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Experimental studies provide objective data on the operation of structures. However, experiments take a lot of time and require special equipment. It is not always possible to consider and simulate all the features of the structure’s operation during tests. Instead of a physical experiment a numerical experiment can be carried out with appropriate justification. Numerical studies are based on the use of the finite-element method. Modern computing systems allow to model structures of any size using flat and spatial finite elements, contact interaction of different materials, and physical nonlinearity. This article describes the finite-element models used in the design of CFRP-reinforced steel rods. The numerical results are compared with experimental data obtained when testing CFRP-reinforced steel elements in tension and bending. Numerical calculations were performed using the FEMAP computer complex, considering the physical nonlinearity of the material. The experimental samples were modeled by volumetric finite elements. Taking into account the symmetry of the problem, one-eighth of the experimental element was considered in tension, while in bending, half was considered with the imposition of the corresponding boundary conditions on the elements along the symmetry axes. The characteristics of the materials of steel and lamella used in the calculations were obtained when testing samples of steel and lamella. The characteristics of the glue were obtained by a series of successive calculations when simulating experiments to determine the strength of the adhesive bond between steel and lamella. Comparison of experimental and numerical data showed that the selected parameters of finite-element models provide reliable results.

The continuous welded rail track is the main design of the track used by the railways and can be operated in accordance with the technical requirements established by the railways on the tracks of all classes. The paper presents the calculation of the possibility of laying a continuous welded rail track. Analysis of works on temporary and final restoration of welded rail strings is carried out. At the final restoring, rail strings can be welded by electric contact or aluminum thermite welding. Depending on the location of cropped rail or the place of temporary restoration relative to the ends of the restored rail string, the final restoration by electric contact welding can be carried out with tightening of the welded rail string or with its preliminary bending. Final restoration of rail strings by aluminum-thermite welding can be carried out immediately after identification of a dangerous defect requiring cutting or after temporary restoration of the string. Laying of continuous welded track with or without replacement of the assembled rails and sleepers should be carried out in accordance with the projects and technologies approved by the railways. When planning work, it is necessary to take into account daily and long-term forecasts of the rail temperature. During the work, continuous monitoring of the rail temperature, carried out with the help of portable rail thermometers, should be organized.

The Research Project ReSHEALience has been launched in 2018 in the framework of the European Programme Horizon 2020. The project aims at developing a new approach for the design of structures exposed to extremely aggressive environments, based on durability and life cycle analysis. In this regards, the starting point is represented by new advanced Ultra-High Performance Fibre Reinforced Cementitious Composites (UHPFRCCs), called Ultra-High Durability Concretes (UHDC) because of their enhanced durability obtained by means of engineered composition, which should be characterized by strain hardening behaviour under tension in both ordinary and very aggressive conditions. In this context, the first step is to develop an effective approach for identifying the main parameters describing the overall behaviour in tension. In the present study, indirect tension tests have been performed via 4-Point Bending Tests (4PBT). Starting from the test results, a combined experimental-numerical identification procedure has been implemented in order to evaluate the effective material behaviour in direct tension in terms of stress-strain law. Finally, the comparison among three mixes differing for fibre and cement type is reported in terms of tensile response and post-crack localization behaviour.

The manuscript is devoted to graph-based mathematical simulation of a widespread steelmaking process, in which cored wire is injected into treatment ladle with molten steel stirred by argon blowing. Despite the process has better effectiveness than other methods its accuracy can be increased further using mathematical modelling. For example there is melt’s depth, where an addition needs to be released after melting of cored wire. Due complexity of wire dynamics many models in literature are oversimplified and don’t take important features. A wire has bending strains, remained after its unpacking, which leads to slightly curved shape of the lightweight wire. As consequence when it reaches a weighty melt there is a risk of swirling on the melt’s surface instead of diving inside. Also ladle wall and hydrodynamic drag of molten steel can significantly influence wire motion. In this work cored wire is replaced by a mechanical system of rigid rods with initially equal length and rotational springs between them. One of the peculiarities is a variable count of rods in the system during injection. A vector-network graph is used to decompose multirod system to basic mechanical elements (rods, spherical joints, and springs) and their relationships with information about forces and torques. An incidence matrix has repetitive nature and it is created using the graph in a way that simplifies getting of cutset and circuit equations. Using sequential substitutions the equations of motion are obtained in accordance to works of other scientists, which do it for systems with kinematically linked two and three bodies. For a computer realisation the semi-implicit Euler’s method is used to numerically solve SLAE. There is a parameters table of conducted numerical experiments and a chart with depth of wire’s tip depending on time, which has good correspondence with a real process. Presented computer simulation helps to find an optimal injection speed (3–5 m/s) of considered cored wire in a ladle. Alternatively a wire with higher elasticity can be taken to immerse it deeper, because increasing of the speed is not always effective, especially when it is already high.

Although ‘press tools’ are special toolings designed and constructed to meet specific forming requirements such as (a) blanking, (b) piercing, (c) shearing, (d) bending, (e) drawing, (f) deep drawing, (g) shaving, (h) curling, (i) embossing and (j) coining, a brief outline of the main equipment used in such operations is explained here in this chapter. This will facilitate the reader to go into details on the subject of ‘press tools’ in the later chapters.

The objective of this work is mainly focused on the structures that support the facilities and machinery present in industrial plants. Service life extension of existing structures is one of the current objectives of the industry. The lay-out of the production has to constantly adapt to changes in production, variations in demand and new products. These changes of model or demand, usually imply important changes in the facilities and machinery and therefore in the structures that support them. Currently, these support structures are destroyed at each lay-out change, mainly because an easy reconfiguration of the support structures is not possible. To achieve service life extension of existing structures it is necessary to use easily reconfigurable, reusable and removable structures. Currently there are already solutions of structures that are removable and reconfigurable but mainly in aluminum beams. Nowadays, there are no definitive solutions for steel structures manufactured with standard shapes (standard steel beams). The use of clamp joints for steel profiles would be a very interesting solution and would allow the manufacture of completely removable and reconfigurable structures. This paper proposes and uses a methodology for the experimental analysis of the bending behavior of this type of joints depending on the length of the profile flange.

Rolling ball sculpture, even the simple one, can be viewed as mechanical design challenge. If sculpture is made of poplar plywood, then bending and twisting of track causes stresses which can destroy rails of track. Another aspect is kinematic and dynamics of rolling ball. Sections of track where the rails is closer together will cause the ball to roll faster, but the ball is more likely to fall off the track. Centripetal force acting on the ball on spiral path increases own intensity with square of velocity and might cause ball to fall off. All these aspects will be analyzed in the paper.

The method of forming, finishing and shape refinement of ribbed panels by local deformation of the panel ribs using the rolling process is considered. The purpose of the article is experimental check of panel forming technology and shape changing accuracy under nominal and critical technical conditions of rib rolling of the monolithic panel as well as drawing up technical recommendations for using this method. In order to shape the profile and panel bending it is proposed to use the method that utilizes two rollers to deform areas of the rib. It provides the significant reduce in the angle of springing and expands the technological capabilities of the equipment. The process was simulated using FEM in the ANSYS software package for the case of oblique bending of ribbed panels. The problem of analyzing local stress-strain state during panel shaping was considered as quasi-static. The values of stresses and deflections of the panel sample at the point of load action and after removing the load were determined. It is shown on the example of aircraft wing panel oblique bending that the practical use of panel bending method with compression of ribs by rollers is expedient in case of sequential deforming the ribs with a counter and a passing sequence. The surface geometry along the axes of ribs that were bent by rollers shows better accuracy compared to the geometry of samples obtained by free bending in a punch. The results were compared to the data obtained by forming an aluminum alloy panel sample in unwinding device. It is shown that the method local forming by rolling allows achieving high accuracy of panel shape by means of correcting one-time impacts.

The roundness and the angle of the edges on the cross-sectional profile at the exit of the fin pass are crucial for the welding quality of the ERW tube. In this paper, the adjustment of the bending angles of the cage rolls was proposed to make a 9-inch tube. The proposed roll forming machine layout is capable of making tubes in a specific range of outside diameters without changing rolls. The CAE simulations were carried out to verify the proposed roll flower designs and the bending angle control strategies of the cage roll stations. The CAE simulations had verified the proposed flower design using different roll adjustments, and proper bending angle control strategies are able to make the demonstrated tube.

Innovative self-correcting process control techniques which adapt to the initial geometric characteristics of the strip are a promising approach to fix the local varying distortion of coiled strips by optimizing the leveling process. This paper presents an innovative strategy to improve straightening of AHSS materials (1.4310). This implies optimized leveling, adding minimal plastic deformation, and, thus, strain hardening. Therefore, an “intelligent straightening machine” is being developed which will be presented. To operate an intelligent straightening machine a reliable online measurement of the surface defects is fundamentally essential. This paper describes an approach towards the measurement of a bent steel strip for an automatic straightening process. Therefore, various ways of measuring the bending curvature are investigated. Optical, tactile, and the electromagnetic induction testing MagnaTest are compared with each other. The bending measurement is linked to open-loop control, providing an optimal straightening result in regards of formability, leveling, and reduced strain hardening.

In order to obtain the accurate B340LA material parameter, in this paper, a dynamic optimization approach was proposed to inverse determine the material parameters in bending springback process. After the inverse determination for material parameters, the finite element simulation result indicates a close agreement with actual experiment, and the relative errors between inverse determined and actual material parameters are also very small. It can be concluded that proposed optimization approach to inverse determine the material parameters is efficient and accurate.

An update on the joint characterization of three-sheet friction stir lap welds (FSLW) in three aluminum alloys (7xxx, 5xxx, and 6xxx) for automotive assembly application is presented. Welding speed of 0.3–2.9 m/min was used with pin length >5 mm with the aim to reduce upturn hooking on the retreating side and avoid wormhole defect on the advancing side. Joints were also made to enable T peel and U peel testing. Stitch welds were used to understand the effects of weld length and ramp length on T peel performance. Hat sections were joined for three-point bending and axial crush testing and tested with promising results. Several key issues that require further investigations are identified including flash management near the trim edge, weld quality with limited clamping, tool failures at speeds greater than 0.5 m/min, and the propensity of incipient melting for 7xxx stack-up.

Aluminum (Al) alloys play a critical role for the transportation applications where weight reduction is a key aspect; however, the poor formability at room temperature limits their application for complex components. An innovative methodology to overcome this limitation is based on subjecting the material to a local, short-term heat treatment before stamping, to obtain a tailored distribution of properties. In addition, Continuous-Bending-under-Tension uses the action of three rollers to remarkably increase the total elongation to failure. In the present work, the combination of the two approaches is investigated to improve the formability at room temperature of a strain-hardenable 5xxx Al alloy, AA5754-H32. Specimens were subjected to both CBT and pre-forming heat treatments, and force-displacement curves were compared to evaluate the formability improvements.

An effective direction for improving drive technology is the rational use of flexible links, elastic deformations of which provide multi-threaded power transmission in the engagement of higher kinematic pairs. The distribution of the force flow in the field of long-distance gearing reduces the specific loads on the teeth, eliminates restrictions on the bearing capacity of wave gears according to the criteria of jamming, bending and contact stresses of the teeth, and ensures the transmission of the highest torques with reduced dimensions and metal consumption. Commercially available small wave gears with a cam wave generator have been used commercially. Their force analysis and strength calculations differ significantly from the formulation and solution of similar problems of large wave transmissions with a disk wave generator. Strength calculations of mass-produced wave gears are performed without taking into account the features of the deflected mode of the wave generator disks. Therefore, studies of the load capacity of large wave transmissions, in particular the disk wave generator, have not found an objective solution yet. In the heavy and transport industry, in the production of road and construction machinery, the tasks of improving the quality, reliability, durability, service life, efficiency of machines and technological equipment, and reducing their metal consumption are of particular importance. The specified set of scientific and technical tasks is largely due to the requirements of a significant increase in labor productivity while reducing the operating costs of the consumer.

In order to ensure the accuracy and efficiency of sheet metal bending, a more efficient bending process planning algorithm is required. First of all, under the premise of comprehensively considering interference discrimination and efficiency guarantee, this paper establishes the fitness function of the process planning problem, and converts the process of selecting the optimal process into a problem of solving the optimal solution of the function. Then, since Particle Swarm optimization is easy to fall into the local optimal solution, an improved algorithm is proposed to solve the optimal process. Finally, the optimal bending process of sheet metal parts with different complexity is solved by experiments. The results show that the improved algorithm can calculate the optimal or nearly optimal results within a reasonable time range when there are more bending steps.

In this paper, the Taguchi method and regression analysis used to evaluate the influence of technological parameters: punch radius, temperature and punch stroke to the spring-back angle after V-bending for SS400 steel plate output. The experiments were designing with a mixed orthogonal array and conducted using the L9 (3 × 3) on the bending and heating testing machines modern system. Analysis of variance (ANOVA) was used to determine the effects of input parameters on the output parameters. The analysis results show that the temperature was the biggest factor affecting the springback angle after forming. Nonlinear regression analysis used a quadratic polynomial function to predict experimental results. The predicted values according to construction and experimental mathematical models were vere close to each other, this shows that the built mathematical model has high reliability.

The paper presents the solution to a problem associated with the locking equipment in water supply systems destruction on the upper floors of high-rise buildings. After the destruction products, quality study reveals no metallographic defects or rejects in the manufacture, and the hypothesis that the destruction cause is low-cycle material fatigue under the dynamic loads influence, arising due to temperature deformations in the pipeline, is proposed. The paper considers a pipeline scheme, in which a temperature gradient arises in the fluid flow direction. At different temperature strains of the pipeline parts, bending stresses emerge. The cyclic nature of these stresses is determined by the hot and cold water consumption frequency. The pipeline model where the locking equipment was installed is a beam with pinched ends. The bending stresses calculation for this beam is performed using the initial parameter method. The plots of moments and transverse forces in the beam section are plotted. The permissible stress calculation under the dynamic loads action is made. The pipeline section size, within which shut-off equipment can be installed without destruction, is determined.

In this chapter, the method for calculation of residual stress and enduring deformation of helical springs is developed. The method is based on the deformational formulation of plasticity theory and common kinematic hypotheses (SAE AE-22, Sect. 8.3.33). Two principal types of the helical springs—the compression springs and the torsion springs are studied. For the first type (axial compression or tension springs) the spring wire is twisted. The basic approach neglects the pitch and curvature of the coil, substituting the helical wire by the straight cylindrical bar. The helical spring is in the state of screw dislocation, accordingly, the wire is twisted. The elastic–plastic torsion of the straight bar with the circular cross-section is examined. For the second type (torsion helical springs) the helical wire is in the state edge dislocation, so the wire is in state of flexure. The elastic–plastic bending of the straight bar with the rectangular and circular cross-section is studied using the Bernoulli’s hypothesis. The material for both types of springs is nonlinearly-hardening elastic–plastic with the elastic unloading. The hyperbolic, Ramberg–Osgood, Ludwik-Hollomon, Swift-Voce, Johnson-Cook laws for the material are surveyed. For both problems the elastic–plastic active deformation and elastic spring-back allow the closed-form solutions. Further, this Chapter examines the calculation of remaining deformation and residual stress for helical springs after long-lasting presetting process. The article extends the model for the immediate presetting process accounting the creep deformation of the spring. The method is based on plasticity theory for the instant flow overexposed by the relaxation over the long-term presetting. In this article the following method is used. The plastic deformation of the helical spring with the circular cross-section occurs instantly. If the shortening of the spring in the tool holder persists, the relaxation of stresses occurs and the force of the spring reduces. As the consequence, after the elastic unloading of the long-time presetting, the residual stresses spring reduce gradually with the squeezing time as well. The final length of the springs considerably shortens with the increasing preset duration. The advantage of the discovered closed form solutions is the calculation without the necessity of complex finite-element simulation of spring length loss and residual stresses after presetting process. The analytical expressions are proposed and the exact calibration applied for evaluation of factors for presetting processes. This Chapter is the closing section of second part, which studies manufacturing processes of the helical springs.

The problem of analyzing a heavy-loaded low-speed multi-pair spiroid gear with account of the influence of elastic and elastoplastic contact, bending and shearing interaction of spiroid gearwheel teeth and spiroid worm threads is considered. The main steps of the developed algorithm for calculating the load distribution and plastic strain of flanks taking into account the elastic and elastoplastic nature of the contact, multi-pair character of meshing, and macro- and micro-roughness of flanks of gear elements are briefly described. For the case of elastoplastic contact, zones of plastic contact on spiroid gear tooth flanks are determined, and the value of plastic strain is calculated. Flanks of spiroid gear teeth are presented in the algorithm as a set of areas (cells) with coordinates of centers calculated taking into account the analyzed factors influencing the load distribution in the spiroid gearing, such as manufacturing and (or) assembly errors, macro- and micro-roughness, and deformation of spiroid gear supports. The manuscript presents numerical results of studying real spiroid gears for gearboxes of pipeline valves (PV) having the elastic and elastoplastic character of contact, presented in the form of summary tables and diagrams of torque distribution, load concentration factors in contact areas and plastic strain areas, demonstrating the efficiency of the algorithm. Results of comparing the gearboxes of different generations are given that show the ways of applying this algorithm at the design stage and results of improving load characteristics of new generations of gearboxes. Numerical results of the algorithm operation correlate well with the operating experience and can be used to analyze the load-carrying capacity of spiroid gears.

This article is about wire rope simplified model method development. This method allows to carry out calculations of different constructions, the elements of which are cables, without detailed strands modeling, which significantly saves computing resources and time. This work focuses on the usage of experimental data description to validate the material model of the rope, on getting deformation curves under axial tension and bending characteristics, on developing a simplified finite element model of the rope, and, finally, on the implementation of the method in the calculations of real constructions. The result of the research is the developed algorithm of transition from 3D elements to 1D and the creation of mathematical material model, which shows the physical and mechanical properties of steel cables.

The increased public interest in green technology combined with new environmental policies results in the need for lightweight vehicles with a reduced global environmental impact. A method that is gaining importance is the reduction of the cradle-to-grave carbon footprint of utilized materials. For structural components, one promising approach is the utilization of biomaterials such as veneer-based hybrid materials since wood is a natural carbon storage. The specific properties of wood are comparable to aluminum and magnesium, and thus have the potential to replace some structural and semi-structural components of a vehicle. When required, the hybridization of veneer-based materials with traditional materials, such as metal sheets, can further increase its structural performance. While it is technologically possible to implement such a material concept, a key challenge is the application-oriented simulation of non-hybridized and hybridized wooden structures. A suitable simulation method and material model must be found and validated. At the Institute of Vehicle Concepts of the German Aerospace Center, the methodology to simulate beech veneer-based structural components for static and crash load cases has been developed over the last three years. The characteristics of the veneer were determined in order to fit a material model in LS-Dyna which was then implemented in various simulation approaches for wooden structures. The findings were also transferred to simulate hybridized structures. This paper presents the chosen approach to simulate a hybridized generic structure that represents a door impact beam. It compares simulation results of different three-point flexural bending tests with testing results. The findings were generated in the project “For(s)tschritt”. The fully qualified simulation approach and material model will contribute to the structural application of non-hybridized and hybridized veneer-based composites in modern vehicle structures.

A new approach to optimization of linear reinforced concrete elements of variable height without prestressing reinforcement is proposed. It is based on the design situation, which is determined by the strength requirements of normal and inclined sections. At the same time, the design and design requirements for sections of various heights are fully met without the need to set the design compressed reinforcement. The study was carried out on the basis of taking into account the regularities of the resistance of reinforced concrete and the main provisions of the regulatory documents governing design and construction activities in the Russian Federation. Also used are the actual works of domestic and foreign scientists, corresponding to the research in this area. During the study, the results of strength calculations of normal and inclined sections were used, as well as the cost indicators of materials used for the manufacture of structures. The method of structural and analytical analysis was used using the correlation dependences of the factors under study. Analytical dependencies and graphic materials are presented that establish the optimal parameters of an element with a minimum cost of materials in order to use them in design practice. The proposed method for determining the efficiency of a structure, taking into account the cost indicators of materials, can be applied in design practice. Recommendations for design are given to ensure the construction of the minimum cost and meet the requirements of strength and durability.

This paper presents a brief review of various research done on bar straightening. Bar straightening can be considered as a significant process in the value stream of bar production. The paper dealt briefly on various types of arrangements available in bar straightening process. The theoretical perspectives have been looked into in simplified manner. Residual stresses, curvature, and bending moment thereof due to reverse kinematic bending have been discussed. A system approach has been taken as how development on bar straightening process emerged over the years. The recent developments in bar straightening using modelling / numerical modelling give an insight of reduction in curvature after reverse bending. Simulation/Numerical simulation approaches in bar straightening process have been looked into. Key aspects like positioning of rolls and minimization of straightness errors have been considered. How control system is applied with Multi-Step Straightening Control System (MSSC) in reducing curvature has been discussed. The paper has been intended to present an overall view of bar straightening from inception till modern times.

The article proposes a mathematical model for the formation process of degradation failures of quarto roll systems according to kinetic criteria of strength and wear resistance of materials. It is a statement of the stationary boundary-value problem of the theory of parametric reliability of the roll-strip system in a quarto stand using the basic equations of the kinetic theory of damage to solids, the energy-mechanical concept of wear of tribocoupling, and the thermodynamic condition of structural destruction. Firstly, the energy density of structural defects of local volumes of materials in the zones of maximum bending stresses in the backup roll, as well as contact stresses in the interaction zones between the rolls and the strip, was selected as parameters determining the state of the roll system according to the criteria of roll strength. Secondly, the values of the current profiles of the active generators of the backup and work rolls are taken as geometric parameters of the quarto system state. Their change in the wear process of the rolls during rolling in the zone of their interaction and the worker in the deformation zone reflect the evolution of the quarto roll system according to the criterion of the profile accuracy of the rolled strips.

In human prostheses, rigid parts commonly use hinges, shafts, ball joints, and bearings to connect. Nevertheless, human anatomy body parts are flexible, and the movement comes from bending flexible parts. In particular, the hand is the member in charge of interacting with the environment. For this reason, when an individual suffers an amputation, his abilities are greatly diminished. Therefore, a prosthesis that restores much of his basic physical abilities is required. This problem can be solved using flexible joints. The human hand has 27 degrees of freedom (DF) or more, of which 9 DF correspond to the interphalangeal joints which can be replaced with the design made in this research since it can be adapted to the different dimensions of each finger.

Thin-walled steel profiles are the key to cost efficient lightweight structures. Structure parts and design elements in cars and trucks are often based on curved and hydroformed profiles. The possible production chains for those parts are often long and complex, and the machines and tools are expensive, and the flexibility is low. For smaller production lots, e.g., for applications in aircraft industry, these processes are not efficient. This paper shows a solution for smaller and middle-sized production lots realized by an integrated process for bending and cross section forming of tubular lightweight parts by a forming operation based on a working media made of metal alloys with high plasticity. The paper shows the process idea, fundamental mechanisms, the process analysis, and the process limits. Furthermore, a strategy is given to find a practical process windows.

Each product consists of a certain material. In order to determine the specific material of a component, it is first necessary to know what load will be exerted on the component and what effect the environment in which the component will be located will have (temperature, humidity, chemical environment, etc.). At the same time, it is necessary to have an overview of the available materials, their properties, price and possibilities of their application in practice. With the ever-increasing volume of technical production, the consumption and quality requirements of technical materials also increase. Natural material resources are depletable and non-renewable. For this reason, new and affordable technologies for the production and processing of technical materials are currently being formed. Composites are currently widely used in various fields, especially for their excellent mechanical properties and ability to fully replace the “basic” resp. Original material in order to optimize the production process, reduce costs and modernize production and the products themselves. Experimental measurement of mechanical and viscoelastic properties of composites under stress (tension, compression, bending, compression) is performed by various methods. One of them is DMA analysis (Dynamic Model Analysis), which is part of the methods of thermal analysis. The purpose of the analysis is to quantify the relationships between deformations and deformation forces (as a function of temperature) in situations where these quantities change over time, which allows the measurement of highly elastic materials such as rubber and plastics. The article offers a brief overview of the basic types of reinforcement and core materials used for layered composite structures, examples of use in practice and experimental measurements using DMA analysis.

Abrasive shavers (gear hones) are applied for gear tooth honing in case of finish processing of lateral faces of hardened gear teeth; they are manufactured from resin bond abrasive materials using uncontrolled casting. Shaver teeth feature contact and bending strains during operation; the total strain value increases significantly from the teeth roots to the tips. Besides, the sliding parameters and the contact area pattern size of the engage teeth vary depending upon the strain values. It can be demonstrated using a geometric model of abrasive shaver teeth profiles contacting with a gear being processed. Due to elastic deformation, the shaver tooth center shifts, which affects the values of the main engagement parameters, primarily the radii of curvature. The values of specific sliding and the contact area pattern size of the tooth-tip profiles decrease and distribute more uniformly along with the teeth height. The influence of such a phenomenon on the gear tooth honing parameters can be anticipated. The optimization criteria are suggested in order to estimate the performance level, quality, and accuracy of processing by the relation of specific sliding values and the contact pattern size. Considering the criteria values, the abrasive shaver parameters and the honing process can be designed optimally.

The 3D concrete printing has been developed as one of the digitized technologies for the construction industry aiming to cope with some drawbacks of conventional construction methods. One of the main particularities of 3D printed cement based materials is its anisotropic/orthotropic behaviour, which is related to the layer wised approach of these addictive manufacturing processes. In this work, a cement based composition reinforced with polyvinyl alcohol fibre was used to evaluate the post-cracking behaviour of printed specimens in two different loading directions related to the layers’ orientation. Three-point bending tests were used to indirectly obtain the tensile behaviour (i.e. stress–crack width relationship) through an inverse analysis procedure. The results of inverse analysis showed that tri-linear relationship was able to accurately model the post-cracking behaviour of PVA-FRC specimens. No significant differences were observed on the tensile behaviour of 3D printed and mould cast specimens.

Reinforced concrete structures are widely used in all areas of modern construction, which is explained by their durability, the possibility of using local building materials, low consumption of steel, and a variety of forms. The increasing requirements for ensuring the reliability of reinforced concrete structures makes it necessary to improve the calculation of bent elements. The main difficulty of the calculation is that “mild” steels, like all real structural materials, are deformed under force loading non-equilibrium and non-linear, while the desired physical relationship “stress – deformation” is usually reflected by analytical dependencies of high degrees (5 and higher). The authors consider the nature of the “stress – deformation” curves taking into account the heterogeneity of the physical properties of various steel components, the elastic limits on the tensile curve, the nature of steel deformation, the transition sections of the experimental tensile curves of reinforcing bars from the elastic limits and proportionality to the yield point determined by the results of experimental data from various devices, and the expression of the secant modulus of deformation of mild” steels is developed, which allows not only to calculate accurately reinforced concrete bending elements, but it also allows getting the elastic coefficients of individual sections of reinforcing steel when they are stretched.

Bent tubes are extensively used in the manufacturing industry to meet demands for lightweight and high performance. As one of the most significant behaviors affecting the dimensional accuracy in tube bending, springback causes problems in tube assembly and service, making the manufacturing process complex, time-consuming, and difficult to control. This paper attempts to present an accurate, efficient, and flexible strategy to control springback based on Machine Learning (ML) modeling. An enhanced PSO-BP network-based ML model is established, providing a strong ability to account for the influences of material, geometry, and process parameters on springback. For supervised learning, training sample data can be collected from the historical production process or, alternatively, finite element simulation and laboratory-type experiments. Using the cold bending of aluminum tubes as the application case, the ML model is evaluated with high reliability and efficiency in springback prediction and compensation strategy of springback.

The trend towards flexible, agile, and resource-efficient production systems requires a continuous development of processes as well as of tools in the area of forming technology. To create load-adjusted and weight-optimized tool structures, we present an overview of a new algorithm-driven design optimization workflow based on mixed-integer linear programming. Loads and boundary conditions for the mathematical optimization are taken from numerical simulations. They are transformed into time-independent point loads generating physical uncertainty in the parameters of the optimization model. CAD-based mathematical optimization is used for topology optimization and geometry generation of the truss-like structure. Finite element simulations are performed to validate the structural strength and to optimize the shape of lattice nodes to reduce mechanical stress peaks. Our algorithm-driven design optimization workflow takes full advantage of the geometrical freedom of additive manufacturing by considering geometry-based manufacturing constraints. Depending on the additive manufacturing process, we use lower and upper bounds on the diameter of the members of a truss and the associated yield strengths. An additively manufactured flexible blank holder demonstrates the algorithm-driven topology design optimization.

Currently, much attention is paid to sustainable development issues, including the search for new environmentally friendly materials and technologies. Such a material is geopolymer, the result of mixing aluminosilicates with an alkaline solution. It has many advantages over conventional concrete, including quick strength gaining. This quality is one of the key ones for the additive manufacturing technology, since the construction mixture for 3D printing must meet certain requirements. The purpose of this article is to determine the effect of fiber on the mechanical properties of geopolymer concrete in terms of 3D printing. In this study the composition of the working mixture with fiber for use in a construction 3D printer was selected and the cone flow diameter for mix and the compressive strength and bending strength of the concrete samples was studied in the age of 1, 3 and 7 days. The highest values of both bending and compressive strength were achieved by samples with 0.5% polypropylene fiber. On the 7th day, the flexural strength was 5.811 MPa, and the compressive strength was 44.035 MPa. The addition of fiber slightly improves the strength of concrete, however, it affects the overall integrity of the mixture and concrete, the technological properties of the mixture improve, the mix becomes more viscous. In the context of 3D printing, the resulting strength values satisfy the need of fast strength gain.

The multi-stage incremental sheet forming is a promising forming strategy to fabricate complex shapes through the rational design of intermediate shapes. To further improve the formability, the ultrasonic-assisted multi-stage incremental sheet forming is proposed. The present work aims to reveal the effect of ultrasonic vibration (UV) on the thickness distribution, strain–stress state and the forming force variation. First, the finite element (FE) model is established through ABAQUS software, in which the trajectory of the forming tool with the high-frequency vibration is defined via the user subroutine VUAMP. Then, after the verification of the FE model, the thickness evolution, the stress–strain state and the forming force are comprehensively analyzed. It is found that the thickness distribution can be effective improved by introducing UV. In addition, the stress concentration in the bending area is effectively alleviated and the equivalent plastic strain is obviously increased under the UV. Final, the application of UV can lead to a notable reduction of forming force and smoother forming force curves at the latter two stages. The findings of this work provides evidences that ultrasonic assistance is an effective strategy to improve the incremental forming process.

An innovative tube bending process supported by hydraulic pressure was patented in 1995. This process was designed for producing butt-welding fittings which particularly fulfil the dimensional specifications of the ASME B16.9, MSS SP-75, and MSS SP-43 standards. Since the patent has meanwhile expired, the bending process is now available for common use. This work presents a novel finite element (FE) model build using the software package LS-DYNA, which enables determining the process window for bending defect-free butt-welding fittings. This model was exemplarily applied for investigating the bending process of a 90° stainless steel elbow based on a straight tube of nominal pipe size (NPS) 6. Comparing the calculated geometry of the elbow with the actual geometry of an industrially produced elbow revealed very good dimensional agreement. This confirms that the presented model can be utilized for determining suitable process conditions, which allow for producing defect-free components.

Selective embossing of sheet metal blanks, prior to processing, offers the possibility of locally modifying material properties. Small indentations applied on the sheet metal surface by a punch lead to increased material strength due to the induced strain hardening. Moreover, such locally embossed sheet metals show an enhanced process window with regard to forming processes and an improved performance under different loading conditions. The experimental study presented in this paper investigates the bending properties of high-strength steel sheets embossed on the tension or the compression surface of the bent blank. The effect of embossing on the bending resistance of two different materials (DP500 and TRIP780) was analyzed by varying the embossing patterns by density and depth. As a result, bending forces required in the tests rise when increasing the proportion of the embossed surface. Therefore, the paper reveals potentials of local embossing with regard to a specific modification of bending properties of sheet metal components, thus enabling their use in lightweight constructions.

Inclined rotary forming (IRF) combines bending and axial compression with rotation and is employed for forming flange shaft-structured parts from round rod billets. Although the forming load is smaller than the one in conventional processes, cracks may develop during this process. However, it is difficult to predict the onset of cracks using conventional ductile fracture prediction equations. In this paper, an equation for predicting ductile fractures is proposed, which considers anisotropic ductile damage. The proposed equation is expressed as a second-rank tensor resulting from the inner product of the stress tensor and the strain increment tensor. Referring to the previously published results on the compression of cylindrical specimens, the difference between diagonal and longitudinal sidewall cracks was clarified by considering the anisotropy of ductile damage. The proposed equation was then applied to the IRF process, wherein diagonal cracks developed at the outer rim of flange. Consequently, it was possible to estimate the requirements for reducing diagonal cracks by controlling lubrication conditions.

3D Printing has become a popular additive manufacturing method for fabricating various components, both in industry as well as at the hobbyist level. While it is often used for prototypes or decorative trinkets, it is increasingly being used to create structural components. Inherent to 3D printing, parts are built in discrete layers and this results in a certain amount of structural uncertainty in the form of discontinuities, voids, and poor inter-layer bonding. This research explores the differences in the ultimate strength and fatigue life for 3D printed acrylonitrile butadiene styrene (ABS) components built by various build/layer orientations and construction parameters using tensile and rotating bending tests. SN fatigue curves and material strengths are reported.

In this paper, the elasto-plastic model in plane stresses was presented to characterize the mechanical behavior of paper sheets of double corrugated cardboard. Tensile tests of three types of paper were performed to obtain the three force-displacement curves (MD, CD and 45°) for each type of paper. By using the Abaqus calculation software and the SiDoLo identification software, the 11 parameters of the elasto-plastic model for the skins and corrugations that constitute the corrugated cardboard were determined. These parameters of the elasto-plastic model allow us to model the corrugated cardboards in 3D structure by using the user subroutine VUMAT implemented in Abaqus/Explicit. The simulation and experiment of crushing and bending of double corrugated cardboards between the mortar and pestle system were carried out and have proved the precision and effectivity of the present model. The present model allows us to predict the mechanical behavior of orthotropic composite plates with the type corrugated cardboards without carrying out the experiments.

The following chapter, adapted from [129], deals with the stochastic optimisation of complex mechanical systems like a beam subject to bending and torsion [88, 177, 178]. The adopted (and proper) theoretical basis for such an optimisation is multi-objective programming [152]. Multi-objective programming allows the designer to find a preferred solution by means of a proper selection among the set of optimal solutions called “Pareto-optimal set”. The designer, by means of the addressed selection, defines a set of parameters (design variable set) which defines the system under consideration. The choice (selection) is made after the optimal combination of the system performances has been identified by the designer.

The paper describes development of a soft-computing-based identification software FRCID-4PB for material parameter determination of ultra-high-performance fiber-reinforced concrete composite material. Such a determination is performed with the help of experimental data from four-point bending tests used in inverse analysis based on artificial neural networks and nonlinear computational modelling of tests. A new tensile softening model for studied composite material has been proposed and tested with the help of sensitivity analysis. The procedure also utilizes stratified statistical simulation method for the preparation of a training set for the artificial neural network. Trained network is then implemented into the software allowing routine and user-friendly identification of material parameters from the test results. The main aspects of the software implementation, its testing and application is described and discussed in the paper.

The gluing process of thin wood veneers is a crucial step for the use of wood as a finishing layer to injected plastic parts, through the overmolding process. Based on the published studies on pine wood gluing for the production of laminated veneer lumber (LVL) and plywood panels, a phenol–resorcinol–formaldehyde (PRF) glue was selected for the assessment of the gluing process of Portuguese maritime pine wood. The gluing of the wood veneers was carried out in a hot pressing machine, equipped with electronic temperature control, under 800 kPa of applied pressure, and a glue mix spread rate of 350 g/m2. The influence of the gluing parameters (gluing temperature and pressing time) on dimensional and physical properties of the glued wood veneers was evaluated. Additionally, experimental determination of bending strength and modulus of elasticity of the glued wood veneers were carried out through three-point bending tests. According to the results obtained, and despite the uncertainties that need to be addressed, it seems feasible to consistently glue maritime pine wood veneers to use them as a top layer in the overmolding process of plastics.

Robots for human are required to have safety while working with them. Therefore, we focused to a pneumatic artificial muscle which has intrinsic flexibility. In this paper, we developed a bending-type pneumatic rubber artificial muscle (BPAM) and a unit driven by 3 BPAMs. We are aiming to develop redundant degree of freedom manipulator by connecting a number of units. We also conducted load characteristic experiment of the unit. Experimental result showed that the unit can drive omnidirectionally as we proposed. However, the unit has uneven output characteristics because these BPAMs were made by hand, individual differences in characteristics of BPAMs were occurred for example thickness of rubber tube and a little misregistration of aramid fiber in axial length. Then, the unit was controlled by neural network learning. Trajectory tracking experiment result showed that actual trajectory was off-center from desired trajectory. Nonetheless, the unit reproduced tendency of trajectory, and we consider that the trajectory control can be improved by adding attitude feedback control.

There are given the investigation results of bitumen modified with the polymer latex Butonal NS 104 depending on temperature, time and the modifying agent amount, taking into account the manufacturing company BASF recommendations. The carried research has shown the possibility to produce bituminous polymer on the polymer latex Butonal NS basis that meets the Ukraine technological normative documents requirements. On the conducted investigations basis, there have been established the rational parameters of bituminous polymer binding agent production process thus allowing determining the conditions of the polymer latex Butonal NS 104 application under the domestic production conditions. The study found that bituminous polymer bending agent physical-mechanical properties change in the wide limits (by 50–100%) depending on the polymer amount, and the preparation process parameters show the possibility of active regulation of its properties under the particular operating conditions. It is established that bituminous polymer bending agent properties resistance and stability under the high process temperatures influence show the possibility of its sufficiently long-term storage under the production conditions with the original properties keeping.

Observations of the operation of the switch chairs show that they are deformed during operation. In some cases, their deformations appear in the form of cracks due to the high level of bending stresses. The switch chair is a plate of variable stiffness lying on an elastic foundation. The paper considers the built probabilistic model of the operation of switch chairs of the rail switches on reinforced concrete bars, well consistent with the results of the trial operation of such switches, which allows calculating the failure distribution of switch chairs depending on the characteristics of the metal from which they are made, the initial tightening of the fasteners and the stress spectrum arising from train load. The graphs of failures of switch chairs in transit at various axial loads, obtained using the developed model, make it possible to plan the replacement of switch chairs of the rail switchers with reinforced concrete beams when changing the main metal parts. With an average network axial load of 140 kN, at the time of the first change of metal parts, it is necessary to prepare a replacement of 2–3% of switch chairs. With increased axial loads of 250 kN, the number of replaceable switch chairs should be about 16%.

Pre-stressed reinforced concrete structures are widely used nowadays in construction industry. Such structures are rather cost-effective and give an opportunity to implement project ideas which are impossible without the use of pre-stressing technology. The issue of metal consumption reduction is highly topical. One of the possible solutions is the usage of steel-concrete elements with external reinforcement. The effectiveness of the use of reinforced concrete structures with external reinforcement has been repeatedly noted at international construction symposia and conferences. Application of advanced technologies and acceleration of scientific and technological progress in the construction field leads to increase in the reinforced concrete structures’ usage and expansion of application fields. Moreover, advanced technologies increase their efficiency and cost-effectiveness. This article describes results of research pre-stressed steel-concrete beams, strengthened with the package of steel bars with different ratio of sheet and rod reinforcement in the zone of pure bending moment action. The purpose of this research was definition of reinforcement percentage influence on loss on compressive forces’ loss in pre-stressed reinforced concrete beams strengthened with a package of steel bars. In addition the aim was to evaluate effectiveness of steel bars’ usage in combined reinforcement. The practical significance of the experiments is to study the loss of compressive forces in pre-stressed bending elements with tape and rod reinforcement, taking into account the influence of different ratios of reinforcement areas within the combined reinforcement and development of design and calculation proposals for such structures.

In the current design of refrigerator turnover beam, it mainly depends on the experience of structural engineers. The overturned beam often has problems such as bending, large assembly gap, large overturning resistance and condensation. The mold needs to be changed repeatedly, extending the product design cycle and increasing the verification cost. It will also bring market complaints and increase the cost of after-sales maintenance. Through the CAE simulation technology, the structure simulation analysis, thermal stress simulation analysis and rotation simulation analysis of the refrigerator turnover beam are carried out, and the targeted optimization design of the refrigerator turnover beam can shorten the design cycle, reduce the design defects of the refrigerator turnover beam, and improve the reliability of the refrigerator turnover beam.

As a result of the constantly increasing world population and its purchasing power, it becomes more and more clear that raw materials are finite and the capacity of the earth to renew the stock of raw materials is almost exceeded. This is also important for construction industry as half of the extracted materials and about one third of the water consumption is absorbed by this sector. During the last years, a lot of progress has been made in creating more energy efficient buildings, but unfortunately, construction represents at this moment still 40% of the energy demand in Europe and 36% of the total CO2 emission [1]. However, the construction sector offers significant potential to handle these struggles and a possible solution to improve the sustainability is through automated construction by for example 3D printing the structural components. This new way of manufacturing has the advantage that there is no need for energy demanding and expensive molding, there is a larger freedom of form and there is the opportunity to use the material in a more eco-friendly way since it is only used where necessary. However, before acceptation of this technique on the construction site, it is necessary to compare the structural behavior of printed and cast specimens. For that reason, two wall types were tested on their compressive strength and also two types of reinforcement above a window opening were investigated through 3-point bending tests. These results showed that, in general, the mechanical performance of the suggested wall types is greater than that of traditional walls consisting of brickwork. This, in combination with the lack of molding and the higher construction speed, can accelerate the application of 3D printing on site.

There are various ways to illustrate how composites are stronger materials than the components parts of the composite. Using a piece of Styrofoam, approximately 12″ × 1″ × 1/2″, have a volunteer place the material over their head, and begin to bend the material ever so slowly. The Styrofoam material will eventually break, showing little ability of restraining the force being applied. Take a send piece of Styrofoam of similar dimensions. Apply a strip of duct on one side of Styrofoam thereby making a composite material. With the “duct” tape on the top, have the volunteer repeat the bending procedure. The composite Styrofoam will bend but not break. The composite material has a new and different characteristic; it can withstand the force applied and is therefore stronger than the original material. What happens when the composite Styrofoam has the duct tape on the bottom? When the volunteer places the composite Styrofoam over their head and applies a force as done in the past, will the material created withstand the force or not? What would occur if a new piece of Styrofoam of similar dimensions has a piece of duct tape wrapped entirely around the Styrofoam and a similar force is applied as in the previous two cases? The tape and Styrofoam system is a form of lamination. “Lamination is the technique of manufacturing a material in multiple layers, so that the composite material achieves improved strength, stability, sound insulation, appearance or other properties from the use of differing materials. A laminate is usually permanently assembled by heat, pressure, welding, or adhesives” (Lamination 2015).