Frattura ed Integrità Strutturale 2022-06-19T13:23:08+00:00 Francesco Iacoviello Open 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. 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 in a dedicated <a href="">YouTube channel</a>. All the issues are also published in a browsable version (<a href="">LINK</a>).</p> Finite Fracture Mechanics and Cohesive Crack Model: Size effects through a unified formulation 2022-06-14T15:34:56+00:00 Francesco Ferrian Pietro Cornetti Liviu Marsavina Alberto Sapora <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> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Francesco Ferrian, Pietro Cornetti, Liviu Marsavina, Alberto Sapora Fracture micrographic analysis of a carbon FML under three-point bending load 2022-06-14T12:04:10+00:00 Costanzo Bellini Vittorio Di Cocco Francesco Iacoviello Larisa Patricia Mocanu <p>The core of the present work concerns the analysis of the failure mode and the fracture process induced by the flexural load in Fibre Metal Laminates (FMLs). The influence of the connection layer placed between the composite ones and the metal sheets on the fracture mode was analysed. The considered FML was made of aluminium sheets interposed with carbon fibre reinforced polymer (CFRP) layers, joined with two different types of interface: by using a structural adhesive, or by relying on the bonding capacity of the prepreg resin. Then, the mechanical performances of the produced laminates were determined through the three-point bending test procedure, and the support span was varied to investigate different loading conditions. Finally, the fracture surface morphology was analysed by using both optical and scanning electron microscopes. The type of interface was found to influence the strength of the studied FML, and different fracture modes were observed, depending on the loading condition.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Costanzo Bellini, Vittorio Di Cocco, Francesco Iacoviello, Larisa Patricia Mocanu Finite-element study of residual stress distribution in Ti-6Al-4V alloy treated by laser shock peening with varying parameters 2022-06-09T15:05:31+00:00 Anastasiia Kostina Maxim Zhelnin Elena Gachegova Alexander Prokhorov Aleksei Vshivkov Oleg Plekhov Sathya Swaroop <p>Laser shock peening (LSP) is used to enhance surface quality of the metallic structures by the generation of compressive residual stresses on it. This work studies the effect of the main LSP parameters on residual stress fields by the finite-element method. The specimen under investigation is a square plate with a thickness of 3 mm made of Ti-6Al-4V. The performed analysis enhances understanding of LSP application to structures manufactured from this material and this information can be useful for a choice of optimal peening parameters. The effect of the spot size and shape, the pulse energy, the number of peen layers, overlapping of spots and temporal variation of the mechanical pressure induced by plasma is considered and analyzed. A 3D finite-element model based on the Johnson-Cook constitutive relation is developed and verified by the results of residual stress measurements performed for the LSP-treated samples under different conditions. From the obtained results the following main conclusions can be drawn: pulse energy provides the more significant effect although the resulting residual stresses profile tends to some saturation curve; temporal pressure pulse shape and its total duration also substantially alter the residual stress field; the least significant parameter is the spot shape.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Anastasiia Kostina, Maxim Zhelnin, Elena Gachegova, Alexander Prokhorov, Aleksei Vshivkov, Oleg Plekhov, Sathya Swaroop Influence of Free Ferrite on the Mechanical Properties of High Strength Intercritical Austempered Ductile Iron 2022-06-09T11:20:39+00:00 Alejandro Daniel Basso Martin Caldera Nicolás Emanuel Tenaglia Diego Fernandino Roberto Enrique Boeri <p>The first stage of this study investigates the precipitation of free ferrite from the austenite on fully austenitized ductile iron. Several sets of samples of low alloy ductile iron are fully austenitized and then cooled down to different temperatures and different times within the intercritical austenite-ferrite-graphite phase field. Based on these results, heat treatment cycles aimed at obtaining microstructures composed of free ferrite and ausferrite are carried out. Tensile, impact and toughness tests are performed to characterize the mechanical properties. The results show that, related to the high strength austempered ductile iron grades, the best combinations of properties were obtained from the mixed structures composed of 5% free ferrite and 95% ausferrite, resulting from the austempering at 280°C. These amounts of free ferrite allow obtaining an increase of the elongation (about 50%) and impact toughness (about 10%) while the tensile strength and fracture toughness decrease by about 1.5 and 15% respectively. &nbsp;</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Alejandro Daniel Basso, Martin Caldera, Nicolás Emanuel Tenaglia, Diego Fernandino, Roberto Enrique Boeri Effect of cenosphere and specimen crack lengths on the fracture toughness of Al6061-SiC composites 2022-05-22T15:41:33+00:00 E. Ashoka C. M. Sharanaprabhu G. Kodancha Krishnaraja <p>Main aim of this work is to investigate the influences of the addition of cenosphere and specimen crack length on the fracture toughness of Al6061-SiC composites. The experimental analysis was carried out for 3, 6 and 9 wt% proportions of cenosphere with the 3 wt% of SiC as reinforcements in the aluminum 6061 matrix for various crack lengths. The fracture toughness of Al6061-SiC-Cenosphere hybrid composites was estimated using compact tension (CT) specimen for the said compositions. The CT specimens were prepared, according ASTM E399 standard, for different crack length to width (a/W=0.3-0.6) ratios. From the experimental outcomes, it is identified that the fracture toughness of the hybrid composite increases upto the 6wt% of cenosphere and further increment in the cenosphere causes the decrement in the values. It is also found that the load bearing capacity and fracture toughness of the hybrid composite decreases with increment in the a/W ratios of the CT specimen.&nbsp;</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 E. Ashoka, C. M. Sharanaprabhu, G. Kodancha Krishnaraja Natural Frequency based delamination estimation in GFRP beams using RSM and ANN 2022-06-01T13:27:12+00:00 T. G. Sreekanth M. Senthilkumar S. Manikanta Reddy <p>The importance of delamination detection can be understood from aircraft components like Vertical Stabilizer, which is subjected to heavy vibration during the flight movement and it may lead to delamination and finally even flight crash can happen because of that. Any solid structure's vibration behaviour discloses specific dynamic characteristics and property parameters of that structure. This research investigates the detection of delamination in composites using a method based on vibration signals.&nbsp; The composite material's flexural stiffness and strength are reduced as a result of delaminations, and vibration properties such as natural frequency responses are altered. In inverse problems involving vibration response, the response signals such as natural frequencies are utilized to find the location and magnitude of delaminations. For different delaminated beams with varying position and size, inverse approaches such as Response Surface Methodology (RSM) and Artificial Neural Network (ANN) are utilized to address the inverse problem, which aids in the prediction of delamination size and location.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 T. G. Sreekanth, M. Senthilkumar, S. Manikanta Reddy Improvement of hydration products for self-compacting concrete by using magnetized water 2022-05-14T12:59:03+00:00 A.A. ELShami Noura Essam El-Shikh M. Yousry <p>Magnetized water (MW) is one of the most effective and economical ways to improve the properties of self-compacting concrete (SCC). Therefore, the aim of this study is to improve the fresh, mechanical, and microstructural properties of SCC using MW. For this purpose, a total of 12 mixes were produced with silica fume (SF) content (5% and 10% by weight of cement), and the mixing water passed through a permanent magnetic field (with a strength of 1.4 T) for 50, 100, and 150 cycles. Tests were performed for fresh properties (Slump flow, T50cm, V-funnel, and L-box), for mechanical properties (compressive, flexural, and tensile strength), and for microstructure properties (SEM, EDX, and TGA/DTG). The optimum result in compressive strength was achieved in the mix M8 using 5% silica fume and 150 cycles of MW. For fresh properties, the mix M4 using 150 cycles without SF had the workability enhanced by 11% compared to the control mix, and SEM and EDX tests indicated that SCC mixes prepared with MW had more C-S-H, less CH, and were denser. In addition, TGA/DTG analysis showed that the rate of hydration of mix M8 was reached by 61% at 28 days. </p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 A.A. ELShami, Noura Essam, El-Shikh M. Yousry Locating and Quantifying Necking in Piles Through Numerical Simulation of PIT 2022-06-09T11:31:25+00:00 Tarek Salem Atef Eraky Abdalla Elmesallamy <p>Defects of concrete piles can occur at any point during the construction of piles. Most common types of pile integrity issues are; presence of voids, inconsistency in concrete mix, entrapped groundwater or slurry, and geometric dislocation. These defects can be categorized based on the place in the construction sequence at which the defect occurs. This research introduces several numerical models of defected piles with various scenarios in order to identify, locate, and quantify the necking occurring in these piles. The finite element software (ADINA) is used to simulate the studied models. The soil domain is modeled as an axisymmetric space around the concrete pile. Five diameters of piles (40, 60, 80, 100 and 120 cm) are studied. Necking is modeled at three different locations along the pile namely; upper, middle, and bottom third. Four ratios between the necking diameter and pile diameter are also studied. The dynamic force used in this research is that simulating the pile integrity test (PIT) case, with 2.5 N impact load applied at the pile head, half wave of sinusoidal pattern, and 0.5 kilo hertz frequency. The time domain of the dynamic force analysis is equal to 0.0175 sec, and applied in 450 steps.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Tarek Salem , Atef Eraky, Abdalla Elmesallamy Experimental and numerical assessment of the location-based impact of grouting defects on the tensile performance of the fully grouted sleeve connection 2022-05-17T02:59:48+00:00 Espoir Kahama Xie Fuzhe Chunhua Lu Isaac Offei <p>The presence of grouting defects emanating from construction operations constitutes a major threat to the structural integrity of the grouted sleeve connection of precast concrete members. This work presents a location-based assessment of the impact of grouting defects on the tensile performance of the grouted sleeve connection. Twenty-two specimens with different configurations of defects were subjected to a uniaxial tensile experiment. Corresponding numerical models were proposed, validated and used to conduct a sensitivity analysis of the connection to the defect's location while considering different design confinements of grouting materials. Experimental and numerical studies revealed the following outcome: In consideration of confinement parameters, when the defect of size 3d is located in the mid-span anchorage length, the variation of the sleeve-to-bar diameter (<em>ds/d</em>) from 2.66 (lower design limit) to 3.55 (upper design limit) changed the drop in the ultimate capacity from 19% to 44% below the connection's design requirement. The governing parameters of the grout-bar bond stiffness were the defect's location and degree of confinement. This work proposes a theoretical diagnosis model and a risk assessment catalogue as a promising step toward establishing a computerized diagnosis model of the defective connection to enlighten rational maintenance actions in actual construction.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Espoir Kahama, Xie Fuzhe, Chunhua Lu, Isaac Offei Couple effects of temperature and fatigue, creep-fatigue interaction and thermo-mechanical loading conditions on crack growth rate of nickel-based alloy 2022-04-07T08:58:36+00:00 Valery Shlyannikov Aleksandr Inozemtsev Aleksey Ratchiev <p>The ambient and high-temperature fatigue crack growth behaviors in C(T) and SENT specimens of Ni-based superalloy for turbine disk application were studied in a wide interval of temperatures 25–750°C using a combination a electro- and servohydraulic test systems and fractographic investigations. The fatigue, creep-fatigue interaction and thermo-mechanical in-phase fatigue (TMF IP) crack growth tests are performed under isothermal and dynamic waveforms loading conditions. The interpretation of the experimental results is given in terms of the traditional stress intensity factors and C-integral as well as new normalized cyclic fracture diagrams. It is found that there are definite temperature-sensitive regions separate for harmonic fatigue and creep-fatigue interaction loading conditions in which the crack growth rate of Ni-based alloy increases sharply. Scanning electron microscopy in longitudinal sections containing cracks revealed the mechanisms responsible for fatigue crack initiation and growth. The couple effect of temperature ranging and isothermal and dynamic waveforms loading conditions on fatigue life was discussed.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Valery Shlyannikov, Aleksandr Inozemtsev, Aleksey Ratchiev Numerical Analysis of the Crack Growth Path in the Cement of Hip Spacers 2022-05-10T03:43:17+00:00 Sahnoun Zengah Abdeljelil Mankour Sahli Abderahmane Hichem Salah Abdelhafid Mallek Mohammed Mokhtar Bouziane <p>The use of temporary hip prosthesis made of orthopedic cement (spacer) in conjunction with antibiotics became a prevalent method used for prosthetic infections remedy; consequently, this method makes bone cement (PMMA) more fragile. Hence, the necessity of reinforcement incorporation is crucial to strengthen the bone cement. In this study, the finite element (FE) method was used to analyze the spacers behavior. FE model using an implicit integration method was used to simulate the mechanical behavior of the spacer under static loading. In addition, the extended finite element method (XFEM) was also used to investigate the fracture behavior of the non-reinforced and reinforced spacers. The results of this numerical analysis showed that the simulated crack initiation and propagation were in a good accordance with in vivo radiography and in vitro experimental observations. The full-stem reinforcement of 8 mm using reduce significantly the stress intensity factor and, consequently prevent the spacer fracture effectively. The FE models developed in this study contribute to help mechanical designers and engineers for prostheses’ quality and durability improvement.</p> <p>Abstract must be 200 words maximum, without figures or refs.</p> <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</p> <p>&nbsp;</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Sahnoun Zengah, Abdeljelil Mankour, Sahli Abderahmane, Hichem Salah, Abdelhafid Mallek, Mohammed Mokhtar Bouziane A simplified constitutive model for a SEBS gel muscle simulant - Development and experimental validation for finite elements simulations of handgun and rifle ballistic impacts 2022-04-28T03:39:40+00:00 Riccardo Andreotti Valentina Leggewri Andrea Casaroli Mauro Quercia Cristian Bettin Mauro Zanella Marco V. Boniardi <p>An original simplified constitutive model is proposed to simulate the effects of ballistic impacts on blocks of synthetic muscle simulant based on mineral oil and styrene ethylene-butylene styrene polymers (<em>SEBS</em>) as a convenient substitute for Fackler ballistic gelatin. The model is based on a quasi-static elastic-plastic model associated with hydrodynamic properties regulated by a polynomial equation of state. The paper illustrates the development and experimental validation of the model to simulate 9x21mm FMJ round-nose, 7.62x39 mm FMJ, and 5.56x45 mm NATO bullets penetrating 145x145x400 mm gel blocks. All material parameters are provided to be implemented in built-in LS-Dyna keywords. The validation confirms the effectiveness of the model and suggests possible further developments. The work also confirms the tested synthetic gel as a valid and convenient substitute for Fackler 10% ballistic gelatin at 4 °C.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Riccardo Andreotti, Valentina Leggewri, Andrea Casaroli, Mauro Quercia, Cristian Bettin, Mauro Zanella, Marco V. Boniardi The influence of sustainable reinforcing particulates on the density, hardness and corrosion resistance of AA 6063 matrix composites 2022-06-08T14:37:27+00:00 Ndudim Ononiwu Chigbogu Ozoegwu Jacobs Ifeanyi Victor Nwachukwu Esther Akinlabi <p>The need for the fabrication of sustainable aluminium matrix composites (AMCs) is being sought after as practical alternatives to conventional metals and their alloys. This study was undertaken to investigate the effect of sustainable materials on the mechanical, physical and corrosion resistant properties of AA 6063. The weight fraction of the hybrid reinforcements was varied at 2.5, 5.0, 7.5 and 10.0 wt.%. For each variation, the fly ash and eggshells were weighed equally. The fabrication route selected was stir casting. The analysis of the density showed that the property decreased with increasing weight fraction of the hybrid reinforcements. Evaluation of the microhardness revealed hardness values of 78.13, 81.19, 81.54, 82.14, and 86.71 HV for the base metal, 2.5, 5.0, 7.5 and 10.0 wt.% samples respectively. The corrosion resistant properties were studied in 3.5 wt.% NaCl medium. The investigation showed that the reinforced AMCs exhibited improved corrosion resistance compared to the base metal. However, the 7.5 wt.% sample exhibited the least corrosion rate of 8.649 X 10<sup>-5</sup> g/h.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Ndudim Ononiwu, Chigbogu Ozoegwu, Jacobs Ifeanyi, Victor Nwachukwu, Esther Akinlabi Evaluation of Tensile properties of FRP Composite Laminates under Varying Strain Rates and Temperatures 2022-05-26T14:37:20+00:00 Prahlad Joshi Shrikant Panigrahi <p>The present investigation deals with the characterization of tensile behavior of various Fiber Reinforced Polymer composites under Thermo-Mechanical loading. Five different types of Uni-Directional (UD) composites of Carbon, Glass, Carbon-Glass hybrid and Metal Laminates of Carbon &amp; Glass were tested for tensile behavior. Tensile tests were performed at strain rates of 10<sup>-3</sup>, 10<sup>-2</sup>, &amp; 10<sup>-1 </sup>s<sup>-1</sup> at Room Temperature,250 <sup>0</sup>C and 450 <sup>0</sup>C. Stress-strain relations reveal the strain rate and temperature sensitive behavior of composites. Glass, Glass-Carbon, Glass-metal epoxy composites showed higher peak tensile stress under room temperature with varying strain rates as compared to neat carbon epoxy composites. Also, high strain rate tensile properties such as peak stress and peak strain of Glass-Carbon-Epoxy specimens were 26%, and 60% higher than that of the neat carbon epoxy composite. The failure mechanisms of both the composites were analyzed through scanning electron microscopy. The composites mainly failed due to matrix crack within elastic range under room temperature and failed with significant plastic deformation of matrix and fibers under test temperatures 250 <sup>0</sup>C and 450 <sup>0</sup>C. Finally, this study reveals that the continuous phase of metal layer embedded between Uni-Directional Glass and Carbon fiber, based composite system can be tailored to act as an energy-absorbing material system under both elastic and plastic stress strain regimes.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Prahlad Joshi, Sk Panigrahi A Simple and Efficient eight node Finite Element for Multilayer Sandwich Composite Plates Bending Behavior Analysis 2022-05-30T11:48:16+00:00 Khmissi Belkaid Nadir Boutasseta Hamza Aouaichia Djamel Eddine Gaagaia Adel Deliou Badreddine Boubir <p>In this paper, a C0 simple and efficient isoparametric eight-node displacement-model based on higher order shear deformation theory is proposed for the bending behavior study of multilayer composites sandwich plates. Difficult C1-continuity requirement is overcome by extracting the seven degrees of freedom from strain relations for each element node: two displacements for in-plane behavior and five bending unknowns namely: a transverse displacement, two rotations and two shear angles, which results in a kinematic approximation formulation having only first order derivative requirement. The governing equations of the element (constitutive, virtual work and equilibrium equations) are implemented for the prediction of approximate solutions of deflections and stresses of sandwich plates linear elastic problems. Thereby, the formulation element is able to present a cubic in-plane displacement along both core and faces sandwich thickness, as well as, the shear stresses are found to vary as quadratic field without requiring shear correction factors and independent from any transverse shear locking problems. The accuracy and validity of the proposed formulation is verified through the numerical evaluation of displacements and stresses and their comparison with the available analytical 3D elasticity solutions and other published finite element results.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Khmissi Belkaid, Nadir Boutasseta, Hamza Aouaichia, Djamel Eddine Gaagaia, Adel Deliou, Badreddine Boubir A Study on microstructure, mechanical and fracture behavior of Al2O3 - MoS2 reinforced Al6061 hybrid composite 2022-04-03T17:29:14+00:00 K. R. Suchendra Reddy M Sreenivasa M. Ravikumar <p>Al composites usage is growing and is gaining importance in aerospace, automotive and marine industries due to their excellent characteristics. Aluminum composites exhibit high resistance to wear and corrosion, possess high strength, offer durability and more such properties. In this study, Al 6061 alloy, reinforced with Al<sub>2</sub>O<sub>3</sub> - MoS<sub>2</sub> was produced by a stir casting technique and its microstructure and mechanical behavior were evaluated. Reinforcements were added in the range of 0 - 9 wt. %. The microstructure analysis, tensile and compressive strength of the hybrid MMCs (Metal Matrix Composites) have been analyzed and examined. From the investigational study, it was found that the reinforcing particulates are evenly dispersed in the base matrix. The porosity and density of the hybrid composites were found to be enhanced. The ultimate tensile and compressive strength of the hybrid MMCs could be improved by addition of ceramic (Al<sub>2</sub>O<sub>3</sub>) particulates compared to monolithic. Further, the strength of hybrid composites was decreased by adding of MoS<sub>2</sub> (solid lubricant) along with hard ceramic particulates. Finally, fractured surface of the UTS test specimens were analysed using a SEM analysis.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 K. R. Suchendra, Reddy M Sreenivasa; M. Ravikumar Identification of the anisotropic behavior of the laser welded Interstitial Free steel HC260Y subjected to uniaxial tensile tests 2022-05-24T15:54:10+00:00 Latifa Arfaoui Amel Samet Amna Znaidi <p>The main purpose of this paper is to study the anisotropic<br>behavior of laser welded interstitial free steel HC 260Y when it is subjected<br>to monotonic tensile tests. The specimens were cut in different orientations<br>according to the rolling direction, annealed and finally assembled by laser<br>welding. The plastic behavior was modelled using an identification strategy<br>based on a behavior law taking into account the anisotropy of this material, a<br>hardening law describing the evolution of the hardening curves and an<br>evolution law. The proposed identification strategy allowed for a good<br>validation of the model. The model was afterwards used to predict the<br>behavior of the welded material when it is subjected to various solicitations.<br>Finally, the fracture surfaces of the specimens were examined using the<br>scanning electron microscope (SEM) to determine the failure characteristics<br>under the tensile loading.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Latifa Arfaoui, Amel Samet, Amna Znaidi Fatigue growth rate of inclined surface cracks in aluminum and titanium alloys 2022-03-17T09:32:57+00:00 Rustam Yarullin Mikhail Yakovlev <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> 2022-03-25T00:00:00+00:00 Copyright (c) 2022 Rustam Yarullin, Mikhail Yakovlev Composite lay-up configuration effect on double and single sided bonded patch repairs 2022-05-29T09:39:48+00:00 Toufik Achour Fayçal Mili <p>Understanding the failure modes of damaged or cracked structures and repaired by bonding a composite patch is an essential point to improve its resistance to failure and subsequently extend its service life. In the present study, a 3D finite element analysis using ANSYS software was performed to elucidate the failure modes of the repaired structures by double and single sided bonded composite. The plate is represented by an aluminum plate (Al2024 T3), cracked at the edge and repaired by three types of laminates, with different fiber orientation in order to determine its effect on the repair. The contact interfaces patch-adhesive and aluminum-adhesive were modeled by cohesive zone modeling (CZM) using bilinear interface of delamination (BID) method to determine the failure at the adhesive layer. The obtained results show the importance of the impact of the composite patch fiber orientation on the structure design for suitable repair.<em>&nbsp;&nbsp; </em></p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Toufik Achour, Fayçal Mili Study of Structural Stability of a Concrete Gravity Dam Using a Reliability Approach 2022-04-18T09:25:43+00:00 Mohamed Essaddik Kerkar Mustapha Kamel Mihoubi <p>The safety of dams is a priority at the international level, based on a large amount of data from a dam-reservoir allows analysts to make optimization on its structural stability, the latter is based on the estimation of the probability of failure from the effects of stress and resistance acting on the dam-reservoir system. This investigation is to establish a methodology in order to optimize the safety of a concrete gravity dam in operation by carrying out a risk analysis which includes the identification of the sources of danger in terms of scenarios that can occur due to a failure on the dam-reservoir system on an implication of natural hazards (floods, earthquakes) and technical accidents such as malfunction of a spillway gate, drain valve, drainage system or important silting. Reliability methods provide a basis for the probabilistic assessment of the structural safety of a dam. They make it possible to take into account in a probabilistic context, the uncertainties in the data associated with the calculation parameters used in the justifications of structural stability and make it possible to assess as closely as possible the intrinsic safety of a concrete gravity dam.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Mohamed Essaddik Kerkar, Mustapha Kamel Mihoubi Impact behaviour of dissimilar AA2024-T351/7075-T651 FSWed butt-joints: effects of Al2O3-SiC particles addition 2022-03-21T18:11:11+00:00 Cindy Morales Mattia Merlin Annalisa Fortini Gian Luca Garagnani Argelia Miranda <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> 2022-03-25T00:00:00+00:00 Copyright (c) 2022 Cindy Morales, Mattia Merlin, Annalisa Fortini, Gian Luca Garagnani, Argelia Miranda An experimental study and a proposed theoretical solution for the prediction of the ductile/brittle failure modes of reinforced concrete beams strengthened with external steel plates 2022-03-07T05:51:37+00:00 Long Nguyen-ngoc Hau Nguyen Van Thanh Bui Tien Phe Pham Van <p>An experimental study and a proposed theoretical solution are conducted in the present study to investigate the ductile/brittle failure mode of reinforced concrete beams strengthened with an external steel plate. The present experimental study has fabricated and tested six steel plate-strengthened RC beams and one non-strengthened RC beam under 4-point bending loads. The proposed theoretical model is then developed based on the observed experimental results to analyze the crack formation, to determine the distance between vertical cracks and to quantitatively predict the ductile/brittle failure mode of plate-strengthened RC beams. The experimental study shows that the failure mode is based on the sliding of concrete along with the external plate. This slip is limited between two vertical cracks, from which the maximum stress in the external steel is determined. Based on comparisons conducted in the present study, excellent agreements of the stresses/strains in soffit steel plates, crack distances, and system failure modes between the current theoretical solution and the previous and present experimental results are observed.&nbsp;</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Long Nguyen-ngoc, Hau Nguyen Van, Thanh Bui Tien, Phe Pham Van Al2O3 and TiO2 flux enabling activated tungsten inert gas welding of 304 austenitic stainless steel plates 2022-02-27T16:54:35+00:00 Hiralal S. Patil D. C. Patel <p>Gas tungsten arc welding (GTAW) is important in those manufacturing where it is significant to control the mechanical and metallurgical characteristics and its weld bead geometry. This work has been committed to study the influence of oxide fluxes on welding of 4 mm thick 304 austenitic stainless steel plates. The Al<sub>2</sub>O<sub>3</sub> and TiO<sub>2</sub> were used as an oxide flux in powder form and are mixed with the acetone. The prepared mixture is applied on bead plate without any joint preparation and without filler wire addition. The Taguchi method with L<sub>9</sub> orthogonal array is used to determine the optimal parameters. The current work aims to explore the influence of weld parameters on weld bead geometry (i.e. weld bead width, penetration and angular distortion), and mechanical &amp; metallurgical characteristics for 304 stainless steel welds. The oxide flux seems to narrow the arc and thereby the current density increases at the anode spot, that results in high weld depth.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Hiralal S. Patil, D. C. Patel Predictive Modelling of Creep Crack Initiation and Growth using Extended Finite Element Method (XFEM) 2022-03-21T15:54:33+00:00 Meor Iqram Meor Ahmad Mohd Anas Mohd Sabri Mohd Faizal Mat Tahir Nur Azam Abdullah <p>In this study, a numerical strategy for predictive modelling of creep in tension tests for the rectangular plate with a single crack and CT-specimen based on the extended finite element method (XFEM) will be described in detail. A model of creep fracture initiation and creep crack growth (CCG) is developed, while the XFEM is employed to spots located inside the finite element for the purpose of predicting crack potential and propagation. In order to characterize the creep fracture initiation, identification of C(t)-integral formula is conducted. In addition, XFEM and analytical solutions are also analyzed to look at the connection of C(t)-integral with time for a rectangular plate with a single crack under plane stress conditions. An illustration showing the se-quence of stress distribution and displacement contour plots are also being presented. The stresses and displacements spread throughout the crack path have also been determined using CT-specimens. In addition, the creep cracks growth length with normalized time and the creep crack growth rate with the C(t)-integral are predicted to be related, indicating that the numerical results are in good accord with the experimental results.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Meor Iqram Meor Ahmad, Mohd Anas Mohd Sabri, Mohd Faizal Mat Tahir, Nur Azam Abdullah Detection of Uniaxial Fatigue Stress under Magnetic Flux Leakage Signals using Morlet Wavelet 2022-03-30T00:01:33+00:00 Syed Muhamad Firdaus Azli Arifin Shahrum Abdullah Salvinder Singh Karam Singh Noorsuhada Md Nor <p>This paper demonstrates the application of continuous wavelet transform technique for magnetic flux leakage signal generated during a uniaxial fatigue test. This is a consideration as the magnetic signal is weak and susceptible to being influenced by an external magnetic field. The magnetic flux leakage signal response of API steel grade X65 is determined using Metal Magnetic Memory under cyclic load conditions ranging from 50% to 85% of the UTS. To facilitate further signal analysis, the magnetic flux gradient, the dH(y)/dx signal were converted from a length base into time series in this study. Magnetic flux leakage readings indicated a maximum UTS load of 56.5 (A/m)/mm at 85%, where a higher load resulted in a higher reading and the signal contained Morlet wavelet coefficient energy of 1.02×106 µe<sup>2</sup>/Hz. As increasing percentages of UTS loads were applied, the signal analysis revealed an increasing linear trend in the dH(y)/dx and wavelet coefficient energy. The analysis revealed a strong correlation between the wavelet coefficient energy and the dH(y)/dx amplitude, as indicated by the coefficient of determination (R<sup>2</sup>) value of 0.8572. Hence, this technique can provide critical information about magnetic flux leakage signals that can be used to detect high stress concentration zones.</p> 2022-06-19T00:00:00+00:00 Copyright (c) 2022 Syed Muhamad Firdaus, Azli Arifin, Shahrum Abdullah, Salvinder Singh Karam Singh, Noorsuhada Md Nor