Frattura ed Integrità Strutturale <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="">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 both in a dedicated <a href="">YouTube channel</a> and in an "on demand" page (<a href="">LINK</a>). All the issues are also published in a browsable version (<a href="">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> Fatigue growth rate of inclined surface cracks in aluminum and titanium alloys <p>In this paper the fatigue crack growth tests were carried out on surface-crack tension (SCT) specimens, made of 7050 and Ti6Al4V alloys, with initial semi-elliptical surface cracks. Pure Mode I conditions were realized on SCT specimens with crack plane located orthogonal to the loading direction, while Mixed-mode conditions were observed on SCT specimens with inclined crack. Optical microscope measurements and the crack mouth opening displacement (CMOD) method were respectively used to monitor crack length and calculate crack depth. Current crack shape during the tests was highlighted by alternation of loading spectrum with baseline load block and a marker load block. The stress strain field along the crack front of semi-elliptical cracks in the SCT specimens was assessed by Finite Element Method (FEM) analysis. The stress intensity factors (SIFs) were calculated along crack fronts and equivalent elastic SIF formulation was used for crack growth rate assessment under mixed mode conditions. As a result, the fracture resistance parameters of aluminum and titanium alloys were obtained for two crack propagation directions under Mode I and Mixed-mode loading. The benefits of using the computational and experimental results of SCT specimen for the assessment of the surface crack growth rate in aluminum and titanium alloys under Mixed-mode loading conditions were stated.</p> Rustam Yarullin Mikhail Yakovlev Copyright (c) 2022 Rustam Yarullin, Mikhail Yakovlev 2022-03-25 2022-03-25 16 60 451 463 10.3221/IGF-ESIS.60.31 Impact behaviour of dissimilar AA2024-T351/7075-T651 FSWed butt-joints: effects of Al2O3-SiC particles addition <p>Dissimilar friction stir welding joints are widely employed in the industrial field due to the excellent microstructural and mechanical properties of the resulting joints. Nevertheless, to further enhance the weld properties, the addition of reinforcement particles on the joint-line during the process has been proven effective for increasing its mechanical performance. In the present investigation, the microstructure and the impact behaviour of FSWed joints between AA2024-T351 and AA7075-T651 aluminium plates were investigated, considering the effect of different process parameters selected through a full factorial 2<sup>k </sup>design of experiments: both the rotational and translational speed of the tool, as well as the addition of Al<sub>2</sub>O<sub>3</sub>-SiC microparticles, were considered as input parameters. Unnotched 10 x 5 x 55 mm impact specimens were tested through an instrumented 50 J Charpy pendulum: total impact energy, the two complementary initiation and propagation energies as well as the peak force were correlated to the adopted process parameters. From the performed analyses, it was found that joints with reinforcing particles are prone to form wormhole defects across the stir zone that not only affect the microstructural development, but also the impact behaviour since they require less energy at break in comparison with joints fabricated without particles addition.</p> Cindy Morales Mattia Merlin Annalisa Fortini Gian Luca Garagnani Argelia Miranda Copyright (c) 2022 Cindy Morales, Mattia Merlin, Annalisa Fortini, Gian Luca Garagnani, Argelia Miranda 2022-03-25 2022-03-25 16 60 504 515 10.3221/IGF-ESIS.60.34 Investigation fatigue crack initiation and propagation cruciform welded joints by extended finite element method (XFEM) and implementation SED approach <p>This study has used the strain energy density (SED) approach to evaluate the stress intensity factor (SIF) of cracked cruciform welded joints in Hardox 450 steel. A microstructural analysis was made of Hardox 450 steel which is composed of refined and tempered low carbon martensite. The obtained results of simulation will be compared with those provided by J-integral methode for different enriched zones and contours based on the extended finite element method (XFEM) coupled with the level set technique (LST).&nbsp; Crack initiation and propagation under cyclic loading have been adopted for the modeling of cruciform welded joints.</p> Hamza Djeloud Mustafa Moussaoui Ahmed Kellai Dahmane Hachi Filippo Berto Benattou Bouchouicha Brahim Elkhalil Hachi Copyright (c) 2022 Hamza Djeloud, Mustafa Moussaoui, Ahmed Kellai, Dahmane Hachi, Filippo Berto, Benattou Bouchouicha, Brahim Elkhalil Hachi 2022-03-25 2022-03-25 16 60 346 362 10.3221/IGF-ESIS.60.24 Structural and seismic vulnerability assessment of the Santa Maria Assunta Cathedral in Catanzaro (Italy): classical and advanced approaches for the analysis of local and global failure mechanisms <p>The evaluation of the seismic vulnerability of existing buildings is becoming very significant nowadays, especially for ancient masonry structures, that represent the cultural and historical heritage of our countries. In this research, the Cathedral of Santa Maria Assunta in Catanzaro (Italy) is analyzed to evaluate its structural response. The main physical properties of the constituent materials were deduced from an extensive diagnostic campaign, while the structural geometry and the construction details were derived from an accurate 3D laser scanner survey. A global dynamic analysis, based on the design response spectrum, is performed on a finite element model for studying the seismic response of the structure. Moreover, a local analysis is conducted to evaluate the safety factors corresponding to potential failure mechanisms along preassigned failure surfaces. Furthermore, pushover analyses are performed on macro-elements, properly extracted from the whole structure and with an independent behavior with regard to seismic actions. A novel model based on inter-element fracture approach is used for the material nonlinearity and its results are compared with a well-known classical damage model in order to point out the capability of the method. Finally, the results obtained with the three different models are compared in terms of seismic vulnerability indicators.</p> Fabrizio Greco Daniele Gaetano Lorenzo Leonetti Paolo Lonetti Arturo Pascuzzo Aurora Skrame Copyright (c) 2022 Fabrizio Greco, Daniele Gaetano, Lorenzo Leonetti, Paolo Lonetti, Arturo Pascuzzo, Aurora Skrame 2022-03-25 2022-03-25 16 60 464 487 10.3221/IGF-ESIS.60.32 Fatigue crack growth analysis of welded bridge details <p>The paper investigates the fatigue crack growth in typical bridge weldments by means of numerical analysis. The extended finite element (XFEM) method is coupled with the low-cycle fatigue (LCF) approach in ABAQUS, and parametric analyses are carried out in order to assess the influence of the main sample/testing features on the fatigue life of the investigated structures. The numerical results are found to be robust and reliable by performing comparisons with past experimental data and regulation design correlations.</p> Danilo D'Angela Marianna Ercolino Copyright (c) 2022 Danilo D'Angela, Marianna Ercolino 2022-03-25 2022-03-25 16 60 265 272 10.3221/IGF-ESIS.60.18 On the peak strength of 7050 aluminum alloy: mechanical and corrosion resistance <p>This work consists of an experimental study on the ageing response and resulting properties of AA7050 plate material. New heat treatments are investigated for achieving a peak-aged temper, as a T6 temper may be said to be, that achieves yield and tensile strengths superior to those of the documented T7 treatments. For this alloy, the Standard establishes T7X tempers which were developed to obtain a very good compromise between mechanical strength and corrosion resistance. Nevertheless, for all those applications in which the environment is not considered critical for corrosion behaviour, the peak strength condition could be beneficial. In this experimental work, the authors use standard hardness testing to investigate mechanical response as a function of ageing time at several ageing temperatures, all applied immediately after solution. Upon identifying specific times and temperatures of interest, specimens aged under the selected treatments were subjected to tensile testing and intergranular corrosion testing. The results show that a single-step ageing heat treatment is able to produce a significantly high both yield and ultimate tensile strength. Moreover, the corrosion test data indicates that this new heat treatment produces corrosion resistance similar to that of the T76 heat treatment.</p> Barbara Rivolta Riccardo Gerosa Marco Boniardi Andrea Casaroli Copyright (c) 2022 Barbara Rivolta, Riccardo Gerosa, Marco Boniardi, Andrea Casaroli 2022-03-25 2022-03-25 16 60 273 282 10.3221/IGF-ESIS60.19 Mesoscale investigation of mass concrete temperature control systems and their consequences on concrete mechanical behaviour. <p>This study investigates the impact of aggregate and pipe cooling systems on concrete behaviour at a mesoscale level. Firstly, a Chemo-Thermo-Mechanical model is developed to investigate the initial stress state of early age hydration concrete followed by a mechanical analysis of the consequences brought by this initial state. Pipe and aggregate cooled concrete samples have been subjected to tensile and cyclic loadings. The results have been discussed in terms of damage and crack openings. It has been concluded that early age hydration modifies the initial conditions of any concrete structures. Regarding the cyclic behaviour, initial state due to the hydration process leads to permanent displacements corresponding to damage and cracking. The cooling methods improve the mechanical behaviour of concrete.</p> Mohammed Matallah Abdelsemi Taibi T.T. Chimoto F.K. Maradzika Copyright (c) 2022 Mohammed Matallah, Abdelsemi Taibi, T.T. Chimoto, F.K. Maradzika 2022-03-25 2022-03-25 16 60 416 437 10.3221/IGF-ESIS.60.29 Influence of Pr6O11 addition on structural and magnetic properties of mechanically alloyed Fe65Co35 nanoparticles <p>This work focuses on the synthesize of nanostructured (Fe<sub>65</sub>Co<sub>35</sub>)<sub>100-x </sub>(Pr<sub>6</sub>O<sub>11</sub>)<sub>x </sub>(x = 0, 5) powders using high energy ball milling. The influence of Pr<sub>6</sub>O<sub>11</sub> on structural, morphological and magnetic properties of Fe<sub>65</sub>Co<sub>35 </sub>nanoparticles were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) with a dispersive energy analyzer (EDS), vibratory sample magnetometer (VSM) and differential scanning calorimetry (DSC). Results show that the praseodymium oxide addition increased the decrement rate of the crystallite size with milling time of about 27 % and decreased the increment rate of the internal micro-strain of 50 %. Moreover, because of its high grain fragmentation tendency, Pr<sub>6</sub>O<sub>11 </sub>increases the hardness and brittleness of Fe-Co powders. Moreover, it minimized the cold welding between Fe-Co ductile particles leading to a significant decrease in the average particle size (~1µm). The magnetic measurements conducted at room temperature show that the saturation magnetisation (<em>M<sub>s</sub></em>) and the coercivity (<em>H<sub>c</sub></em>) increased with milling time in both compositions. A low <em>M<sub>s</sub></em> and high <em>H<sub>c</sub></em> values were detected in (Fe<sub>65</sub>Co<sub>35</sub>)<sub>95 </sub>(Pr<sub>6</sub>O<sub>11</sub>)<sub>5 </sub>nanoparticles. The results demonstrated a soft ferromagnetic nature in all of the synthesized nanoparticles with <em>M<sub>s</sub></em> in the range 207 – 216 emu/g and <em>H<sub>c</sub></em> is found to be 113 Oe.</p> Nacira Djellal Djamel eddine Mekki Elena Navarro Pilar Marin Copyright (c) 2022 Nacira Djellal, Djamel eddine Mekki, Elena Navarro, Pilar Marin 2022-03-25 2022-03-25 16 60 393 406 10.3221/IGF-ESIS.60.27 Microstructure and anisotropic tensile performance of 316L stainless steel manufactured by selective laser melting <p>The selective laser melting (SLM) technology is widely used to manufacture 316L stainless steel (SS) components for industrial applications. To understand the microstructure and the mechanical properties of additively manufactured 316L alloy, bulk materials were fabricated in longitudinal and transverse directions from which subset tensile specimens were then machine. Bulk materials were subjected to porosity detection with X-ray computed tomography and texture analysis with electron backscatter diffraction (EBSD). Microstructural investigations reveal that the SLM-built specimens had a porosity of 1.87%, and a preferential {110} orientation parallel to the build direction. The transverse specimens show significantly better properties in elastic modulus <em>E</em> (215.1±4.7GPa), yielding stress <em>σ<sub>y</sub></em> (548.2±8.3MPa) and ultimate tensile strength UTS (705.6±2.9MPa) than the longitudinal ones (<em>E</em> of 175.9±9.8GPa, <em>σ<sub>y</sub></em> of 495.3±15.5 and UTS of 608.8±3.6MPa). The anisotropic mechanical performance was attributed to the preferential {110} texture caused by thermal conditions during manufacturing and the embedded voids due to insufficient melting. A three-parameter Weibull distribution was adopted to further describe the mechanical anisotropy of SS316L based on stochastic experimental measurements. Fractography indicated the existence of manufacturing defects drive to premature failure of SS316L specimens—around half SS316L specimens failed of elongation less than 0.4.</p> Lin Wang Copyright (c) 2022 Lin Wang 2022-03-25 2022-03-25 16 60 380 391 10.3221/IGF-ESIS.60.26 Synthesis and Characterization of Fe2O3 Nanoparticles Reinforced to Recycled Industrial Aluminium Scrap & Waste Aluminium Beverage Cans for Preparing Metal Matrix Nanocomposites <p>Increased material demand in all sectors is primarily due to exponential growth in population to fulfill human needs and comforts. Recycling of collected aluminium beverage cans and Al 6061 alloy scraps from industries ensures energy savings with reduced environmental problems in fabricating composite parts economically. The iron oxide (α-Fe<sub>2</sub>O<sub>3</sub>) nanoparticles were prepared by precipitation method using ferric chloride and ammonia as a precursor. The prepared nanoparticles were characterized by using Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR). Stir cast processing route ensures uniform mix of reinforcement nanoparticles in matrix material. The prepared nanocomposites (matrix: Al Scrap (90% Scrap Al 6061 alloy + 10% Waste Al can); reinforcement: 2%, 4% and 6% wt. of Al matrix) were mechanically characterized for hardness and tensile strengths. It was observed that, increased percent of Fe<sub>2</sub>O<sub>3</sub> nanoparticles in the metal matrix nanocomposite (MMCs) resulted in significant increase in hardness and tensile strength values. Fractography analysis examined viz. scanning electron microscope (SEM) revealed a ductile failure for as-cast Al scrap followed by brittle failure in Al MMC's.</p> Ganesh R. Chate Raviraj M. Kulkarni Manjunath Patel Gowdru Chandrashekarappa Avinash Lakshmikanthan H.M. Harsha Simran Tophakhane Nazafali Shaikh Suman Kongi Pouravi Iranavar Copyright (c) 2022 Ganesh R. Chate, Raviraj M. Kulkarni, Manjunath Patel Gowdru Chandrashekarappa, Avinash Lakshmikanthan, H.M. Harsha, Simran Tophakhane, Nazafali Shaikh, Suman Kongi, Pouravi Iranavar 2022-03-25 2022-03-25 16 60 229 242 10.3221/IGF-ESIS.60.16 Experimental and numerical evaluation of compression confinement techniques for HSC beams reinforced with different ratios of high strength steel reinforcement <p>This work presents experimental and numerical research to evaluate the compression confinement techniques of HSC beams reinforced with different ratios of high-strength steel reinforcement. Twelve specimens of high-strength reinforced concrete beams with two different compression confinement techniques were tested experimentally. The first method is used carbon fiber reinforced polymers sheets (CFRPs) around the compression zone, CF, and the steel fibers reinforced concrete is used in the compression zone by 1% of volume fraction, SF, in the second case. A 3-D finite element analysis was done; using the ANSYS program to simulate and idealize all experimental specimens. The numerical and experimental results of the RC beams were validated and compared in this work. The results showed that there is a good idealization using 3-D finite element models with the experimental specimens. Also, it was found that using the suggested techniques can increase the strength ratio and increase the ductility index depending on the tensile reinforcement ratios. Moreover, the energy absorption and the mode of failure were enhanced.</p> Seleem Ahmad Abdo-Alfatah Graf Abd El-Monem El-Kholy Mohamed Bneni Ahmed Elkilani Copyright (c) 2022 Seleem Ahmad, Abdo-Alfatah Graf, Abd El-Monem El-Kholy, Mohamed Bneni, Ahmed Elkilani 2022-03-25 2022-03-25 16 60 310 330 10.3221/IGF-ESIS.60.22 Statistical evaluation of the effect of hygrothermal aging on the interlaminar shear of GFRP <p><span style="vertical-align: inherit;"><span style="vertical-align: inherit;">Изучение закономерностей изменения свойств, накопления повреждений и разрушения конструкционных композитов после гигротермического старения представляет собой актуальное и важное направление. </span><span style="vertical-align: inherit;">В работе представлены результаты механических испытаний на межслойный сдвиг образцов электротехнического конструкционного стеклопластика и эпоксидного композита до и после предварительного гигротермического старения в рабочих средах (техническая вода, морская вода, машинное масло) различной продолжительности (15, 30 и 45 суток. ) и различных температур (22, 60 и 90ºС). </span><span style="vertical-align: inherit;">Результаты испытаний были использованы для статистической оценки значимости немонотонных изменений прочности в случае межслойного сдвига после предварительного гигротермического старения относительно номинального материала с использованием ANCOVA и регрессионного анализа. </span><span style="vertical-align: inherit;">Такие методы показали, что морские и технологические водные растворы отрицательно влияют на прочность на межслойный сдвиг, но их влияние было немного различным и сильно зависело от эффекта взаимодействия между временем воздействия и температурой раствора. </span><span style="vertical-align: inherit;">Таким образом, максимальная разница составляет около 15% и 12% после 45 дней внутри технологической и морской воды при температуре 90 ºC соответственно. </span><span style="vertical-align: inherit;">Напротив, воздействие машинного масла привело к увеличению прочности, но эффект более слабый по сравнению с водными растворами (около 6%).</span></span></p> Dmitriy Lobanov Andrey S Yankin Nataliya I Berdnikova Copyright (c) 2022 Dmitriy Lobanov, Andrey S Yankin, Nataliya I Berdnikova 2022-03-25 2022-03-25 16 60 146 157 10.3221/IGF-ESIS.60.11 Web post-buckling strength of thin-webbed cellular beams using carbon PFRP profiles <p>Currently, cellular steel beams are widely used by structural engineers and major companies due to their useful structural applications and serviceable performance. However, these types of steel beams are susceptible to different states of instability and failure mechanisms such as web post-buckling. The aim of this paper is to investigate the effectiveness of using externally bonded pultruded carbon fiber (CFRP) profiles for the strengthening of web post-buckling in thin webbed cellular beams as an alternative to the typical welding technique of reinforcement. A proposed numerical model created with the finite element software ABAQUS capable of capturing the de-bonding and fracture along the adhesive layer between steel and CFRP has been validated using published experimental results.&nbsp;The suggested numerical model is then used to simulate the parametric analysis of using pultruded CFRP T and U sections to strengthen six cellular beams of various sizes. It was found that this novel technique was able to prevent the web post-buckling failure mode or delay it to a grater load with a considerable strength enhancement comparable to control beams.</p> Hamda Guedaoura Yazid Hadidane Copyright (c) 2022 Hamda Guedaoura, Yazid Hadidane 2022-03-25 2022-03-25 16 60 43 61 10.3221/IGF-ESIS.60.04 PVC failure modelling through experimental and digital image correlation measurements <p>This paper analyses industrial PVC sheets structural integrity assessment widely used for different ranges of industrial applications. We investigated combined approaches focused on fracture toughness assessment to predict PVC mechanical behavior against failure. We ran a series of tests on tensile and single-edge notched samples at various crosshead speeds on a tensile test machine. PVC sheets' stress intensity factors were evaluated using both theoretical and experimental approaches to model crack growth. In the experimental procedure, we used the digital image correlation (DIC) method. We also developed a semi-empirical model to predict crack length over time. Furthermore, we proposed that the crack growth rate and stress intensity factor were satisfactorily correlated at all crosshead speeds and that the crack growth rate could be represented using a power-law model. In pre-cracked PVC specimens, the results showed that crack growth appears to be influenced by crosshead speed.</p> Najat Zekriti Fatima Majid Rajae Rhanim Ibrahim Mrani Hassan Rhanim Copyright (c) 2022 Najat Zekriti, Fatima Majid, Rajae Rhanim, Ibrahim Mrani, Hassan Rhanim 2022-03-25 2022-03-25 16 60 488 503 10.3221/IGF-ESIS.60.33 Analysis of the adhesive damage for different shapes and types patch’s in Aircraft Structures corroded with an inclined crack <p>In this study, the finite element method is used to analyze the effect of corrosion and the behavior of inclined cracks of an aluminum plate Al 2024 -T3 under thermomechanical loading.&nbsp; The effects of the inclination of the crack and the effect of temperature for and different types and shapes of adhesives are highlighted.&nbsp; The results obtained show the increase of the crack inclination leads to a decrease of the damaged area and the damaged area ratio of the adhesive.&nbsp; In addition, the ratio D<sub>R</sub> increases with increasing temperature variation ΔT.&nbsp; The best performing patch shape that gave interesting results during this analysis is the circular and for type the Boron/epoxy is the best.</p> Mohamed Berrahou Hayet Benzineb Mohamed Serier Copyright (c) 2022 Mohamed Berrahou, Hayet Benzineb, Mohamed Serier 2022-03-25 2022-03-25 16 60 331 345 10.3221/IGF-ESIS.60.23 Mechanical behaviour of sandy soils embankments treated with cement and reinforced with discrete elements (fibres) <p>It is well known that the reinforcement of the Soil is considered as a solution to its stability problems. This technique ameliorates the mechanical and physical comportment of the soil. Based on this, this research paper aims at investigating the behaviour of a specific type of dried-cemented-sandy soil reinforced with discrete elements such as polypropylene fiber basically through experimental tests. The latter are a series of consolidated drained triaxial tests which were carried out on samples of sand that are prepared with 0, 3 and 6% of cement, reinforced with 1% of polypropylene fiber (12, 18 mm) randomly distributed. Furthermore, those contents are measured by the volume of dry sand. In addition to these tests, a parametric study has also been conducted on a road embankment using a finite element program such as Plaxis 2D in order to observe the variation of different parameters like safety factor and the displacements (Ut, Ux, Uy). The test results showed that the addition of cement and polypropylene fiber of different accommodations increased both cohesion and friction angle of sands while the numerical results indicated that the presence of these additions improved the safety factor and decreased significantly the displacements.</p> Yasmine Med Bouteben Boudaoud Zeineddine Copyright (c) 2022 Yasmine Med Bouteben, Boudaoud Zeineddine 2022-03-25 2022-03-25 16 60 174 186 10.3221/IGF-ESIS.60.13 Flexural behaviour of reinforced concrete beams strengthened by NSM technique using ECC <p>Bendable concrete is also defined as engineered cementitious composites because of its great ductility and tight fracture width limitation. ECC mixtures by adding additional Portland cement, silica sand and fly ash, fiber types (polypropylene (PP), and polyvinyl alcohol (PVA)). The objective main aim of the research is to investigate the flexural performance of a series of RC beams that were externally bonded (EB) with steel bars using the engineered cementitious composite (ECC) matrix near-surface mounted technique. A total of 5 RC beams by 1500 mm as a length, 150 mm as width, and 200 mm as height, including one control and four strengthened, were prepared and tested. The test parameters are strengthening configurations and glue matrix (ECC and Epoxy). The test results revealed that ECC is an ideal cement matrix for reinforcement applications where ECC and Epoxy mortar bonded with steel bars are used as exterior reinforcement. As a result of what ECC has a number of attractive properties. The most unique aspect is the high tensile ductility, which is hundreds of times that of concrete while maintaining compressive strengths similar to concrete or high strength.</p> Fady Awad Mohamed Husain Khaled Fawzy Copyright (c) 2022 Fady Awad, Mohamed Husain, Khaled Fawzy 2022-03-25 2022-03-25 16 60 291 309 10.3221/IGF-ESIS.60.21 Improvement of mechanical properties of railway track concrete sleepers using ultra high performance concrete (UHPC) <p>In recent times, the shape of the beams evolved from wooden sleepers and then to steel sleepers until they reached concrete sleepers. These sleepers play a very important role in transferring the loads from the train wheels to the subgrade layers fixed by the railway. This development took place in concrete sleepers until we reached mono-block concrete sleepers. This paper discusses, through laboratory experiments, the effect of ultra-high performance concrete mixtures on the behavior of mono-block concrete sleeper B70. The ability of these new sleepers to resist train loads was also studied, compared to its conventional concrete sleepers. This research aimed to determine through experiment if these sleepers' behavior fulfilled the European requirements standers for prestressed concrete sleepers, and make comparisons between the UHPC sleepers and conventional concrete sleepers. All these sleepers were tested under static load tests at the rail seat and center section and pull-out tests for cast-in fastening components. These initial results suggest that a new generation of Ultra-high performance concrete sleepers can be created; the long-term efficiency of this category of sleeper will need to be confirmed by dynamic and fatigue tests and practical use.</p> Sayed Ahmed Hossam Atef Mohamed Husain Copyright (c) 2022 Sayed Ahmed , Hossam Atef, Mohamed Husain 2022-03-25 2022-03-25 16 60 243 264 10.3221/IGF-ESIS.60.17 Fracture toughness of matrix cracked FRC and FGC beams using equivalent TPFM <p>In the present work, the fracture toughness (K<sub>IC</sub>) of full-depth (FD) fiber-reinforced concrete (FRC) and layered functionally graded concrete (FGC) matrix cracked (MC) beams has been determined by the equivalent relationships of the two-parameter fracture model (ETPFM). Forty-eight MC-FGC and MC-FD FRC beam specimens with span-depth ratios (L/d) equal 4, 5, and 6 were tested under the 3PB configuration. The MC length-depth ratio (a<sub>o</sub>/d) remained constant equal to one-third. All FRC beams have the same constitutes materials with hooked-end steel fiber volume fraction equals 1%. The FGC beams are composed of three equal layers, i.e., FRC in the bottom layer at the tension side, normal strength concrete (NSC) at the middle layer, and high strength concrete at the upper layer in the compression side. The results showed that the predicted values of K<sub>IC</sub> obtained from ETPFM are considered logic according to the maximum size of the non-damaged defect concept. The crack mouth opening displacement estimated from ETPFM showed acceptable values close to the present experimental results. The K<sub>IC</sub> values calculated within the presence of fibers in front of and through the MC for FRC beam specimens having 1% SFs is more than twice the value of NSC.</p> Hossam El-Din M. Sallam Ahmed Elakhras Mohammad Seleem Copyright (c) 2022 Hossam El-Din M. Sallam, Ahmed Elakhras, Mohammad Seleem 2022-03-25 2022-03-25 16 60 73 88 10.3221/IGF-ESIS.60.06 Elastic surface crack interaction and its engineering critical assessment within the framework of fitness-for-service standards <p>In real industrial conditions, it’s common to witness the interaction of multiple cracks such that their stress fields and crack driving forces are disturbed. For coplanar cracks, a greater hazard is expected because of the amplification phenomenon. FFS standards deal with this by proposing interaction rules and idealizing a single bonding flaw for the FAD methodology to be used. The goal of this paper is to analyze the effectiveness of this standards methodology considering twin surface semielliptical cracks on a plate under mode I loading on the interaction range using FE analyses. Results confirm that the amplification phenomena due to the interaction are higher on the interacting crack tip and progressively higher as the coplanar horizontal distance decreases. The loss of constraint was observed to decrease as the coplanar horizontal distance decreased, but little change was observed regarding its parametric angular position. A higher amplification was found at the coplanar horizontal distance on which crack interaction is to be considered meaningful, which indicates inconsistency regarding the interaction criteria used on FFS standards. To conclude, the engineering critical assessment of the bonding flaw proved to be over-conservative as the remaining operational life was observed on the assessment of the interacting flaws.</p> Gabriel Coêlho Antonio Silva Marco Santos Copyright (c) 2022 Gabriel de Castro Coêlho, Dr. Antonio Almeida Silva, Dr. Marco Antonio dos Santos 2022-03-25 2022-03-25 16 60 134 145 10.3221/IGF-ESIS.60.10 Numerical analysis of bonded composite patch efficiency in the case of lateral U and V-notched aluminium panels <p>In this study, the finite element method is applied to investigate the mechanical behavior of aluminium notched structures reinforced by composite patch. In order to evaluate the efficiency of patches in the case of lateral semicircular and V-notches, it is very important to analyze the stress distribution at the notch tip and to take in consideration the influence of the geometrical and mechanical properties of the patch and the adhesive. Simple and double patch were used as reinforcement techniques. Results showed that the stress concentration factor is reduced at the notch tip by using a double patch reinforcement. This reduction becomes more noticeable when the patch thickness increases.</p> Mohammed A. Bouchelarm Abdelkader Boulenouar Meriem Chafi Copyright (c) 2022 Mohammed A. Bouchelarm, Abdelkader Boulenouar, Meriem Chafi 2022-03-25 2022-03-25 16 60 62 72 10.3221/IGF-ESIS.60.05 The critical influence of some “tiny” geometrical details on the stress field in a Brazilian Disc with a central notch of finite width and length <p>The role of some geometrical characteristics of the notches ma­chined in circular discs, in order to determine the mode-I fracture tough­ness of brittle materials, is discussed. The study is implemented both analyti­cally and numerically. For the analytic study advantage is taken of a recently intro­duced solution for the stress- and displacement-fields developed in a finite disc with a central notch of finite width and length and rounded corners. The vari­ation of the stresses along strategic loci and the deformation of the peri­me­ter of the notch obtained analytically are used for the calibration/validation of a flexible nu­mer­ical model, which is then used for a parametric investiga­tion of the role of geometrical features of the notched disc (thickness of the disc, length and width of the notch, radius of the rounded corners of the notch). It is con­cluded that the role of the width of the notch is of critical im­port­ance. Both the ana­lytic and the numerical studies indicate definitely that ignoring the ac­curate geo­metric shape of the notch leads to erroneous results concerning the actual stress field around the crown of the notch. Therefore, it is possible that misleading values of the fracture toughness of the material of the disc may be obtained.</p> Stavros K Kourkoulis Christos Markides Ermioni Pasiou Andronikos Loukidis Dimos Triantis Copyright (c) 2021 Stavros K Kourkoulis, Christos Markides, Ermioni Pasiou, Andronikos Loukidis, Dimos Triantis 2021-12-22 2021-12-22 16 60 405 422 10.3221/IGF-ESIS.59.27 Novel 2D strain-rate-dependent lamina-based and RVE/phase-based progressive fatigue damage criteria for randomly loaded multi-layer fiber-reinforced composites <p>Two implicit progressive fatigue damage models that rely on new equivalent-damage and equivalent-stress criteria are presented for the prediction of various failure modes of the composites. The criteria are coupled with lamina-based and representative-volume-element-based damage progression approaches. The common concepts of residual strength and residual stiffness are revisited and modified. A fatigue life assessment algorithm that incorporates the strain-rate-dependence of the fatigue strengths and stiffnesses, and random and asynchronous changes of the stress components, distinct mean values, and phase shifts of the stress components is employed. New ideas and new post-processing procedures are employed in the current research. It is the first time that the significant impacts of the strain-rate-dependence of the properties of the composites on stress and fatigue life analyses are investigated. Results of the proposed fatigue criteria are first implemented to a composite plate with a complex lamination scheme under a random transverse load and the predicted fatigue lives are verified by the experimental results. Then, these criteria are implemented to a composite chassis frame of an SUV car under realistic random road inputs and the theoretical results are verified by the experimental results. Results confirm the significant role of the strain-rate-dependence effects on the fatigue lives.</p> M. Shariyat Copyright (c) 2021 M. Shariyat 2021-12-22 2021-12-22 16 60 423 443 10.3221/IGF-ESIS.59.28 Mechanical Characterization and Tensile Fractography of Al7075-WCP-CoP Composite <p>The demand for materials with an unusual combination of properties has increased tremendously at a level that cannot be attained through the use of conventional materials. This is especially true for materials used in aircraft, automotive and power generation applications. The microstructure and mechanical properties of Al7075 – 6, 9 and 12 wt.% WC-Co particles reinforced composites are shown in this study. Liquid metallurgy is used to create the composites. The planetary ball milling method is utilized to turn the WC-Co mixtures into cermets, and the particles with a size range of 30-40 µm are employed as reinforcement. SEM and EDS analyses were used to characterise the microstructure. ASTM standards are used to test the mechanical characteristics of both as cast Al7075 and Al7075-6, 9 and 12 wt.% WC-Co composites. SEM was used to perform fractography study on the prepared composite.</p> U. B. Gopal Krishna B. Vasudeva Virupaxi Auradi Madeva Nagaral Copyright (c) 2022 U. B. Gopal Krishna, B. Vasudeva, Virupaxi Auradi, Madeva Nagaral 2022-03-25 2022-03-25 16 60 283 290 10.3221/IGF-ESIS.60.20 Experimental and computational study on dynamic analysis of cracked simply supported structures under moving mass <p>In this study, the influences of crack parameters like crack location from the left end, crack height, number of cracks and the magnitude of mass and the velocity of the transit load on the vertical displacements of the cracked simply supported beams subjected to transit mass are investigated. The transverse open cracks with numerous damage scenerios are considered for the mathematical modelling of the system. The governing equations of motion for the system have been obtained and the equations have been solved by the help of Duhamel integral technique. The theoretical formulation has been exemplified with numerical studies. By utilizing ANSYS Workbench 2020, transient&nbsp; structural analysis has been carried out. The mode shapes and the frequency ratios of damaged simply supported beam have also been determined.&nbsp; To validate the numerical and FEM models, the experiments with damaged beams have been carried out in the laboratory. It has been proven that the results of the theoretical and FEM models are well convergent with the experimental data. The results gathered from the numerical analysis, FEA as well as experimental study have been presented with comparative graphs and tables. The outcomes of the examinations have been interpreted in the conclusions part. It has been observed that subject parameters are of considerable significance on the time dependent response of the cracked beams.</p> Shakti P. Jena Cihan O. Bulut Serpil Kurt Copyright (c) 2022 Shakti P. Jena, Cihan O. Bulut, Serpil Kurt 2022-03-25 2022-03-25 16 60 114 133 10.3221/IGF-ESIS.60.09