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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.

This article presents the design of an atmospheric control system for the VEGA launcher using Linear Parameter-Varying (LPV) synthesis techniques, both non-rate and rate-bounded. Following the Space industry traditional approach, the control problem is first formulated to design a rigid-body controller. Subsequently, it is shown how the launcher control problem can be systematically augmented to obtain the rigid-body controller and bending filters in one single procedure. The resulting LPV controller is analyzed in terms of classical linear stability margins and compared with the VEGA baseline controller via Monte-Carlo analyses using a high-fidelity, nonlinear simulator developed by industry. In addition, the LPV design is benchmarked using extended uncertainty ranges against two other advanced controllers: a structured H ∞ and an adaptive augmented design. The results show that the LPV controller provides satisfactory stability margins and excellent performance and robustness characteristics, with the advantage of the design technique offering a systematic and methodological design framework.

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.

This paper introduces an integrated computational design framework for the design and realization of arbitrarily-curved bending-active architectural structures. The developed framework consists of a series of methods that enable the production of a complex 3D structures composed of a set of flat 2D panels whose mechanical properties are locally tuned by varying the shape of embedded spiraling patterns. The resulting panels perform as variable stiffness elements, and they are optimized to match a desired target shape once assembled together. The presented framework includes all the steps for the physical delivery of architectural objects, including conception, static assessment, and digital fabrication. The developed framework has been applied to an architectural scale prototype, which demonstrates the potential of integrating architectural design, computational simulation, structural engineering, and digital fabrication, opening up several possible novel applications in the building sector.

In recent years, utilizing energy dissipation devices in building structures has been of great concerns due to the severe earthquake activities around the world. The performance evaluation of friction devices, buckling restrained braces and structural fuses as the recently introduced control systems proved their usability in dealing with different structural systems; however, there has been an increasing interest in decreasing the overall cost of the controlled building structures by developing devices with lower levels of complexity, reusable and easy to be implemented and manufactured after severe vibrations. The main objective of this paper to propose Boxy Bending Damper (BBD) as a novel energy dissipation device with partially lower constructional cost which prepares acceptable levels of stiffness, damping and ductility. This device is constructed by utilizing standard stainless-steel plates and bolts without any welded joints which provides a device with lower constructional complexity and can be considered as an improvement in the passive control devices. The performance of this new device is evaluated through the numerical and experimental analysis in which the optimal geometric configuration of the energy dissipation device is achieved by conducting multiple numerical analysis. The experimental tests have been conducted in order to evaluate the overall feasibility of the device in practice in which a cyclic test is carried out by means of a universal testing machine with maximum displacement of 75 mm. Besides, a parameter identification process is also conducted in order to calculate the required dynamical parameters of the device such as the stiffness, damping and ductility. The overall performance of the device in the experimental and numerical testing processes proved that the proposed device is capable of increasing the energy dissipation levels of structural systems by providing 35% of equivalent viscous damping and ductility ratio of about 33.

The accuracy of different fire design methodologies for hollow cross-sections subject to compression and major-axis bending is studied and compared in this paper. For that purpose, a numerical model based on shell finite elements is developed and validated against existing experimental results available in the literature. Comprehensive numerical parametric studies are then carried out by means of the validated numerical model, including different cross-section dimensions, loading conditions, steel grades and temperatures, to obtain a large set of results of the ultimate resistance of hollow sections in fire. Based on these results, the existing design rules of the Eurocode 3 Part 1–2, the AISC 360 specification and the recent design proposals of Couto et al. [1,2] and the Direct Strength Method adapted to fire are assessed in terms of their accuracy for predicting the section capacity, including the resistance against local buckling at elevated temperatures. It is demonstrated that the cross-sectional classification procedure for the case of fire, available in the Eurocode 3 and AISC specifications, results in inconsistencies and should be further investigated and revised in the future. To overcome the Eurocode 3 limitations it is proposed that the design methodology of Couto et al. [1,2] is adopted irrespective of the cross-section classification and for the AISC specification it is suggested the use of a reduced stress based on the 0.2% proof strength until more efficient design methods are developed.

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.

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.

Three dimensional (3D) tubes, which possess the characteristics of space saving, lightweight and high strength, are widely used in many high-end industries such as aviation, aerospace, automobile and shipbuilding. However, when manufacturing a 3D tube in flexible bending process, springback is a big obstacle for improving the forming quality. In this paper, a new comprehensive strategy for springback control of 3D tubes is proposed. The strategy can be described as follows: (1) define the desired shape and manufacture shape; (2) optimize the manufacture shape using two tooling design methods (e.g. DA (displacement adjustment) method and BT (3) make a discretization of the manufacture shape to acquire the optimized forming parameters. Additionally, experiment is implemented to validate the effectiveness of the new strategy. Results show that forming parameters acquired by the new strategy are partially effective. The new strategy also demonstrates that, during 3D tubes forming, the deviation caused by over-bent elements can be counteracted by the deficient-bent elements. This principle is helpful to reduce the difficulty of parameter determination in future.

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.

This paper describes a simplified methodology for the assessment of unreinforced masonry (URM) walls under out-of-plane two-way bending seismic action. The methodology involves a force-based check derived from the principle of virtual work. This check is proposed based on experimental observations of significant cracking resistance associated with two-way spanning URM walls, indicating methodologies considering such walls to be pre-cracked or to be non-laterally supported as overly conservative. The methodology incorporates several findings and developments from recent experimental campaigns: ranging from novel characterization tests on masonry couplets to incremental dynamic tests on full-scale buildings. Such incorporations include new formulation to calculate the torsional shear strength of a bed joint and accounting for possible changes in the boundary conditions of an OOP wall during dynamic loading. Testing standards as well as recommendations in several international guidelines for masonry structures addressing the input properties required to implement the proposed methodology are enlisted and reviewed. The methodology requires the definition of the period of vibration of the assessed URM walls, to calculate which plate theory based formulation is provided. Open research questions and potential avenues for further development of the methodology are ultimately highlighted.

This research presents the mechanical performance of self-tapping screw-reinforced slotted-in bamboo-steel-bamboo (BSB) connections and the corresponding capacity models. The yield strength of self-tapping screws (STS) and bolts commonly used in practical constructions were obtained through the three-point bending tests. The withdrawal tests of the screws from the engineered bamboo panels were reported. The BSB connections using STS reinforcement in different positions were studied, and the performance and mechanical parameters were compared with the connections without reinforcement. The test results show that STS application in the BSB connections can significantly improve its ductility and bearing capacity. Compared with the connection without STS reinforcement, the bearing capacity and ductility of the reinforced connection with STS reinforcement near the top were increased by 8% and 3.8 times. For STS application near the bottom and at both ends, the increased values were 26% and 4.3 times, 35% and 4.6 times, respectively. The brittle row shear failure mode of the unreinforced BSB connections can be changed to be the ductile yielding failure modes by applying STS reinforcement reported in this study. Based on the existing theoretical models, the capacity predictions of the BSB connections based on two different failure modes were calculated and compared with the test results. According to the experimental research conducted in this paper, it is strongly recommended that the STS reinforcement be used in the unidirectional bamboo connections to confirm the ductile failure modes, which can be estimated through the well-established European Yield Model (EYM) included the current design standards.

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.

Conventional braces are a one-size-fits-all solution requiring doctor time to reposition brackets and bend wire to achieve a reasonable finish. Digital indirect bonding has brought conventional braces into the digital world by allowing the orthodontist to optimize bracket positioning. However, perfect bracket positioning commonly fails to achieve all 3 orders of tooth movements, and therefore, wire bending is still needed. For bracket systems to improve, they must be both digital and custom. The goal of the KLOwen custom bracket system is to realize the practice efficiency of a true straight wire system.

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%.

In steel structures, owing to technological aspects, frequently bolting access is difficult. To overcome these issues, technological research has proposed in the last decades several blind bolt systems that allow the installation of a bolt working only on one side of the connection. The simplest type of blind bolt is the thread-fixed one side bolt (TFOSBs), in which the connecting elements are fastened through threaded holes, and the connection is assured by the contact between bolt and hole threads. This type of bolting system is very easy to apply, but, currently, there are only a few design rules available. While the mechanical behaviour of TFOSBs is conceptually easy to understand, there are still some specificities that need to be accounted for and deserve specific investigations. A first aspect regards the behaviour in tension that must be characterized properly because it depends on some local effects such as the threads’ bending both bolt and hole. Similarly, regarding the behaviour in shear, due to the lack of confinement in the nut area, as already shown for similar bolt typologies, the bearing resistance may be lower compared to standard assemblies. To provide design rules for the behaviour of TFOSBs in tension and shear, in this paper, FE models and parametric studies are developed. The collected data are used to provide a prediction of the resistance of these fasteners, suggesting design rules of immediate applicability developed along the same lines of Eurocode 3 part 1.8 provisions. The results obtained suggest that, compared to standard bolt assemblies, an average reduction of 15% of the bearing resistance should be considered for the design of TFOSBs. Instead, for what regards the behaviour in tension, the shank necking failure of the bolt be achieved only by assuring minimum bolt screwing depths, which are suggested in this paper, confirming similar proposals already available in technical literature. Conversely, provided that the failure of the hole’s threads is accepted a reduction coefficient of the tensile resistance to be used in design, ranging from 0 to 1, has been proposed based on the FE studies’ results.

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.

This article summarizes the known methods for calculating the internal resistance of tracked undercarriages. The values of the coefficient of internal resistance for sample tracked vehicles are available in the literature and presented in this paper. Although they are suitable for simple computations, they cannot be used to optimize the energy efficiency of new generation tracked undercarriages. This problem might be solved by the models where every phenomenon leading to energy dissipation during vehicle motion is described by a separate submodel as a function of vehicle speed, track tension, undercarriage layout, design features of the undercarriage components, etc. This kind of model is still missing for vehicles with conventional rubber tracks. The article presents multiple state-of-the-art models describing rolling resistance of road wheels, bending resistance of rubber belts, etc., including the models of belt conveyors resistance. A vast majority of the phenomena discussed herein are described by several incompatible models whose parameters have not yet been determined for conventional rubber tracks. Consequently, in the second and the third part of the article, the authors have undertaken a theoretical and experimental studies on the methods for calculating and optimizing the internal motion resistance of vehicles with conventional rubber tracks.

The manufacturing of hollow section profiles using high strength metallic alloys may suffer of relevant drawbacks such as springback, reduced formability as well as wrinkling, which often limit the process capabilities. Localized heating of cross section sectors may allow a significant reduction of these issues thanks to the neutral layer shift and lowered yield stress. The paper describes an analytical approach to provide a fast prediction of the stress and strain distributions in the cross-section and their effects on the springback as consequence of the process thermal and mechanical parameters. Experimental and numerical validations confirm the analytical model reliability.

Diamond/SiC composites with high thermal conductivity are important materials for electronic industry, especially electronic packaging, but their complex structures and high-precision manufacturing are still challenging issues. Stereolithography-based manufacturing method combined with the reactive melt infiltration to make diamond/SiC composites with high-precision complex structures has been proposed in this paper. Diamond particles were used as the raw material, and as the particle size is a key factor affecting composite performance its influence was studied by means of measuring parameters, examining microstructure, and detecting components, whereas related mechanisms are discussed as necessary. Subsequently, a diamond/SiC composite with the thermal conductivity of 245.68 W/(m K) has been prepared and used in experiment. The experiment shows that the precision is affected by light-scattering and bending in the printing plane and in the vertical plane respectively, with the size errors of 0.25 and 0.12 mm.

In order to solve the problems of excess ovality and cross-section distortion of longitudinally submerged arc welding pipes after forming, a new three-roller continuous setting round process was proposed. This process can be divided into three stages: loading stage, roll bending stage and unloading stage. Based on the discretization idea, the mechanical model of the primary statically indeterminate problem of the longitudinally submerged arc welding pipes at the roll bending stage was established, and the deformation response was obtained. The simulation and theoretical results show that there are three positive bending regions and three reverse bending regions along the circumference of the pipe. The loading force of each roller shows growth, stability and downward trend with time. The error between the theoretical fitting curve and the simulated data point is very small, and the simulation results verify the reliability of the theoretical calculation. The experimental results show that the residual ovality decreases with the increase of the reduction, and the reduction of the turning point is the optimum reduction. In addition, the residual ovality of the pipe is less than 0.7% without cross-section distortion, which verifies the feasibility of this process.

The accurate consideration of the local (plate) buckling resistance and the determination of the effective width is highly important in the design of civil engineering structures. The current effective width calculation method provided by the EN 1993-1-5 is mainly developed for I-sections subjected to bending. Several previous studies proved that the current design rules can overestimate the plate buckling resistance especially in case of square box sections subjected to pure compression. The purpose of the current study is (1) to investigate the local buckling resistance of welded square box section columns loaded by pure compression and pure bending moment separately, (2) to investigate the applicability of the Winter curve for these worst cases and (3) to provide the necessary partial factor to the application of the Winter curve according to the safety requirements of Eurocode. Another aim of the current study is to investigate the differences between normal strength steel (NSS: S235 – S355) and high strength steel (HSS: S420 – S960) structures on the local buckling resistance. Deterministic and stochastic numerical and experimental research programs are conducted to investigate the effect of residual stresses and geometric imperfections on the local buckling resistance of welded square box sections and the necessary partial factor is determined.

Friction In the present work, friction stir welding has been carried out with AA 6101-T6 and AA 6351-T6 dissimilar aluminium alloys (plate thickness being 6 mm). The different the process parameters are tool rotational speed, weld speed and axial force and a cylindrical threaded profile tool pin have been used. For the fabrication of the joints the experiments have been carried out with a tool shoulder diameter 18 mm and different tool rotational speeds (900, 1100, 1300 and1500 rpm) with constant welding speed 60 mm/min. Visual inspections confirm the absence of external macro defects. The microstructure studies of weld zone reveal mechanically mixing pattern of both the aluminum alloys around the tool pin. X-ray diffraction (XRD) analysis confirms the presence of intermetallic compound Mg2Si in base metals and FSW joints too. Tensile, hardness, bending tests have been conducted. It is found that the rotational speed of 1300 rpm produces better mechanical and metallurgical properties joints compared to joints fabricated by other rotational speeds. Thus mechanical properties of weld joints depends on combined effect of both microstructure of alloys and processing welding parameters. The fracture surface of tensile test samples presents ductile and dimple fibrous fracture.

Unmanned Aerial Vehicles of group 1 category are small in size with Maximum Gross Take-off Weight between 0 and 20 lbs and normal operating altitude as 1200 AGL (Above Ground Level). Light weighting in aerial vehicles is one of the major concerns and is mostly favoured by the change in materials. Tyres used for UAVs are extensively made up of rubber and are quite heavy in weight thus rising a concern. These rubber tyres add to the dead weight during the flight and also adds to the drag. For this study, lightweight 3D – printed wheels for better performance and lesser drag during the flight are designed and analysed for the group I UAV vehicles. The target is to reduce the weight by 50%, to achieve this, a rigorous analysis was performed for choosing the best possible configuration using various 3D – printing materials like ABS, PLA, Nylon and Carbon fibre mix. Additive manufacturing commonly known as 3D – printing favours the production of high strength light weighing parts. It also offers a broader range of design selection and favours iterative design approach and thus was opted as the method of production. The iterative design approach was followed to obtain the best results. Wheels with 4, 5, and 6 spokes were considered for the study. The wheel designs were modelled in Solidworks and analysis was conducted in Ansys using Finite Element Analysis to study the static and dynamic strength of the wheel in the radial direction, ignoring the bending and torsion of wheels during landing. Furthermore, the Charpy impact test was conducted on the specimen to study the crack propagation on impact.

Using the example of the rotary bending process, 3D-printing technologies are used to integrate sensors and actuators into the working area. This enables to obtain information directly from the working area, which can be used for setting up the process parameters or for predictive maintenance. Especially in terms of maintenance, the aim of research is to find out how the hybrid tools behave in action. Therefore, an optical measurement system is used to detect the strain of the hybrid tool and the forming machine itself.

The realization of hybrid materials allows to achieve high mechanical performances; for this reason, FMLs (Fibre Metal Laminates), which are the combination of composite material and sheet metal, have been used for several applications in different fields, such as aeronautic, aerospace, and automotive. In fact, the best characteristics of both constituent materials are present in FMLs. In the present article, a numerical model is introduced to predict the flexural behaviour of FMLs by using FEM software. The model takes into consideration several phenomena developing in the specimens during the three-point bending loading, such as the material failure due to the normal stress, the progressive damaging, and the delamination due to the shear stress. In such a manner, to simulate different load conditions, given by disparate supports span, is possible. To validate the proposed numerical model, a comparative evaluation between the results obtained from the model and the experimental ones was carried out. The elevated similarity obtained, in terms of both load-displacement curves and failure modes, allowed concluding that the proposed model is suitable for simulating the mechanical behaviour of the FML materials.

Goals. To carry out experimental studies of enforcing the reinforced concrete bending elements with pre-stressed composite materials. Research Methods. Rectangular reinforced concrete elements enforced with polymer composite materials were used as laboratory samples, the measurement was carried out using strain gauges and analog indicators. Research results. A laboratory research program has been developed. The technology for enforcing the reinforced concrete samples by using pre-stressing of fibre-reinforced polymer has been developed. The results of experimental studies regarding the bearing capacity of laboratory reinforced concrete samples enforced with pre-stressed fibre-reinforced polymer are presented. The new enforcement technology was developed. It implies using a device patented by the authors, and the fundamentally new patterns for destruction of samples are presented. The impact of a various strip tension degree (12 kN compared with 6 kN) was analyzed, a difference of 31 % was determined for bearing capacity and 17% for the cracking resistance of reinforced concrete samples. Conclusions. The conducted analysis of the experimental study allows concluding that reinforcement with pre-stressed composite materials (bands) allows increasing the strength of the samples up to 70%, and also increases cracking resistance by 80 %.

Currently there is a trend in the use of alternative composite materials to be implemented in the manufacture and repair of aircraft flight surfaces of the CIDFAE (Center Research and Development of Ecuadorian Air Force); In order to obtain a material with similar or superior properties to conventional ones, studies are generated where new materials are investigated. This research proposes a method of optimization of the mechanical properties to traction, bending and impact, with a factorial approach, based on the analysis of the desirability function, this statistical methodology allows to determine the optimal combination of manufacturing parameters, in which we can measure the overall quality of the statistical model used and control the statistical significance. With the present investigation it is defined that the optimal combination that takes advantage of the mechanical properties analyzed is the one that is composed of: 6 layers of carbon fibers at 0°, 1 layer of carbon fiber at 135° and 1 layer of copper fiber at 0°. The general factorial regression model used in this research, to globally describe the analyzed properties of the alternative compound, explains the variability of the data obtained with the tests by 95.01%. This model efficiently reduces the uncontrolled variability.

The intension of this work is to conduct a failure analysis and optimize the design of the shaft in a 4.5KW alternator used in rail coaches. The shafts in alternator of rail coaches are continuously subjected to sudden and repeated loads. The alternator shaft is made from carbon steel rods supplied by SAIL (Steel Authority of India Limited) and is machined as per the design. This shaft is subjected to stress reversals and found to have failed in several occasions during the operation. Visual inspection of fractured surface showed cracks initiated from the stepped surface. The breakage occurs at the specific region where the stress concentration is high. The stress concentration is also due to the tool marking seen in the machined surface of the fillet region of the shaft. Under the different test conditions, the various problems related to the finish and design of the shaft was observed. According to the observation, failure and design problems of the shaft will be analyzed using finite element method based on which an alternate design is suggested. In this analysis, we consider only bending load on two dimensional axi-symmetrical model of the shaft.

The incremental operation of swivel bending machines is a rewarding forming process as it adds up to the manufacturing flexibility associated with this bending technique in terms of geometric variability. In the context of a purposeful production on demand, it is particularly crucial to understand the relation between kinematic process parameters and the emerging geometry to cope fluctuating quantities down to batch size one. Up to now, however, the incremental operation mode lacks an analytical process model so that the machine parameters required for production are derived in extensive try outs. The present study provides a plasto-mechanical model, which calculates spring-back of a bend formed in an incremental step and approximates the alternating sequence of bends and fed distances in a circular way. The process model is validated by a FEM simulation and in a practical bending experiment of a stainless steel cone from sheet metal. The provided process model thus contributes to laying out the swivel bending process for the flexible manufacture of parts featuring diverse geometric properties such as folding, hemming as well as cylindrical and conical surfaces. By swivel bending, these features are manufacturable in an automated way on one and the same machine with the same tooling.

The present study investigates the effects of the process parameters on cold forming process of an automotive component in AISI 1006 low carbon steel. The material formability was characterised up to 250°C. The material flow behaviour and the related thermal distributions during the geometrical transformations were analyzed. Coining and forming operations were investigated by using a coupled 3D Thermo-mechanical FEM with different die geometries and friction conditions in order to optimize the final die geometry and to reduce the energy consumption. FEM simulation results were validated by comparison with the experimental trials. The detailed study of the component allowed defining the energy required by the severe bending of the initial thick plate. The FEM predictions led to a reduction of deformation energy of about 20%, a mass reduction of 28% on the final product and permitted avoiding secondary machining operations.

This experimental research is intended to study the mechanical functioning of natural hybrid particulate fiber composites. The fiber and matrix fraction is held at varying percentages and the samples are produced by hand from several specific cocoa coats, soil nuts, walnut coats, and rice husk fiber. For different tensile tests and bending test samples in the flat bar, all steps shall be held in compliance with the requirements of ASTM. Composite materials have many benefits over traditional engineering materials. It can be used to replace various traditional materials in automobiles because of the enormous use. Currently, if a vehicle has mechanical features of traditional steel, the integrated composite material substitutes the framework and axis.

Automation is ubiquitous in today’s industrial landscape and is finding its way into more and more highly specialised applications - also in the field of cryopreservation. The extreme work conditions in cryobanks place exceptionally high demands on the mechanical and electronic components used. The preservation and storage of biological samples take place at temperatures between -130 °C and -196 °C using liquid nitrogen as a cooling medium. The bearings and joints used in industrial parallel kinematic robots (for example, ball bearings or Cardan joints) jam at these ambient parameters and are unsuitable for an application within a cryobank. We, therefore, develop methods and technologies to enable fully automated handling of biological samples under cryogenic working conditions. The basis for this is a parallel kinematic robot structure that allows the drives to be placed outside the cold environment. In contrast, the rest of the robot structure can be actuated in a cryogenic container. In this context, the passive joints for this parallel robot are designed as additively manufactured monolithic flexure hinges. This paper presents the design, simulation, and construction of the parallel robot and focuses on the flexure hinges fabricated using the selective laser melting process (SLM). We describe the design of the flexure hinges, their intended use in the robot, and the experimental setup used for their validation. We also compare the operating parameters recorded in experiments (such as bending angle, bending moment) with the data obtained in finite element method simulations (FEM). In addition, we describe the geometric constraints and deviations of the manufactured joints due to the manufacturing process.

In the course of series production of high-performance automotive traction motors, the so-called hairpin technology is increasingly coming into focus. An essential process step is the bending of the hairpins, which is significantly influenced by variations in the wire material. Therefore, this paper will investigate how machine learning techniques can be used to monitor the dimensional accuracy of hairpins solely based on bending process data such as torque curves. In this way, deviations can be detected at an early stage and measures can be taken to prevent further rejects.

Bearings are used to allow the relative motion between the two surfaces. A piston is to slide about the cylinder and shaft has to rotate about its casing. Both requires the relative motion for least frictional losses to be happened. A flexure bearing is a spring which allows relative motion by bending a load element. Flexure bearings have the advantage over most other bearings that they are simple and thus inexpensive. They are also often compact, lightweight, have very low friction, and are easier to repair without specialized equipment. This paper presents design, analysis and manufacturing of flexure bearing for a linear compressor which increases the efficiency of system by achieving maximum stiffness, less stresses and more fatigue life. For this, modelling is done in NX&CATIA and analysis in ANSYS with physical validation of final results by manufacturing actual prototype.

The main task, especially targets at checking out the standard joint at exceptional operating angles and specific materials in order that the time to failure of the accepted joint may be reduced to a degree. The strength generated inside the engine due to the fact the stop result of combustion of gasoline is converted to wheels through the transmission gadget inside the car. This machine in particular encompasses device container, propeller shafts, tremendous joints and differential gears. The stress shaft imparts torque from the engine (Kamal et al., 2011). The screw ups that added on to the energy shaft is especially because of vibration strain, fatigue, bending pressure or maybe the misalignment of the driveshaft. a majority of those defects especially because of the overloading or even repeated extra time use (Hummel and Chassapis 1998). The main result of all these are the pre-mature failure of the drive shaft at the operation times. For almost all the cases, the failure occurs at the area around the universal joints, as the angle difference and the velocity variations occurs in that area.

Currently, sheet metal parts are widely used, involving fastening of various components to them using a threaded fastener. As a rule, the sheet thickness is not sufficient for shaping the minimum required number of threads, ensuring reliability of the fastener. To increase the length of unscrewing, various methods are used: sheet bending, welding of bushings or nuts, stamping in closed and open dies, etc. These methods are not technologically advanced. This problem can be solved using the method of thermal drilling of holes - the process of shaping holes by plastic deformation in sheet blanks with a temperature effect from friction forces of the tool on the workpiece. The main problem is the lack of available data on the geometric parameters of the obtained flanged edges in the available reference books. These data are needed to determine the number of threads in the hole being shaped and the strength of the threaded fastener. The article examines dependences of the geometrical parameters of flanged edges on cutting modes and sheet thickness as a result of thermal drilling.

Corten A588 grade structural steel is a high strength low carbon alloy with high atmospheric corrosion resistance. A significant defect in Corten A588 grade steel is its mechanical, metallurgical and corrosion properties gets altered and gets affected after post welding process. This is due to the Corten A588 grade steel during welding process gets exposed to high temperature in and around the weld zone making it less reliable after the fabrication. Laser beam welding (LBW) is an autogenous welding method in which the heat affected zone and weld zone formed is considered to be very narrow. In this research Carbon dioxide laser beam welding (CO2 - LBW) is performed on a 2 mm thick Corten A588 grade steel under optimal welding condition. Then the mechanical property such as tensile, impact, bending and hardness of the LBW Corten A588 grade steel weld joints are evaluated as per ASTM standards. This research gives detailed information about laser beam welding (CO2 - LBW) of Corten A588 grade steel, various issues faced by the material and helps in widening the applications of this material in various other sectors.

Additive manufacturing of continuous carbon fiber reinforced plastic composites (C-CFRP) has raised considerable interest. Developing continuous printing trajectories to improve the mechanical properties of the as-built parts is of great significance. However, myriad jumping paths and gathered connection paths occur in the existing printing strategies causing inferior part quality. In this study, we present a novel continuous printing strategy to avoid jumping paths and achieve the unique dispersion of connection paths. Tensile and three-point bending tests are conducted to verify the enhanced mechanical performance. This work enables us to eliminate the cutting mechanism in the commercial C-CFRP printers.

This paper presents a new bending method of sheet metal for forming diversified shapes and enhancing operability. The method, “asymmetric bending”, uses a punch and a pair of front and back dies. While the punch moves down for bending, the two dies move at different velocities so that the movement of the front side of the sheet metal can severely be restricted. The front side of the metal can be deformed with diversity in advance as it can escape from geometric interference with the bending tools. The method also improves operability and safety for operators due to the movement restriction.

In case of a crash due to collision of vehicles, effective impact energy absorption by the vehicle safety structure is significant as it reduces the damage to the vehicle and its occupants. Components made of composite materials have a more complex mode of deformation, unlike metals, which in general deform with buckling or bending modes. The deformation mode of the component made of a composite is of great importance as the energy absorption level depends on it. Deformation mode can be modified by introducing special geometric features known as triggers in the design of the crash box. A trigger can also be useful in achieving required deformation mode and thereby helpful in attaining target energy and force values. The present study focuses on the effect of geometric shapes along with three novel trigger types on the level of energy absorbed for the GFRP composite material passenger car crash box in a low-velocity impact, named as “RCAR Test” in the automobile industry. All possible combinations of four different types of geometric cross sections, namely, square, cylindrical, hexagonal, and decagonal, and three novel patterns of notch trigger, imparted to a GFRP crash box were considered for study in the present work. The force distribution, energy absorbed, and SEA (specific energy absorption) were estimated. The relative merit of crash boxes with different combinations of cross-sections and trigger types for these parameters was assessed. The best performing combinations made from various notch triggers and different cross sections of crash boxes have been identified.

The bumpers are provided in the front and the backside of a vehicle, which plays an important role during low-speed impacts by acting as a low-speed energy absorber. In this paper, experimental and numerical investigations for three different bumper beams having different geometries, to be proposed for Indian passenger cars are discussed. The strength of these bumper beams in elastic (static) mode is investigated with energy absorption capacity. Experimentations for three quasi-static 3-point bending tests as well as its static FEA based numerical simulation are presented and validated against experimental results. Based on the results, the bumpers are proposed for the Indian passenger cars.

In this study, two types of prefabricated steel structures with a new type of semi-rigid connection were investigated, and the effects of prestressed cable and wall panel were evaluated. A semi-rigid connection test was carried out to evaluate the rotational properties, and the initial cross-sections of structural components were optimized using a proposed optimization program. The prefabricated high-rise structures were significantly affected by the bending properties of semi-rigid connections, and the stiffness of the steel frame was found to be much more significant than that of modular structures. This proposed method provides a theoretical supplement to the design code of steel modular structure.