Finite Element Analysis (Engineering)

Corrosion in concrete prevents in-situ observation, necessitating models to provide insight into the local reaction currents. We present a computational method for predicting corrosion rates of reinforcements within concrete under natural conditions, i.e. requiring the corrosion current to be supported by equal cathodic currents. In contrast to typical corrosion models, where these two counteracting currents are required to be co-located, we allow these currents to be separated such that pitting corrosion can be supported by cathodic reactions over a much larger area. Pitting corrosion is investigated, elucidating the effects of the concrete porosity and water saturation, the presence of dissolved oxygen, and chlorine concentration within the pore solution. The presented model is capable of capturing the dynamic growth of acidic regions around corrosion pits, showing the limited region over which the hydrogen evolution reaction occurs and how this region evolves over time. The ability of oxygen to diffuse towards the metal surface due to increased porosity is seen to have a major effect on the corrosion rate, whereas changes in the chlorine concentration (and thus changes in the conductivity of the pore solution) play a secondary role. Furthermore, external oxygen is seen to enhance corrosion but is not required to initialise and sustain acidic corrosion pits.

The aerodynamic performance of an aircraft can be enhanced by incorporating wingtip devices, or winglets, which primarily reduce lift-induced drag created by wingtip vortices. This study outlines an optimization procedure for implementing winglets on a Class I fixed-wing mini-UAV to maximize aerodynamic efficiency and performance. After the Conceptual and Preliminary design phases, a baseline UAV was developed without winglets, adhering to specific layout constraints (e.g., wingspan, length). Various winglet designs-plate and blended types with differing heights, cant angles, and sweep angles-were then created and assessed. A Computational Fluid Dynamics (CFD) analysis was conducted to evaluate the flow around both the winglet-free UAV and configurations with each winglet design. The simulations employed Reynolds-Averaged Navier-Stokes (RANS) equations coupled with the Spalart-Allmaras turbulence model, targeting the optimal winglet configuration for enhanced aerodynamic characteristics during cruise. Charts of lift, drag, pitching moment coefficients, and lift-to-drag ratios are presented, alongside flow contours illustrating vortex characteristics for both baseline and optimized configurations. Additionally, dynamic stability analyses examined how winglets impact the UAV's stability and control. The results demonstrated a significant improvement in aerodynamic coefficients (C Lmax , L/D max , C La , C ma), leading to an increase in both range and endurance.

BackgroundThe aim of this study was to compare the crown preparation dimensions produced from two different techniques of preparation for posterior all‐ceramic crowns.MethodsTwenty‐four fourth year dental students undertook a course of advanced simulation training involving education in an alternative technique of preparation for a 36 all‐ceramic crown. Crown preparations performed using the traditional technique were compared with an alternative technique for total occlusal convergence (TOC) and reduction difference (RD) using digital scanning and comparative software.ResultsGroups that spent the most time performing the alternative technique produced crown preparations with significantly lower buccolingual (BL) TOC. The training resulted in crown preparations that were closer to ideal TOC and RD measurements.ConclusionsThe alternative technique of crown preparation for a posterior all‐ceramic crown showed initial promise in creating a less buccolingually tapered and more ideally o...

The Small Punch technique is a miniature test used mostly for irradiated materials or when the test material is scarcel y available. The main aim of small specimen mechanics is to figure out the mechanical behavior with a great reduction or small volume of material. This document emphasizes the development of correlations between mechanical characteristics determined from small punch tests and uniaxial tensile tests. Recommended techniques for specimen design, specimen preparation, experimental design, experimental implementation, and data analysis are used according to ASTM SPT 888. The test involves bending the disk symmetrically about the center, producing a simple, axisymmetric stress state. First, the right conditions were simulated via Finite Element Analysis and then stress and deformation analysis were done for all the specimens, and the results were obtained. These equations are applied to all the copper alloys at a temperature of 295 K. The equations can be used to determine the uniaxial tensile stress-strain behavior of copper and its alloys.

Reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) can improve the sustainability of asphalt concrete (AC) due to cost savings and environmental factors, but it is necessary to ensure that pavement performance is not compromised. To study the effects of aging and increasing asphalt binder replacement levels, chemical characterization and rheological properties of binders from various sources were investigated. Binders from five ACs designed with varying ABR percentages (0% to 60%) were recovered using the standard Rotovap test procedure. The base binder used in the AC design and binders recovered from RAP and RAS were also tested. In addition to standard aging protocols, base binders were subjected to a second pressure aging vessel (PAV), whereas one PAV was applied for the extracted binders. Rheological parameters for low-temperature cracking susceptibility and block and fatigue cracking derived from dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests appeared to have consistent trends with aging and increasing ABR levels. These parameters are helpful in evaluating progression in brittleness of binders with ABR and aging. It was concluded that AC with ABR levels above 20% could suffer from short-and long-term cracking potential. Aging happens as a result of oxidation, which can be seen by an increase in carbonyl and sulfoxide components and larger molecular size components such as resins and asphaltenes. The difference in chemical composition of binders aged via rolling thin-film oven (RTFO) and PAV is small, but this gap increases on double PAV. It was also observed that the double-PAV binders have a chemical composition similar to those with a higher content of reclaimed binders. Asphalt concrete with high ABR content can be at an already critically aged condition immediately after production; moreover, aging progresses much faster in the binders of such mixes.

Geometric inspection of non-rigid (flexible) parts in free-state can aid manufacturers to automatically and inexpensively improve quality by detecting defects on manufactured parts. Non-contact optic data acquisition devices (scanners) are used to measure point clouds on the boundary of manufactured part in free-state and compare it with its nominal computer aided design (CAD) model in a common coordinate system. In the case of non-rigid parts, deformation during free-state inspection, mostly due to weight and to residual stresses, causes specific problems since this deformation has to be distinguished from defects. In this study the generalized numerical inspection fixture (GNIF) method is applied to generate a prior set of corresponding sample points between CAD and scanned models. These points are then used to deform the CAD model to conform to scanned data, through finite element non-rigid registration. Corresponding sample points generated using GNIF are evenly distributed over both models. Therefore, some sample points may be located on defects, which makes that these defects cannot be measured accurately. In this paper we introduce a method, aimed at automatically removing these sample points, which is based on von Mises stress and curvature criteria. Once removed, these points are no longer used in non-rigid FEA registration, which makes that associated defects can be identified and measured accurately.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

SOMMARIO In questo lavoro viene presentato un esempio di progettazione damage tolerant di una fusoliera di elicottero. In particolare, l'attenzione è posta sulla parte finale della fusoliera compresa tra la cabina e il rotore di coda. Data la complessità della struttura in esame, la ...

The paper analyses the thermomechanical coupling between a cantilever aluminium beam and an embedded SMA ribbon. The SMA is selected to be Nickel-Titanium (NiTi) because of the high strength and large strains associated with this material. The actuation of the beam is achieved by applying a current across the SMA ribbon in order to heat the beam above the transition temperature. We show that the actuated beam exhibit the essential functions of an active system, i. e. the deflected beam may return to the initial configuration.

Bu çalışmada, genel yapı çeliği (Ç1020) ve paslanmaz çelik (AISI 316) malzemelerin yüzeyine sıcak daldırma yöntemiyle alüminyum (Al) kaplama uygulanmıştır. Yüzeyde oluşan Al kaplamanın mikroyapısı incelenerek, yüksek sıcaklık oksitlenmesine karşı gösterdiği direnç incelenmiştir. Numuneler 750 °C'deki sıvı Al içinde 10 dakika süreyle bekletilerek yüzeyleri Al ile kaplanmıştır. Daha sonra bu numunelere 800 °C sıcaklıkta 1 ve 6 saat süre ile nötr ortamda difüzyon tavlaması uygulanmıştır. Elementlerin difüzyonu, difüzyon tabakası kalınlığı ve oksitlenmeye karşı gösterdiği direnç incelenmiştir. Al kaplama yapılan ve yapılmayan numuneler 900 °C sıcaklıkta ve farklı sürelerde yüksek sıcaklık oksidasyonuna maruz bırakılarak yüzeyde oluşan ağırlık değişimleri ölçülmüştür. Al kaplanmış çelik numunelerde önemli miktarda ağırlık değişimi olmaması, Al kaplamanın çeliği oksitlenmeden koruduğunu göstermiştir. Malzemelerin bileşimindeki Fe, C, Al, Ni ve Cr elementlerinin Al kaplama ve difüzyon tabakasındaki değişimleri mikroprob analizi ile incelenmiştir. In this study, the surface of SAE 1020 and AISI 316 were applied to aluminium (Al) coating by hot deep method. The oxidation resistance and microstructures were investigated of Al coating applied to the surface of different steels. Sample surfaces were coated with Al at the temperature of 750 °C in 10 minutes durations. Experimental samples were subjected to at the 800 °C temperature and diffusion tempering with 1 and 6 hours durations. The changes in the thickness of diffusion layer and microstructure of the surface, as a result of the processes applied, were examined. Weight variations in the samples oxidized in atmospheric conditions under the temperature of 900 °C with varying durations have also been measured. It was found that steel material which changes of little weight of the samples coated with Al resisted more than without coated Al for oxidation. It was indicated that coated with Al surface of steel protected from oxidation The changes of elements Fe, C, Al, Ni and Cr were investigated by microprobe analyses in surface region.

Bu calismada, genel yapi celigi (C1020) ve paslanmaz celik (AISI 316) malzemelerin yuzeyine sicak daldirma yontemiyle aluminyum (Al) kaplama uygulanmistir. Yuzeyde olusan Al kaplamanin mikroyapisi incelenerek, yuksek sicaklik oksitlenmesine karsi gosterdigi direnc incelenmistir. Numuneler 750 °C’deki sivi Al icinde 10 dakika sureyle bekletilerek yuzeyleri Al ile kaplanmistir. Daha sonra bu numunelere 800 °C sicaklikta 1 ve 6 saat sure ile notr ortamda difuzyon tavlamasi uygulanmistir. Elementlerin difuzyonu, difuzyon tabakasi kalinligi ve oksitlenmeye karsi gosterdigi direnc incelenmistir. Al kaplama yapilan ve yapilmayan numuneler 900 °C sicaklikta ve farkli surelerde yuksek sicaklik oksidasyonuna maruz birakilarak yuzeyde olusan agirlik degisimleri olculmustur. Al kaplanmis celik numunelerde onemli miktarda agirlik degisimi olmamasi, Al kaplamanin celigi oksitlenmeden korudugunu gostermistir. Malzemelerin bilesimindeki Fe, C, Al, Ni ve Cr elementlerinin Al kaplama ve difuzyon taba...

This study investigates the critical impact of heat treatment flaws on the structural integrity and safety of compressed natural gas (CNG) pressure vessels made from Al 6061 and AISI 4130 steel through finite element analysis (FEA) in SolidWorks 2023 and factorial design optimization via Design Expert 13. Simulations were conducted under pressures of 20, 25, and 30 N/mm² with varying flaw severities (none, minor, major), revealing that AISI 4130 steel at 25 N/mm² exhibited a maximum stress of 2.998E+10 N/m², deformation of 15.14 mm, and a safety factor of 0.01534, while Al 6061 at 20 N/mm² showed 1.412E+4 N/mm² stress, 14.70 mm deformation, and a safety factor of 0.01948. At 30 N/mm², AISI 4130 steel demonstrated increased risk with stress reaching 1.814E+4 N/mm², deformation of 18.30 mm, and a safety factor of 0.01516, accompanied by a strain of 1.511E-01. ANOVA results indicated that pressure significantly influenced deformation (p = 0.0382) and safety factor (p = 0.0051), while heat treatment flaws impacted stress (p = 0.0381). Fatigue life varied from 8.00E+05 cycles (AISI 4130 steel, 30 N/mm², minor flaws) to 3.1E+06 cycles (Al 6061, 25 N/mm², no flaws), with all factors showing high significance (p < 0.0001). The optimal configuration-Al 6061, no flaws, and 30 N/mm²-yielded a stress of 3.41E+10 Pa, fatigue life of 2.5E+06 cycles, deformation of 32.366 mm, and a desirability score of 1.000. These findings underscore the importance of minimizing heat treatment flaws and controlling operational pressures below 30 N/mm² to enhance vessel safety and durability, offering valuable insights for design optimization and regulatory standards in sustainable energy applications.

This investigation studied load/deflection (LDR) of four simple orthodontic closing loops: U loop, helical loop, U loop with reversed arms and helical loop with reversed arms by Universal Testing Machine (UTM). The 30 loops per each design were hand formed of 0.019x0.025 inch SS wire and tested on the UTM-LR 30 K-Lloyd instrument. The results revealed that the load/deflection rate (LDR), from the lowest to the highest, for the helical loop with reversed arms, the helical loop, the U loops and then the U loop with reversed arms were 2.72 ± 0.56, 3.11 ± 0.45, 4.00 ± 0.43 and 5.07 ± 0.75 N/mm, in that order. From ANOVA and Post Hoc Tests, the means of LDR of the four studied loops were significantly different when compared to each other (p < 0.001). The maximum deflection limit was reported by UTM suggested that the extension distance of the four closing loop designs do not exceed 2 mm.

Industrial Safety Helmets, commonly known as hard hats, play a vital role in safeguarding workers from head injuries in various industrial settings. These helmets are designed to provide protection against falling objects, impact from protruding objects, electric shock and other occupational hazards. This project explores the key features, standards and benefits associated with industrial safety helmets. This project made an attempt to investigate the strength and rigidity of safety helmets fabricated using Banana Fiber, Coir Fiber and Polyester Resin. Composite Materials are widely used because of their high strength to wear ratio, high performance at elevated temperature. Natural Fibers have the following advantages: high density, low cost, biodegradability, acceptable particular characteristics, and less wear during extraction and composite production. A Polymer Matrix Composite (PMC) is made with Banana Fiber and Coir Fiber loaded with Polyester resins. Three proportions of safety hare fabricated and various tests are conducted on the product namely Shock Absorption Test, Penetration Resistance test, Flammability Resistance Test, Electrical Resistance test and Water Absorption Test. As per IS: 2925-1984 the results are satisfied.

Vibration analysis is an essential aspect of engineering design and diagnostics, critical for ensuring the safety, durability, and performance of mechanical and structural systems. This paper presents a comprehensive guide to the application of Finite Element Analysis (FEA) in vibration studies, covering three primary techniques: modal analysis, harmonic response analysis, and power spectral density (PSD) analysis. Each method is explored in depth, with practical examples demonstrating their roles in identifying resonance conditions, predicting structural responses under periodic and random excitations, and guiding design optimizations to mitigate vibrational risks. Case studies on pump assemblies, water gliders, and space structures (FPSS) showcase real-world applications, providing insight into how FEA enhances engineering reliability and operational efficiency. The study underscores the importance of simulation-based vibration analysis in modern engineering workflows and advocates for its integration into iterative design processes to preempt failures and extend service life across industries.

This paper gives the results of the probabilistic s eismic analysis of the site Mochovce including deagregation effects. On the base of the geophysical and seismological monitoring of locality the peak ground acceleration and the uniform hazard spectrum of the acceleration was defined for the return period 10 000 years using the Monte Carlo simulations. The algorithms to generate a synthetic ground motion accelerogram compatible with a response spectrum taking soil damping into account was presented.

Self-centering steel moment resisting frames (SC-MRFs) for seismic resistant buildings have been developed in the past decade as an alternative to conventional welded steel moment-resisting frames (WMRFs). While conventional WMRFs are expected to sustain cyclic inelastic deformations in critical regions of the beams during a moderate or severe earthquake, SC-MRF systems are designed to exhibit similar stiffness and strength as WMRFs and provide stable energy dissipation, while sustaining only minor damage to structural elements and essentially no residual drift under the design basis earthquake. In this paper, the concepts and mechanics of an SC-MRF are presented, followed by an overview of the experimental and numerical research that has been conducted to develop and validate SC-MRFs. The main issues that are central to the seismic design and performance of these SC-MRFs are discussed. Finally, critical aspects related to the practical implementation of SC-MRFs are outlined and a discussion of the steps that are still needed for practical implementation is presented.

Transformer saturation is an area of major concern as the transformers are designed to run near peak magnetizing flux value and if voltage/frequency (V/f) ratio increases, it may cause the transformer to reach into saturation, which can affect normal operation of the transformer and even cause mal-operation of the protective equipments. This paper explains different techniques of transformer saturation detection and current waveform improvement.

Purpose: of this paper is based on the damage analysis by fretting wearing occurred on the composite steel sheets reinforced with TiB2 ceramic particles. There is a real lack to find a reliable data and detail research in literature that makes the purpose of this manuscript. Design/methodology/approach: Fretting is a surface degradation process in which removal of material is induced by small amplitude oscillatory movement between contacting components, such as flexible coupling joint structures etc. The main parameters affecting fretting wear are reported to be normal load, slip amplitude, frequency of the oscillatory movement, contact geometry, surface roughness and material properties. In this study, a finite element-based method is presented for simulating the contact of a rigid cylinder on flat fretting wear for the composite steel sheets reinforced with TiB2 ceramic particles. Findings: The general purpose commercial code ABAQUS was employed; this model can be used to facilita...

Shear deformation of subsurface layers in wire drawing leads to marked non-uniformity of strain across the wire cross section. In wires intended for products operating under dynamic loads, such as ropes and springs, the variance in work hardening level across the cross section may cause fatigue fractures. <In this paper we used mathematical modelling in an attempt to show how the non-uniformity of strain in drawing can be reduced by changing key process parameters. For this purpose, a full factorial experiment involving three factors was undertaken. (The factors included the approach angle 2α, friction coefficient µ and single pass strain Q d or the number of passes n.) The simulation involved drawing of 2.5 mm C75 steel spring wire from 5.5 mm thick rolled rod. FormFEM 1.6 simulation software was used for the modelling. For the purpose of this experiment, the strain non-uniformity is defined as the difference between the maximum (normally on or just below the surface) and minimum (in the centre of the wire) levels of strain intensity. In addition to this key parameter, the impact of other factors (and their combinations) on the total drawing power will be evaluated as well. Mathematical analysis revealed that the strain distribution across the wire cross section strongly depends on the single-pass strain (the lower this reduction, the greater the difference between the maximum and minimum levels) and on the reduction zone angle (the greater the angle the less uniform the strain intensity). Then, the impact of friction is only significant in regard to the overall drawing power.

Spring-back is a very common and critical phenomenon in sheet metal forming operations, which is caused by the elastic redistribution of the internal stresses after the removal of deforming forces. Spring-back compensation is absolutely essential for the accurate geometry of sheet metal components. This paper reviews the various parameters affecting spring back such as punch angle, grain direction of sheet metal material, die opening, ratio of die radius to sheet thickness, sheet thickness, punch radius, punch height, coining force, pre stressed condition of strip etc.

This study brings new insights into the advantages of using more sophisticated design methods for steel portal frames (e.g. geometrically and materially nonlinear analysis with imperfections or GMNIA, and the general method introduced in Eurocode 3), compared to the commonly used member checks with interaction formulae. The differences between the design alternatives are discussed, focusing on assessing lateral-torsional stability, and the potential benefits of using advanced shell model instead of widely used beam elements. In addition to the advanced design methods, the topic of shape optimization of frames was explored using realcoded genetic algorithm (GA). The developed optimisation tools highlight the possibility of using GA in everyday design in the future. The results of the study clearly point to the advantages of using advanced modelling, e.g. GMNIA, instead of the classical member checks. While both methods are accepted by the current steel design code EN 1993, using GMNIA can result in important savings, because it eliminates some of the conservativeness brought in by the unavoidable simplifications of the other methods. The experience shows that using complex 3D models is possible with current computational capabilities.

Environmental design replaces structure as the principal problem of architectural science" [Cowan, 1966]. In response, more than 20 years later, Manning writes: "Despite enormous amounts of research that has been undertaken into many aspects of building environment, and the store of knowledge that has accumulated, design of the environment too often appears to be a matter of chance. Users of today's new buildings are just as liable as were users of earlier buildings to be uncomfortable." .

Hole-flanging is a crucial operation in sheet metal forming technology, where the material around a prefabricated hole is deformed by a spherical, conical, or cylindrical punch to create a flanged hole wall. This study aims to determine the limiting hole-flanging coefficient of AA1050-O aluminum alloy sheet using the Cockroft-Latham ductile fracture criterion. Numerical simulations of the hole-flanging process using the Cockroft-Latham ductile fracture criterion were conducted to identify the limiting hole-flanging coefficient of AA1050-O aluminum alloy sheet. The limiting hole-flanging coefficient of the material was found to be 0.61 and was further verified through experiments. Additionally, the effects of the hole-flanging coefficient on the Cockroft-Latham damage value, minimum thickness, and height of the flanged hole wall were evaluated within the formability region of the material when the coefficient exceeded the limiting value. The findings from this study provide valuable insights for designing hole-flanging operations for AA1050-O aluminum alloy sheet.

Les choix technologiques sont naturellement orientés vers l'utilisation des pièces légères dont au moins une des dimensions est beaucoup plus petite que les autres, tels que des profils ou des plaques, mais le comportement des pièces souples présente des défis particuliers pour les ingénieurs lors de la spécification géométrique, la raison est que les pièces souples peuvent prendre à l'état libre une forme substantiellement différente de leur géométrie nominale. Avec le développement de la conception des systèmes mécaniques, les méthodes traditionnelles d'analyse des tolérances, tels que la méthode pire des cas et la simulation de Monte Carlo, ne sont pas applicables à des assemblages flexibles en raison de la déformation possible de la pièce pendant le processus d'assemblage. Cette communication porte sur la présentation du tolérancement des mécanismes déformables à travers l'illustration de la problématique générale afin d'aborder dans un deuxième temps une étude des mécanismes déformables (flexibles) en utilisant la méthode des coefficients d'influence et enfin la modélisation d'un mécanisme de ce type à travers un exemple en vue d'une analyse des tolérances dimensionnelles et géométriques. Mots clefs -tolérancement, analyse des tolérances; mécanismes déformables ; méthode de Monte Carlo ; méthode des coefficients d'influence.

The necessity to rehabilitate a Reinforced Concrete (RC) structure emerges from several reasons such as new safety requirements, change of structure occupancy, incorrect design calculations and/or degradation of materials with time. One of the most commonly used mitigation practices to strengthen and repair RC beams is the application of RC jackets at either one side or three sides of the beams. The use of these jackets to improve the flexural performance of RC beams is investigated in this study. An iterative incremental algorithm that takes into account the influence of slip along the interface between the old and new concrete layers is developed. In addition, the distribution of interfacial strain gradient, slip and shear stresses along the interface are predicted. A very good agreement is shown between the current proposed analytical model and the published experimental data on RC jacketed beams. Based on an extensive parametric study, effective flexural modification factors of these beams are developed and verified.

In this study, statistical values of microhardness were investigated in terms of temperature and duration of aged aluminium 2XXX and 6XXX alloys. AA 2024 and AA 6063 aluminum alloys were solution treated at two different temperatres of 490°C and 520°C. Then all samples were cooled to room temperature. After this process, the samples were aged at three different temperatures (140°C, 180°C, 220°C) for ten different periods of time (2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 h.). The microstructure of the aged samples was examined by optical SEM-EDS and X-Ray analysis. The hardness values of the aged samples were tested by microhardness tests. The samples were examined by Multivariate Analysis of Variance (MANOVA) with a confidence level of %95 to find out whether a statistically significant difference occurs. As a result of this analysis, temperature and duration on the wear behaviours of aged aluminium 2XXX and 6XXX alloys were statistically significant in microhardness values.

Survival of historical buildings after earthquakes is the concern of people from many disciplines. Although, everyone advocates safeguarding of these cultural heritages from seismic hazards, the foreseeable inflicted damage to the Archeological, Architectural and Aesthetical values (AAA values) of these monuments (due to retrofitting process) hinders a required decisive consensus on whether or not an action should be taken to save these treasures. This may be due to the lack of a common ground in weighing the added values of seismic risk reduction on the building (due to strengthening of the structure) and the damage to AAA values attributed to any particular retrofitting techniques. In this study a methodology is proposed in which different possible techniques for rehabilitation of any particular historical building can be weighed and compared based on their risk mitigation added value, their reduction on AAA values and their predictable costs. The proposed methodology offers a rat...

Diffusivity is a strong function of concentration and an important transport property. Diffusion of multiple species is far more frequent than the diffusion of one species. However, there are limited experimental data available on multi-component diffusivity. The objective of this study is to develop an optimal control framework to determine multi-component concentration-dependent diffusivities of two gases in a non-volatile phase such as polymer. In Part 1 of this study, we derived a detailed mass-transfer model of the experimental diffusion process for the non-volatile phase to provide the temporal masses of gases in the polymer. The determination of diffusivities is an inverse problem involving principles of optimal control. Necessary conditions are determined to solve this problem. In Part 2 of this study, we utilized the results of Part 1 to determine the concentration-dependent, multi-component diffusivities of nitrogen and carbon dioxide in polystyrene. To that end, solubilit...

Cross equal channel angular pressing (Cross-ECAP) is a revision of equal channel angular pressing which employs cross shaped die instead of L shaped die. In the present work, 3D finite element method was used to study the deformation behavior of pure aluminum during Cross-ECAP. Plastic strain and strain rate distribution during this processing technique was calculated and compared with conventional ECAP process.

Computer simulation offers the potential for improved understanding of the local and global mechanisms that determine the response of structures to severe loading. The research presented here focuses on development of a finite element model using ABAQUS software to be used in investigating the behaviour of precast concrete exterior beam-column connection and compared with conventional beam column connection. Laboratory investigation of reinforced and precast concrete beam-column connections indicates that component failure may result from inelastic material behaviour of plain concrete and reinforcing steel. Thus, model development includes investigating and characterizing the behaviours of these materials. Concrete damaged plasticity model is used to represent the response of plain concrete. Comparison of computed and observed behaviour of reinforced and precast concrete elements indicates that the model used represents the local response mechanisms that determine global behaviour correctly. The current research helps one to have an improved understanding of finite element modelling of precast reinforced concrete and conventional concrete subassemblies in ABAQUS software. Comparison of load displacement diagram of RCC and precast beam column joint subjected to monotonic loading by using ABAQUS software and nonlinear modeling of connections are represented. It is observe that the precast beam column connection is giving good load displacement behaviour than conventional connection.

This paper portrays the various combinations of nanomaterials and matrix materials analysis was made on the various ways of preparing the nano influenced matrix and compositewhich were used to fabricate the nanocomposite laminates.An in-depthpanels. The analysis ranks the 5 types of processes for suitability of use in manufacturing automotive bumper beam based on 6 main selection factors and 12 subfactors. Determining the right manufacturing process was performed based on AHP concept through utilizing Expert Choice software. Fiber-reinforced polymer matrix composites offer a range of potential advantages over conventional construction matrial. But present challenges in design and manufacturing. This chapter commences with a discussion on application of polymer composites to illustrate where they may be competitive, and then briefly introduces constitutent materials and composite properties, whereas the bulk of the article covers the most common manufacturing techniques and their cha...

Static loadings resistance is always the first design criteria. However, further investigation should also be conducted for a structure like floors, bridges, and stairs which are subjected to dynamic loadings in the form of human activities such as walking, running, or jumping; these loadings often result in vibrational effects associated with the user’s comfort. While most researches were mostly about walking force on flat surfaces, this study will mainly focus on reinforced concrete cantilever staircase which has been reported to encounter a significant level of vibration due to periodic walking motion. Therefore, this paper presents the attempt to study the characteristics and response of RC cantilever stair design once being subjected to human-induced vibration and to propose the application of extra reinforcing steel used to lessen the dynamic effects. Numerical analysis is done on an RC cantilever stairs model having dimensions of 100 centimeters in length, and 25 centimeters ...

Bu çalışmada, 38MnVS6 mikroalaşımlı çelik ve 41CrMo4 çelik malzemelere 900 0 C'de 1 saat tavlama sonrası yağda soğutma işlemi uygulanmıştır. Yağda soğutulan çelik malzemeler 300 0 C, 400 0 C ve 500 0 C sıcaklıklarda 1 saat sürede temperleme işlemine tabi tutulmuş olup, temperleme işleminin mikroyapı ve mekanik özelliklerine etkisi incelenmiştir. Numunelerin mikroyapı incelemeleri yapılmış olup, temperleme öncesi ve sonrası sertlik testi uygulanmıştır. Sonuçlar, çeliklerde temperleme sıcaklığına bağlı olarak martenzitik yapıdan beynitik yapıya dönüşüm gözlemlenirken, sertlik değerlerinin de temperleme sıcaklığına bağlı olarak düştüğünü göstermiştir.

In Vietnam, 102 species with 19 geniuses of bamboo families are recorded. But the most popular is Dendrocalamus membranaceus Munro. It has been selected forestation in the provinces from the North Central to Central area of Vietnam. Fabricated bamboo fibers by mechanical and steam exploded techniques consist of short and long fibers. Different methods of bamboo fiber surface treatment have been carried out and alkaline treatment was the best method. Thermoplastic resin (polypropylene -PP) and thermoset resin (unsaturated polyester -UP and epoxy -EP) were used as matrices of composites. Maleic anhydride grafted polypropylene (MAPP) was chosen as coupling agent to improve adhesion between PP and bamboo fiber. Polymer composite materials were reinforced by only bamboo fiber according to skin-core and ply-by-ply structure. Bamboo-PP resin composites with 50 wt. % of bamboo fiber has higher mechanical properties in comparison with pure PP. Bamboo-UP resin composites possess good mechanical and chemical properties, whereas bamboo-EP resin composites show unsatisfied water and chemical resistance. Skin-core structure hybridization of jute with glass fiber in skin increased impact strength significantly (1.8-2.0 times). This hybrid composite was used for making chair, tables, boats, construction panels, etc Short bamboo fiber-PP composites are going to prepare pall rings using for waste water treatment in the present of micro-organism.

The shear loading applied to structures is resisted by implementation of hysteric dampers as structural seismic force resisting system. Recently, steel plates with engineered cut-outs are introduced to have controlled yielding. These structural elements behave as shear links are able to post pone brittle limit states, leading to resistance against early fracture. Among which, a promising type of link is butterfly-shaped link, for which the demand moment diagram aligns with capacity moment diagram to efficiently implement the steel. Previous studies show that these elements are used as appropriate choice for structural seismic fuse system since they are able to experience large drifts with sufficient ductility and full hysteric behavior. Therefore, the appropriate geometrical properties for these links are in need of further investigations. In this study, the finite element methodology is initially validated with experimental test. Then optimization criteria is introduced for set of ...

This paper is part of a study investigating the structural characteristics of concrete using various combinations of lateritic sand and quarry dust as complete replacement for conventional river sand fine aggregate. Samples of concrete (eg. cubes) were made using varying contents of laterite and quarry dust as fine aggregate. The quantity of laterite was varied from 0% to 100% against quarry dust at intervals of 25%. The samples were cured for specified periods and tested in the laboratory for compressive strength. Workability tests were earlier carried out to determine the optimum water/cement ratios for three different mixes, namely: 1:1:2, 1:1.5:3 and 1:2:4. It was found that 0.5 water/cement ratio produced higher compressive strengths for 1:1:2 mix, while 0.6 water/cement ratio exhibit better workability for 1:1.5:3 mix proportion. Specifically compressive strength ranged from 17-34.2 N/mm 2 for the mixes considered. These results compare favourably with those of conventional concrete. The concrete was found to be suitable for use as structural members for buildings and related structures, where laterite content did not exceed 50%.

To solve problems of hydrogen power engineering, there is an intensive search for materials for hydrogen storage. Thermal desorption spectrometry (TDS) is one of the effective experimental methods for studying the interaction of structural materials with hydrogen isotopes. A sample (we consider a thin plate made of a material with metallic properties) pre-saturated with dissolved atomic hydrogen is heated relatively slow in a vacuum chamber. The degassing flux is registered using a mass spectrometer. The spectrum is the dependence of the desorption flux density from a two-sided surface of the sample on the current temperature. Quite often, several local peaks are registered on the spectrum. Traditionally, this is associated with the reversible capture of various kinds of traps (inhomogeneities of the material) with different binding energies. However, numerical experiments on models with dynamic boundary conditions describing the dynamics of surface concentrations show the possibility of a different scenario. The following scheme is possible: The first peak occurs when hydrogen leaves the surface and the subsurface volume. Then, a large concentration gradient is formed at the surface. For this reason, and during continued heating, diffusion influx from the volume is significantly activated, which leads to the next peak of desorption. Recommendations on how to distinguish degassing scenarios corresponding to these essentially different physicochemical reasons are given. This is fundamentally important for the correct recalculation of modeling results from laboratory samples to real constructions. The hybrid thermal desorption model can be considered as a computational algorithm for solving a partial differential system using an approximation by an ODE system (but this is not a straight-line method).

In recent years, breakthrough in the development of modelling techniques and impact analysis of composite materials subjected to high velocity has been made. The study methodically reviews the modelling techniques for the structural response of composite materials under high velocity. Although, report gives numerical model as widely used method, yet experimental test is always required to validate both analytical and finite element designs. The assessment shows that all modelling methods are suitable for application based on loading conditions of the composite structure. Lastly, the reference list provides databank for future researchers and engineers on composite structure subjected to high velocity impact. GJRE-A Classification: FOR Code: 091399 PerformanceofCompositeStructuresSubjectedtoHighVelocityImpactReview Strictly as per the compliance and regulations of: Global Journal of Researches in Engineering: A Mechanical and Mechanics Engineering Volume 16 Issue 4 Version 1.0 Year 2...

Some numerical models are proposed for simulate the aircraft tyre behaviour on the ground in critical situations. Fully coupled thermo-mechanical analysis procedures taking into account finite deformation, dynamics and frictional contact are studied. The proposed models are compared with experimental data such as contact area, lateral and longitudinal stiffnesses, surface temperature evolution due to friction, self-alignment torque, and lateral friction coefficients. A good agreement is observed at low speed (less than 70 km/h). Thus, the model is extrapolated to high speeds and seems able to predict results in cases for which it is not possible to obtain realistic experimental data.

Some numerical models are proposed for simulate the aircraft tyre behaviour on the ground in critical situations. Fully coupled thermo-mechanical analysis procedures taking into account finite deformation, dynamics and frictional contact are studied. The proposed models are compared with experimental data such as contact area, lateral and longitudinal stiffnesses, surface temperature evolution due to friction, self-alignment torque, and lateral friction coefficients. A good agreement is observed at low speed (less than 70 km/h). Thus, the model is extrapolated to high speeds and seems able to predict results in cases for which it is not possible to obtain realistic experimental data.

This study investigates the impact of various element and concrete material models on the finite element analysis (FEA) of reinforced concrete (RC) structures. A comparative evaluation was conducted using 1D, 2D, and 3D finite element models. The research includes the numerical modeling of an experimentally tested RC beam with different finite element and concrete material models. The modeling process was carried out using DIANA FEA software, and the results were compared with experimental data. Furthermore, a parametric analysis was carried out to evaluate the impact of mesh size. Although mesh size varies depending on the element type and geometric properties, the study provides valuable insights for selecting appropriate mesh refinement in similar analyses. The results indicate that the most accurate element model is the 3D model, while the Eurocode concrete model exhibited the best agreement with experimental results. However, other concrete models also demonstrated reasonable accuracy. It was concluded that selecting the smallest feasible mesh size, within the constraints of computational efficiency and analysis requirements, leads to improved numerical accuracy.

With the emerging technology, it has been made practically possible to create and analyze any product or process virtually, without actually manufacturing or performing it in the real-life replicating scenarios. Simulation is an approximate imitation of the operation of a process or system, as it may behave in the real world. To achieve this, different variables are used to imitate various factors that may influence the system practically. The paper describes the simulation of CANINE: An Autonomous Quadruped Walking Robot in MATLAB Simscape. The gait mechanism of the quadruped robot is simulated in Simscape Multibody.

The effective electric resistivity of conductive thermoplastics manufactured by filament extrusion methods is determined by both the material constituents and the printing parameters. The former determines the multifunctional nature of the composite, whereas the latter dictates the mesostructural characteristics such as filament adhesion and void distribution. This work provides a multi-scale computational framework to evaluate the thermo-electro-mechanical behaviour of printed conductive polymers. A full-field homogenisation model first provides the influence of material and mesostructural features (i.e., filament orientations, voids and adhesion between filaments). Then, a macroscopic continuum model elucidates the effects of thermo-electro-mechanical mixed boundary conditions. The in-silico multi-scale methodology is validated with extensive original multi-physical experiments and a functional application consisting of an electro-heatable printing cartridge. Overall, this work establishes the foundations to virtually break the gap between mesoscopic and macroscopic multifunctional responses in conductive components manufactured by additive manufacturing techniques.

Prediction of hydrogen embrittlement requires a robust modelling approach and this will foster the safe adoption of hydrogen as a clean energy vector. A generalised computational model for hydrogen embrittlement is here presented, based on a phase field description of fracture. In combination with Part I of this work, which describes the process of hydrogen uptake and transport, this allows simulating a wide range of hydrogen transport and embrittlement phenomena. The material toughness is defined as a function of the hydrogen content and both elastic and elastic-plastic material behaviour are incorporated, enabling to capture both ductile and brittle fractures, and the transition from one to the other. The accumulation of hydrogen near a crack tip and subsequent embrittlement is numerically evaluated in a single-edge cracked plate, a boundary layer model and a 3D vessel case study, demonstrating the potential of the framework. Emphasis is placed on the numerical implementation, which is carried out in the finite element package COMSOL Multiphysics, and the models are made freely available.

Hydrogen threatens the structural integrity of metals and thus predicting hydrogen-material interactions is key to unlocking the role of hydrogen in the energy transition. Quantifying the interplay between material deformation and hydrogen diffusion ahead of cracks and other stress concentrators is key to the prediction and prevention of hydrogen-assisted failures. In this work, a generalised theoretical and computational framework is presented that for the first time encompasses: (i) stress-assisted diffusion, (ii) hydrogen trapping due to multiple trap types, rigorously accounting for the rate of creation of dislocation trap sites, (iii) hydrogen transport through dislocations, (iv) equilibrium (Oriani) and non-equilibrium (McNabb-Foster) trapping kinetics, (v) hydrogen-induced softening, and (vi) hydrogen uptake, considering the role of hydrostatic stresses and local electrochemistry. Particular emphasis is placed on the numerical implementation in COMSOL Multiphysics, releasing the relevant models and discussing stability, discretisation and solver details. Each of the elements of the framework is independently benchmarked against results from the literature and implications for the prediction of hydrogenassisted fractures are discussed. The second part of this work (Part II) shows how these crack tip predictions can be combined with crack growth simulations.