unsharp Mask filters. The performance of the Gaussian filter is better than the Median and Unsharp mask filters. This research demonstrates that DIC is an effective technique for monitoring deformation and understanding the failure mechanism with the best-suited filter.</p> Najat Zekriti Fatima Majid Hachimi Taoufik Yassine Tounsi Rajaa Rhanim Ibrahim Mrani Hassan Rhanim Copyright (c) 2022 Najat Zekriti, Fatima Majid, Hachimi Taoufik, Yassine Tounsi, Rajaa Rhanim, Ibrahim Mrani, Hassan Rhanim https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 61 71 10.3221/IGF-ESIS.63.06 Numerical analysis of isolated end-flattened steel bars under compression in space trusses https://www.fracturae.com/index.php/fis/article/view/3807 <p>This research aims to characterize the behavior of isolated end-flattened steel bars under compressive loading, in which global instabilities or excessive local deformations represent a significant part of the causes of structural collapse. The association of numerical analyses using the finite element method (FEM) with previously collected experimental data is performed, and their respective results are the core object of critical analysis in this work. Numerical simulations are based on the modified Riks method, complemented in part by modal analysis, whose results demonstrate the occurrence of the aforementioned failure modes in prototypes with slenderness ratios varying in the spectrum from 20 to 200. Finally, the analytical formulations that describe the phenomenon from the approach of global and local instabilities incorporated into current normative expressions are applied in a comparison with the results gathered in the numerical approach.</p> Henrique de Araujo Rosa Cruz Luciano Mendes Bezerra Welington Vital da Silva Ramon Silva Copyright (c) 2022 Henrique de Araujo Rosa Cruz, Luciano Mendes Bezerra, Welington Vital da Silva, Ramon Silva https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 271 288 10.3221/IGF-ESIS.63.21 Optimization of the Mechanical Property of Friction Stir Welded Heat Treatable Aluminum Alloy by using Bio-Inspired Artificial Intelligence Algorithms https://www.fracturae.com/index.php/fis/article/view/3767 <p>The concepts and inspiration of biological evolution in nature are used to create new and effective competing tactics in the burgeoning field of bio-inspired computing optimization algorithms. In the present work, nine specimens of similar alloys i.e., AA6262 were Friction Stir Welded. Spindle Speed (RPM), Traverse Speed (mm/min), and Plunge Depth (mm) were the input parameters while the Ultimate Tensile Strength (MPa) was an output parameter. The main objective of the work is to obtain the maximum optimized Ultimate Tensile Strength (MPa) by using Bio-Inspired Artificial Intelligence Algorithms i.e., Differential Evolution and Max Lipschitz optimization (Max LIPO) Algorithm. The results showed that the Differential Evolution algorithm resulted in a slightly higher value of the Ultimate Tensile Strength in comparison to the Max LIPO algorithm.</p> Akshansh Mishra Anish Dasgupta Copyright (c) 2022 Akshansh Mishra, Anish Dasgupta https://creativecommons.org/licenses/by/4.0 2022-09-22 2022-09-22 17 63 448 459 10.3221/IGF-ESIS.62.31 Influence of hBN and MoS2 fillers on toughness and thermal stability of carbon fabric-epoxy composites https://www.fracturae.com/index.php/fis/article/view/3765 <p>Hexagonal boron nitride (hBN) and molybdenum disulfide (MoS<sub>2</sub>) fillers of 2 to 8 wt.% influence on toughness, microhardness and thermal stability of carbon fabric-reinforced epoxy composite (CFREC) reported. Mode-I, mixed-mode I/II toughness and microhardness of CFREC improved due to the addition of hBN and MoS<sub>2</sub> separately upto 6 wt.% filler loading. The epoxy matrix in CFREC modified by hBN and MoS<sub>2</sub> strengthens the matrix, deflects the crack path and resists delamination. Toughness reduced beyond 6 wt.% filler addition due to agglomeration and poor fiber-filler-matrix bonding as revealed by the surface morphology of the fracture specimen. Thermal analysis reveals decomposition temperature at 25% weight loss increased from 395 to 430 °C and 395 to 411 °C due to 4 wt.% MoS<sub>2</sub> and 4 wt.% hBN addition to CFREC respectively. Impermeable characteristics of MoS<sub>2</sub> and hBN fillers caused tortuous diffusion path for gas molecules and delayed thermal decomposition.</p> Yermal Shriraj Rao Shivamurthy Basavannadevaru Nanjangud Mohan Subbarao Nagaraja Shetty Copyright (c) 2022 Mr. Yermal Shriraj Rao, Dr. B. Shivamurthy, Dr. Nanjangud Subbarao Mohan, Dr. Nagaraja Shetty https://creativecommons.org/licenses/by/4.0 2022-09-22 2022-09-22 17 63 240 260 10.3221/IGF-ESIS.62.17 Compressive behavior of Co-Cr-Mo radially graded porous structures under as-built and heat-treated conditions https://www.fracturae.com/index.php/fis/article/view/3764 <p>Additive manufacturing research is continuously growing, and this field requires a full improvement of the capability and reliability of the processes involved. Of particular interest is the study of complex geometries production, such as lattice structures, which may have a potentially huge field of application, especially for biomedical products.<br />In this work, the powder bed fusion technique was utilized to manufacture lattice structures with defined building angles concerning the build platform. A biocompatible Co-Cr-Mo alloy was used. Three different types of elementary cell geometry were selected: Face Centered Cubic, Diagonal, and Diamond. These cells were applied to the radially oriented lattice structures to evaluate the influence of their orientation in relation to the sample and the build platform. Moreover, heat treatment was carried out to study its influence on microstructural properties and mechanical behavior. Microhardness was measured, and compressive tests were performed to detect load response and to analyse the fracture mechanisms of these structures.<br />The results show that the mechanical properties are highly influenced by the cell orientation in relation to the building direction and that the properties can be further tuned via HT. The favorable combination of mechanical properties and biocompatibility suggests that Co-Cr-Mo lattices may represent an optimal solution to produce customized metal implants. </p> Francesco Cantaboni Paola Ginestra Marialaura Tocci Andrea Avanzini Elisabetta Ceretti Annalisa Pola Copyright (c) 2022 Francesco Cantaboni, Paola Ginestra, Marialaura Tocci, Andrea Avanzini, Elisabetta Ceretti, Annalisa Pola https://creativecommons.org/licenses/by/4.0 2022-09-22 2022-09-22 17 63 490 504 10.3221/IGF-ESIS.62.33 Heat dissipation and fatigue crack kinetic features of titanium alloy Grade 2 after laser shock peening https://www.fracturae.com/index.php/fis/article/view/3742 <p>The work is devoted to experimental investigation of the laser shock peening (LSP) effect on fatigue crack propagation rate and heat dissipation at the crack tip in specimens made of titanium alloy Grade 2 with a stress concentrator. It is shown that the LSP can leads both to positive and negative effect on fatigue lifetime. The effective processing scheme, which includes stress concentrator zone, was proposed. This type of treatment forms an optimal residual stress field, which slows down the crack initiation and propagation processes. The effective LSP processing scheme reduces the value of the stress intensity factor and, as a consequence, effects on an intensity of plastic deformation at the crack tip. This effect can be visualised by measurement of heat flux from the crack tip area. Both heat flux from the crack tip and crack rate are less in the LSP processed specimens. Structural investigations of LSP treated material near fatigue crack path have shown that structural defects (twins) that appear on the surface of the material as a result of LSP do not have a significant effect on the fatigue crack propagation, and the configuration of the residual stresses field created by LSP plays a decisive role.</p> Anastasia Iziumova Aleksei Vshivkov Aleksandr Prokhorov Elena Gachegova Denis Davydov Copyright (c) 2022 Anastasia Iziumova, Aleksei Vshivkov, Aleksandr Prokhorov, Elena Gachegova, Denis Davydov https://creativecommons.org/licenses/by/4.0 2022-09-22 2022-09-22 17 63 516 526 10.3221/IGF-ESIS.62.35 Delamination effect on the mechanical behavior of 3D printed polymers https://www.fracturae.com/index.php/fis/article/view/3740 <p>&nbsp;This study aims to assess the delamination effect and predict the evolution of damage in 3D printed specimens to investigate the mechanical behavior occurring due to the delamination of the layers of 3D printed thermoplastic polymers. Thus, additively manufactured ABS samples are subjected to tensile tests Made for different thicknesses of specimens by subtracting layer by layer.</p> <p>The mechanical behavior of the layers and the adherence between the layers are studied in this paper. The deposition of the layers is modeled as a laminated material.</p> <p>The delamination effect on the resistance of printed material is evaluated experimentally by comparing the mechanical characteristics of homogenously printed specimens, and laminated layers gathered together. Thus, the global resistance is reduced significantly due to the lack of adherence.</p> <p>Besides, crack growth, and critical intensity factor investigation are based on damage and rupture mechanics theories.</p> <p>Furthermore, the results allowed us to evaluate the energy behavior of the 3D printed material subjected to static loads and subsequently predict the evolution of the damage and find out the impact of layers' delamination. Indeed, we determined three stages of damage along with the critical life fraction leading to the failure of the specimen.</p> Fatima Majid T. Hachimi H. Rhanim R. Rhanim Copyright (c) 2022 Fatima Majid, T. Hachimi, H. Rhanim, R. Rhanim https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 26 36 10.3221/IGF-ESIS.63.03 Justification of fracture criteria for salt rocks https://www.fracturae.com/index.php/fis/article/view/3734 <p>The study of salt rocks deformation and fracture processes is an essential part of mining parameters justification for mineral salt deposits. The results of uniaxial compression tests on large salt rock specimens are presented as a loading curve and diagrams of the transverse-longitudinal displacements at various distances from the side faces. Based on an isotropic elastoplastic model, a multivariant numerical simulation was performed. Its purpose was to select of fracture criteria that accurately describe the loading diagram of specimen and its transverse-longitudinal deformations. The following fracture criteria are considered: Tresca with the associated plastic flow rule, the associated and non-associated Mohr-Coulomb, the parabolic analogue of Mohr-Coulomb criterion and the volumetric fracture criterion. Numerical simulation was carried out by the displacement-based finite element method. Three-dimensional hexahedral eight-node isoparametric elements were used for discretization of the solution domain. It has been established that within the elastoplastic model of media the process of uniaxial compression of a large cubic salt rock specimen is adequately described by the linear Mohr-Coulomb fracture criterion with the non-associated plastic flow, as well as by the associated volumetric parabolic yield criterion with the linear isotropic hardening.</p> Alexander Baryakh Andrey Tsayukov Copyright (c) 2022 Alexander Baryakh, Andrey Tsayukov https://creativecommons.org/licenses/by/4.0 2022-09-22 2022-09-22 17 63 585 601 10.3221/IGF-ESIS.62.40 Effect of Ti addition and cast part size on solidification structure and mechanical properties of medium carbon, low alloy cast steel https://www.fracturae.com/index.php/fis/article/view/3732 <p>In this work, the effect of Ti addition and the cast part size on the solidification structure and mechanical properties of a medium carbon, low alloy cast steel was analyzed. The experimental analysis involved the design of the melts by using Thermo-Calc® software, where different amounts of Ti added to a standard chemical composition of an AISI 13XX steel were simulated. Then, the solidification macrostructure (dendritic pattern and grain size) and microstructure were characterized by using conventional and specific metallographic techniques. Finally, the mechanical behavior in terms of hardness and tensile properties were evaluated.</p> <p>The results show that the addition of 0.12% of Ti promotes a fine dispersion of Ti nitrides and carbides, but when the Ti concentration raises to 0.2%, the size of the Ti nitrides and carbides increases while its amount decreases. Ti nitrides and carbides particles act as nucleation sites for the precipitation of ferrite from austenite, and it was found that the addition of Ti in the higher concentrations refines the solidification macrostructure (dendritic pattern) for both cast part sizes evaluated.</p> <p>Regarding mechanical properties, the addition of Ti does not significantly vary the ultimate tensile strength but reduces the total elongation for cast part sizes</p> Nicolás Emanuel Tenaglia Diego Fernandino Alejandro Daniel Basso Copyright (c) 2022 Nicolás Emanuel Tenaglia, Diego Fernandino, Alejandro Daniel Basso https://creativecommons.org/licenses/by/4.0 2022-09-22 2022-09-22 17 63 212 224 10.3221/IGF-ESIS.62.15 Effect of friction-welding parameters on the tensile strength of AA6063 with dissimilar joints https://www.fracturae.com/index.php/fis/article/view/3729 <p>In this paper, the effect of welding parameters of rotary friction welding between AA6063 and AISI4130 and AA6063 and Copper are investigated. The major influencing parameters considered are upset pressure, friction time and friction pressure of friction welding are considered for this study. The Taguchi’s design of experiments was conducted for the influencing parameters and their levels. The tensile test experimentation was carried out and the results of the AA6063 and AISI4130 and AA6063 and Copper are compared. The ultimate tensile strength of AA6063-AISI4130 joint and AA6063-Copper joint was improved by increasing upset pressure up to 97MPa with FP of 71 MPa and FT of 4 sec. On the side of AA6063, intermetallic compounds have formed, as seen in SEM micrographs. Microcracks are forming on the side of AA6063 and propagates along the grain boundaries. The effect of the influencing parameters on the tensile strength of the dissimilar joints are studied using the Taguchi’s DOE and ANOVA. From the outcomes it is observed that the friction pressure influence more on the strength of the AA6063 dissimilar joints.</p> Yashwanth Chapke Dinesh N. Kamble Copyright (c) 2022 Yashwanth Chapke, Dinesh N. Kamble https://creativecommons.org/licenses/by/4.0 2022-09-22 2022-09-22 17 63 573 584 10.3221/IGF-ESIS.62.39 Analysis of the structural integrity of a frozen wall during a mine shaft excavation using temperature monitoring data https://www.fracturae.com/index.php/fis/article/view/3728 <p>This paper describes the results of the temperature monitoring of a frozen wall (FW) around the skip shaft of a potash mine under construction. The data on temperature measurements in control-thermal boreholes were used to parameterize the mathematical model of heat transfer, which allowed for the reconstruction of the temperature field throughout the entire cooled and frozen soil volume. The resulting temperature distribution in the FW zone for greater than 1 year was used to determine the distribution of the strength properties and calculate the temporary change in the limiting value of the external lateral load on an FW of a given thickness and specified thermomechanical properties. The obtained dependencies of the maximum external load on the FW can be used to optimize the operation mode of the freezing station at the ice holding stage (or passive freezing) to increase the energy efficiency of the system and ensure the structural integrity of the FW.</p> Lev Levin Mikhail Semin Ivan Golovatyi Copyright (c) 2022 Lev Levin, Mikhail Semin, Ivan Golovatyi https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 1 12 10.3221/IGF-ESIS.63.01 Study of the slant fracture in solid and hollow cylinders: Experimental analysis and numerical prediction https://www.fracturae.com/index.php/fis/article/view/3726 <p>This paper is devoted to the numerical and experimental study of ductile fracture in bulk metal forming of the 2017A-T4 aluminum alloy. From an experimental standpoint, the ductile fracture of the 2017A-T4 aluminum alloy is investigated under compressive load. Two cross-sections of solid and hollow specimens are considered. The mechanical behavior and the microstructure of the 2017A-T4 aluminum alloy were characterized. It is found that the well-known barrel shape is obtained when a compressive load is applied. Analyses of fracture topographies show a ductile fracture with&nbsp;dimples under tension and coexistence of ductile fracture with&nbsp;dimples and slant under compression. The classical physically-based Gurson-Tvergaard-Needleman (GTN) model and its extension to incorporate shear mechanisms to predict failure at low-stress triaxiality are considered. These two models have been extended to take into account the thermal heating effect induced by the mechanical dissipation within the material during the metal forming process. The two models have been implemented into the finite element code Abaqus/Explicit using a Vectorized User MATerial (VUMAT) subroutine. Numerical simulations of the forging process made for hollow and solid cylindrical specimens show good agreement with experimental results. In contrast with the GTN model, the modified GTN model incorporating shear mechanisms can capture the final material failure.</p> Nassima Ben Chabane Nassim Aguechari Mohand Ould Ouali Copyright (c) 2022 Nassima Ben Chabane, Nassim Aguechari, Mohand Ould Ouali https://creativecommons.org/licenses/by/4.0 2022-12-21 2022-12-21 17 63 169 189 10.3221/IGF-ESIS.63.15