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> en-US <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> iacoviello@unicas.it (Francesco Iacoviello) gruppofrattura@gmail.com (Support) Thu, 22 Sep 2022 16:55:39 +0000 OJS 3.3.0.11 http://blogs.law.harvard.edu/tech/rss 60 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 https://www.fracturae.com/index.php/fis/article/view/3855 Thu, 22 Sep 2022 00:00:00 +0000 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 https://www.fracturae.com/index.php/fis/article/view/3767 Thu, 22 Sep 2022 00:00:00 +0000 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> Mr. Yermal Shriraj Rao, Dr. B. Shivamurthy, Dr. Nanjangud Subbarao Mohan, Dr. 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 https://www.fracturae.com/index.php/fis/article/view/3765 Thu, 22 Sep 2022 00:00:00 +0000 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 https://www.fracturae.com/index.php/fis/article/view/3764 Thu, 22 Sep 2022 00:00:00 +0000 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 https://www.fracturae.com/index.php/fis/article/view/3742 Thu, 22 Sep 2022 00:00:00 +0000 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 https://www.fracturae.com/index.php/fis/article/view/3734 Thu, 22 Sep 2022 00:00:00 +0000 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 https://www.fracturae.com/index.php/fis/article/view/3732 Thu, 22 Sep 2022 00:00:00 +0000 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 https://www.fracturae.com/index.php/fis/article/view/3729 Thu, 22 Sep 2022 00:00:00 +0000 High-quality nodule analysis in spheroidal graphite cast iron using X-ray micro-computed tomography https://www.fracturae.com/index.php/fis/article/view/3723 <p>This work is a continuation of the studies presented in a recent paper by the authors, where a methodology to obtain different nodule quality categories in spheroidal graphite cast iron, was proposed. In this study, an exhaustive analysis of the highest-quality graphite nodules was performed. The experimental methodology involves X-ray micro-computed tomography analysis and digital image post-processing of the high-quality graphite nodule population. Furthermore, different subpopulations were selected, following a nodular size criterion. The procedure involves the evaluation and comparison of the sphericity and compactness distributions and the distances between neighbouring nodules by using ad-hoc image processing software. The results reveal the complementary nature of the sphericity and compactness parameters, which allow classifying, with great accuracy, different nodular quality categories of spheroidal graphite cast iron. Additionally, new viewpoints about the nodular morphology study and the distribution of quality nodules in the metallic matrix was provided, which could be extended to other heterogeneous materials.</p> Juan Toledo, Felipe Diaz, Matías Peralta, Diego Fernandino Copyright (c) 2022 Juan Toledo, Felipe Diaz, Matías Peralta, Diego Fernandino https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3723 Thu, 22 Sep 2022 00:00:00 +0000 Effect of composition and heat treatment on the mechanical properties of Fe Mn Al steels https://www.fracturae.com/index.php/fis/article/view/3681 <p>Starting from the research aimed at the development of substitute alloys for stainless steels, with the aim of replacing strategic metals such as chromium and nickel with the more available manganese, FeMnAlC alloys have been studied and developed for several years. These alloys exhibit an attractive strength/ductility combination, low density, and some of them show good oxidation behaviour at high temperatures. After a preliminary study, in this paper the effect of a solubilization treatment followed by aging in the temperature range 550 - 750 °C has been evaluated. The results of the investigation revealed that the steel characterized by the higher amount of Mn and Al shows, after heat treatment, the formation of phases that make the alloy very brittle. Considering the obtained results, it is evident that optimizing the alloy chemical composition is of paramount importance to guarantee a high fracture toughness if the steel works for limited time intervals at high temperature.</p> Avishek Mondal, Daniela Pilone, Andrea Brotzu, Ferdinando Felli Copyright (c) 2022 Avishek Mondal, Daniela Pilone, Andrea Brotzu, Ferdinando Felli https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3681 Thu, 22 Sep 2022 00:00:00 +0000 Failure analysis of compressed earth block using numerical plastic damage model https://www.fracturae.com/index.php/fis/article/view/3687 <p>In the last decade, several studies have been introduced to the development and use of compressed earth blocks in green building construction. Studying the evaluation of existing cracks in construction builders by these blocks is an important industrial and safety subject in recent research. This objective opens a new field in building construction where we describe the mechanical behavior of compressed earth solid blocks. In addition, we offer a solution to rupture damages presented by the propagation of masonry cracks. This paper aims to explore a numerical study in ABAQUS where we analyze the mechanical properties of this block. We started by investigating the elastic phase for this material and it has been generalized to a study in the plastic regime and rupture for the studied block. The different results of numerical simulation of the studied shape are presented, compared, and criticized.</p> Samir Bouhiyadi, Laidi Souinida, Youssef El hassouani Copyright (c) 2022 Samir Bouhiyadi, Laidi Souinida, Youssef El hassouani https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3687 Thu, 22 Sep 2022 00:00:00 +0000 Elastic and nonlinear crack tip solutions comparison with respect to failure probability https://www.fracturae.com/index.php/fis/article/view/3673 <p>This study represents a methodology to assess the probability of failure based on three the driving force formulations defined by the corresponding brittle and ductile fracture criteria for compact and bending specimens made of 34XH3MA and S55C steels. The elastic stress intensity factor (SIF) and two types of the non-linear plastic SIFs were considered as the driving force or generalized parameter (GP) to determine the probability of failure assuming a three-parameter Weibull distribution. The elastic SIF were experimentally obtained for studied materials and specimen geometries whereas the plastic SIFs were numerically calculated for the same material properties, specimen configurations and loading conditions according to classical <em>J<sub>2</sub></em> and strain gradient plasticity theories. Different specimen types with varying relative crack lengths and thicknesses were investigated. Proposed the normalized generalized parameter accounting for brittle or ductile fracture can be used as a suitable failure variable that is confirmed by comparison of the obtained failure cumulative distribution functions based on the three studied GPs.</p> Valery Shlyannikov, Andrey Tumanov , Nataliya Boychenko Copyright (c) 2022 Valery Shlyannikov, Andrey Tumanov , Nataliya Boychenko https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3673 Thu, 22 Sep 2022 00:00:00 +0000 On the use of the stepped isostress method in the prediction of creep behavior of polyamide 6 https://www.fracturae.com/index.php/fis/article/view/3672 <p>The stepped isostress method (SSM) is an advanced technique which allows the prediction of the long-term behavior and enables the construction of creep master curves of materials with short-term experimental tests. However, the performance of this method is highly dependent on the numerical model and the time spent in data processing. In this paper, the effect of the extrapolation techniques on the creep curves trend is investigated using the SSM data of Polyamide test. Three extrapolation functions are used to offset the delay of the stress history: polynomial, power and exponential functions. Furthermore, a numerical routine is developed during the last step of the SSM, where the shift factors are computed taking into account the rescaling and the dwell times of each level of stresses. The processing of the SSM raw data has revealed that the rescaling parameters are the most determining factors to reach an accurate long-term creep curves. The rescaling process has shown an appropriate time, whether achieved by the exponential or power functions. Larger shift factors for exponential functions are assessed and therefore a long period of creep master curve was obtained.</p> Lakhdar Sedira, Mohsein Tedjini, Belhi Guerira, Kamel Meftah Copyright (c) 2022 Lakhdar Sedira, Mohsein Tedjini, Belhi Guerira, Kamel Meftah https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3672 Thu, 22 Sep 2022 00:00:00 +0000 Beam-like damage detection methodology using wavelet damage ratio and additional roving mass https://www.fracturae.com/index.php/fis/article/view/3670 <p>Early damage detection plays an essential role in the safe and satisfactory maintenance of structures. This work investigates techniques use only damaged structure responses. A Timoshenko beam was modeled in finite element method, and an additional mass was applied along their length. Thus, a frequency-shift curve is observed, and different damage identification techniques were used, such as the discrete wavelet transform and the derivatives of the frequency-shift curve. A new index called wavelet damage ratio(WDR) is defined as a metric to measure the damage levels. Damages were simulated like a mass discontinuity and a rotational spring (stiffness damage). Both models were compared to experimental tests since the mass added to the structure is a non-destructive tool. It was evaluated different damage levels and positions. Numerical results showed that all proposed techniques are efficient techniques for damage identification in Timoshenko's beams concerning low computational cost and practical application.</p> Juliana C. Santos, Marcus V. G. de Morais, Marcela R. Machado, Ramon Silva, Erwin U. L. Palechor, Welington V. Silva Copyright (c) 2022 Juliana C. Santos, Marcus V. G. de Morais, Marcela R. Machado, Ramon Silva, Erwin U. L. Palechor, Welington V. Silva https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3670 Thu, 22 Sep 2022 00:00:00 +0000 Influence of manufacturing shrinkage and microstructural features on the strength properties of carbon fibers/PEEK composite material https://www.fracturae.com/index.php/fis/article/view/3661 <p>This research discusses the micromechanical modelling for thermoplastic composite material. Elastoplastic and damage model for PEEK matrix composite with the dependency of properties to stress state is presented. Plasticity initiation conditions and failure criterion are analyzed. The influence of manufacturing residual stresses is considered. All typical engineering experiments for neat PEEK under different stress state are good predicted by the model. Numerical experiment for macro-properties estimation based on micromechanical model is conducted and the results are compared with the test data.</p> Evgeny Lomakin, Boris Fedulov, Alexey Fedorenko Copyright (c) 2022 Evgeny Lomakin, Boris Fedulov, Alexey Fedorenko https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3661 Thu, 22 Sep 2022 00:00:00 +0000 Mechanical characterization and analysis of tensile fracture modes of ultrasonically stir cast Al6082 composites reinforced with Cu powder premixed Metakaolin particles https://www.fracturae.com/index.php/fis/article/view/3658 <p>The major drawback observed in the ceramic particles reinforced aluminium matrix composites (AMCs) is the reduction of ductility. Incorporating fine metallic particles along with the ceramic reinforcements in the aluminium matrix tends to improve the ductility of the AMCs. This work highlights the effects of dispersing micro (5-10 μm) copper (Cu) particles along with the nano (100-400 nm) Metakaolin particles in the Al6082 matrix. The Metakaolin particles were premixed with Cu powder by means of manual stirring followed by ball milling before embedding into the Al6082 matrix. The total reinforcement composition was maintained as 7.5 wt.% in which 2.5 wt.% consisted of Cu powder. The composites were synthesized using ultrasonication-aided stir casting process. The composites samples were subjected to T6 heat treatment before performing mechanical characterization. The composites with Cu powder premixed Metakaolin particles showed improvement in tensile strength, ductility, compressive strength and hardness. The microstructure evaluation of the composites was performed by Scanning Electron Microscope (SEM) and Optical Microscope (OM). The tensile fracture modes were studied by analysing the fracture surface morphology using SEM.</p> Renjin J Bright, P. Hariharasakthisudhan Copyright (c) 2022 Renjin J Bright, P. Hariharasakthisudhan https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3658 Thu, 22 Sep 2022 00:00:00 +0000 Experimentally evaluation of high-performance concrete mixes used for tunnels and containing silica fume and polypropylene fiber after exposed to high temperatures https://www.fracturae.com/index.php/fis/article/view/3655 <p>This work introduces an experimental study to evaluate the effect of elevated temperatures on the mechanical properties of high-performance concrete (HPC) mix with changes in Water-Cementitious ratios, W/(C+SF), Silica Fume percent, SF, and Polypropylene, PP, fiber contents. This mix was typically designed to satisfy the requirements of tunnel concrete. The compressive and indirect tensile strengths were measured at room temperature, RT, and after exposure to 400°C and 800°C. Moreover, SEM micrograph and EDS spot analysis tests were done to evaluate the effect of elevated temperatures. Fifteen mixes of HPC with different ratios of W/(C+SF), SF, and PP fiber were tested. According to the test results, the compressive strength values of design mixes increased significantly after exposure to 400°C. Moreover, using SF = 10%, the results indicated remarkable improvements in the compressive strength at 400°C and 800°C, in the case of the W/(C+SF) ratio of 0.31. On the other hand, the highest effect of the presence of PP fibers was 0.211, depending on variable ratios of the W/(C+SF) ratio and the SF content. In the case of PP=0.106 and SF=10%, the mass loss was higher at exposure to temperatures of 800°C.</p> Mohamed Elmesiri, Mohamed Fawzy Ahmed, Mohamed Bneni, Ahmed ElShami, Seleem Ahmad Copyright (c) 2022 Mohamed Elmesiri, Mohamed Fawzy Ahmed, Mohamed Bneni, Ahmed ElShami, Seleem Ahmad https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3655 Thu, 22 Sep 2022 00:00:00 +0000 Estimation of the nonlinear dependence of the indications of a fiber Bragg grating on temperature and strain from experimental data https://www.fracturae.com/index.php/fis/article/view/3653 <p>The readings of the Bragg grating are determined based on the optical radiation reflected from it. A quantitative characteristic of this radiation is the wavelength at which the maximum power of the optical signal is achieved. This characteristic is called the central wavelength of the grating. The central wavelength shift depends on temperature and strain. As a rule, a linear approximation of this dependence is used. However, from the available literature it is known that, the grating wavelength shift demonstrates a strong nonlinear dependence on temperature at 5&lt;<em>T</em>&lt;200K and a weak quadratic dependence close to room temperature. Thus far, the authors have not found studies that consider all terms in the quadratic expansion of the central wavelength of the Bragg grating as a function of temperature and strain at near-room temperatures. Our work is intended to fill this gap. The article describes an experiment in which an optical fiber with Bragg grating was subjected to loading using three different weights. A step-wise temperature change from 5 to 100 <sup>0</sup>С was realized for each weight. Based on these data, all terms of the quadratic expansion of the desired function are determined. The contribution of each term is estimated.</p> Aleksey Shestakov, Igor Shardakov, Irina Glot, Valery Yepin, Georgiy Gusev, Roman Tsvetkov Copyright (c) 2022 Aleksey Shestakov, Igor Shardakov, Irina Glot, Valery Yepin, Georgiy Gusev, Roman Tsvetkov https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3653 Thu, 22 Sep 2022 00:00:00 +0000 The Mechanical properties and statistical analysis of the Charpy impact test using the Weibull distribution in jute-polyester and glass-polyester composites https://www.fracturae.com/index.php/fis/article/view/3652 <p>In recent years, the use of natural fiber composites to provide a possible replacement for synthetic fiber composites for practical applications has been the subject of several studies. This study deals with the fabrication and investigation of jute-polyester composites and the comparison of it with glass-polyester composites. The static mechanical properties of the composites is obtained by testing the composite lamina for tensile and flexural strength. The dynamic mechanical properties of the composites is determined by using the Charpy impact test. By the Williams method based on the principle of linear elastic fracture mechanics, the impact toughness of the composites is deduced. The experimental results were statistically analyzed by using the Weibull theory to better understand the impact behavior of the composites. It is found that the glass-polyester composite has better properties than the jute-polyester composite.</p> Tahar Tioua, Djamel Djeghader, Bachir Redjel Copyright (c) 2022 Tahar Tioua, Djamel Djeghader, Bachir Redjel https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3652 Thu, 22 Sep 2022 00:00:00 +0000 Impact behaviour and fractography of 6061 alloy with Trace addition of Sn https://www.fracturae.com/index.php/fis/article/view/3643 <p>The impact behaviour of 6061 alloy with trace amount of 0, 0.04, and 0.08 wt.% Sn was studied in the as-cast (AC), as-roll (AR) and peak-age roll (PAR) processing state. Additionally, the fracture mechanism was also studied in the AC and PAR state. The experimental investigation revealed that at all processing states, trace addition of Sn improves the impact strength of the 6061 alloy. Compared to the other processing states, the PAR condition contribute most to the impact strength. Fractography analyses showed that the fracture in the alloys occurred primarily by the crack propagation of Al(Fe, Mn)Si particles. The fractures in the AC alloys took place by mixed ductile and brittle mode by larger ductile dimples, cracks and cleavages, while in the PAR alloys was primarily by ductile mode by the smaller dimple fractures.</p> Monoj Baruah, Anil Borah Copyright (c) 2022 Monoj Baruah, Anil Borah https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3643 Thu, 22 Sep 2022 00:00:00 +0000 Quantitative description of low-cycle fatigue damage accumulation in contact interaction zone by local strain evolution https://www.fracturae.com/index.php/fis/article/view/3642 <p>The novel non-destructive method for quantitative description of low-cycle fatigue damage accumulation is expanded to a case of contact interaction in the stress concentration area. Investigated objects are plane aluminium specimens with the centred hole filled by cylindrical steel inclusion. The specimen is subjected to cyclic pull-push loading. The key point, that defines scientific novelty and powerfulness of the developed approach, consists of involving local deformation parameters as current damage indicators. Required strain values follow from distributions of all three displacement components along the filled hole edge measured by reflection hologram interferometry. The data, which are derived at different stages of low-cycle fatigue for the single specimen, provide normalized dependencies of local strain values from number of loading cycle, which are a source of damage accumulation functions. These functions are constructed for the specimen with the filled hole and geometrically analogous specimen with the open hole. Obtained data quantitatively describe a difference in damage accumulation rates for two cases.&nbsp;&nbsp;&nbsp;&nbsp;</p> <p><strong>&nbsp;</strong></p> Sviatoslav Eleonsky, Yury Matvienko, Vladimir Pisarev, Igor Odintsev Copyright (c) 2022 Sviatoslav Eleonsky, Yury Matvienko, Vladimir Pisarev, Igor Odintsev https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3642 Thu, 22 Sep 2022 00:00:00 +0000 Influence of additional static stresses on biaxial low-cycle fatigue of 2024 aluminum alloy https://www.fracturae.com/index.php/fis/article/view/3637 <p>In this paper, a previously developed modification of the Sainz model of multiaxial fatigue is reduced to an invariant form. Model constants were determined for different sets of setup experiments. It was supposed to introduce an additional summand to account for the phase shift between loading modes. The model is used to describe the fatigue behavior of the D16T aluminum alloy. Low-cycle fatigue tests under biaxial loading conditions are presented, with one mode changing cyclically and the other mode remaining constant in magnitude throughout the test. The results of cyclic durability prediction by the modified model provide good convergence.</p> Andrey Yankin, Anastasia Lykova, Artur Mugatarov, Valeriy Wildemann, Artem Ilinykh Copyright (c) 2022 Andrey Yankin, Anastasia Lykova, Artur Mugatarov, Valeriy Wildemann, Artem Ilinykh https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3637 Thu, 22 Sep 2022 00:00:00 +0000 Numerical investigation on strengthening steel beams with web openings using GFRP https://www.fracturae.com/index.php/fis/article/view/3631 <p>This study presents the first investigation into the use of glass fiber reinforced polymer GFRP to strengthen steel beams with web openings. Based on previous research about the strengthening of steel beams with web perforation using carbon fiber reinforced polymer (CFRP) conducted by one of the contributing authors of this paper, it was decided to investigate the ability of pultruded glass fiber reinforced polymer, which is less expensive than CFRP materials, to strengthen single rectangular web openings of steel beams. The previous published experimental test was used to validate the proposed numerical model developed with the finite element software ABAQUS, capable of acquiring important phenomena such as debonding between FRP and steel material. The validated simulation was then used to operate a parametric study involving four proposed GFRP strengthening techniques and three distinct pultruded GFRP product thicknesses to reinforce the same steel beam used in the earlier experimental test, having a single rectangular opening shape in two separate positions along the span. From these numerical models, an adequate GFRP strengthening arrangement was found and the possibility of using low-modulus FRP materials rather than the more expensive high-modulus FRP materials for strengthening steel beams with web penetration was confirmed.</p> Hamda Guedaoura, Yazid Hadidane, Mohammed J Altaee Copyright (c) 2022 Hamda Guedaoura, Yazid Hadidane, Mohammed J Altaee https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3631 Thu, 22 Sep 2022 00:00:00 +0000 Microstructure characterization of sustainable light weight concrete using trapped air additions. https://www.fracturae.com/index.php/fis/article/view/3629 <p>Light-weight aggregate and trapped air additions (TAD) affect concrete performance and lead to the production of light-weight concrete (LWC). In this research, fourteen mixes were designed to study the effects of TAD type and content and pozzolanic material (PZ) type on the microstructure characterization of concrete. Aluminum powder (AP) and lightcrete (LC) were used as TAD with content equal to (0%, 0.25%, 0.50%, 0.57%). The PZ included silica fume (SF) and fly ash (FA) with a content equal to 10% of the weight of cement. Tests were performed for compressive strength, density, SEM, EDS, XRD, and TGA/DTG. The results show that compressive strength and density are reduced as TAD ratios are increased.</p> Said Maaty, Ahmed Elshami, Fryal Kamel Copyright (c) 2022 Said Maaty, Ahmed Elshami, Fryal Kamel https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3629 Thu, 22 Sep 2022 00:00:00 +0000 Finite Fracture Mechanics and Cohesive Crack Model: Size effects through a unified formulation https://www.fracturae.com/index.php/fis/article/view/3624 <p>Finite Fracture Mechanics and Cohesive Crack Model can effectively predict the strength of plain, cracked or notched structural components, overcoming the classical drawbacks of Linear Elastic Fracture Mechanics. Aim of the present work is to investigate size effects by expressing each model as a unified system of two equations, describing a stress requirement and the energy balance, respectively. Brittle crack onset in two different structural configurations is considered: (i) a circular hole in a tensile slab; (ii) an un-notched beam under pure bending. The study is performed through a semi-analytical parametric approach. Finally, theoretical strength predictions are validated with experimental results available in the literature for both geometries, and with estimations by the point criterion in the framework of Theory of Critical Distances.</p> Francesco Ferrian, Pietro Cornetti, Liviu Marsavina, Alberto Sapora Copyright (c) 2022 Francesco Ferrian, Pietro Cornetti, Liviu Marsavina, Alberto Sapora https://creativecommons.org/licenses/by/4.0 https://www.fracturae.com/index.php/fis/article/view/3624 Sun, 19 Jun 2022 00:00:00 +0000