https://www.fracturae.com/index.php/fis/issue/feedFrattura ed Integrità Strutturale2024-03-06T14:34:24+00:00Francesco Iacoviellofrancesco.iacoviello@gruppofrattura.euOpen Journal Systems<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.</p> <p>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>https://www.fracturae.com/index.php/fis/article/view/4838Improving the performance of damage repair in thin-walled structures with analytical data and machine learning algorithms2024-01-31T22:03:49+00:00Abdul Aabid Shaikhaaabid@psu.edu.saMd Abdul Rahemanmararkeri@nitte.edu.inMeftah Hrairimeftah@iium.edu.myMuneer Baigmbaig@psu.edu.sa<p>In the last four decades, bonded composite repair has proven to be an effective method for addressing crack damage propagation. On the other hand, machine learning (ML) has made it possible to employ a variety of approaches for mechanical and aerospace problems and such significant approach is the repair mechanism and hence ML algorithms used to enhance in the present work. The current work investigates the effect of the single-sided composite patch bonded on a thin plate under plane stress conditions. An analytical model was formulated for a single-sided composite patch repair using linear elastic fracture mechanics and Rose's analytical modelling. From the analytical model, the stress intensity factors (SIF) were calculated by varying all possible parameters of the model. Next, ML algorithms were selected, and comparative studies were conducted for the best possible performance and to identify the parametric effects on optimum SIF. Also, the analytical model is validated with existing work, and it shows good agreement with less than 10% error. This study is particularly important for designing the single-sided composite patch repair method based on analytical modelling. Also, it is important to compare ML algorithms with analytical solutions in regression applications.</p>2024-03-05T00:00:00+00:00Copyright (c) 2024 Abdul Aabid Shaikh, Md Abdul Raheman, Meftah Hrairi, Muneer Baighttps://www.fracturae.com/index.php/fis/article/view/4837On the stress- and strain-based fatigue behavior of welded thick-walled nodular cast iron2024-01-31T20:31:13+00:00Christoph Bleicherchristoph.bleicher@lbf.fraunhofer.deSteffen Schoenbornsteffen.schoenborn@lbf.fraunhofer.deHeinz Kaufmannheinz.kaufmann@lbf.fraunhofer.deMasoud Alizadeh-Shmaaliz@dtu.dk<p>Nodular cast iron (GJS) represents one of the most widely used materials for vehicle, energy and heavy machinery industry. Nevertheless, foundries struggling with the influence of local material defects in GJS like pores, shrinkages and dross often leading to a locally reduced fatigue strength of the entire component. One measure to tackle those negative effects is the welding of the affected areas. This measure is then successful when locally achieved material strengths and surface qualities are higher than the component with the casting defect. Unfortunately, data for the lifetime and fatigue assessment of welded GJS are not present right now.</p> <p>Thus, the research project »nodularWELD« assessed the local stress- and strain-based fatigue data of different thick-walled GJS grades for building a basis for a successful usage even of defect affected components. So, three ferritic and pearlitic GJS grades were investigated in the heat-affected zone, the base material, the welding filler and more over in an integral material state comprising all those three aforementioned states based on axial and bending investigations. Additionally metallographic and fractographic analysis were conducted.</p>2024-03-15T00:00:00+00:00Copyright (c) 2024 Christoph Bleicher, Steffen Schoenborn, Heinz Kaufmann, Masoud Alizadeh-Shhttps://www.fracturae.com/index.php/fis/article/view/4831Ultrasonic welding of lap joints of PEI plates with PEI/CF-fabric prepregs2024-02-24T05:48:10+00:00Vladislav Alexenkovl.aleksenko@mail.ruDefang TianDefan1@tpu.ruSergey Paninpaninsergey71@mail.ruSvetlana Bochkarevasvetlanab7@yandex.ruIliya Panovpanov.iliya@mail.ru<p>In this study, ultrasonic welding (USW) of lap joints of polyetherimide (PEI) plates (adherends) with carbon fiber (CF) prepregs impregnated with PEI was investigated. No energy director (ED) was used, so binder contents were varied in the prepregs to compensate for the lack of the polymer in the fusion zone. In addition, the effect of the USW parameters on the structure and the mechanical properties of the lap-joints were analyzed. The most homogeneous macrostructure, the maintained structural integrity of both the CF-fabric in the prepregs and the lap-joined PEI adherends, as well as the maximum strength properties (tensile strength) were revealed for the USW joints with the minimum polymer content in the prepreg. In this case, rising the USW time from 400 up to 800 ms radically changed the macrostructure of the fusion zone, while the strength properties did not vary significantly (shear stresses were 42–48 MPa). Computer simulation of the influence of the PEI/CF-fabric ratios in the prepregs on the deformation response of the USW joints showed that the prepreg thicknesses and, accordingly, the PEI/CF ratios did not exert a noticeable effect on the strain–stress (tensile) diagrams, while the determining factor was the adhesion level.</p>2024-03-15T00:00:00+00:00Copyright (c) 2024 Vladislav Alexenko, Defang Tian, Sergey Panin, Svetlana Bochkareva, Iliya Panovhttps://www.fracturae.com/index.php/fis/article/view/4812Modelling of crack propagation in miniaturized and normal SENB specimens based on local failure criterion2024-02-05T14:41:22+00:00Bernadett Spisakbernadett.spisak@bayzoltan.huZoltán Bézizoltan.bezi@bayzoltan.huRéka Erdeireka.erdei@bayzoltan.huSzabolcs Szávaiszabolcs.szavai@bayzoltan.hu<p>The use of miniaturized specimen testing methods is a promising way to solve the problem of limited materials in RPV monitoring programs. The use of miniature specimens allows the evaluation of fracture toughness from other specimen materials used. In particular, the small-size compact tensile test specimen (0.16T CT) is promising for the determination of fracture toughness, as it can be produced from the standard size Charpy specimen that has already been tested. However, if we have only 0.16T CT test, we cannot investigate the dimensional response and also have only one restricted deformation state, which may pose problems in verifying geometry independence and determining local parameters for state-of-the-art analyses. It is therefore recommended to prepare at least two tests with two different restricted deformation specimens. Therefore, the testing of mini single edge notched bending (SENB) is also required and can be worked out from the Charpy specimens. The paper presents the determination of fracture toughness for these miniaturized specimens by modifying the virtual crack closure technique (VCCT) simulation method using GTN parameters instead of energy release as the driving force. This allows the calculation of the J-integral to proceed in parallel with the crack propagation.</p>2024-02-27T00:00:00+00:00Copyright (c) 2024 Bernadett Spisak, Zoltán Bézi, Réka Erdei, Szabolcs Szávaihttps://www.fracturae.com/index.php/fis/article/view/4809A method for rapid estimation of residual stresses in metal samples produced by additive manufacturing2024-01-15T16:12:13+00:00Alexey Fedorenkoalexey.n.fedorenko@gmail.comDenis Firsovd.firsov@skoltech.ruStanislav Evlashins.evlashin@skoltech.ruBoris Fedulovfedulov.b@mail.ruEvgeny Lomakinevlomakin@yandex.ru<p>The mechanical methods for measuring residual stresses typically rely on so-called destructive techniques where some stress components can be determined based on part deflection after material removal (cutting, etching, drilling, etc.). While these methods don't provide a comprehensive representation of residual stresses within the entire part, they can be readily applied in most manufacturing labs. In this study, we propose an efficient method for determining residual stress within additively manufactured cylindrical samples of stainless steel. The method is based on the assumption of a relation between the axial component of residual stress (normal to cross-section) and the cylinder radius. The general form of this relation is proposed based on data from numerical simulations using linear, parabolic or piecewise approximations. The parameters for the proposed relation are defined using equilibrium equations for total force and moment. The proposed method relies on an experiment with a mechanical cut along the cylinder. Consequently, the deflection of the cylinder halves after the cut allows for obtaining the equivalent bending moment.</p>2024-02-24T00:00:00+00:00Copyright (c) 2024 Alexey Fedorenko, Denis Firsov, Stanislav Evlashin, Boris Fedulov, Evgeny Lomakinhttps://www.fracturae.com/index.php/fis/article/view/4810Numerical Cohesive Zone Modeling (CZM) of Self-Anchoring AM Metal-CFRP joints2024-01-15T15:11:31+00:00Fikret Enes Altunok fikret.altunok@polito.itGiorgio De Pasqualegiorgio.depasquale@polito.it<p>The escalating importance of lightweight design in engineering demands innovative strategies to tackle this challenge. Traditionally, the joining of these materials involves rivets, bolts, or adhesives. However, contemporary manufacturing techniques, such as 3D printing, present the potential to fabricate joints without the necessity for additional binding mechanisms. This paper delves into a promising initiative concerning the joining of multimaterial systems, specifically composites and metals. The fabrication of the metal component of the joint through additive manufacturing (AM) enables the manipulation of surface geometry by incorporating patterned anchors. This, in turn, facilitates the direct co-curing of the composite onto the modified metallic surface. The primary objective is to enhance mechanical interlocking without relying on traditional fastening elements or adhesives. The study evaluates various anchor geometries to assess their efficacy in increasing the overall joint strength. This assessment employs the cohesive zone modeling (CZM) method to simulate joint specimens, followed by comparative analyses to quantify the strengths of the joints.</p>2024-02-24T00:00:00+00:00Copyright (c) 2024 Fikret Enes Altunok , Giorgio De Pasqualehttps://www.fracturae.com/index.php/fis/article/view/4800Machining effects and multi-objective optimization in Inconel 718 turning with unitary and hybrid nanofluids under MQL2024-01-13T06:00:20+00:00Satish Chinchanikarsatish091172@gmail.comParesh Kulkarniparesh.219p0014@viit.ac.in<p style="margin: 0in; text-align: justify; line-height: normal;">Designing tooling and cooling systems to prevent cutting tool damage is crucial while machining difficult-to-cut nickel alloys. This study investigates the machining effects during turning Inconel 718 using unitary aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) and hybrid aluminum oxide+multi-walled carbon nanotube type (Al<sub>2</sub>O<sub>3</sub>+MWCNT) nanofluids under minimum quantity lubrication (NFMQL) through mathematical modeling and multi-objective optimization. The worn-out tools were analyzed for damage and wear mechanisms through images captured using optical and scanning electron microscopes. The study indicates that hybrid nanofluids outperform unitary nanofluids, which could be attributed to the better lubricating and cooling capabilities of MWCNT and the higher surface tension and thermal conductivity of Al<sub>2</sub>O<sub>3</sub> nanoparticles. The cutting parameters were optimized by combining the Technique for Order of Preference by Similarity to the Ideal Solution (TOPSIS) and genetic algorithm. The study reveals an average error of less than 10% between experimental and predicted responses from the proposed optimization model. This study found lower cutting force up to 80 N, surface roughness of 0.6–0.7 µm, and tool life over 10 minutes with a cutting speed of 50–70 m/min and a lower feed and depth of cut of 0.1 mm/rev and 0.2 mm, respectively, using a hybrid Al<sub>2</sub>O<sub>3</sub>+MWCNT nanofluid under NFMQL conditions.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Satish Chinchanikar, Paresh Kulkarnihttps://www.fracturae.com/index.php/fis/article/view/4790Shapley additive explanation on machine learning predictions of fatigue lifetimes in piston aluminum alloys under different manufacturing and loading conditions2024-01-06T09:52:24+00:00Mohammad Azadim.azadi.1983@gmail.comMahmood Matinmahmoodmatyn@gmail.com<p>Various input variables, including corrosion time, fretting force, stress, lubrication, heat-treating, and nano-particles, were evaluated by modeling of stress-controlled fatigue lifetimes in AlSi12CuNiMg aluminum alloy of the engine pistons with different machine learning (ML) techniques. Bending fatigue experiments were conducted through cyclic loading with zero mean stress, and then experimental data was predicted by five different ML-based models. Moreover, when the optimal ML prediction model was found, it was analyzed using the Shapley additive explanation (SHAP) values method. Results illustrated that extreme gradient boosting (XGBoost) had superior data for estimations, with average training coefficients of determination of at least 63% and 90%, respectively for fatigue lifetime and its logarithmic value. The SHAP values interpretation of the XGBoost model revealed that fretting force, stress, and corrosion time were the most significant inputs in estimating the logarithm values of fatigue lifetimes, respectively.</p>2024-03-11T00:00:00+00:00Copyright (c) 2024 Mohammad Azadi, Mahmood Matinhttps://www.fracturae.com/index.php/fis/article/view/4783Predictive Modeling of Fracture Behavior in Ti6Al4V Alloys Manufactured by SLM Process2024-03-06T14:34:24+00:00Mohsen SarparastMohsen.Sarparast@rockets.utoledo.eduMajid Shafaiemagician754@aut.ac.irMohammad Davoodim.e_davoodi@yahoo.comAhmad Memaran Babakanahmadmemaran1991@gmail.comHongyan Zhanghongyan.zhang@utoledo.edu<p>This study focuses on ductile fracture behavior prediction for Ti6Al4V alloys fabricated via Selective Laser Melting (SLM). A modified Gurson-Tvergaard-Needleman (GTN) model characterizes void growth and shear mechanisms under uniaxial stress. The research explores the impact of Artificial Neural Network (ANN) architecture, specifically hidden layers and neurons, on predicting fracture parameters. Results reveal that increasing hidden layers substantially enhances accuracy, particularly for fracture displacement. Notably, predicting maximum force requires fewer layers than fracture displacement. Using selected layers and neurons, the system consistently achieved R<sup>2</sup>-values exceeding 0.99 for both maximum force and fracture displacement. The study identifies the initial void volume fraction (f<sub>0</sub>) parameter as having the most significant influence on both properties.</p>2024-03-10T00:00:00+00:00Copyright (c) 2024 Mohsen Sarparast, Majid Shafaie, Mohammad Davoodi, Ahmad Memaran Babakan, Hongyan Zhanghttps://www.fracturae.com/index.php/fis/article/view/4781Revisiting classical concepts of Linear Elastic Fracture Mechanics - Part II: Stretching finite strips weakened by single edge parabolically-shaped notches 2023-12-28T15:53:30+00:00Christos Markidesmarkidih@mail.ntua.grStavros K Kourkoulisstakkour@central.ntua.gr<p>This is the second part of a short three-paper series, aiming to revisit some classical concepts of Linear Elastic Fracture Mechanics. Being the intermediate step of the analysis between infinite domains (discussed in Part-I) and finite bodies (that will be discussed analytically in the third part of the series), the present part offers an alternative theoretical approach for the confrontation of problems dealing with both infinite and finite bodies with geometrical discontinuities. The method is here applied to a stretched, single-edge notched strip. Assuming that the strip is made of a linearly elastic and isotropic material, the complex potentials technique is used. The solution is achieved by extending Mushkelishvili’s procedure, for the confrontation of the problem of an infinite perforated plane. Closed form, full-field formulae are obtained for the stresses all over the notched strip. Using these formulae, the stress concentration factor at the base (tip) of the notch is quantified and studied in terms of the geometrical features of the notch and its dimensions relatively to the respective ones of the strip. The stress distributions plotted along characteristic loci, resemble closely, from a qualitative point of view, the respective ones provided by well-established analytical solutions. Preliminary numerical analyses in progress provide results in very good agreement with those of the present analysis.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Christos F. Markides, Stavros K Kourkoulishttps://www.fracturae.com/index.php/fis/article/view/4777Effect of fiber orientation-based composite lamina on mitigation of stress intensity factor for a repaired plate: a finite element study2023-12-25T19:01:13+00:00Abdul Aabid Shaikhaaabid@psu.edu.saMuneer Baigmbaig@psu.edu.saMeftah Hrairimeftah@iium.edu.myJaffar Syed Mohamed Alijaffar@iium.edu.my<p>The bonded composite repair has proven to be an effective method for addressing crack damage propagation. Numerous studies have employed experimental and simulation techniques to demonstrate the repair performance through the composites. These studies have explored various parameters related to bonded composites, such as size and properties, to enhance repair effectiveness. However, one aspect that has not been thoroughly investigated is the impact of fiber orientation within the composites. Therefore, the current work investigates the effect of the fiber direction of the composite patch bonded on a thin plate under plane stress conditions. Three types of fiber orientation of composite patch have been considered. In this investigation, the finite element method was used to determine the stress intensity factor using the ANSYS commercial code. The research findings showed that the fiber direction influenced the mitigation of stress intensity factor. This study is particularly important for designing the composite patch based on the fiber direction. </p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Abdul Aabid Shaikh, Muneer Baig, Meftah Hrairi, Jaffar Syed Mohamed Alihttps://www.fracturae.com/index.php/fis/article/view/4752Application of Machine Learning in Fracture Analysis of Edge Crack Semi-Infinite Elastic Plate2023-12-12T09:04:34+00:00Saeed Hossein Moghtaderip116028@siswa.ukm.edu.myAlias Jedialiasjedi@ukm.edu.myAhmad Kamal Ariffinkamal3@ukm.edu.myPrakash Thamburajap.thamburaja@ukm.edu.my<p>This paper discusses the application of machine learning techniques, notably artificial neural networks (ANN), in the fracture analysis of semi-infinite elastic plates with edge cracks. The Stress Intensity Factor (SIF) model for a semi-infinite plate with a tip crack is employed in the study, and Finite Element Analysis (FEA) is performed via ABAQUS CAE to build a comprehensive dataset containing numerical simulations data. To improve accuracy and reliability, data preprocessing is implemented, and ANN as a valuable machine learning model is trained with various variables describing crack propagation, stress distribution, and plate structure as input parameters. The suggested method is compared to established fracture analysis methods, proving its accuracy in predicting crack behavior and stress distribution under a variety of loading circumstances. The model provides useful insights into the behavior of edge cracks in semi-infinite elastic plates, enhancing material engineering and structural mechanics. The study demonstrates the potential of combining FEA and machine learning to improve fracture analysis capabilities, and it discusses limitations and future research directions, encouraging the exploration of advanced machine learning techniques and broader fracture scenarios for future fracture mechanics innovation.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Saeed Hossein Moghtaderi, Alias Jedi, Ahmad Kamal Ariffin, Prakash Thamburajahttps://www.fracturae.com/index.php/fis/article/view/4725Material choice to optimise the performance index of isogrid structures 2023-12-04T15:25:49+00:00Costanzo Bellinicostanzo.bellini@unicas.itFilippo Bertofilippo.berto@uniroma1.itVittorio Di Coccovittorio.dicocco@unicas.itFrancesco Iacoviellofrancesco.iacoviello@unicas.itLarisa Patricia Mocanularisapatricia.mocanu@unicas.it<p>Three key qualities should define the structures used in the aviation industry: they should be light, rigid, and strong. These goals can be met by selecting lightweight, high-performance materials like titanium alloy or composites, but careful structural design is also crucial to improve mechanical performance. The structures known as isogrids, which consist of a skin reinforced by a lattice frame, offer an effective way to meet the aforementioned specifications. The structural performances of isogrid-stiffened cylinders composed of various materials were compared in the current work. The structures under investigation were composed of titanium alloy, carbon fibre composite material, or a combination of both. A FEM model was proposed and validated by comparison with experimental results obtained from a composite material structure, and then it was used to simulate the behaviour of all the other structures. While there was some variation in the strength of the parts, it was discovered that the stiffness was almost uniform throughout all of the structures that were examined. But when the weight of the various constructions was taken into account, some very intriguing findings emerged: the composite material-only structure proved to be the most effective because it had the highest specific performances.</p>2023-12-17T00:00:00+00:00Copyright (c) 2023 Costanzo Bellini, Filippo Berto, Vittorio Di Cocco, Francesco Iacoviello, Larisa Patricia Mocanuhttps://www.fracturae.com/index.php/fis/article/view/4723Evolution of prototyping in automotive engineering: a Comprehensive Study on the reliability of Additive Manufacturing for advanced powertrain components2023-12-04T13:17:35+00:00Silvia Cecchels.cecchel@streparava.comRiccardo Ferraresir.ferraresi@streparava.comMatteo Magnim.magni@streparava.comLeonardo Guerinil.guerini@streparava.comGiovanna Cornacchiagiovanna.cornacchia@unibs.it<p>Additive manufacturing (AM) could be used to reduce the production times of prototypes; however, further research is required to address metals structural parts. To obtain the correct properties, some relevant factors to be considered are the build volume, shape factor, and the need for specific heat treatments. This study aims to evaluate the reliability of AM prototypes applied at a new powertrain system developed to reduce vehicle emissions. Firstly, it was investigated the mechanical behavior, microstructure, and the effect of sample size and heat treatments on both specimens and prototypes made of AM 17-4PH steel. Finite Element Analysis (FEA) was performed to evaluate the structural resistance. Finally, the prototypes were produced, analyzed, and tested on a functional engine test bench to evaluate their reliability. The mechanical properties decreased with an increase in the sample volume. After heat treatment, the yield strength increased, due to the transformation of δ-ferrite in martensite and the reduction of retained austenite. The engine test bench was successfully completed. The conclusions set the basis for similar future applications of time-effective prototypes that can be dimensioned owing to appositely developed postprocesses that guarantee the required resistance.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Silvia Cecchel, Riccardo Ferraresi, Matteo Magni, Leonardo Guerini, Giovanna Cornacchiahttps://www.fracturae.com/index.php/fis/article/view/4695Interleaving Carbon-Glass Veil in Glass Epoxy Composite for Improved Mode-I Fracture Toughness – A Hybrid Approach2023-11-24T10:47:43+00:00Vinayak Uppinursuppin@gmail.comShivakumar Goudaursshivu@gmail.comI. Sridharsridhari74@gmail.comUmarfarooq M. A.umarfarooq.ma@gmail.comAravind Muddebihal aravindbm21@gmail.comAbhilash Edacherianedalheriad@kku.edu.sa<p>The present study investigates the influence of hybrid interleaving technique using Glass and Carbon veils to improve the mode-I fracture toughness in Glass epoxy laminates. Commercially available non-woven Carbon and Glass veils with different areal densities were used to develop hybrid interleaved composites. Two approaches of interleaving, namely inter-ply and inter-weaved veils, were followed to manufacture the interleaved composite laminates using the hand layup technique. Double Cantilever Beam (DCB) samples were tested to estimate the interlaminar fracture toughness (IFT). Test results indicate that the inter-ply interleaved composite (I-C30G30) exhibited an improved initial and propagation fracture toughness of about 16.98% and 3.08%, respectively. A decreased IFT during initiation and propagation was observed for I-C15G30 and I-C20G30 when compared to plain samples. In case of inter-weaved veil interleaving approach, an improved fracture toughness (G<sub>IC</sub> and G<sub>IP</sub>) of about 7.96% and 12.94%, respectively, was observed for W-C15G30 sample, nevertheless W-C20G30 and W-C30G30 showed a drop in fracture toughness (G<sub>IC</sub>) of an about 12.15% and 9.22%, respectively, and an improvement in fracture toughness (G<sub>IP</sub>) of about 12.37% and 13.82%, respectively, when compared to plain sample. Scanning electron photo images (SEPI) of cracked laminates witnessed the fracture mechanisms involved in hybrid ply interleaved and non-interleaved composite laminates.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Vinayak S. Uppin, P.S.Shivakumar Gouda, I.Sridhar, M. A. Umarfarooq, Aravind Muddebihal , Abhilash Edacherianhttps://www.fracturae.com/index.php/fis/article/view/4693Fracture processes numerical modeling of elastic-brittle bodies with statistically distributed subregions strength values2024-02-05T07:56:38+00:00Eugeniia Feklistovacem.feklistova@mail.ruArtur Mugatarovcem_mugatarov@mail.ruValeriy Wildemannwildemann@pstu.ruAnton Agishevagishevanton1017@gmail.com<p>This work is devoted to the fracture processes numerical modeling of elastic-brittle bodies taking into account the statistical distribution of subregions strength values and stress concentration. The novel formulation of the boundary value problem and its solution algorithm are developed. The loading diagrams obtained in computational simulations, the corresponding growth curves of the destroyed elements relative number and the damaging process kinetics are analyzed. The presence of the postcritical deformation stage at the macro-level is noted. The influence of the strength properties distribution range and the depth of the concentrator on the maximum load value and the damage evolution is determined. The significant influence of the finite elements’ properties distribution on the fracture processes modeling results is concluded.</p>2024-03-05T00:00:00+00:00Copyright (c) 2024 Eugeniia Feklistova, Artur Mugatarov, Valeriy Wildemann, Anton Agishevhttps://www.fracturae.com/index.php/fis/article/view/4691A nonlocal elasticity theory to model the static behaviour of edge-cracked nanobeams2023-11-29T14:53:23+00:00Daniela Scorzadaniela.scorza@unipr.itAndrea Carpinteriandrea.carpinteri@unipr.itCamilla Roncheicamilla.ronchei@unipr.itAndrea Zanichelliandrea.zanichelli@unipr.itRaimondo Lucianoraimondo.luciano@uniparthenope.itSabrina Vantadorisabrina.vantadori@unipr.it<p>In the present paper, the mechanical behaviour of edge-cracked nanobeams under Mixed-Mode loading is analytically investigated by means of the Stress-Driven nonlocal model. Firstly, the proposed formulation is outlined, and then applied to the case of a cantilever edge-cracked nanobeam. A parametric study is performed by varying both the crack depth and the crack position along the beam axis. Finally, the above formulation is applied to simulate some experimental tests available in the literature.</p>2023-12-17T00:00:00+00:00Copyright (c) 2023 Daniela Scorza, Andrea Carpinteri, Camilla Ronchei, Andrea Zanichelli, Raimondo Luciano, Sabrina Vantadorihttps://www.fracturae.com/index.php/fis/article/view/4686Using the wavelet transform to process data from experimental studies of the discontinuous plastic deformation effect2023-11-21T19:23:49+00:00Evgeniia Chechulinazhenya-chechulina@yandex.ruPeter Trusovtpv@matmod.pstu.ac.ruRoman GerasimovRMGerasimov@pstu.ruValeriy Vildemanwildemann@pstu.ruMikhail Tretyakovcem_tretyakov@mail.ru<p>Vast number of theoretical and experimental works has been devoted to the study of discontinuous plastic deformation (the Portevin-Le Chatelier effect), which manifests itself for most widely used alloys in certain ranges of both temperatures and strain rates. Due to the statistical nature of this phenomenon, difficulties arise in processing, qualitative analysis and quantitative comparison of test results and calculations. Using of statistical methods for these purposes makes it possible to get only some averaged characteristics of the obtained data (usually - moments of the first and second orders in amplitudes and frequencies). A possible alternative for processing of experimental and theoretical results of this effect research is wavelet analysis using.</p> <p>The results of experimental studies of the Portevin–Le Chatelier effect, realized during the deformation of thin-walled tubular specimens made of aluminum alloy AMg6M at certain strain rates at room temperature are presented. Diagrams of deformation under uniaxial tension, shear, proportional and disproportionate loading of specimens were obtained. The inhomogeneity of strain fields and their rates is shown, illustrating the manifestation of the Portevin – Le Chatelier effect under conditions of complex loading of thin-walled tubular specimens made of AMg6M alloy. A brief overview of existing methods and means of non-destructive testing is presented that make it possible to non-contactly record the spatial heterogeneity of plastic yielding. Some possibilities of using the wavelet transform to process certain types of non-monotonic stress-strain diagrams obtained for the specimens made of the aluminum alloy in question are discussed. Using wavelet analysis, a compact presentation of data from field experiments in the form of amplitude-frequency characteristics was obtained. The scalograms analysis of specimen loading diagrams was carried out.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Evgeniia Chechulina, Peter Trusov, Roman Gerasimov, Valeriy Vildeman, Mikhail Tretyakovhttps://www.fracturae.com/index.php/fis/article/view/4685Mechanical behavior of fiber-glass plastic with hole pattern using digital image correlation and acoustic emission methods2023-12-28T14:31:07+00:00Elena Strungarcem.spaskova@mail.ruDmitrii Lobanovcem.lobanov@gmail.comEkaterina Chebotarevacem.chebotareva@mail.ruYaroslava Kochnevayaroslavaviktorovna@gmail.com<p style="font-weight: 400;">In this paper, tensile tests of specimens with a pattern of holes made of fiber-glass plastic based on combined epoxy and phenol-formaldehyde resins are carried out in order to study the processes of damage accumulation and tension fracture. The Vic-3D video system is used to evaluate damage development and inhomogeneity of strain localization during loading. Continuous recording of acoustic emission signals is carried out during the tests, resulting in obtaining data on fracture mechanisms in the material. Ranges of peak frequencies are identified. Surface analysis of specimens was carried out using a microscope. A significant reduction in strength occurs due to the presence of a circular hole in the material, although additional holes do not exacerbate this effect. Fracture patterns of specimens with a hole pattern have been analyzed, and different "paths" of fracture have been observed. The comparison of strain fields obtained on the basis of application of three-dimensional digital optical system with the configuration of strain fields constructed as a result of numerical modeling by the finite element method has been carried out. It is found that the strain fields for different open hole patterns are quantitatively and qualitatively similar and identical.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Elena Strungar, Dmitrii Lobanov, Ekaterina Chebotareva, Yaroslava Kochnevahttps://www.fracturae.com/index.php/fis/article/view/4679Uniaxial fatigue study of a natural-based bio-composite material reinforced with fique natural fibers2023-11-19T16:11:17+00:00Maria Camila Chaves Garciamaria2180664@correo.uis.edu.coJuan Dayal Castro Bermudezdayalcastro@gmail.comAlberto David Pertuz Comasapertuzc@uis.edu.co<p>This research addresses environmental concerns by exploring environmentally friendly composite materials as substitutes for non-biodegradable synthetic fibers. The study proposes the development of polymer matrix composites reinforced with natural fique fibers, sourced from a plant cultivated in Colombia. A BioPoxy 36 polymer matrix with a high carbon content was used and reinforced with fique fabric using the vacuum-assisted lamination method. To improve the adhesion between the fibers and the matrix, an alkaline chemical treatment was applied to the fiber using 2% sodium hydroxide by weight. Mechanical properties were assessed through ASTM D3039 tensile and ASTM D3479 fatigue tests. A fractographic analysis was also conducted to identify the different modes of failure present. In terms of material degradation, distinct stages were observed, characterized by stiffness loss and loss factor indicators. The Coffin-Manson model was used to obtain the strain life curve for R = 0.1, using these factors as criteria. The static properties of the composite reinforced with fique fibers indicate an increase of 45% in ultimate strength, 145% in strain, and 27% in Young's modulus compared to the unreinforced matrix. In terms of dynamic properties, the elastic modulus showed a maximum variation of up to 7.88%. Electron microscopy reveals the failure mechanism, a distinct separation between the matrix and the fiber can be observed as a result of mechanical stress. The analysis reveals the brittle fracture of the hard fique fiber and some matrix separation, as well as possible fractured bubbles that may have occurred during the manufacturing process.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Maria C. Chaves, Dayal Castro, Alberto David Pertuz Comashttps://www.fracturae.com/index.php/fis/article/view/4675In-Plane Mixed-Mode Brittle Fracture Assessment of Harsin Marble Using HCSP Specimen2024-01-13T04:42:46+00:00Hadi Salavatihadi_salavati@uk.ac.irZuhair MoqadaszadehMoqadaszadeh@eng.uk.ac.itMorteza Rashidi Mogaddammorteza2046@gmail.com<p>The primary objective of this manuscript is studying the effect of T-stress term (T) on the crack propagation angle (CPA) and fracture toughness of in-plane mixed mode loading by utilizing a generalized form of minimum strain energy density (SED) criterion. The generalized criterion considers the influence of the first non-singular term of the Williams stress field as well as the conventional stress intensity factors (SIFs). A specimen known as a holed-cracked square plate (HCSP) composed of white Harsin marble is used for a wide range of in-plane mixed-mode fracture studies. HCSP is a square plate containing two cracks that are placed along each other in the circumference of a hole at the center of the specimen. The experimental results from mixed-mode fracture test by using proposed geometry are then compared with the results obtained theoretically from the conventional and generalized form of SED. It is demonstrated that the generalized criterion which includes the T, is substantially in agreement with the experimentally observed in-plane mixed-mode fracture results when compared to the SED criterion.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Hadi Salavati, Zuhair Moqadaszadeh, Morteza Rashidi Mogaddamhttps://www.fracturae.com/index.php/fis/article/view/4664Longitudinal elastic nonlinearity of composite material 2023-11-07T17:05:34+00:00Boris Fedulovfedulov.b@mail.ruDaria Bondarchukbondarchuk.da@mail.ruEvgeny Lomakinevlomakin@yandex.ru<p>It is known that the initial waviness of the fiber affects the stiffness characteristics and strength of the polymer composite material. The article presents a continuum model taking into account the nonlinearity of the longitudinal stiffness of the unidirectional composite. In this study, a finite element experiment was conducted to investigate the variations in the longitudinal stiffness of the composite material subjected to uniaxial compression. The experiment considered a range of different degree of fiber’s waviness to comprehensively examine the impact on the material's stiffness. Obtained results explain the difference in stiffness observed in fiber composites in the longitudinal direction under uniaxial tension and compression. Special constitutive relations proposed to model compressive stiffness reduction in longitudinal direction. </p>2023-12-17T00:00:00+00:00Copyright (c) 2023 Boris Fedulov, Daria Bondarchuk, Evgeny Lomakinhttps://www.fracturae.com/index.php/fis/article/view/4637Ultrasonic fatigue testing of AISI 304 and 316 stainless steels under environmental and immersion conditions 2023-12-09T07:20:53+00:00Luis M. Torres Duarteing.lmtd@gmail.comGonzalo Mariano Domínguez Almarazdalmaraz@umich.mxHipólito M. Venegas Montaño0468633k@umich.mx<p>Ultrasonic fatigue tests were carried out on stainless steel AISI 316 and 304, under two modalities: at room temperature and in immersion (water for 316 and antifreeze for 304 steels); all tests were carried out with a loading ratio R=-1. The results obtained in the tests at room temperature (without immersion), for both materials exhibited a significant increase in temperature, leaving heat marks on the narrow section of the specimens. This phenomenon occurred due to the low coefficient of thermal conductivity of these stainless steels (16.2 W/ (m °K)), and the recorded temperatures were around 200 °C, generating instantaneous failure of material. Analyzes of fracture surfaces on specimens tested at room temperature reveal that crack initiation was related to the high temperature, causing alteration at the granular scale of the material, followed by a typical behavior crack propagation and failure. For specimens tested under immersion conditions, it was possible to reduce the temperature below 100 °C, which solved the problem of failure due to thermal effect. The results for 316 stainless steel immersed in water showed a fatigue life of 1.188×1010 cycles at188 MPa of stress loading in the specimen; while specimens subjected to 263 MPa stress showed a fatigue life of around 7×106 cycles, representing a significant reduction with an approximate factor of 1700. On the other hand, specimens of 304 stainless steel immersed in antifreeze with the lowest loading values of 169 MPa, showing an infinite ultrasonic fatigue life; while tests subjected to 263 MPa loading stress attains 3.62×106 cycles of ultrasonic fatigue life. The scanning electron microscopy visualizations for both cases of immersion tests showed that the initiation and propagation of the crack occurred on the surface of the specimens, exhibiting the typical mechanical fracture behavior without any apparent thermal influence.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Luis M. Torres Duarte, Gonzalo Mariano Domínguez Almaraz, Hipólito M. Venegas Montañohttps://www.fracturae.com/index.php/fis/article/view/4626Fatigue assessment of a FSAE car rear upright by a closed form solution of the critical plane method2023-11-21T16:03:40+00:00Andrea Chioccaandrea.chiocca@unipi.itMichele Sgammamichele.sgamma@phd.unipi.itFrancesco Frendofrancesco.frendo@unipi.itFrancesco Bucchifrancesco.bucchi@unipi.itGiuseppe Marulogiuseppe.marulo@it.rheinmetall.com<p>Material fatigue is extensively discussed and researched within scientific and industrial communities. Fatigue damage poses a significant challenge for both metallic and non-metallic components, often resulting in unexpected failures of in-service parts. Within multiaxial fatigue assessment, critical plane methods have gained importance due to their ability to characterize a component's critical location and detect early crack propagation. However, the conventional approach to calculate critical plane factors is time-consuming, making it primarily suitable for research purposes or when critical regions are already known. In many real-world scenarios, identifying the critical area of a component is difficult due to complex geometries, varying loads, or time limitations. This challenge becomes particularly crucial after topological optimization of components and in the context of lightweight design. Recently, the authors proposed an efficient method for evaluating critical plane factors in closed form, applicable to all cases that necessitate the maximization of specific parameters based on stress and strain components or their combination. This paper presents and validates the proposed methodology, with reference to a rear upright of a FSAE car, which is characterized by a complex geometry and is subjected to non-proportional loading conditions. The efficient algorithm demonstrated a substantial reduction in computation time compared to the standard plane scanning method, while maintaining solution accuracy.</p>2023-12-17T00:00:00+00:00Copyright (c) 2023 Andrea Chiocca, Michele Sgamma, Francesco Frendo, Francesco Bucchi, Giuseppe Marulohttps://www.fracturae.com/index.php/fis/article/view/4624Numerical investigation of an extra-deep drawing process with industrial parameters: formability analysis and process optimization2023-10-18T12:21:35+00:00Amina Belgueblia.belguebli@univ-chlef.dzIbrahim Zidanei.zidane@univ-chlef.dzAdel Hadj Amara.hadj94@univ-chlef.dzAbdessoufi Benhamoua.benhamou@univ-chlef.dz<p>Extra-deep drawing is one of the most important sheet metal forming processes. The appearance of rupture and wrinkling are the most commonly encountered problems in this process. These defects are also very common at a local company, particularly in the manufacturing of wheelbarrow trays. As a consequence, substantial time and costs are incurred in industrial production. To thoroughly analyze and address these defects, the extra-deep drawing operation of the wheelbarrow tray was modeled by the FE method using Abaqus software. A defect-free manufactured wheelbarrow tray was used to validate the accuracy of the numerical approach. Precise measurements of its dimensions were taken through the reverse engineering process using a 3D scanner. Furthermore, other measurements were made with an ultrasonic thickness gauge to have more precise measurements of the product’s thickness. Comparing experimental and numerical results showed good agreement. The outcomes of the numerical analysis indicate that the final shape of the wheelbarrow tray does not contain rupture or wrinkling defects, accurately corresponding to the real cases manufactured at the company. Numerical modeling and optimization of the extra-deep drawing process performed in this study could potentially reduce production losses and improve the overall efficiency of industrial manufacturing.</p>2024-02-15T00:00:00+00:00Copyright (c) 2024 Amina Belguebli, Ibrahim Zidane, Adel Hadj Amar, Abdessoufi Benhamou