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There are many photovoltaic (PV) applications where lighter weight and/or bendable PV power would be beneficial. This includes the curved surfaces of buildings, buildings with weight limitations, boats, automobiles, or other portable applications. In many of these cases, the bending will be only a single occurrence at installation or the amount of bending, even if repeated, is not dramatic. This allows for crystalline silicon modules to be used. For flexible applications, the dominant material for the frontsheet is polyethylene tetrafluoroethylene (PETFE). As a fluoropolymer it resists soiling, is UV stable, and PETFE is a more mechanically durable fluoropolymer. However, in the interests of keeping costs down, less expensive alternative polymers are desirable. In this study, highly accelerated ultraviolet light and heat stresses are applied to candidate materials and the degradation kinetics are determined to provide information to evaluate their suitability for use in a PV application.

Creep age forming (CAF) is an advanced forming technology that combines creep deformation and age hardening processes. When compared with the conventional forming technologies including roll bending and shot-peen forming, CAF has many advantages of low residual stress, excellent dimensional stability, good service performance and short production cycle. It is an optimal technique for precise manufacturing for shape and properties of large-scale complicated thin-walled components of light-weight and high strength aluminum alloys in the aviation and aerospace industries. Nevertheless, CAF has an inevitable disadvantage that a large amount of springback occurs after unloading, which brings a challenge on the accurate shape forming and property tailoring of components. Therefore, how to achieve accurate prediction and control of springback has always been a bottleneck hindering the development of CAF to more industrial applications. After the factors of affecting springback and measures of reducing springback are summarized from the internal and external aspects, constitutive models for predicting springback and springback compensation methods for CAF of aluminum alloy panel components are reviewed. Then, a review of research progresses on tool design for CAF is presented. Finally, in view of the key issue that it is difficult to predict and control the shape and properties of components during CAF, the technical challenges are discussed and future development trends of CAF are prospected.

Additive manufacturing using carbon-fiber-reinforced plastics (CFRP-AM) allows for fabricating machine parts that are lightweight with high strength and high stiffness. Here, continuous carbon fibers inside a base structure improve the strength and stiffness in the fiber direction. For CFRP-AM fabrication, it is important to design the structure with some consideration of the carbon fiber arrangement. This study aimed to propose a design optimization method for CFRP-AM. The target structure is a two-dimensional infill pattern structure that is lightweight, has a low volume, and easily fabricated using CFRP-AM. To optimize the infill structure and the carbon fiber arrangement, we represented the structure as a geometric graph and discretized for restraining computational costs. We encoded these aspects into a chromosome composed of binary genes considering a continuity of carbon fibers and optimized them using a genetic algorithm. To explain the proposed method's effect, we conducted case studies using a cantilever beam. The first involved optimizing the carbon fiber arrangement to reinforce the structure with less fiber and reduce material costs. The second involved simultaneously optimizing the infill structure and the carbon fiber arrangement to reduce both the base materials and the carbon fiber while retaining the high strength. Following this, we applied the proposed method to optimizing a 3-point bending structure. In addition, the proposed method was applied to designing a bicycle brake lever and the optimized structures were fabricated with CFRP-AM. The results confirmed that the proposed optimization method would be useful in the area of CFRP-AM fabrication.

The components made out of spring steel are usually subjected to different environmental conditions when in service. The hydrogen embrittlement is one such process which is inevitable for spring steel. The embrittlement will make the material brittle and induce cracks at the edges and corners. In the presentation experimental investigation has been focused on the analysis of the behavior of embrittled spring steel with edge and corner cracks, under impact and bending loads. The specimen preparations and experimentations have been carried out according to ASTM standards. The results have revealed that the embrittlement induced side and corner cracks play a vital role in the fracture process of the spring steel. The mechanism of fracture in edge and corner notched samples has been analyzed with the aid of scanning electron microscopy. The microscopic observations have shown that the failure in the edge and corner cracked samples is almost catastrophic, and increase in the rate of crack growth in these embrittled samples is highly influenced by the embrittlement induced cracks.

The friction stir welding and its weld properties such as tensile, micro structure of weld, grain size, and fine mixture of two alloys at to joint using testing methods. To determine the weld quality and conclude properties such as weld quality, weld strength, maximum stress that weld can withstand during operation conditions. There are various processes that involve testing the welded joint from which many are the destructive ones that are used to find the tensile strength, hardness of the joint, bending test and other tests. This paper gives an overview on how important is the fine mixture of the samples that undergo friction stir welding and how it impacts the welded sample properties. Friction stir welding creates more opportunities that are related in understanding the quality of the joint such as testing methods to increase the production by faster analysis of defects. This testing method effectively utilizes that modern computation and means to boost the production. This level of understanding creates the path to innovate new techniques to resolve industry level problems in quality control. As the non-destructive testing methods provided with no loss of the testing specimen and understanding the quality of the material after they are assembled. Such initial developments made the usage of NDT in quality control and effective results to determine the quality.

Latent heat thermal energy storage was widely used to solve the problem of the intermittency in time and space for solar energy systems. To improve the energy storage efficiency, metal fins were typically further added to the shell side to increase thermal conductivity of phase change materials (PCMs). However, the positive effect of metal fins on enhancing heat transfer has not been fully utilized. In this paper, a novel design on angled fins was proposed to improve the thermal transport for PCMs in a shell-and-tube thermal storage unit. A numerical model was built and verified by comparing with experimental observations on the melting front evolution and temperature history. Bending angles for fins ranging from 0° to 75° were designed upwardly and downwardly and quantified on the melting front shape and location, melting time, and temperature field. Results demonstrated that melting rates were improved for the angled-fin cases other than cases with large bending angles. The case with a 10° downward angle exhibited as much as 55.41% reduction in full melting time. Simultaneously, the temperature uniformity can be improved by 20.00%. The novel design strategy on fin angles engendered a promising solution to enhancing thermal storage for emerging engineering applications.

Friction stir welding (FSW), a solid-state joining process, is commonly used to join Aluminum alloys in aerospace, marine, car industry, and numerous industrial applications. Lightweight materials are commonly used in the transport industry to minimize component weight, and thin-walled structures are increasingly being used as energy-absorbing components in the industry. Even though FSW of plates is well established, FSW of pipe is still at the laboratory level. In this work, FSW for 6063 aluminum alloy pipe has been experimented through a novel procedure and it’s flexural and crashworthiness studies are carried out. The attempt of FSW is performed with a unique welding fixture mounted on a traditional milling machine. The crashworthiness test is conducted to analyze the ability of the structure to nullify the life loss during impact and the crash force efficiency of the pipe is identified. It is further analyzed for the flexural test to identify the bending load of welded aluminum alloy pipes. This study also exposes the basic understanding of the FSW procedure and its metallurgical implications of a friction stir welded pipe.

Welding is one of the join processes of any materials with usage of filler metal along with addition of heat, pressure on the surface parts. Gas Tungsten Arc welding (GTAW) is one type of joint method in which electric-arc formed and preserved amid non-consumable electrodes. the aim of this particular paper is to comparing the defects instigated of welded-Joint and mechanical behaviors such as tensile testing, bending, hardness, and impact test under various loads and conditions performing on work specimen in destructive testing. The effort of butt joints is made on stainless steels 304(SS304) plates via TIG welding apparatus the inner defects of specimens found from radiography testing in Nondestructive testing. Finally, explore the performance and conditions of TIG welded- plates after completing the work to compare radiography testing defects and mechanical properties.

A composite material is created by combining at least two materials to create a unique combination of qualities, one of which comprises stiff, long strands and the other of filaments. And it is mainly concerned with improving ordinary fibre composites to explore the extra possibilities of use. Such typical fibre composites in the accommodation and building areas are suitable as wood alternatives. Many large loads of different yields are supplied, but much of their squandering has no practical use. Horticultural squandering incorporates a variety of dry natural resources and the influence of silanee coupling agents on mechanical characteristics like bending strength, tensile strength, and impact intensity in sugar cane baggage and PP (polypropylene) composites discussed in this Research. The reinforcing material was treated with a 0 percent coupling agent, 10 percent, and 20 percent. This substance was present for the production of composite boards via compression molding. The influence on mechanical parameters such as stress, bending, and impact strengths of the composites were analyzed by the silanee coupling agent.

The continuation of optimization of channels and I-beams bent closed profiles (BCP) with tubular flanges made of rolled sheet of different thicknesses is presented. Such profiles are intended for light steel thin-walled structures (LSWS), which are distinguished by high technical and economic indicators and massive demand in industrial and civil construction, which confirms the relevance of their further development. The main results of the calculation of the optimal bending arrangement of composite sections of I-beams from sheet blanks of different thicknesses, including channel-type BCPs unified in terms of optimal parameters, are also presented. The aim of the study is to show that the characteristics of the LSWS can be further improved by shaping profiles, combining straight and round outlines of closed and open contours in a composite section. Methods. By means of experimental design studies, solution of optimization problems and variant design of I-profiles, their composite sections from sheet blanks of different thicknesses, including blanks of channel profiles, have been refined. The originality of channels and I-shaped BCP has been confirmed by patent examination. Results. The I-shaped BCP consists of two tubular shelves and one double thickness wall. Calculation of the optimal layout of an I-shaped BCP made of rolled sheet of different thicknesses for bending showed that the bearing capacity is limited by the ratio of the thickness of the flanges and the wall of its composite section. In particular, when the thickness of the flanges is 2 times the wall thickness, the strength is maximum at a ratio of width to height of 1/11, and when the thickness of the flanges is 0.6 times the wall thickness, the strength is maximum at a ratio of 1/3.3. With the ratios of the width and height of I-shaped BCP of 1/2.68...1/3 and channel-type BCPs of 1/5.36...1/6, their composite sections should be optimally assembled from standardized blanks.

This paper introduces a novel type of cold-formed steel box girder assembled from C-section flanges and sinusoidal corrugated webs, and the structural performance of such box girders was experimentally and numerically investigated. A total of seven cold-formed steel box girder specimens were fabricated by self-drilling screws and were tested subject to three-point bending. Prior to testing, the initial geometric imperfections of the sinusoidal corrugated webs were accurately determined using the 3D optical scanning technique. The structural behaviour of the tested box girder specimens, including load versus displacement curves and corresponding failure modes, was obtained and reported herein. The load-carrying properties of the adopted self-drilling screw connections were examined by separate single lap shear tests. Elaborate finite element (FE) models of the cold-formed steel box girders were developed by ABAQUS and were further validated against the obtained test results. Upon validation of the numerical models, the influences of key parameters including the number of screws, the corrugation ratio a/q, and the initial geometric imperfections were discussed in detail. It has therefore been recommended that the double-screw connections and appropriate corrugation ratios be adopted for design of cold-formed steel box girders with C-section flanges and sinusoidal corrugated webs.

Fused deposition modeling (FDM) is a practical 3D printing technology to print thermoplastic and composite materials. The FDM 3D printing process has gained substantial attention due to its capability to produce complex and accurate components. Recently, the wood particles-based filament in 3D printing has become a subject of interest, which is due to their prominent advantages, such as thermal resistivity, corrosion resistivity, biodegradable characteristics, and being environmentally friendly. Therefore, this research study aims to investigate the mechanical properties and statistical prediction model development for coconut wood–polylactic acid (PLA). The experimental investigation was carried out according to the ASTM standards (tensile—ASTM D638 Type 1, compression—ASTM D695, and bending—ASTM D790) at different infill densities (25, 50, and 70%) and five different infill patterns. The obtained results proved that concentric infill pattern accompanied by 75% infill percentage achieved the most outstanding tensile and bending behavior. For compression testing, grid infill pattern accompanied by 75% infill percentage exhibits maximum compression properties. In overall, the octagram spiral infill pattern shows the weakest properties among all the infill patterns. The experimental results were further analyzed using response surface methodology to identify the effectiveness of studied parameters on mechanical properties and to derive a mathematical model. The derived mathematical models related to studied mechanical properties have been proposed to predict the desired mechanical properties with respect to the variation of infill patterns and percentages.

Ribs in aircraft wings maintain the airfoil shape of the wing under aerodynamic loads and also support the resulting bending and shear loads that act on the wing. Aircrafts are designed for least weight and hence the wings are made of hollow torsion box and the ribs are designed with cut-outs to reduce the weight of the aircraft structure. These cut-outs on the ribs will lead to higher stresses and stress concentration that can lead to failure of the aircraft structures. The stresses depend on the shape of the cut-outs in the ribs and thus in the present work, the commercial software ANSYS was used to evaluate the stresses on the ribs with different shapes of cut-outs. Four different shapes of cut-out were considered to study the effect of cut-out shape on the stresses in the ribs. It was found that the best shape for the cut-outs on the ribs of wings to reduce weight is elliptical.

Flexible pipes are complex structures made of different layers and different materials. They are used in the oil and gas production in the off-shore platforms to conduct the oil or gas between different units, such as platforms, Christma's tree and transportation ships. The internal carcass of flexible pipes is made of duplex stainless steels type 2205 (UNS S32205 or S31803). In the production line, sheets of 1.8 mm thickness of this material are submitted to uncoiling and cold bending operations to form “S” profiles which are assembled to form the internal carcass. The end of one coil is welded to the begin of another, to make the process continuous. The welding process is autogenous automatic gas tungsten arc (GTAW). This work analyses the microstructure and corrosion resistance of the weld metal and compares to the base metal. Besides, non-destructive tests and electrical resistance measurements were conducted in the welded joint and base metal. The samples analyzed were from a flexible pipe manufacturer. It was concluded that the joints of this producer were not heat treated, which results in inadequate microstructure and lower corrosion resistance in the weld metal.

Thin-walled pipes have been widely used in chemical facilities and propulsion structures, where the distortion problem induced by welding fabrication is common and prominent, deteriorating assembly accuracy and even reducing load-bearing capacity. External constraint has shown great capacity to control the residual stresses and welding deformation. The objective of this research is to investigate the effect of constraint on welding process in thin-walled 304 stainless steel pipes through experiments and numerical simulation. To include the clamping effect in the welding simulation, the external constraint was modeled as the additional heat dissipation and mechanical restraint. The seam welded pipes with and without constraints were both modeled for comparison purpose. Good agreement was obtained between numerical modelling and measurements in both pipes. The results show that the welding deformation and residual stresses are both obviously reduced under the effect of external constraint, which was found to work mainly in the cooling process by generating more tensile plastic strain so as to reduce the shrinkage force in both axial and hoop directions. The maximum distortion is observed on the middle section of constrained pipe and on the end sections in the unconstrained one, which is caused by the combined effect of bending direction on the circumference and shrinkage force in the axial direction according to the inherent strain analysis. Moreover, the analysis of welding deformation mode reveals that the inward bending induced by hoop constraint contributes to the dimensional accuracy of the pipe ends under axial shrinkage forces. Parametric simulation analysis of the external constraint strategy was performed, and the results showed that reducing the constraint distance was the most effective way to mitigate welding distortion in seam welded pipes.

To overcome the problem of welding distortion on conventional multiple segment structures, and the problem of requiring large-scale forming equipment and severe thinning occurs in high-pressure hydroforming process, a novel less-loading hydroforming process is proposed for manufacturing large-size hollow components in this paper. The geometrical relationship of the tube blank during less-loading hydroforming process is firstly discussed. Then, experiment and numerical simulation are conducted to investigate the forming behavior of a large-size tubular component of aluminum alloy 5A06 with rectangular cross-section. It is found that the needed internal pressure, die closing force, and axial force for the less-loading hydroforming are significantly reduced, which are about 1/22, 1/8 and 1/28 of those required in high-pressure hydroforming, respectively. During the less-loading hydroforming process, the tube blank is firstly deformed by bending to fill the die corners, and then deformed by circumferential compression. Moreover, the compression deformation characteristics make the thickness increase. However, a too large circumferential compression and/or an insufficient supporting pressure will cause a wrinkle defect. These results provide insights for less-loading and approaching uniform manufacturing of large-size hollow components.

The combination of hot-stamped steels and fibre-reinforced thermoplastics (FRTP) offers great potential for lightweight design. The process steps of hot stamping and thermoforming for the manufacturing of such hybrid structures are usually carried out in two separate steps. After hot stamping, the blank has to be reheated for the application of FRTP in order to enable the bonding of FRTP to the blank. Process integration of the individual processes means that reheating of the blank during thermoforming is no longer necessary. Due to non-uniform contact conditions during hot stamping between blank and tool, an inhomogeneous temperature distribution in the blank occurs, which would lead to non-uniform bonding properties between blank and FRTP after thermoforming. The aim of this work is to determine this non-uniform contact and the resulting heat transfer by a numerical model. By segmenting the tool in the model, a possibility is shown to control the non-uniform contact and to achieve a homogeneous temperature distribution in the blank after hot stamping. Furthermore, the temperature adaptability of the used tool and the resulting temperature distribution in the blank is investigated. Finally, the manufactured structures are tested in a numerical three-point bending test in order to be able to make a statement about their performances.

Analytical inspection showed that with a long service life of reinforced concrete structures of hydraulic structures, their individual elements such as reinforcing bars are destroyed due to insufficient fatigue and corrosion strength of the reinforcement metal. They occur mainly under the action of the main variable loads − bending, vibrations of reinforced concrete slabs, mechanical and erosion of the environment. The main causes of failure of the valve are its rupture and wear due to repeated action of force factors. The surface zone of the reinforcement in connection with concrete is especially intensively destroyed due to weak adhesion strength. The use of low-strength reinforcing steels can also be one of the reasons for the failure of reinforcement joints with concrete. Improving the corrosion and mechanical reliability of reinforced concrete structures of hydraulic structures is possible through the use of: for the manufacture of reinforcing bars which are the main power structure of reinforced concrete economically modified alloy steels, which undergo complex heat treatment and are characterized by high corrosion and fatigue properties. alternating) loads; The resistance against SCRN, VIR and corrosion-mechanical fatigue of reinforcing steels intended for the construction industry has been studied. It was found that the experimental steels, economically modified REE, copper-nickel, especially chromium niobium and vanadium meet the requirements of the International Standard NACE MR 0175-96 on chemical composition and mechanical properties, and steels of grades10HSNDA and 20F do not have a sufficiently high resistance SCRN 6% and CTR> 3%). Therefore, it is necessary to carry out a full (100%) input control of corrosion and mechanical resistance of all materials involved in the manufacture of reinforced concrete structures for hydraulic purposes for operation in hydrogen sulfide-containing environment.

Bent components and deep drawn cups are produced by direct usage of aluminium chips without melting following a new process chain: hot extrusion of aluminium chips to a cylindrical open profile, flattening, subsequent rolling and bending or deep drawing. The properties of the hot extruded chip-based AA6060 sheets are examined by tensile tests and microstructural investigations and the results are compared with those obtained from material extruded from conventional cast billets. The chip-based sheets were used to form components by bending or deep drawing. No significant differences between the bent components or deep-drawn cups made of chips and those from cast material are observed regarding their capability for further plastic forming operations. This makes the new process route a resource-efficient alternative for the production of aluminium sheet products., International journal of precision engineering and manufacturing-green technology;Vol. 9. 2022, pp 1035-1048

A novel method to improve the robustness of steel end plate connections is presented in this paper. Existing commonly adopted techniques alter the stiffness of the beam or the end plate to improve the connection’s robustness. In this study, the robustness is enhanced by improving the contribution of the bolts to the rotational capacity of connections, the higher the bolts’ elongation, the higher the rotational capacity that can be achieved. However, the brittleness of the bolt material, combined with its small length, results in negligible elongation. Alternatively, the load path between the end plate and the bolts can be interrupted with a ductile element to achieve the required elongation. This can be achieved by inserting a steel sleeve with a designated length, thickness, and wall curvature between the end plate and the washer. The proposed sleeve should be designed so that its ultimate capacity is less than the force in the bolt at failure, accordingly, the sleeve develops a severe bending deformation before the failure of any connection components. Using a validated finite element model, end plate connections with various parameters are numerically investigated to understand the performance of the sleeve device. The proposed system substantially enhances the rotational capacity of the connections, ranging between 1.37 and 2.46 times that of the standard connection. It is also concluded that the sleeved connections exhibit a consistent elastic response with the standard connections, indicating the proposed system is compatible with codified elastic design approaches without modification. Furthermore, for a specific connection, various ductile responses can be achieved without altering the connection capacity nor configuration.

Roll forming is increasingly used in the automotive industry for the manufacture of structural and crash components from ultra-high-strength steel (UHSS). Springback and end flare are common shape defects in roll forming and increase with material strength. The conventional roll forming process is limited to the manufacture of components with a uniform cross section while flexible roll forming can produce parts with variation in width and depth. In this paper, the flexible roll forming of an automotive component from three different high-strength sheets of steel is investigated. The experiments are carried out with a flexible roll forming prototyping facility and combined with finite element analysis. The study shows that the flexible roll forming of high-strength automotive components is possible. Springback and end flare depend on the material strength and the forming sequence and can be reduced with a flexible forming approach where the material is first overbent followed by bending back. Wrinkling of the flange was observed but the severity of wrinkling reduced with an increasing number of forming passes.

Thin construction is an advantage in the design of mechanisms. Among them, the soft-bending thin sheet actuator can fit into the shape of an object and grasp it after inserting a finger into a narrow space. However, to facilitate bending, these mechanisms are thin or made of soft materials, which leads to low stiffness. In this study, we proposed a thin metal sheet actuator that deforms its cross-section in accordance with the bending motion to achieve both thinness and rigidity. It was composed of two metal sheets connected with rotational joints and links. We focused on the anisotropic bending stiffness of the metal sheet and realized a three-dimensional deformation structure; it can be driven only with rotary-driven input using both torsional and bending deformations of the sheet. The experimental results indicate that the stiffness is up to 8.7 times higher compared to the undeformed sheet structure. In addition, we used this mechanism to realize a thin finger mechanism with a lifting motion after inserting a narrow gap between the object and the floor. Additionally, we realized a compliant contacting motion by focusing on different elasticities depending on the direction of bending.

Sandwich structures with Miura-ori core are supposed to be a promising substitution to traditional sandwich structures with honeycomb core in the aerospace industry. To reveal the failure mechanism of carbon-fiber-reinforced Miura-ori core sandwich panels subjected to in-plane compressive load, a multi-failure theory considering five potential failure modes, including bending and shear global buckling, face local buckling, face debonding and face crushing, is proposed. The critical failure loads of specific geometrical configurations are predicted and failure mechanism map is deduced to figure out the optimizing route for lightweight design. Three groups of the specimens with different face sheet thickness are designed and fabricated by adopting a hot-press molding and twice curing technique. Two typical failure modes including face local buckling and face debonding are revealed by the in-plane compressive tests, and the analytical results are in a reasonable agreement with the tested. Compared to corrugated core sandwich panels with the same dimension, Miura-ori core sandwich panels possess a higher anti-local-buckling capacity thanks to the stronger constraint of Miura-ori core to the face sheet. It is expected that this work can provide a significant guideline for the practical application and design of such kind of sandwich structures.

Different types of wood are used to manufacture of various wood products. In direct production processes, additional resources such as energy, adhesives, labor, etc. are also used. In line with sustainable environmental policies, all resources must be used more rationally, while simultaneously increasing the efficiency of the direct production processes. This research examined whether it is possible to reduce energy and labor resources in the technological process of hot pressing of birch plywood (nominal thickness 9 mm), by varying the holding time under pressure, pressure, and adhesive consumption. The Box-Behnken experimental design for a multifactor experiment was used to investigate the influence of technological parameters of plywood pressing. The highest strength in static bending both parallel and perpendicular to the plywood grain was achieved by pressing plywood with the following gluing parameters: highest pressing pressure, 3.2 MPa; minimal holding time under pressure, 9 minutes; and average phenol-formaldehyde adhesive consumption 150 grams per square meter.

Improving the mechanical efficiency is not the most important objective in the design of wind turbine gearboxes since the available wind energy is abundant and costless. The most important criteria for dimensioning the gearbox are the fatigue strength—bending and pitting—, noise emission, vibrations, and maintenance requirements. Nevertheless, mechanical losses increase the lubricant temperature and induce thermal stresses, which increases wear and cracking risk. This means that friction losses should be reduced as much as possible, but always regarding the contact and tooth-root stress levels, as well as the other operating parameters which should be kept for ensuring the required operating conditions.In this paper, a study on the variation of the friction losses with the tooth shift coefficients is presented. All the other geometrical parameters—number of teeth, tooth height, pressure angle, helix angle, face width, and center distance—are unalterable, since all of them have been chosen according to more important design requirements. In addition, to keep the contact and tooth-root stress levels, the shift coefficients of the sun, planets and ring are calculated in such a way that the transverse contact ratios are kept, and therefore the critical load points for bending and pitting are also unchanged. The radial clearance is also kept in order to allow the proper evacuation of the lubricant. Finally, all the geometrical constraints (undercut, pointing, root interference, secondary interference, backlash) are also imposed. With all these restrictions, the optimal shift coefficients for all the gears are calculated to minimize the friction losses.

In this work, the influence of material models used in the FEM simulation on the springback prediction is investigated. The interest of this paper is to extend the knowledge base regarding springback predictions in numerical simulation. The springback effect of a V-shaped sheet metal part made of TRIP steel, with a thickness of 0.75 mm was investigated. The bending angle was set to 90°. In the numerical simulation, Hill48 and Barlat yield criteria were used in combination with Ludwik's and Swift's hardening models. Achieved data from the numerical simulations were compared and evaluated with experimental test results. The experimental results showed the relation between springback and calibration force. The effect of specimen cut direction on the springback was smaller in comparison with the calibration force. The numerical results of the springback were not identical with the experimentally achieved springback values in most cases. Particularly, when a calibration force of 1 800 N was used in the simulation. The simulation results showed a good correlation between experimental and numerical results, when Hill48 and Barlat yield criteria were used in combination with Ludwik hardening law and calibration force F with the value 900 N was applied.

The continuing efforts of automotive technology aim to deliver even greater safety benefits and reduce the weight of a vehicle. Thin-walled beams (TWB) are widely used as strengtheners or energy absorbers in vehicle bodies due to their lightweight and excellent energy absorption capacity. Thus, researchers are interested in the collapse behaviour and mechanical properties of thin-walled beams under static and dynamic loadings. Circular TWB is commonly used in vehicle side doors. In the event of a side collision, this beam deforms and absorbs the greatest amount of impact energy. In this study, the energy absorption capability and crashworthiness of polygonal cross-section TWBs subjected to lateral impact was investigated using numerical simulations. Polygonal TWB ranging from square to dodecagon, as well as circular cross section, were selected for this study. Energy absorption (EA), specific energy absorption (SEA) and crash force efficiency (CFE) crashworthiness indicators are employed to evaluate the bending collapse performance. Because TWB thickness and weight have a greater impact on bending performance, they were kept constant across all polygons. In ABAQUS explicit dynamic software, finite element simulations are performed, and plastic hinges and flattening patterns of all polygons are examined. The results show that heptagon, octagon, and nonagon cross-section TWB perform better in crashworthiness than square and circular TWB.

Heat-assisted rotary draw bending (HRDB) is a promising technique for manufacturing difficult-to-form tubular components comprising high-strength titanium tubes (HSTTs) with small bending radii. However, as a multidie constrained and thermomechanical coupled process with many uncertainty factors, a high risk of several defects, such as cross-section distortion, over wall thinning, or even cracking, is present. Achieving the robust design optimization (RDO) of complex forming processes remains a nontrivial and challenging scientific issue. Herein, considering a high-strength Ti-3Al-2.5V titanium alloy tube as a case material, the five significant uncertainty factors in HRDB, i.e., temperature distribution, tube geometrical characteristics, tube material parameters, tube/tool friction, and boost velocity had been analyzed. Subsequently, considering the preheating and HRDB of HSTT, a whole-process thermomechanical three-dimensional finite element model was established and validated for virtual experiments. Further, considering the maximum section distortion Q and maximum wall-thickness thinning t as the optimization objectives and the mean and variance of material and forming parameters, an RDO model was established. Finally, the Pareto optimal solutions were obtained using the nondominated sorting genetic algorithm II, and a minimum distance selection method was employed to obtain the satisfactory solution. Results show that the optimized solutions considering the uncertainty factors reduce the maximum section distortion rate of HSTT after bending by 38.1% and the maximum wall-thickness thinning rate by 27.8%.

In the present work, springback behaviour of a three-ply clad sheet metal, comprising of layers of SS430 and SS304 sandwiched with a layer of AA1050 is investigated in V-bending by using analytical, experimental and simulation techniques. The developed analytical model is based on theory of bending using Hill’s anisotropic yield criterion. The tensile properties of the clad sheet and individual layers oriented at three different directions w.r.t. the rolling direction are characterized. The tensile properties of the individual layers are used in the material model of analytical and numerical predictions of the springback. It is observed that the samples of the clad sheet which are transverse to the rolling direction, exhibit highest springback values due to higher tensile strength of the sheet when compared with the results acquired for other two orientations w.r.t. the rolling direction. These results are endorsed by the springback results obtained from analytical and simulation methods. The effect of sheet setting on the die during bending is also investigated using different techniques. The resulting longitudinal stresses before and after springback are analysed on inner and outer layers of the tested samples using experimental and numerical simulation procedures. In both the cases of sheet settings, the results of residual stress after springback predicted by simulations agree with the experimental results except a few cases.

The microstructure and mechanical properties of a welded joint from heat resistant steel SA-335 P5 have been studied directly after welding (as-welded), after post-weld open-flame heat treatment (PWOFHT), and after post-weld electric heat treatment (PWEHT). The elemental content of the welded joint and Vickers hardness were determined. Tensile and bending tests were conducted. A positive effect of heat treatment (especially, PWEHT) on the mechanical properties and structure of the welded joint was shown. It was established that after the PWEHT, the welded joint from steel P5 meets the material requirements of the petrochemical industry. The use of as-welded joint from this steel is not recommended.

Linear friction welding (LFW) is widely used for the fabrication of high-value components in the aero-industry. The versatility of use and high integrity of joints produced by LFW, suggest that this technology could contribute greatly to sustainable engineering of the future. For example, in near-net-shape manufacturing, LFW is predicted to offer a substantial reduction in material waste and processing time, in addition to offering the capability of bonding material pairs currently difficult to fusion weld. LFW of steel components is seldom researched in published literature, with little information available on fatigue strength and fracture behaviour of such joints. This may hamper the confidence needed to popularise LFW in wider industry. Thusly, authors conducted a discovery-oriented fatigue study, followed by metallography and micro-hardness tests, conducted on a 100Cr steel LFW coupon and corresponding batch of parent material. The weld coupon was dissected into a set of fatigue specimens, to allow mapping of the joint's internal properties through individual fatigue estimates and fracture morphology of each specimen in the set. A prototype fatigue machine was constructed, designed to deliver independent displacement and force controlled bending or torsional loadings, representing complex real-world conditions more accurately than common, uniaxial tests. The hour-glass shape of fatigue specimens allowed for targeting strictly the weld region, inducing fracture at the weakest material section, which was found to lay far outside the immediate contact interface. Referencing distances from fracture points to the theoretical weld interface plane in each fatigue trial, resulted in discovery of a macroscopic pattern. Interpolated to a crack initiation plane, this pattern is proposed to reflect the heat-affected zone, across the greater LFW coupon. Authors also studied crack paths and suggest a link between fracture direction, residual stresses in joint and angular orientation of the crack initiation plane in respect to the theoretical weld interface.

System-in-foil technology continues to realize relevance in industry and research. In this article, a digital process chain for the fabrication of bend-sensitive sensor structures on a flexible polyimide foil is described. This means that none of the steps in this process chain requires the manufacturing of a structured mask or cliche. Therefore, an arbitrary layout can be manufactured and easily be changed without major effort. Patterning of the sensor layout is realized by direct imaging of a laminated dry film photoresist. The sensor structure is fabricated by a liftoff process using sputtering of a NiCr layer. Finally, the sensor structures are characterized by a static bending test.

Розроблено дуплексні технології Avinit, які об'єднують плазмове азотування Avinit N остаточно готових високоточних деталей з подальшим нанесенням надтвердих антифрикційних покриттів Avinit в єдиному технологічному процесі. Завдяки відсутності на азотуючій поверхні крихкого шару після прецизійного азотування, збереженню вихідних геометричних розмірів, які не потребують подальшої механічного доопрацювання, і сумісності процесів плазмового високоточного азотування Avinit N і вакуум-плазмового нанесення функціональних покриттів Avinit З дуплексні технології дозволяють забезпечити нанесення міцно-щеплених, високоякісних покриттів. Досліджено вплив дуплексного процесу на розміри деталей при плазмовому азотуванні високоточних шестерень і нанесенні функціональних покриттів Avinit С, вивчені властивості азотувального шару і параметри покриттів Avinit. Плазмова прецизійна технологія Avinit N дозволяє виконувати азотування остаточно готових деталей без зміни розмірів, в тому числі шестерень по 4 ступеню точності. Час азотування Avinit N в 2...4 рази менше, ніж при газовому азотуванні. Покриття деталей Avinit С310 підвищує мікротвердість поверхонь деталей і знижує коефіцієнт тертя, при цьому володіє достатньою адгезією до робочих поверхонь зубів шестерень і бігових доріжок підшипників. Проведено виготовлення високоточних зубчастих коліс за ступенем точності 4 з використанням дуплексних технологій Avinit. Аналіз результатів показує, що в межах точності вимірювання ніяких змін профілів зубів, їх розташування на зубчастому вінці, а також розташування зубчастого вінця щодо вимірювальних баз не спостерігається. Плазмове азотування дозволяє скоротити час азотування більш ніж в два рази в порівнянні з газовим азотуванням, при цьому товщина шару тендітної фази з максимальною поверхневою твердістю забезпечується в межах заданих величин для забезпечення необхідних показників контактної і згинальної тривалої міцності при виготовленні зубчастих коліс за ступенем точності 4 без шліфування після азотування. Вимірювання зубчастого вінця після азотування і покриття показали, що змін геометрії шестерні, обробленої по дуплексной технології, не спостерігається. Антифрикційне покриття Avinit С310 товщиною 1,5 мкм не спотворює геометрію профілів зубів. Всі параметри зубчастого вінця, виготовленого за дуплексною технологією Avinit, відповідають ступеню точності 4 відповідно до вимог технічної документації. Випробування виготовлених по дуплексній технології Avinit шестерень здійснювалося в складі редуктора двигуна АІ-450М на гідротормозному стенді ДП “Івченко-Прогрес” за програмою еквівалентно-циклічних випробувань. Пара експериментальних зубчастих коліс була встановлена в редуктор двигуна замість серійних коліс другого ступеня редуктора. Сумарний час випробувань коліс склав 26 годин. Після випробувань ніяких пошкоджень шестерні, включаючи покриття Avinit, не встановлено. Антифрикційне покриття Avinit С310 товщиною 1,5 мкм не спотворює геометрію профілів зубів в процесі випробувань в складі редуктора двигуна АІ-450М. Обмір параметрів зубів показав повну відсутність зносу. Avinit duplex technologies have been developed, combining Avinit N plasma nitriding of finished high-precision parts with subsequent application of Avinit superhard antifriction coatings in a single technological process Due to the absence of a brittle layer on the nitrided surface after precision nitriding, the preservation of the original geometric dimensions that do not require further mechanical refinement, and the compatibility of the processes of plasma precision nitriding of Avinit N and the vacuum plasma depo-sition of functional coatings Avinit C, duplex technologies allow the deposition of strong adhered, high-quality coatings. The effect of the duplex process on the dimensions of parts during plasma nitriding of high-precision gears and the application of Avinit C functional coatings was investigated, the properties of the nitrided layer and the parameters of Avinit coatings were studied. Plasma precision technology Avinit N allows nitriding of finished parts without changing dimensions, including gears of 4 degrees of accuracy. Avinit N nitriding time is 2 ... 4 times less than with gas nitriding. The coating of Avinit C310 parts increases the microhardness of the surfaces of the parts and reduces the coefficient of friction, while it has sufficient adhesion to the working surfaces of the gear teeth and bearing raceways. Manufacturing of high-precision gears with accuracy grade 4 using Avinit duplex technologies was carried out. Analysis of the results shows that, within the measurement accuracy, no changes in the profiles of the teeth, their location on the ring gear, as well as the location of the gear ring relative to the measuring bases are observed. Plasma nitriding makes it possible to reduce the nitriding time by more than two times compared to gas nitriding, while the thickness of the layer of the brittle phase with the maximum surface hardness is ensured within the specified values to ensure the necessary indicators of contact and bending long-term strength in the manufacture of gears according to the degree of accuracy 4 without grinding after nitriding. Measurements of the ring gear after nitriding and coating showed that there were no changes in the geometry of the gear processed by duplex tech-nology. Avinit C310 anti-friction coating 1.5 microns thick does not distort the geometry of the tooth profiles. All parameters of the ring gear manu-factured using the Avinit duplex technology correspond to accuracy grade 4 in accordance with the requirements of technical documentation. The gears manufactured using the Avinit duplex technology were tested as part of the AI-450M engine reducer at the Ivchenko-Progress hydraulic brake stand according to the program of equivalent cyclic tests. A pair of experimental gears were installed in the engine reducer instead of the serial wheels of the second stage of the reducer. The total test time of the wheels was 26 hours. After testing, no damage to the gear, including the Avinit coating, was found. Antifriction coating Avinit C310 with a thickness of 1.5 microns does not distort the geometry of the tooth profiles during testing as part of the AI-450M engine reducer. Measurement of the parameters of the teeth showed a complete absence of wear. Разработаны дуплексные технологии Avinit, объединяющие плазменное азотирование Avinit N окончательно готовых высокоточных деталей с последующим нанесением сверхтвердых антифрикционны хпокрытий Avinit в едином технологическом процессе Благодаря отсутствию на азотируемой поверхности хрупкого слоя после прецизионного азотирования, сохранению исходных геометрических размеров, нетребующих дальнейшей механической доработки, и совместимости процессов плазменного прецизионного азотирования Avinit N и вакуум-плазменного нанесения функциональных покрытий Avinit С дуплексные технологии позволяют обеспечить нанесение прочносцепленных, высококачественных покрытий. Исследовано влияние дуплексного процесса на размеры деталей при плазменном азотировании высокоточных шестерен и нанесении функциональных покрытий Avinit С, изучены свойства азотированного слоя и параметры покрытий Avinit. Плазменная прецизионная технология Avinit N позволяет выполнять азотирования окончательно готовых деталей без изменения размеров, в том числе шестерен по 4 степени точности. Время азотирования Avinit N в 2 – 4 раза меньше, чем при газовом азотировании. Покрытие деталей Avinit С310 повышает микротвердость поверхностей деталей и снижает коэффициент трения, при этом обладает достаточной адгезией к рабочим поверхностям зубьев шестерен и беговых дорожек подшипников. Проведено изготовление высокоточных зубчатых колес по степени точности 4 с использованием дуплексных технологий Avinit. Анализ результатов показывает, что в пределах точности измерения никаких изменений профилей зубьев, их расположение на зубчатом венце, а также расположение зубчатого венца относительно измерительных баз не наблюдается. Плазменное азотирование позволяет сократить время азотирования более чем в два раза по сравнению с газовым азотированием, при этом толщина слоя хрупкой фазы с максимальной поверхностной твердостью обеспечивается в пределах заданных величин для обеспечения необходимых показателей контактной и изгибной длительной прочности при изготовлении зубчатых колес по степени точности 4 без шлифовки после азотирования. Измерения зубчатого венца после азотирования и покрытия показали, что изменений геометрии шестерни, обработанной по дуплексной технологии, не наблюдается. Антифрикционное покрытие Avinit С310 толщиной 1,5 мкм не искажает геометрию профилей зубьев. Все параметры зубчатого венца, изготовленного по дуплексной технологии Avinit, соответствую тстепени точности 4 соответствии с требованиями технической документации. Испытания изготовленных по дуплексной технологии Avinit шестерен осуществлялось в составе редуктора двигателя АИ-450М на гидротормозном стенде ГП “Ивченко-Прогресс” по программе эквивалентно-циклических испытаний. Пара экспериментальных зубчатых колес была установлена в редуктор двигателя вместо серийных колес второй ступени редуктора. Суммарное время испытаний колес составило 26 часов. После испытаний никаких повреждений шестерни, включая покрытие Avinit, не установлено. Антифрикционное покрытие Avinit С310 толщиной 1,5 мкм не искажает геометрию профилей зубьев в процессе испытаний в составе редуктора двигателя АИ-450М. Обмер параметров зубов показал полное отсутствие износа.

This study evaluated the effects of the types (MFL and acetate anti-icing filler) and the replacement rate of anti-icing additives on the performance of asphalt mixtures. Additionally, the road performance as well as ice inhibition capacity between environmental (acetate anti-icing filler) and conventional (MFL) anti-icing materials were compared. The equivalent volume displacement method was applied to determine the amount of anti-icing filler in asphalt mixture. In this paper, the high-temperature stability, low-temperature bending properties, water stability, ice inhibition properties and anti-icing persistence of the mixture were investigated in the laboratory. The results show that the ice inhibitor has negative effects on the rutting resistance, crack resistance and moisture sensitivity of the asphalt mixture. Additionally, the adverse effects become more obvious as the replacement rate increases. There was a similar trend in the mixtures with three kinds of ice inhibition filler in general. The tests also proved that the anti-icing fillers can effectively delay and inhibit the occurrence of road icing, weaken the bonding force between pavement surface and the ice layer and make the ice layer easy to be removed. It is found that the comprehensive performance of traditional ice inhibitors is better. Moreover, the high-temperature stability, anti-icing capacity and ice inhibition persistence of environmentally friendly anti-icing additives need to be improved.

Machining distortion is extensively observed in the milling of multi-frame components due to residual stress and low rigidity. Therefore, it is critical to accurately predict the distortion and develop corresponding reduction technology in the milling of multi-frame components. In this paper, a novel analytical model to predict the machining distortion of multi-frame components was established based on the energy method. The influence of bulk residual stress inner the material, machining induced residual stress and the characteristics of workpiece structure were taken into account in this theoretical model. Milling experiments were performed on two classical multi-frame components including rib, web and hole to verify the proposed model. Measurement results of 3D and 2D distortions of the components were compared with prediction results. Fine consistency between the two results demonstrated the accuracy of the established theoretical model. According to the theoretical results, a new parameter with general consideration of the influence of bending curvature in x- and y-direction was formulated as distortion coefficient and further applied to adjust the processing parameters to reduce the distortion. Furthermore, the corn starch suspension with shear thickening property was also successively employed to reduce the machining distortion at the mean time. Milling experiment results successfully proved the effectiveness of the proposed methods in this work, and the machining distortion can be reduced nearly by 20%.

With excellent mechanical properties and electromagnetic properties, compact superconducting cables are considered as potential candidates for large capacity power applications and fusion magnets. In this paper, the concept of a novel compact cable, conductors in tube (CIT) cable is introduced from the aspect of design, fabrication, and performance evaluation, respectively. The principal advantages of CIT cables are that the cable can release the residual stress created from the fabrication process, and the outer former of the cable can be used as both the supporter as well as the container of refrigerant liquid. Firstly, the topological structure and the detailed fabrication process of a CIT cable are presented. Then, a typical CIT cable is manufactured. The feasibility of this new structure is verified by its critical current test. Moreover, bending characteristics of CIT cables are evaluated and compared with Conductors on Round Core (CORC) cables from the aspect of both simulation and experiments. The superior bending performance enables it to be potential in the future compact magnet application.

Eco-efficient Ultra-High Performance Concrete (E-UHPC) containing Recycled Steel Fibres has been recently developed to reduce the cost and environmental impact of UHPC in the construction industry. Nevertheless, currently there are no design guidelines for high-performance fibre reinforced materials with hardening post-crack tensile characteristics, such as UHPC. The determination of the post-crack tensile characteristics of UHPC is also a major challenge experimentally and numerically. In this paper, the notched three-point bending test is used in conjunction with Finite Element (FE) inverse analysis to characterise the tensile properties of E-UHPC. To address issues of spurious mesh dependency in smeared crack FE models, the post crack tensile properties are determined using a fracture energy approach. A mesh independent solution is developed by using a characteristic length scaling procedure as a function of finite element size. Based on that, a simple and precise model for predicting the constitutive tensile stress strain ( σ - e ) law of UHPC using simple strength and mix parameters (compressive strength, flexural strength, fracture energy, fibre dosage and recycle steel fibre content) is developed. This model is then used to derive E-UHPC specific design guidelines in line with current fib Model Code design provisions.

In the event of damage to additively manufactured components whose shape cannot be produced by machining, an additive repair can potentially be not only ecologically but also ecologically more favorable than the production of a new component. In addition, a number of hurdles that otherwise often impede the use of additive repair, e.g. the availability of the material of the damaged component for the additive process, are eliminated. As far as the authors are aware, this publication is the first to present a process for the additive refurbishment of additively manufactured components using the example of a wheel carrier. In this context, the possibility of increasing the fatigue strength of a structural component in refurbishment is discussed for the first time. To increase the fatigue strength of the wheel carrier, the chosen approach is to integrate the effect of particle damping into the component. Particularly in the case of components subjected to bending stresses, the effect of particle damping can be integrated into the component's interior without having to accept a significant loss of strength.

The damping properties of as-cast and austempered Al-alloyed ductile iron produced by rotary furnace melting process and sand casting technique were investigated. Two Al-alloyed ductile irons, which contain 2.29 wt% Al and 3.02 wt% Al, were produced and test samples were machined, followed by heat treatment process. The samples were subjected to both conventional single step and two-step austempering processes. The microstructure of the Al-alloyed ductile irons, after chemically analysed, was characterized using scanning electron microscopy, while the storage modulus, loss modulus and damping capacity were evaluated using a dynamic mechanical analyser of model DMA 242E (Artemis) with NETZSCH format, using three-point bending mode procedure in accordance with ASTM E756-05. It was found that the ausferrite structure of the Al-alloyed ductile iron exhibited improved damping capacity than the pearlite-based Al-alloyed ductile iron of the same composition. Also, the two-step austempered Al-alloyed ductile iron yielded more improved damping capacity values of 0.23194 (1 Hz) and 0.23351 (5 Hz), respectively, at room temperature than the as-cast ductile irons investigated in this study.

A V-bending experimental setup has been designed, to analyze the impact of blank geometry and process parameters over the springback in hot-rolled high-tensile-strength sheet metals (JSH590 steel). In this setup, a hydraulic press having the ability to vary load and holding time has been used. JSH590 sheet-metal blanks with varying geometric parameters are bend to acute, right and obtuse angles. Springback in each blank is determined which is found to be varying due to the different combinations of blank geometry and process parameters. To analyze the significance of thickness, width, bend angle, applied load and holding time, analysis of variance is applied, regression model is also derived relating the parameters with the springback, and finally, Genetic Algorithm has been applied to optimize the process parameters for the minimum springback. The outcomes of the research can be used in the industry, to evaluate the outcome in very-high-tensile-strength steel sheets.

Additive manufacturing (AM) has emerged as an alternative tool to overcome the challenges in conventionally processed metallic components. It is gaining wide acceptability because of the superior properties of the manufactured components compared to their wrought processed counterparts. Among the available AM processed materials, austenitic stainless steel 316L is widely explored wherein an excellent strength-ductility trade-off has been reported. However, the mechanisms underlying fracture toughness of AM stainless steel 316L vis-a-vis wrought processed stainless steel 316L material are not yet explored. The present investigation is aimed at examining the mechanisms accountable for the fracture toughness of AM processed stainless steel 316L. The specimens are produced by two different AM techniques namely, selective laser melting (SLM) and wire arc additive manufacturing (WAAM). A wrought processed stainless steel 316L was used as a control material for comparison. Three-point bending tests were carried out on fatigue pre-cracked single edge notched specimens and crack initiation fracture toughness was evaluated. Digital image correlation was used for strain analysis and to monitor crack propagation. The SLM manufactured sample has shown higher fracture toughness whereas WAAM has exhibited nearly the same fracture toughness when compared to the wrought processed stainless steel 316L sample. Microstructure of fractured samples consists of a significantly higher twin density and a higher propensity of dislocation slip was observed in the SLM sample than the other two. It has been argued that a very fine cellular structure, minimized process-induced defects, enhanced twin density led to promising toughness in the SLM processed stainless steel 316L.

Sheet springback and structural deformation of the folding mechanism are key issues in the sheet metal–forming process. Elastic-plastic bending theory and numerical simulation are applied to study the forming performance of sheet metal. First, a springback prediction model under general assumptions is established, based on the constitutive relationship of the elastic-plastic linear hardening material. In addition, the influences of processing parameters, such as sheet thickness and forming angle on springback, are analysed according to the theoretical model and verified by experiments. Then, a laser tracker is used to acquire the folding trajectory, and the structural deformation of the folding mechanism is confirmed by trajectory comparison. On this basis, numerical simulations are performed to collect deformation parameters, and a formula for mechanical compensation is obtained by linear fitting to the simulation data. Finally, experimental tests are carried out to verify the accuracy of the compensation model. The results show that the forming precision of the sheet metal can be controlled in the range of $\pm 10^{\prime }$ . The proposed method is generally applicable to linear hardening materials and operation conditions where the sheet thickness ranges from 0.8 to 3 mm.

Origami-based sheet metal, a novel emerging technique, is explored in this paper. The process is similar to traditional process of making the Origami art from paper. Sheet metal forming is also con...

The problem of springback is one of the most significant factors affecting the forming accuracy for aluminum 3D stretch-bending parts. In order to achieve high-efficiency and high-quality forming of such kind of structural components, the springback behaviors of the AA6082 aluminum profiles are investigated based on the flexible multi-points 3D stretch-bending process (3D FSB). Firstly, a finite element simulation model for the 3D FSB process was developed to analyze the forming procedure and the springback procedure. The forming experiments were carried out for the rectangle-section profile to verify the effectiveness of the simulation model. Secondly, the influence of tension on springback was studied, which include the pre-stretching and the post-stretching. Furthermore, the influences of the bending radius and bending sequence are revealed. The results show that: (1) The numerical model can be used to evaluate the effects of bending radius and process parameters on springback in the 3D FSB process effectively. (2) The pre-stretching has little effect on the horizontal springback reduction, but it plays a prominent role in reducing the springback in the vertical direction. (3) The increase of bending deformation in any direction will lead to an increase of springback in its direction and reduce the springback in the other direction. Besides, it reduces the relative error in both directions simultaneously. This research established a foundation to achieve the precise forming of the 3D stretch-bending parts with closed symmetrical cross-section.

The article discusses the mechanical properties and cold resistance of austenitic stainless steel (analogue 07Cr25Ni13) obtained by 3D printing by electric arc surfacing from ER309LSI welding wire on a CNC machine. These properties were investigated in the process of physical tests of samples cut along and across the layers of 3D printing for tensile and impact bending. Using optical microscopy, the microstructures of steel sections were obtained for various temperature conditions of interlayer exposure, as well as the values ​​of the recommended microhardness. In the process of 3D printing, an intelligent system for monitoring the dynamic stability of the electric arc was applied, which made it possible to guarantee the stability of the structure and properties of the obtained samples throughout the entire process of surfacing. Additional heat treatment of experimental samples (austenitization) was considered as a way to improve mechanical properties and cold resistance. It has been established that the dynamic stability of an electric arc, modes of interlayer temperature holding and subsequent heat treatment largely determine the mechanical properties and cold resistance of ER309LSI steel obtained by 3D printing by electric arc surfacing.

The structure type of porthole die has a crucial impact on metal flow balance in die cavities, strength of seam weld, and die strength. At present, there was little industrial case for the application of protection-type porthole die. In this study, a novel combined porthole die which includes protection, upper, and lower dies was designed to manufacture a multi-cavity and thin-walled profile. The plastic deformation behavior and flow velocity distribution of metal in die cavities were examined by numerical simulation. Seam weld strength and porthole die strength were quantitatively analyzed. In order to eliminate extrusion defects, multiple structure modifications for protection-type porthole die were proposed to balance metal flow and improve seam weld strength. Extrusion experiments were carried out on the horizontal extruder to validate the accuracy of numerical model and the rationality of modified dies. The research results showed that the relative velocity difference at die exit corresponding to the theoretical flow velocity for the designed die is at the range of −54.96 ~ 5.86 mm/s. The weld strength at the outer edges of profile is larger than that at the connecting edges of profile. The comprehensive effect of above factors that leads to an uneven front end, bending defect and seam weld cracking in extruded profile. After optimization, the relative exit velocity difference is decreased to at the range of −1.478 ~ 1.641 mm/s. The welding pressures on the concerned welding planes are obviously improved. The maximum stresses on the optimized porthole dies are both far less than the yield strength of H13 tool steel. The simulated front end shape for extruded profile agrees well with experimental one as well as the grain size and distribution on different observation positions are relatively uniform, which validate the rationality of design method for protection-type porthole die.

The object of research is the technology of metal processing by high-speed and high-energy methods, plastic deformation of layered metal compositions. Theoretical studies are based on the main provisions of the theory of joining metals in the solid phase, the theory of plasticity, explosion welding technology, plastic deformation of layered metal compositions, and their heat treatment. The main problem of creating layered metal compositions using explosion energy, including wear and corrosion resistant, electrical, materials with high ballistic resistance, etc., is that they have not yet taken their rightful place in the range of modern structural and functional materials. This can be explained by the limited application of this process, as well as the lagging behind the theory and experimental base in the field of joining various metals in the solid phase and providing the necessary performance properties according to the needs of modern industry. The process of deformation of the cladding blank during the explosion welding is considered. The process of the workpiece collision is considered in three stages: the movement of the element of the cladding workpiece before the collision, its inertial movement and deformation. The equations of motion and equilibrium of the elements of the workpiece are described. A joint solution of the equations of plasticity and equilibrium of the blank element in the double inflection zone is presented. The work is devoted to solving the problem of increasing the level of production and economic indicators of the manufacture of layered metal compositions through the development of methods for calculating and optimizing the technological parameters. Explosion welding, as the most versatile, promising, and economical method, which still has many possibilities for the application of mathematical modeling and process optimization, has been investigated for the production and subsequent processing of the main groups of industrial metal compositions. This makes it possible to solve the problem of replacing traditional materials with layered metal compositions. The results obtained are important from the point of view of the application of cost-effective materials with high mechanical, operational, and technological properties.

The existing cross arms in high transmission towers are made of pultruded glass fibre reinforced polymer composite (PGFRPC). The moisture, temperature change in the atmosphere, and other environmental factors affect the performance of these members and cause a complete failure. It is apparent that any material used in such applications is susceptible to attack from environmental factors. Therefore, a feasible solution for this issue is to enhance the PGFRPC with a composite-filled sandwich structure as an alternative that could sustain longer than the existing cross arms due to its superior performance under bending and compressive loads. This paper presents a case study on experimental and analytical mechanical performance of both PGFRPCs and composite-filled sandwich structure. In this review, the composite-filled sandwich structure is proposed as an alternative to the conventional PGFRPC.

Determining the root causes of Noise, Vibration and Harshness (NVH) phenomena in modern automotive drivetrains is a task of critical importance. This research investigates the stability of dry clutch systems vibrational behaviour during engagement. A fully coupled dry clutch numerical model including the influence of friction is presented and validated using vehicle measurements. The clutch component frictional properties are measured using parts that exhibit aggressive NVH behaviour using representative tribometric experiments. The validated numerical tool highlights the occurrence of instabilities which are caused by modal couplings, particularly between the input shaft bending and clutch disc radial motions. Such a validated transient dynamics model of a dry clutch system has not hitherto been presented in the open literature.