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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.

As members of Project Team SC4.T5, the authors of this paper present the main outcomes from the work that are intended for implementation within EN 1994-1-1 (Eurocode 4). General design and application rules for shallow floor beams will be presented, with a particular focus on: the classification of the composite cross-section; non-linear bending resistance; and the introduction of transverse bars as shear connectors.

Robotic grasping has become increasingly important in many application areas such as industrial manufacturing and logistics. Because of the diversity and uncertainty of objects and environments, common grippers with one single grasping mode face difficulties to fulfill all the tasks. Hence, we proposed a soft gripper with multiple grasping modes in this study. The gripper consists of four modular soft fingers integrated with layer jamming structure and tendon-driven mechanism. Each finger's rotating shaft of the base uses a torsional spring to decouple the bending deformation and relative rotation. An octopus-mimicking vacuum sucker is installed in the fingertip to generate suction. The effectiveness of the bending deformation and variable stiffness of the design were proved by finite element simulation. Thus, the control model of the finger was built, and the control strategy of multimode grasping of the gripper was proposed. Three control modes were designed to realize the four anthropomorphic grasping modes, including wrap, pinch, hook, and suck. Furthermore, the grasping performance was evaluated to show the abilities. The experiments indicated the superior performance of the proposed gripper and the multimode grasping ability that satisfies various grasping tasks.

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.

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 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.

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.

In this article, a 10-MHz low-profile converter for bendable equipment based on aircore inductor is proposed. The mathematical model and inductance calculation method of the bendable planar circular spiral coil under different bending situations is analyzed. An optimal design method of the T type matching network is depicted in detail which helps to guarantee soft-switching characteristics and high efficiency within the whole bending range by realizing weak inductive equivalent input impedance. A 32 V input, 9V/6.3 W output prototype is proposed in the laboratory and the experimental results verify the feasibility of the proposed optimal design methodology, the system efficiency can be improved by 4% than the traditional method.

The beauty of the beach and underwater of Bangsring beach make this beach one of the leading destinations in Banyuwangi Regency. However, until today how to enjoy the beauty of the underwater can exclusively be done by diving or snorkeling, which is quite troublesome and exhausting, especially for tourists who want to enjoy and looking entertainment in a simpler way. So the concept of bottom-glass in this design is offered as a problem solving in this study, while the concept of flat plate and flat-bottom is carried out to efficiently time and cost of shipbuilding, because with this flat plate concept, there is no rolling and other material bending process. The design of the main dimensions is made based on owner requirements are obtained based on field study and literature studies, then the main parameters are obtained (LOA = 12 m, total B = 5.6 m, B each hull = 0.94 m, hull spacing = 3.72 m, T = 0.7 m, H = 1.85 m, Vs = 10 knots). To maximize the design, 4 ship models were designed with these primary parameters, based on the analysis of resistance using Maxsurf Resistance, model 4 with a maximum resistance of 4.3 kN was chosen which tend to be more effective compared with the designs of model 1, model 2, and model 3 which has a maximum resistance of 8 kN, 4.9 kN and 5.3 kN. The results of the stability analysis carried out in this design with the load case 100%, 80%, 60%, 40%, and 20%, has met all requirements for intact stability IMO MSC.36 (63) for HSC multihull Annex 7.

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.

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.

The cable-driven segmented manipulator with cable-constrained synchronous rotating mechanisms (CCSRM) is a new type of continuum manipulator, which has large stiffness and less motors, and thus exhibits excellent comprehensive performance. This paper presents a dynamic modeling method for this type of manipulator to analyze the friction and deformation of the cables on the dynamical behaviors of the system. First, the driving cables are modeled based on the ALE formulation, the strategies for detecting stick-slip transitions are proposed by using a trial-and-error algorithm, and the stiff problems of the dynamic equations are released by a model smoothing method. Second, the dynamic modeling method for rigid links is presented by using quaternion parameters. Third, the connecting cables are modeled by torsional spring-dampers and the frictions between the connecting cables and the conduits are considered based on a modified Coulomb friction model. Finally, the numerical results are presented and verified by comparing with experiment results. The study shows that the friction and cable deformation play an important role in the dynamical behaviors of the manipulator. Due to these two factors, the constant curvature bending of the segments does not remain.

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.

A Building 3-storey construction project using reinforced concrete construction was failure and collapse in Johor Baru Central Jakarta. The impact of construction failure is work accidents (injury and death), damage to construction/infrastructure, and there are legal consequences for failures that occur and the causes of failure. The research method is to examine the condition of the installed structure, check the level of damage, test the quality of concrete, structural modeling with SAP (Structure Analysis Program) 2000, analyze and calculate the strength of the column cross section, analyze and conclude from the overall inspection results with implementing regulations and reinforcement in SNI 03 -2847-2002. The results of the study concluded that the initial failure was in the column with a size of 33 x 10 centimeters on the south side of the 1st floor with a buckling type failure that caused it to collapse due to pressure from above (floors 2 and 3). The results of the structural modeling of the SAP 2000 program and the calculation of the column cross-sectional strength obtained that the cross-sectional strength capacity of the column is 32.80 tons, this value is still able/safe to withstand the load of the structure above it. The failure and collapse of the column was caused by the implementation of the principles and details of the reinforcement that were not standardized and did not follow the rules of SNI 2847:2013 on the spacing of the stirrups and the details of bending of the iron.

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.

This letter presents a novel Pneumatic Elastomer Robot (PER), called Deterministically Adjusted Stiffness-Pneumatic Elasotmer Robot (DAS-PER), that can concurrently display preprogrammed elongation and bending behaviors. Our design methodology integrates a comprehensive analytical modeling and additive manufacturing-based fabrication to (i) address current ad-hoc and arduous PERs’ fabrication limitations, and (ii) enable deterministic stiffness and deformation behavior tuning based on the desired application. To thoroughly evaluate the efficacy of the presented modeling and fabrication approaches, based on the developed model, we first designed and fabricated two DAS-PERs with different bending and elongation stiffnesses. Next, we performed experimental studies to thoroughly evaluate and compare the expected and obtained deformation behaviors. Results demonstrated the efficacy of the fabrication procedure and model fidelity for successful tunability of DAS-PERs solely based on adjusting two internal structure diameter parameters.

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.

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.

Textile antennas are currently being researched and developed so that they can be integrated into clothing. In this paper, two textile antennas with cotton and silk substrate are presented. The antennas operate at GPS L1 frequency, which is 1.575 GHz. This paper discusses the effect of antenna parameters on free space and on-body conditions, and the effect of antenna bending. Based on simulation and measurement results, the parameter values obtained indicate that the antenna can operate properly at a frequency of 1.575 GHz and is safe to use on the body.

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.

With the advantages of continuous bending, small bending diameter, and variable curvature, the spatial variable curvature (SVC) bent metallic tube (MT) is widely used in the aeronautics industry. Due to the complex characteristics of its central axis, SVC MT bending is prohibitive in terms of modeling and analysis, which results in a rather high calculation complexity. The springback is the primary detection that directly affects the axial forming accuracy. To achieve higher forming accuracy, this paper provides a numerical approximation springback prediction and compensation method considering cross-section distortion for SVC MT. The curvature and torsion mapping function of MT central axis before and after springback is constructed. According to the characteristics of different SVC MT, the differential equations in the SVC springback prediction model are solved by using three numerical approximation methods. The springback compensation method is subsequently obtained by inverse operation of the mapping relationship. To verify the feasibility of the proposed method, a 00Cr17Ni14Mo2 tube is bent with a multi-roll bender into the spiral shape. The results of the three springback numerical approximation methods and the numerical simulation result are compared. It illustrates that the Runge–Kutta method owns the highest prediction accuracy, so that we choose the Runge–Kutta method for bending compensation. The result indicates that the position deviation of each node is less than 1.4% along with the average position deviation of 0.80% after springback compensation.

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.

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.

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.