Advances in Mechanical and Power Engineering II
Selected Papers from The International Conference on Advanced Mechanical and Power Engineering (CAMPE 2023), October 16-19, 2023
- 2025
- Book
- Editors
- Holm Altenbach
- Xiao-Wei Gao
- Stavros Syngellakis
- Alexander H.-D. Cheng
- Piotr Lampart
- Anton Tkachuk
- Book Series
- Lecture Notes in Mechanical Engineering
- Publisher
- Springer Nature Switzerland
About this book
This book covers theoretical and experimental findings at the interface between fluid mechanics, heat transfer and energy technologies. It reports on the development and improvement of numerical methods and intelligent technologies for a wide range of applications in mechanical, power and materials engineering. It reports on solutions to modern fluid mechanics and heat transfer problems, on strategies for studying and improving the dynamics and durability of power equipment, discussing important issues relating to energy saving and environmental safety. Gathering selected contributions to the XV International Conference on Advanced Mechanical and Power Engineering (CAMPE 2023), held online on October 16-19, 2023, from Kharkiv, Ukraine, this book offers a timely update and extensive information for both researchers and professionals in the field of mechanical and power engineering.
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Table of Contents
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Dynamics and Strength of Power Equipment
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Frontmatter
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Multi-scale Finite-Element Methodology for Predicting the Thermodeformed State of Welded Large-Size Structures
Alexey Milenin, Elena Velikoivanenko, Galina Rozynka, Nina Pivtorak, Serhii VolkovThe chapter discusses the optimization of assembly welding for large-size structures, focusing on the prediction of stresses and strains (SSS) during the welding process. It highlights the challenges posed by the different scales of temperature kinetics and SSS, and the resource-intensive nature of conventional simulation methods. The authors introduce a multi-scale finite-element methodology that combines meso- and macro-level models to accurately predict the thermodeformed state of welded structures. This approach involves solving interrelated problems of heat conduction and thermoplasticity, and transferring calculation data between scales to maintain accuracy while reducing computational resources. The methodology is validated through a case study of assembly welding of a cylindrical pressure vessel, demonstrating high correspondence with verification calculations and significant potential for analyzing complex operational loads and brittle strength. The chapter concludes by emphasizing the effectiveness and resource efficiency of the proposed multi-scale approach for predicting the SSS of large-size welded structures.AI Generated
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AbstractThe determination of thermodeformed state of large-size structures is a crucial step in optimizing assembly welding and assessing structural reliability. Conducting extensive laboratory tests for this purpose can be challenging, which high-lights the need for modern modeling methods to predict stress and strain kinetics and its impact on the structural integrity under different external loads. However, the resource-intensive nature of computer simulations, particularly in finite-element analysis, imposes limitations on numerical analyses. To overcome these limitations and reduce computational time and resource requirements, a multi-scale modeling methodology has been developed. This methodology involves two levels of analysis: the level of welding stresses and strains, and the level of macroscopic deformation of the entire structure. The connection between these levels is achieved through the averaging of properties and numerical parameters of specific finite elements. The developed methodology has been successfully applied to a typical case study involving the assembly welding of a large aluminum pressure vessel. The study also demonstrates the limitations of the proposed approach, highlighting its applicability. -
Creep and Damage Processes in Cyclically Loaded Model of Turbine Rotor
Holm Altenbach, Dmytro Breslavsky, Alyona Senko, Oksana TatarinovaThe chapter delves into the critical issue of long-term strength in turbines, particularly focusing on irreversible creep strains and the accumulation of hidden damage due to creep and fatigue processes. It discusses the mathematical formulation of the stress-strain state through boundary-initial value problems and constitutive equations. The impact of cyclic temperature and load variations on turbine elements is examined, with a focus on high cycle fatigue damage and its interaction with creep processes. The chapter presents an innovative approach using finite element methods and time integration to model these complex phenomena, providing valuable insights into the behavior of turbine rotors under cyclic conditions. The analysis includes the development of macroscopic defects and the evaluation of safe operating times, offering practical solutions for engineers to assess the structural integrity of turbine components.AI Generated
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AbstractA novel approach to solving the creep-damage problem of cyclically loaded elements of power engineering structures is presented. Cycles of short duration caused by vibration as well as long cycles caused by turbine shutdowns are considered. The total hidden damage of the material is estimated taking into account the damage due to creep and high cycle fatigue. A formulation of the boundary – initial value problem based on the methods of many time scales and averaging over cycle periods is presented. The new results of solving the creep-damage problem in the model of the rotor are given for different cases of static and cyclic loading. It is shown that taking into account the accumulation of high cycle fatigue damage significantly reduces the time until the completion of the hidden damage accumulation and leads to the fracture development in rotor. -
Structure Formation Features of White Chrome Cast Irons Inside Working Layer of Massive Mill Rolls
Oksana Klochko, Volodymyr Volchuk, Mariia Bilinska, Evgeniya Deryabkina, Oleksandr VoronovThe chapter delves into the structure formation features of white chromium cast irons used in the working layer of massive mill rolls. It highlights the challenges posed by excessive retained austenite under high unit pressures and thermal cyclic loads. The study focuses on reducing retained austenite through alloying additives such as molybdenum, tungsten, and niobium, and explores the relationship between mechanical properties and fractal structure. The research methodology involves microstructural analysis using SEM and XRD, as well as fractal analysis to evaluate the effects of dispersion hardening. The results indicate that alloying with tungsten and niobium reduces residual austenite and enhances the performance of the working layer material. The chapter concludes with recommendations for heat treatment to improve the performance of white chromium cast irons, emphasizing the practical relevance of these findings in the manufacturing of mill rolls.AI Generated
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AbstractOur present study is aimed at increasing the operational durability of massive two-layer mill rolls with a working layer of white chrome cast iron (15.9–16.4%Cr) by decreasing the retained austenite fraction. The latter is achieved by additional alloying with molybdenum and tungsten, as well as by applying cyclic annealing with double heating at subcritical temperatures (450 or 550 ℃, depending on the chemical composition of studied cast iron). The scientific novelty includes establishing the differing influence of molybdenum or tungsten alloying on the properties of the studied alloys. Via the fractal analysis of the microstructure it is discovered that the microhardness level is sensitive to the fractal dimension of the structural components. The difference in microhardness value is especially noticeable in a metal matrix: its levels are 1.5 times higher if the matrix is only alloyed with Mo. Such difference is associated with an increase in the fraction of ferritic component due to precipitation hardening which happens in the as-cast condition in alloys containing W. The practical value of our study lies in decrease of the residual austenite fraction, and, accordingly, in the reduction of tendency to cracking during the operation of products which is possible due to both dispersion hardening in the process of additional alloying with carbide-forming elements and cyclic annealing. The obtained results confirm possibility of using the fractal dimension to assess the microhardness of precipitation hardening products in cases when measuring via standard methods is difficult due to the small size of the objects of study. -
Buckling of Cylindrical Sandwich Panels with Imperfections in Honeycomb Cores Manufactured by Fused Deposition Modeling
Maryna Chernobryvko, Konstantin Avramov, Christophe PierreThe chapter delves into the critical issue of buckling in cylindrical sandwich panels with honeycomb cores manufactured via Fused Deposition Modeling (FDM). It examines how imperfections, such as cell breakings, affect the structural integrity under both longitudinal compression and radial pressure. The study employs finite element analysis to evaluate the global and local buckling behaviors, highlighting the significant impact of imperfections on critical buckling loads. Notably, the research reveals that even a single cell breaking can drastically reduce the critical buckling pressure under radial pressure, while multiple imperfections have a moderate effect under longitudinal compression. The findings are crucial for optimizing the design and manufacturing processes of thin-walled structures in various industries, particularly where weight and strength are critical.AI Generated
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AbstractThe sandwich panels are elements of launch vehicles and autonomous aerospace vehicles. The buckling of cylindrical sandwich panels with imperfections is considered. The core layer of such panel is a honeycomb structure made from polylactide (PLA) material and manufactured by fused deposition modeling (FDM) additive technology. The inner and outer panel layers are made of carbon fiber-reinforced materials. The purpose of this work is determination the effect of cell breakings on the buckling cylindrical sandwich panels with imperfections under longitudinal compression and radial pressures. This will make possible to use some sandwich panels with imperfections in the production. The scientific novelty of this study is the following. The influence of honeycomb imperfections in the form of cell breakings on the critical buckling modes is studied. Eight cases of imperfection patterns, in terms of numbers and locations of the cell breakings, are considered. Numerical computations show that the sandwich panels under longitudinal compression are moderately sensitive to imperfections, with decreases in critical load ranging from 5.3% for a single cell breaking in the center of the honeycomb to 8.6% for multiple cell breakings located along different directions. Also, the corresponding buckling mode is global. In contrast, the buckling behavior of sandwich panels subject to radial pressure is highly sensitive to imperfections, such that the presence of a single cell breaking results in a critical load more than three times smaller than that of the perfect panel. The results on cell breakings influence on the shell buckling can be used for thin-walled structure design. -
An Improved Stress State Mathematical Model for the Adhesive Joint of Coaxial Tubes
Sergiy S. Kurennov, Kostiantyn P. Barakhov, Olexandr G. Poliakov, Daria V. DvoretskayaThe chapter introduces an advanced mathematical model for the adhesive joint of coaxial tubes, addressing the deficiencies in existing models that assume uniform stress distribution. By employing a Vlasov-Pasternak multi-parameter elastic base model, the authors aim to satisfy boundary conditions and accurately describe the deflected mode of the adhesive layer, particularly in the highly stressed regions near the joint edge. The proposed model is applicable to various structures, including pipelines and telescopic joints, and can be extended to dynamic problems, offering a comprehensive solution for designing and analyzing adhesive joints in critical applications.AI Generated
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AbstractAn improved axisymmetric deflected mode analytical model of the adhesive joint of two cylindrical tubes is proposed. An important difference from classical mathematical models is that a more accurate deflected mode model of the adhesive layer is used. The paper is based on the hypothesis that the adhesive layer acts on shear and cleavage. It is also assumed that tangential stress values vary linearly over the thickness of the adhesive layer. To describe the normal stress values in the adhesive layer, the two-parameter Vlasov-Pasternak elastic base model is used. The proposed approach makes it possible to satisfy the boundary conditions at the load-free butt of the adhesive layer and to describe its deflected mode with high accuracy. The problem is reduced to a system of linear differential equations of the fourth order relative to displacements. The solution of the problem is obtained in an analytical form. The model problem is solved. -
Analysis of Shape Distortion of the Composite Reflector Antennas During Assembly
Oleksandr Gaidachuk, Igor Taranenko, Tetyana Nabokina, Andrii KondratievThe chapter delves into the critical issue of shape distortions in composite reflector antennas during assembly, a common challenge in telecommunications systems. It begins by highlighting the advantages of reflector antennas, including high gain factor and wide bandwidth, and their common use in telecommunication systems. The focus then shifts to the manufacturing process of these antennas, particularly the distortions that occur in the shape of the reflecting surfaces due to process-induced deformations. The author presents a comprehensive review of existing literature, discussing various methods and models proposed to predict and minimize these distortions. The research methodology is meticulously detailed, outlining the assumptions and calculations used to derive analytical dependencies for predicting tolerance bands during assembly by gluing or screws. The chapter concludes with a practical example and results, demonstrating the application of these analytical models and their impact on the assembly process. The findings have significant implications for improving the accuracy and reliability of composite reflector antennas, making this chapter a valuable resource for specialists in the field.AI Generated
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AbstractDevelopment of the modern communication systems necessitates the creation of mirror reflectors for antennas made of polymer composite materials. It allows to significantly reduce the weight of reflectors making them more precise and dimensionally stable. However, the actual process of manufacturing of the composite reflectors is often associated with distortions of their reflecting surface occurring because of process-induced deformations. The analytical dependences have been obtained that allowed predicting the regulated tolerance band for assembly by gluing or connection with screws of the composite products with frames such as parabolic antenna reflectors. These dependences take into account the product design and assembly process parameters, as well as strength characteristics of the adhesive, the rational combination of which allows achieving a high quality of the reflector. As shown by the example, recording of spring action depending on the unbalance of internal forces of the assembled product does not make a substantial correction to the tolerance for the theoretical contour of the mirror antenna reflector at the actual design parameters of its elements. Tolerance bands for gluing and connecting with screws are compared. It is proved that the frame to reflector connection with screws can be more effective at their rational number, but when this number is fairly large, the realizable tolerance band is almost the same. Our findings allow solving the new process tasks in order to determine the maximum permissible deviations of composite shells from their theoretical contour at the assembly stage. -
Investigation on Induced Intra/Interlaminar Damage Propagation in CFRP Subjected to Cyclic Tensile Loading After Impact (TAI)
Francisco Maciel Monticeli, Felipe Ruivo Fuga, Mariano Andrés Arbelo, Maurício Vicente DonadonThe chapter explores the progressive adoption of carbon fibre-reinforced polymer (CFRP) composites in aerospace, highlighting their significance in achieving lightweight design without compromising structural integrity. The study focuses on the complexities of analysing and controlling damage propagation in composite aerostructures, particularly intra- and interlaminar fractures caused by impact damage. Traditional non-destructive evaluation techniques often fall short in detecting smaller-scale damage, necessitating advanced experimental techniques and physical-based models. The research employs ultrasound microscopy and a finite fracture mechanic model to assess damage propagation under cyclic tensile loading, revealing the intricate behaviour of damage growth and its dependence on impact energy levels. The findings provide valuable insights into the crack propagation rates and failure modes, contributing to the design of damage-tolerant structures in the aerospace industry.AI Generated
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AbstractImpact damage to composite structures results in multiple, complex failure modes, often requiring the replacement of entire components and thereby escalating aircraft maintenance costs. To address this issue, the present study investigates the damage propagation behaviour with particular emphasis on intra- and interlaminar failure modes. Carbon fibre/epoxy composites were subjected to tensile after impact (TAI) fatigue tests at different energy levels to induce different damage modes and extents within the specimens. A non-destructive testing technique (C-scan) was used to assess the interlaminar damage propagation, while the intralaminar fracture toughness of the post-impact specimens was characterised using a finite fracture mechanics model. The results show that the crack propagation behaviour is strongly influenced by the initial impact damage characteristics, in particular the impact energy level. Lower impact energies tend to promote interlaminar failure modes leading to fatigue crack propagation by delamination. Conversely, higher impact energy levels induce fibre fracture, resulting in a self-similar relationship between intra- and interlaminar propagation. -
Special Constraints of Packing Problems in Materials Structure Research
Andrii Chuhai, Yuriy Stoyan, Tetyana Romanova, Georgiy Yaskov, Olha StarkovaThis chapter delves into the critical role of mathematical modeling and packing problems in the investigation of material structures, essential for understanding and predicting material properties. It discusses various techniques such as finite element analysis, molecular dynamics simulations, and lattice-based approaches, which enable researchers to study material structures at different scales. Packing problems, in particular, are crucial for optimizing the arrangement of particles within materials, leading to advancements in fields like nanotechnology and biomaterials. The chapter also addresses the challenges and benefits of these approaches, including the accuracy and computational resources required for large-scale simulations. A notable focus is on the relaxation of constraints when estimating porosity, which enhances the accuracy of calculations by considering boundary and edge effects, statistical representation, and pore connectivity. The chapter introduces a fast heuristic algorithm combining block coordinate descent and a cylindrical lattice decomposition strategy to solve large-scale sphere packing problems. Numerical experiments using titanium powder data demonstrate the effectiveness of relaxation techniques in improving porosity estimation. The findings underscore the importance of integrating relaxation methods into materials structure research, offering a more reliable approach to modeling complex material systems.AI Generated
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AbstractThe paper considers a relaxation technique in a sphere packing problem with a specific focus on study of materials structure. The objective is to maximize the number of non-overlapping spheres in a cylindrical container regarding a given ratio of the different radii spheres appearance. Two scenarios are discussed to examine an effect of relaxing constraints on the packing spherical objects. In the first scenario, spheres packed within the container while adhering to strict containment conditions. The second scenario violates the containment condition by allowing spheres intersect the container boundary. This relaxation provides a more accurate estimation of the material's porosity by eliminating artificial effects caused by boundary constraints. A fast heuristic approach is developed that combines a modification of the block coordinate descent algorithm and a new cylindrical lattice decomposition strategy. Computational results are presented and illustrated with examples for two scenarios. The findings highlight the importance of the proposed techniques in materials structure studies and can be extended to packing particles of various shaped. -
Optimized Designing of Parts for Additive Manufacturing
Georgiy Yaskov, Yuriy Stoyan, Tetyana Romanova, Andrii Chuhai, Luis GutierrezThe chapter delves into the intricacies of designing parts for additive manufacturing, emphasizing the importance of support-free structures to enhance efficiency and reduce costs. It introduces topological optimization techniques and discusses the challenges of designing geometries that eliminate the need for supports during the manufacturing process. The paper also presents a mathematical model for generating spherical void structures within 3D parts, maximizing the volume of voids while adhering to 3D printing standards. A heuristic approach is proposed to solve the complex optimization problem, illustrated with numerical examples that showcase the practical application of the proposed technique. The chapter concludes by highlighting the potential of the approach in designing complex-shaped parts for support-free 3D printing technologies.AI Generated
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AbstractThe paper presents a novel technique for optimizing the design of parts intended for 3D printing, with a focus on enhancing structural integrity and material utilization. The study addresses the challenges of lightening of 3D parts bounded by cylindrical, spherical surfaces, and planes. A smart technique of generating spherical voids of varying diameters within 3D parts of complex geometry is proposed. The optimization procedure is aimed to maximizing the total volume of spherical voids while considering 3D printing standards. A mathematical model of the nonstandard packing problem is constructed, using normalized and adjusted phi-functions for describing distance constraints. A solution algorithm is developed reducing the problem to a sequence of subproblems with smooth functions. An illustrative example is provided for a 3D part with complex geometry. The findings emphasize the significant benefits of utilizing the proposed technique in designing 3D components, with a particular focus on achieving substantial weight reduction. -
Thermal Stress Analysis of Multilayer Glazing Elements Subjected to Interlayer Heat Sources
Natalia Smetankina, Serhii Misiura, Anatolii Vasiliev, Ievgeniia Misiura, Kateryna KrenThe chapter delves into the critical issue of thermal stress analysis in multilayer glazing elements, particularly those subjected to interlayer heat sources. It reviews existing methods and models for heat conduction and thermal elasticity in homogeneous and inhomogeneous structures, highlighting the challenges in solving these problems. The study focuses on the development of a refined model for calculating temperature fields and stresses in multilayer plates and shells with complex shapes, taking into account convective heat exchange and distributed film interlayer heat sources. The methodology involves a first-order theory that accounts for strain of transverse shear and normal element compression in each layer. The solution is obtained through a variational Lagrange principle and expanded to an auxiliary simply supported shell with a rectangular plan shape. The chapter presents numerical results and comparisons with finite difference methods, demonstrating the reliability and efficiency of the developed approach. It also showcases the application of the method to a seven-layer aircraft glazing element, illustrating the distribution of principal stresses under different flight modes. The study concludes by emphasizing the potential of the method for analyzing thermal stresses in various structural elements and optimizing heating conditions in vehicle heating systems.AI Generated
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AbstractThe problem of studying the thermal stress state of structures arises in many areas of mechanical engineering. The paper deals with a method for studying multilayer glazing elements of aircrafts under temperature effects. We consider a glazing element as the multilayer shell with constant thickness isotropic layers and various physical properties. The number of layers and their layout is arbitrary. Convective heat exchange occurs on the shell surfaces. The multilayer shell with a non-canonical form in plan is heated with interlayer film heat sources. Temperature fields are obtained by solving the nonstationary heat conduction problem. The problem of thermoelasticity of shells is solved by the extension method. This method is based on extending a non-canonical-shaped shell to a simple domain. It enables to present the problem solution in analytical form. We describe a behavior of the shell by using of the of the first-order refined theory with account transverse shear strains in each layer. The thermal elastic equilibrium equations and the boundary conditions on the contour are obtained using Lagrange's variational principle. The method feasibility has tested on five- and seven-layer glazing. Results of calculation of stresses in layers are compared with the data obtained by the finite difference method. The method proposed can be used for defining thermal stresses in the multilayer structural elements and designing anti-icing systems. -
The Efficiency and Durability of a Nuclear Power Plant Turbine Without the Stage of Damaged Blades
Vitalii Peshko, Olexandr Usatyi, Olga ChernousenkoThe chapter delves into the critical issue of turbine blade damage in nuclear power plants, specifically examining the K-1000-60/3000 turbine's high-pressure cylinder. It investigates the effects of operating without the damaged 5th stage, revealing changes in steam parameters and internal efficiency. The study employs sophisticated mathematical models and computational methods to assess the thermal and stress-strain state of the rotor, ultimately concluding that the absence of the 5th stage does not negatively impact the turbine's service life. The findings offer valuable insights into optimizing turbine performance and extending operational lifespan, making it a must-read for professionals in the field.AI Generated
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AbstractEvents that lead to damage to the blades can occur during the operation of turbine equipment at nuclear power plants. In some cases, it may not be possible to quickly replace damaged parts. The purpose of this study is to investigate the possibility of operating the K-1000-60/3000 turbine with dismantled nozzle and working blades of the 5th stage. A mathematical model of the flowing part of a high-pressure cylinder based on the object-oriented approach is developed. The main thermodynamic and kinematic parameters of the flow are investigated. A significant change in the steam parameters in the extraction III, which feeds the main deaerator of the unit, has been established. The steam pressure in this extraction decreases by 37% and is insufficient to ensure the nominal deaeration of the feeding water. At the same time, the total power of the cylinder without the 5th stage is reduced by 3%. The thermal and stress-strain state of a high-pressure rotor in the project version and without a damaged stage was investigated. A decrease in the overall stress level and migration of the areas of maximum stresses were observed. The low-cycle fatigue of the rotor was investigated at typical operating conditions. It was found that the individual rotor life without the 5th stage increases by 5.6%. -
Analysis and Selection of SMAW Welding Process Parameters of Cr-Mo P11 Steel for Power Plant Applications
Mohamed Farid Benlamnouar, Nabil Bensaid, Tahar Saadi, Yazid Laib Dit Laksir, Riad BadjiThis chapter delves into the critical role of welding processes, particularly SMAW, in ensuring structural integrity for power plant components. It focuses on Cr-Mo P11 steel, prized for its corrosion resistance and mechanical properties. The study employs Taguchi design to experimentally determine optimal welding parameters and AHP method to rank welding rods based on their influence on mechanical properties. The analysis reveals that welding current significantly affects tensile strength, strain, and depth penetration, while welding speed impacts impact energy. The integration of Taguchi design and AHP method provides a robust framework for decision-making, ensuring high-quality welds and informed rod selection in power plant applications.AI Generated
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AbstractThis work presents an analysis and multi-criteria selection by hybrid operation combined of analytic hierarchy process (AHP) and Taguchi design for the selection of optimal welding parameters to produce shielded metal arc welding (SMAW) of Cr-Mo P11 low alloy steel used in power plant. In our investigation, three welding parameters i.e. intensity (I (A)), voltage (V (v)) and welding speed (S (mm/min)) have been tested to evaluate four output mechanical properties i.e. penetration depth and maximum strain (ε (%)), tensile strength (σ (MPa)) and impact energy (IE (MPa)). Taguchi L9 orthogonal array is employed to extract mathematical models and welding parameters effects on output properties. It was deduced that welding current has a significant influence on tensile strength, strain and penetration depth properties followed by welding speed and voltage. This study delves into the investigation of sub-criteria of welding process through the use of AHP method coordinately with Taguchi results to identify the optimal filler rod (Ri). Taguchi's biggest effect parameter is included in the AHP matrix to choose the best welding rod by adopting different welding parameters with preheating temperature (T °C). -
Boundary and Finite Element Methods in Crack Propagation Analysis
Kyryl Degtyariov, Vasyl Gnitko, Alexander Steinwolf, Ivan VierushkinThe chapter delves into the critical issue of crack propagation in structural materials, highlighting the significance of boundary and finite element methods in predicting catastrophic failures. It offers an in-depth review of various numerical methods, such as the Galerkin free element method and the boundary element method, to estimate stress intensity factors and analyze crack growth. The research methodology is rigorously detailed, including the formulation of boundary value problems and the application of hypersingular integral equations. The chapter presents benchmark tests and practical examples, such as the analysis of a fuel tank and a cracked shell, demonstrating the accuracy and reliability of these methods. The discussion on the durability and service life of structures under cyclic loads provides valuable insights into the practical implications of these advanced numerical techniques.AI Generated
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AbstractThe main goal of this paper is developing the advanced numerical methods for stress analysis of structures with crack-like defects. The novelty of proposed research consists in application of hypersingular integral equations for solutions of a benchmark test, and in stress analysis of the fuel tank under harmonic loads during transportation from the place of manufacture to the launch site. Boundary and finite element methods have been used for the benchmark test, whereas the finite element method is applied for the fatigue strength analysis of the tank. The fatigue analysis with finite amplitude cyclic loading was carried out. That has showed a high service life, which allows the intact structure to be successfully transported. When the model penny-shaped crack was placed in the zone of maximum stresses, an essential drop in the expected service life before destruction has been observed. From the point of view of practical applications, it was enough to transport such structures over short distances. However, a long-distance transportation can cause the mechanism of fatigue cracks propagation inside the shell with subsequent depressurization and failure. -
Structure Elements with Crack-Type Defects Durability Estimation
Olena Sierikova, Denis Kriutchenko, Konstanin Vandyshev, Ivan VierushkinThe chapter delves into the critical issue of extending the service life of hydro-turbine, petrochemical, and power equipment by addressing microdefects, particularly crack propagation. It highlights the significance of predicting dangerous crack growth using advanced numerical methods, such as the hypersingular integral equation technique. The research methodology involves determining the durability of hydraulic turbine structural elements under cyclic loads, with a focus on penny-shaped cracks. The study provides analytical solutions for the hypersingular integral equation in the context of circular cracks and offers a comprehensive approach to estimating the stress intensity factor. The results demonstrate the effectiveness of the method in predicting the time to failure for structural elements with different initial crack sizes. The chapter concludes with a discussion on the future research directions, including the application of the method to composite and nanocomposite materials.AI Generated
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AbstractThe objective of this study consists in elaborating computational procedures to analyze durability of structural elements with crack-type defects under remote alternating loads. The novelty of the proposed method consists both in applying new benchmark tests for crack propagation analysis, and analyzing structure durability for structure elements with different defects. The problem of the stress intensity factor estimation for mode I loading is reduced to solution of a hypersingular integral equation. Analytical solutions of this equation with different right parts are obtained for penny-shape cracks. It is the basis for verifying boundary-type numerical methods. The problem of determining the number of cycles to failure for structural elements subjected to cyclic loading (tension-compression) with a given frequency and amplitude is solved. The Paris dependence for fatigue crack growth has been used to determine the critical number of cycles before failure. Numerical results characterizing the durability of structural elements with crack-like initial defects have been accomplished. -
Effect of Alloying Elements in Weldability of API X70 HSLA Steels
Nabil Bensaid, Mohamed Farid Benlamnouar, Yazid Laib Dit Laksir, Tahar Saadi, Riad BadjiThe study delves into the impact of alloying elements on the weldability of API X70 high-strength low-alloy (HSLA) steels, crucial for pipeline construction in the oil and gas industry. It investigates how variations in chemical composition, specifically carbon content and microalloying elements like niobium, vanadium, and titanium, affect the microstructure and mechanical properties of welded joints. The research focuses on four different X70 steels, examining their heat-affected zones (HAZ) and fusion zones (FZ) through extensive microstructural analysis and mechanical testing. Key findings include the role of precipitates like TiN and V(C, N) in refining austenite grains, the influence of welding parameters on HAZ characteristics, and the optimization of alloying elements to enhance cracking behavior. The study concludes with recommendations for optimizing the properties of microalloyed X70 steels, contributing to the development of new alloys for robust pipeline construction.AI Generated
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AbstractThis study aims to investigate and compare the evolution of microstructure and mechanical behavior in API X70 steels welded using SMAW techniques. A comprehensive analysis of the microstructure revealed that the weldability of low-carbon X70 steels is significantly influenced by the carbon content and microalloying elements. The microstructural evolution demonstrated that higher carbon content in X70 steel results in increased levels of martensite-austenite (M-A) compounds in the heat-affected zone (HAZ). Additionally, higher carbon content also leads to enhanced growth of ferritic grains in the HAZ. Furthermore, the rate of M-A compound formation in the HAZ increases with higher carbon content, but this rate is limited when a high proportion of niobium is introduced. Optimal mechanical properties, appropriate grain coarsening, and an acceptable ratio of M-A compounds throughout the HAZ were observed at a carbon content of 0.082%. These findings suggest that the weldability of HSLA-X70 steels can be improved by incorporating microalloying elements, without the need for complex metallurgical processes to enhance the microstructure. Fractographic examinations revealed a shift in the failure mode from low to high carbon ratios in X70 steels.
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Backmatter
- Title
- Advances in Mechanical and Power Engineering II
- Editors
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Holm Altenbach
Xiao-Wei Gao
Stavros Syngellakis
Alexander H.-D. Cheng
Piotr Lampart
Anton Tkachuk
- Copyright Year
- 2025
- Publisher
- Springer Nature Switzerland
- Electronic ISBN
- 978-3-031-82979-6
- Print ISBN
- 978-3-031-82978-9
- DOI
- https://doi.org/10.1007/978-3-031-82979-6
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