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In the manufacturing process of cross-laminated timber (CLT), lumber selection and grading are essential steps for the quality control of CLT. In this work, a density-based lumber grading method was preliminarily evaluated for hem-fir CLT manufacturing. Based on the univariate regression model of hem-fir lumber modulus of elasticity (MOE) and its density, a density-based grading model was developed. To identify the effectiveness of the model, 470 pieces of thin hem-fir lumber, were segregated into four grades: E1, E2, E3, and E4 based on their density values. Two 3-ply thin-type customized CLT panels were also fabricated with E2 grade lumber as the parallel layer and E3 grade lumber as the transverse layer. Then, five CLT beam specimens were cut from each panel for flatwise bending test. Comparing the experimental and the theoretical values of the MOE, the relative errors were found to be + 11.95% (using shear analogy theory) and − 7.21% (using gamma theory), respectively. By comparison, for this hem-fir lumber, the accuracy of this density-based grading method is close to that obtained by other means of non-destructive testing. However, it seems to be simpler and more cost-effective for the potential hem-fir CLT manufacturing in some circumstances.

In this paper, design of a flexible antenna which is used in the field of biomedical applications. This technology consists of two methods mainly i.e. 1.Magnetron sputtering method, 2.Laser ablation method. Magnetron sputtering method is use to set slight copper coating upon polyimide substrate. Secondly Laser ablation method is mainly used to incise an antenna as of copper coat. The different parameters are simulated and measured practically. The outcomes of the verified results are good and have a satisfactory response. There are many advantages such as price, momentum, elasticity over lithography process frequently used for such applications.

The advance of flexible robots enables a more efficient and safer way to perform endoscopic submucosal dissection surgery. The robot should be flexible enough for easy insertion and able to maintain a rigid shape to transmit the forces applied on instrumentation during the operation. This article presents a snake-like flexible endoscope design which consists of an active snake robot and a passive flexible body. The active section is composed of metal printed spring-like joints actuated by tendons arranged in a novel fashion. To analyse the performance and clinical feasibility of the proposed flexible robot, Finite Element Analysis, workspace analysis, path following accuracy and force test have been performed. The results have shown that the robot can reach a minimum retro-flex bending radius of 23 mm and the distance errors of each joint when advancing along a simulated colon path are analysed. Validation of the proposed robot demonstrates its potential for ESD surgeries.

A previous study has demonstrated that welding distortion can be accurately predicted by using the thermo-elastic-plastic finite element method (TEP-FEM) in a steel-pipe joint. Nevertheless, this method still requires excessive computational time. In this study, to overcome this aforementioned limitation, a deformation computing algorithm is developed to estimate welding distortion rapidly and effectively. This algorithm solution process has three main steps. The first step is to collect the weld information. The second step is to calculate bending deformation caused by each weld according to the function of the bending angle. The last step is to make a summation for total welding distortion. However, due to the interaction between adjacent welds, it has a significant influence on the accuracy of prediction results. To improve the performance of this algorithm, a compensation factor has been introduced. Comparing the results of this algorithm with the TEP-FEM analysis, it is discovered that there is a good coincidence. Therefore, it was verified that the proposed algorithm can accurately predict the bending deformation induced by multi-seam welding of a pipe structure.

The increasing demand for a wider access to additive manufacturing technologies is driving the production of metal lattice structure with powder bed fusion techniques, especially laser-based powder bed fusion. Lattice structures are porous structures formed by a controlled repetition in space of a designed base unit cell. The tailored porosity, the low weight, and the tunable mechanical properties make the lattice structures suitable for applications in fields like aerospace, automotive, and biomedicine. Due to their wide-spectrum applications, the mechanical characterization of lattice structures is mostly carried out under compression tests, but recently, tensile, bending, and fatigue tests have been carried out demonstrating the increasing interest in these structures developed by academy and industry. Although their physical and mechanical properties have been extensively studied in recent years, there still are no specific standards for their characterization. In the absence of definite standards, this work aims to collect the parameters used by recent researches for the mechanical characterization of metal lattice structures. By doing so, it provides a comparison guide within tests already carried out, allowing the choice of optimal parameters to researchers before testing lattice samples. For every mechanical test, a detailed review of the process design, test parameters, and output is given, suggesting that a specific standard would enhance the collaboration between all the stakeholders and enable an acceleration of the translation process.

In this study, an efficient numerical approach for automotive sheet forming simulation is proposed in consideration of deformation of tools. The proposed algorithm is based on sequential update of local contact state and pressure at the sheet metal-tool interfaces, which determines the deformation of tools. The material properties of both sheet metal and tool are determined from the standard tests, while the optimum numerical parameters such as tool mesh size are determined from numerical sensitivity analyses using 3-point bending and simplified benchmark problem. The proposed numerical approach is applied to the prediction of springback and draw-in of S-rail automotive part, which results in improved accuracy compared to the conventional rigid-body based forming simulation. Finally, in-depth analysis is provided for the deformation characteristics of a side-outer automotive part in the aspect of deformation in punch, die and blank holder. The analysis shows that tool deformation, particularly the blank holder deformation, is critical for forming quality of sheet metal parts, and the proposed method can be an efficient numerical scheme as an alternative to the conventional sheet forming simulation with rigid tool.

This study presents a case study investigation on failure analysis of drill pipe during the drilling operation and to establish a general understanding of fatigue failure with experiments and several tests. Drill pipe load comprises tensile, compression, bending, hydrostatic pressure and vibration, which causes damage due to fatigue failure to the drill pipe. The method involves subjecting a 2 in length and nominal diameter 3.25 in connection NC50 19.5 ppf drill pipe to predetermined caused failure by experimental tests and analysis. Mechanical examination such as tensile test and hardness test, and metallurgical examination such as spectrometry, fractography, SEM and EDX testing are conducted. The result shows that the cause of failure on the thread drill pipe was due to fatigue failure. It showed by the presence of microcracks, which accumulated from the load in the drill pipe. In addition, propagation of the crack at critical depth resulting in failure during drilling operations.

The goal of the study is to reveal the impact of change in the structural state of steel 07Kh3GNMYuA after heat treatment on the values of the critical stress intensity coefficient (K1c) obtained at a temperature of 50°C and on the velocity of ultrasound wave propagation, as well as to determine a correlation between them for rapid assessment of the crack resistance using acoustic characteristics. The mechanical characteristics of the material and the critical stress intensity coefficient K1c were obtained on the test machine «Inspekt 100 Table». The tangent method is used for determination of K1c. Three samples per K1c value were used in the experiment for a three-point bending scheme at the operating temperature T = –50°C. Acoustic parameters were measured using the echo-pulse method. The results of ultrasonic scanning of heat-strengthened samples made of steel 07Kh3GNMYuA demonstrated the possibility of non-destructive quantitative evaluation of the critical stress intensity coefficient. New data on the mechanical properties of steel 07Kh3GNMYuA and on the correlation between the velocity of longitudinal elastic waves and the values of the critical stress intensity coefficient of structures were obtained. Deviation of the calculated values of K1c obtained using acoustic measurements from the experimental values does not exceed 10%. The proposed model, which explains change in the acoustic characteristics of steel 07Kh3GNMYuA on the basis of phase changes occurring in the steel structure upon tempering, provides conducting of similar studies for other modes of heat treatment and other steel grades. The method is a low labor- and time-consuming procedure for determination of the mechanical characteristics of the products made of steel 07Kh3GNMYuA, since it does not require the manufacturing of samples and their testing. The developed procedure can be proposed for manufacturing application, as the main or additional method for evaluation of the mechanical parameters of materials after various modes of heat treatment.

Machining distortion has been a long-term obstacle in the machining of aircraft monolithic parts. Furthermore, its stability has to be considered. The machining distortion stability represents the fluctuation degree of the machining distortion. This paper investigates the evolution of elastic energy induced by initial residual stress inside materials, revealing that this evolution directly affects machining distortion. In this paper, the concept of machining distortion stability and bending potential energy is defined. By analyzing bending potential energy releasing, this study proposes a novel method for improving machining distortion stability through optimization of material removal sequence. Numerical simulation and milling experiments are performed to verify and validate the model, respectively. The results indicate that the machining distortion stability is significantly improved when optimized material removal sequence is applied. By controlling the machining distortion stability, the final distortion can be further reduced via re-machining the machining datum at the beginning of the finishing stage.

3D printing plays a crucial role in industry 4.0 as an evolving technology for manufacturing industries, which has broader applications in the fields of construction, medical, food, dental, and automotive sectors. The progress has been rapid in recent years, and it is important to find suitable materials as well as process parameters for its implementation straight away without any delay. The objective of the present work is to investigate the mechanical properties of polyethylene terephthalate glycol (PETG) material for making products under fused deposition modeling (FDM). The effects of process parameters such as infill percentage, layer height and infill pattern are explored on the mechanical properties of polyethylene terephthalate glycol (PETG) material used for the manufacture of specimens under FDM technology. The process parameters are set according to the Taguchi method of orthogonal array experimental design, and the specimens are manufactured for tensile, bending and hardness tests according to the ASTM standards. The mechanical properties for PETG material under FDM process are found to be better when the set of process parameters is selected at infill percentage of 80%, layer height of 0.3 mm and infill pattern of hexagonal as optimal parameters.

Isogrid is a highly efficient stiffened plate structure which was developed in the aerospace industry for use in rocketry and space structures. Its current form is unviable outwith these applications, as the available production methods are expensive due to excessive machining time in addition to considerable material wastage. The method detailed in this body of work was developed to manufacture Isogrid in a more efficient manner, so that its weight-saving properties may become more widely accessible. This novel Isogrid manufacturing process uses a rolling mill with patterned rollers to imprint a 3D structure of ribs into the surface of a billet material. To validate this method, a patterned roller was designed, manufactured and fitted to a rolling mill to produce sheets of aluminium AA1050 Isogrid. This process successfully created Isogrid in a sustainable, rapid manner. The samples produced were tested in 3-point bending and compared against flat plate of the same material. They were found to be 100% stronger in bending compared to a neutral flat plate with a strength shape factor of 1.6 after discounting the effect of cold work.

Continuous flexible rolling is a novel plastic forming process for 3D curved parts. In this work, asymmetry forming technology was firstly applied in continuous flexible rolling process, which can effectively compensate the lack of longitude bending deformation caused by work hardening. In the process of asymmetry forming technology, by changing the relative longitude elongation between the tensile surface and compressive surface of the sheet metal, the adjusting of longitudinal bending deformation is achieved. In this paper, the finite element model with different friction ratio was designed; the effect of asymmetry forming technology on longitude curvature radius of 3D curved parts was studied. As results demonstrate that: When the friction ratio between the upper (compressive) and lower (tensile) surface are 0.2:0.2, 0.2:0.15, 0.2:0.10, 0.2:0.05 and 0.2:0.2, 0.15:0.2, 0.10:0.2, 0.05:0.2 in turn, the corresponding longitude curvature radiuses of convex curved parts are 226 mm, 236 mm, 254 mm, 272 mm and 226 mm, 219 mm, 207 mm, 199 mm in turn. When the friction ratio between the upper (tensile) and lower (compressive) surface are 0.2:0.2, 0.2:0.16, 0.2:0.12, 0.2:0.08 and 0.2:0.2, 0.16:0.2, 0.12:0.2, 0.08:0.2 in turn, the corresponding longitude curvature radius of saddle curved parts are 330 mm, 321 mm, 315 mm, 306 mm and 330 mm, 339 mm, 345 mm, 350 mm in turn. The longitude bending deformation of sheet metal can be effectively adjusted in the asymmetry forming technology, so the feasibility of this technology is verified.

The aim of this project is to investigate the causes of the failure of an FSAE (Formula SAE) car front wheel hub which broke down during testing. A Formula student car’s hub has to sustain forces in various dynamic conditions like cornering, braking and during accelerating. The wheel hub was manufactured with Aluminium 6061-T6 alloy which was anodized to a depth of 25 micron. The SEM analysis of the failed component was performed to identify the root causes of the failure of the hub. The finite element analysis of the hub was carried out in order to study the distribution of stresses which were found to be higher near the holes in the hub. It was established that the combined effect of bending, torsional shear and axial stresses led to the initiation of a crack which propagated during testing of the car ultimately resulting in the catastrophic failure of the hub.

In this study, a simple PFEM approach for analyzing large deformation problems in geotechnical practice is implemented in the commercial FEM package Abaqus. The main feature of the proposed Abaqus-PFEM approach lies in its capability to absorb the advantages of the functionality available in Abaqus and integrate them into PFEM with a single Python script, which leads to a considerable reduction in coding work. By utilizing the built-in functions in Abaqus to fulfil the standard incremental FEM analysis, as well as the powerful mesh-to-mesh solution mapping technique, the proposed Abaqus-PFEM approach allows for the large deformation analysis automatically running with a single Python script and requires no intervention from the user. The accuracy of the proposed Abaqus-PFEM approach is firstly validated through a simple elastic cantilever beam bending problem. Then, the performance and robustness of the proposed Abaqus-PFEM approach are further examined by three illustrative numerical examples: penetration of rigid footing, penetration of T-bar and pipeline–soil interaction problem. The numerical results demonstrate that the proposed Abaqus-PFEM approach as a powerful and easily extensible numerical tool is capable of handling large deformation and soil–structure interaction problems in geotechnical engineering, and consequently, it offers an alternative way to tackle such problems.

Two types of high power alternating current (AC) locomotive in China are prone to serious high-order polygonal wear, which has significant negative effects on the operation of locomotives. This study investigates factors influencing polygonal wear in locomotive wheels and determines methods of minimizing operation damage. We designed experiments to analyze the process of polygonization formation of wheels to identify the key influencing factors, finding that natural vibration of wheelsets is the central inherent factor of wheel polygonization and that these vibrations can be easily stimulated by wheel or rail irregularities. We found that poor re-profiling quality is the key external factor in these irregularities. The wheelset bending resonance is activated when the remaining wheel polygonal wear has a wavelength of 200 mm in the 1/3 octave band, in turn leading to significant increases of wheel polygonal wear. In this study, we review a new wheelset design that can mitigate and/or eliminate the polygonal wheel wear due to increased stiffness in wheel bending. We evaluate the potential capacity of the newly designed wheelset and propose two proven effective measures to further improve the wheel re-profiling quality for polygonal wear.

Flexible pressure sensors with excellent pressure sensing performance have been developed rapidly in recent years, but they still suffer from the disadvantages of a complex manufacturing process and high cost. Here, a flexible paper-based (PB) capacitive pressure sensor is constructed by using daily use materials such as paper, polyester conductive tape and polyimide tape. Thanks to the simplicity of the fabrication method, the proposed PB pressure sensor can be even fabricated via a do-it-yourself approach. The rough surface microstructure of paper and polyester conductive tape endows the PB pressure sensor with good pressure sensing performance properties. Specifically, the optimized PB pressure sensor with two-sided microstructure interfaces exhibits a wide pressure detection range (0.1–80 kPa), an acceptable sensitivity of 0.23 kPa−1 (0.1–2 kPa), a low detection limit of about 3 Pa, fast response speed (∼41 ms at the finger tapping), and good durability (5000 cycles at 10 kPa). The pressure sensing mechanism of the PB pressure sensor is explained by analyzing the in situ cross-sectional optical photographs and video of the sensor at different pressures. Like many flexible pressure sensors based on complex technologies and high cost, the PB pressure sensor has also been successfully applied in many application scenarios (e.g., finger bending, wrist pulse, nasal respiration, recording walking steps, early stage of Parkinson's disease, and proximity switch). Given the simple fabrication method, low cost and acceptable pressure sensing performance, we believe that the proposed PB pressure sensor is of extensive and practical application values in the field of wearable electronics and some underdeveloped areas, and is expected to help ordinary people become “home” engineers.

With the development of the shipbuilding, chemical engineering, and military industry, the demand for bending the metal plates with large curvature is increasing dramatically. Take the shipbuilding as an example, the line heating method is widely applied. However, this traditional method has significant disadvantages. In order to improve the manufacturing efficiency and precision, a novel method called incremental bending has been presented by our team, which is based on the minimum energy principle and model-less control method. However, due to the limited formability of the metal plates at room temperature, the bending curvature of the plates during the incremental bending process cannot meet the requirements of the shipbuilding industry. Researches show that heating can reduce springback and improve the metal formability effectively. So here in this paper, a new method called heat-assisted incremental bending is presented. In this method, the metal plate is supported by several supporting pillars and the punch moves according to the loading trajectory, which is calculated by minimum energy method. In addition, the induction heating system is applied to heat the plates at the punching positions. The bending process continues step by step until the metal plate achieves the designed shape finally. During this study, the springback behavior of the metal plates during the heat-assisted incremental bending process was investigated based on theory, numerical simulation, and experiment. Then, the metal plates with large single curvature and variable curvature were deformed based on the novel thermal-mechanical coupled metal forming process. The experimental results show this new forming process can better control the springback behavior of the metal plates and achieve the objective metal plates with lager curvature with higher processing efficiency and accuracy.

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.

The high-strength bolted end plate connection is widely used in the construction industry with its green environmental protection and excellent seismic performance. The joints of the joints are semi-rigid, the force performance is extremely complicated, and the experimental research cost is relatively high, and the cycle is very long. Therefore, the establishment of an efficient numerical model is of great significance for evaluating the force performance of high-strength bolt end plates. In this paper, the influence of different material models on the rotation performance of the joint is studied by numerical simulation, and the bending moment-rotation curve is obtained. The numerical simulation and the experimental results are in good agreement, so as to provide a reference for the design and application of this kind of joint.

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 conditions of processing corrosion-resistant chromium–nickel steel and commercial-purity aluminum on a precision EcoMaster® 25 mangle are considered when the input gap is smaller than the value recommended by the mangle manufacturer. The influence of this processing on the mechanical properties of strips made of these materials is determined. The features of the initial stage of processing, which are mainly affected by the deformation resistance of the metal material, are analyzed. To analyze and explain these features, we propose a scheme for the interaction of a strip with work rolls when it is bitten at the entrance to the mangle.

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.

Most technological processes of metal products manufactured by plastic deformation methods are associated with the formation of a self-balanced system of residual stresses in finished products. In many cases, the level of residual stresses is an important parameter that determines the product quality obtained as a result of plastic deformation. Reasons for the formation of residual stresses are diverse (inhomogeneity of plastic deformation, temperature field, phase transformations, etc.), which in their magnitude can exceed stresses from external loads. Currently, additional requirements are imposed on metal products in order to create machines and structures operating under high loads and speeds, sharp fluctuations in the parameters of the external environment. The experience of operating structures in various fields of technology and the results of numerous experiments show that residual stresses significantly affect the reliability and durability of machines and mechanisms. Based on the A.A. Ilyushin theory of unloading, analytical dependences were obtained for calculating the diagram of the change in residual stresses across the sheet thickness during bending under the rollers of leveler, as well as the springing angle. The diagram formation of residual stresses along the sheet thickness during leveling for the second, third and subsequent rollers of the leveler is considered. As a result of the superposition principle, it was found that the residual stress diagrams under the second and third rollers are added, forming a total diagram after the second and third rollers. For the fourth, fifth, sixth and subsequent leveler rollers, an algebraic addition of the residual stress diagrams also occurs. It is shown that for a 45 steel sheet with a thickness of 10 mm, a width of 500 mm, r/h = 200, the maximum residual tensile stress of 200 MPa is observed at a distance of Z/h = 0.3 from the neutral line along the sheet thickness. And in this case, the discrepancy between the experimental and calculated values of residual stresses is 10 –26 %, which makes it possible to recommend a method for calculating the residual stresses when leveling a sheet on a roller leveler for estimation of its quality.

The gear shaft needs to measure its radial runout for straightening before finishing, while it is difficult to measure the gear shaft radial runout without rotating the gear shaft by the existing measurement technology, which results the measurement inefficient. Present work puts forward a method of measuring a gear shaft radial runout with line structured light vision. This method can measure the radial runout value and direction online for straightening the bending of the gear shaft. The center position of the gear shaft cross section is obtained by the ellipse geometric fitting on the laser plane to eliminate the influence of projection distortion. The measurement method is tested by a specialized experiment, and the experimental results show that measurements of the method meet the requirements of straightening the gear shaft. The method can realize online measurement of the gear shaft radial runout just by a single image without rotating the gear shaft, so it features fast measurement compared with the existing measurement technology.

In recent years, the scope of application of reinforced concrete and combined-reinforced structures in load-bearing structures is expanding. Studies by many authors indicate the significant advantages of reinforced concrete and combined-reinforced bending elements over the classic reinforced concrete. Current state regulations do not take into account all the properties of reinforced concrete, and therefore the load-bearing capacity of structures can in many cases be underestimated. Therefore, it is advisable to take into account, when calculating, all the properties of this material. The current state national standards for the calculation and design of fiber reinforced concrete structures are based on the fact that reinforced concrete is considered as one of the types of disperse-reinforced material. However, with this approach, many factors are taken into account, the value of which, in real conditions, can be in a wide range of values, so they are taken into account with a margin. The article proposes an improved deformation method for calculating the stress-strain state characteristics and the bearing capacity of combined-reinforced concrete bending elements. Improved diagrams of deformation of reinforced concrete under compression and tensile obtained on the basis of experimental tests are taken into account. To evaluate the effectiveness of the method and study a number of other characteristics, two series of experimental studies of inseparable combined - reinforced reinforced concrete beams were performed. Research methods and the nature of the beams in the test process, described in [8-9]. For comparison with the obtained experimental data, the article presents the calculation of experimental beams, performed according to state standards and a simplified force method. The proposed deformation method shows better convergence compared to the DSTU method. The average ratio of theoretical destructive bending moments to experimental is km = 0.98 for the proposed deformation technique, km = 0.843 for the method according to DSTU

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.

With the popularization of friction stir welding (FSW), 5083-H321 and 6061-T6 aluminum alloy materials are widely used during the FSW process. In this study, the fatigue life of friction stir welding with two materials, i.e., 5083-H321 and 6061-T6 aluminum alloy, are studied. Fatigue tests were carried out on the base metal of these two materials as well as on the butt joints and overlapping FSW samples. The principle of the equivalent structural stress method is used to analyze the FSW test data of these two materials. The fatigue resistances of these two materials were compared and a unified principal S–N curve equation was fitted. Two key parameters of the unified principal S–N curve obtained by fitting, Cd is 4222.5, and h is 0.2693. A new method for an FSW fatigue life assessment was developed in this study and can be used to calculate the fatigue life of different welding forms with a single S–N curve. Two main fatigue tests of bending and tension were used to verify the unified principal S–N curve equation. The results show that the fatigue life calculated by the unified mean 50% master S–N curve parameters are the closest to the fatigue test results. The reliability, practicability, and generality of the master S–N curve fitting parameters were verified using the test data. The unified principal S–N curve acquired in this study can not only be used in aluminum alloy materials but can also be applied to other materials.

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.

A testing apparatus, namely, touch sensation tester for fabrics (TST-F), was introduced to evaluate the touch properties of fabrics. This novel apparatus enables a simultaneous measurement of different mechanical properties of the sample with a combination of temporal and spatial resolution, enhancing the measuring accuracy and reliability of the time-dependent physical behavior of textile materials. The prototype of the TST-F and details of the measurement principle were exhibited, and nine indices relating to fabric’s deformation performance during wearing were extracted from measured force–displacement curve to characterize the mechanical properties relating to fabric’s touch sensory attributes. Stepwise regression was used to develop a series of prediction models for assessing human sensations toward bending stiffness, compression softness, and stretching tightness of fabrics by linking the measured indices to subjective assessments. Moreover, the prediction models were validated using a set of independent fabric samples. Results show that prediction values have good agreements with subjective grades as indicated by the coefficients of determination R2 higher than 0.887 and reasonably low mean square errors (MSEs). Also, the repeatability of the measured curves was confirmed by statistical analysis. Therefore, the TST-F provides an alternative to evaluate the touch properties of fabrics objectively.

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 market's increasing demand for portable electronic products has made the research in flexible devices very attractive. Flexible solar cells are one of the most eye-catching devices in the field of flexible photovoltaic devices. And the perovskite material has become a powerful candidate material for manufacturing flexible solar cells due to its excellent optical properties, low price and the ability to tolerate more stress accumulation. However, as an active layer, the perovskite film still faces the issue that cracks are easily generated when bending and encountering temperature changes for the limited flexibility. There are many factors that affect the mechanical stability of the perovskite layer: the characteristics of the material itself, the influence of the other layers in the device and the presence or absence of a protective layer. This work reviews some reported strategies of improving the perovskite bending durability, classifies them according to the influencing factors mentioned above, and describes them in detail respectively.

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.

Actuators have wide applications in soft robotics and bionic devices. Since the healing ability not only makes actuators have longer service lives, but also allows them to be programmable through welding and assembling, it is regarded as an important feature for state-of-the-art actuators. Nevertheless, it remains a great challenge to integrate multi-functional merits, such as multi-responsiveness, programmable shape-morphing, healing and self-sensing function, simultaneously into a monolithic actuating material. Here, we introduce Chinese ink, a carbon-based material used in traditional calligraphy, to develop programmable, dual-responsive and self-sensing actuators by a healing-assembling method. The ink is combined with graphene oxide (GO) to fabricate a double-layer ink/GO actuator, which shows bi-directional bending under near-infrared light or humidity, owing to the mismatch of the volume change between ink and GO films. The maximal bending curvature is up to 5.2 cm-1. Importantly, the entire ink/GO actuator can be healed with the aid of ink solution. Using the healing-assembling method to fabricate advanced structures including a Mobius ring, triangular rings and square rings, diverse actuating modes and complex 3D deformations such as a wavy shape and saddle shape are realized. This method also enables the construction of an artificial mimosa that shows a biomimetic stimulus-responsive behavior. In addition, the ink/GO actuator shows a self-sensing function, which is attributed to the thermoresistivity of the ink film. This research shows the huge potential of Chinese-ink-based actuators for use in smart materials, providing a new idea for the development of new generation multi-functional actuators.

Expanding the plate mill product range implies the improvement of control algorithms for the mechatronics control system drives of the reversing stands. The most important objectives include increasing the accuracy of geometric dimensioning and tolerancing, as well as improving the profile and surface flatness of rolled pro­ducts. The structure explaining the automatic ROLL-GAP CONTROL concept is provided, which allows controlling the thickness and gap between SMS-Demag AG rolls. This concept is implemented in the '5000' mill stand of Magnitogorsk Iron and Steel Works. The structural diagram of the automatic gauge control system (AGS) is presented. The functional diagram of the hydraulic gap control (HGC) system is presented, which includes a fast proportional control channel and a relatively slow integral position control channel. The principle of automatic thickness control is discussed, implemented in the automatic gauge control (AGC) system of the mill stand TCS controller. The diagram and dependences are prepared for the calculation of the nonlinear thickness controller parameters. The functions of the RAC regulator are described, intended for compensation of the tensile difference (gap spacing) at the mill stand sides. The dynamic impact compensation system functions are considered. The removal of the roll bending and deformation control signals is substantiated. The disadvantages of AGC are noted for sheets with a thickness below 10 mm. The most dangerous case is the tearing of metal fragments from the rear sheet side caused by the incorrect operation of the gauge control system. A method for hydraulic gap control is proposed based on the fast increase of the roll gap in the rear part of the rolled sheet during the last passage when rolling thin sheets. The results of experimental studies made on the '5000' mill are presented. The efficiency of the proposed control method has been confirmed. The oscillograms of signals are presented characterizing thickness variations. HGC and AGC systems with the proposed adjustments are proven to provide high-accuracy hydraulic position control and thickness control along the sheet length and width.

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.

Skilled operators have a vital role in Industry 4.0 manufacturing, especially in a small manufacturing environment. To implement Industry 4.0 concepts, it is necessary to find an innovative solution that will improve the skills of operators in manufacturing. Augmented reality (AR) has become a part of this innovative solution by providing interactive live guidance, i.e. easy transfer of information to operator, especially the production, assembly and maintenance information. This paper demonstrates a simple method for implementing AR, particularly in small enterprises. It also shows benefits of implementing AR: the production quality is improved by offering an interactive and reliable training for technicians to improve their skills, which leads to the minimisation of errors occurring during the production. Moreover, this paper sheds light on the industry trends during the COVID-19 pandemic and presents the effectiveness of augmented reality during the pandemic. A real example has been implemented on a busbar bending process in order to simplify the task of the operator especially when the complex bent shape is produced.

Recently, eliminating the gap between design and formability analysis of sheet metal parts has been studied to simulate sheet metal stamping processes. In this regard, a transfer-based inverse isogeometric formulation has been proposed. This method has various advantages such as solving the governing equations in two-dimensional networks without any concern about the convergence; however, it neglects the bending effect which is a major contributor in die/punch profile radii. The present work aims to consider the bending effects by introducing a bending-dependent inverse isogeometric formulation. The developed model deals with the minimization of potential energy, deformation theory of plasticity, classical plate theory, and considering a yield criterion in stress-resultant space. In addition to all advantages of the transfer-based inverse isogeometric formulation, one major benefit of this study is that the bending effects are included with a slight increase in the computation time. This methodology allows for accurately predicting the effects of changing die/punch profile radii and initial sheet thickness on the formability of the final part by presenting a new material updating process. To assess the credibility of this approach, an experimental setup and forward FEM software have been utilized to form a rectangular box. The results acquired by the developed method and those achieved by experiment and forward FEM reveal acceptable accuracy in the presented model. Also, strains and thicknesses predicted by the developed method, membrane inverse isogeometric model, and forward FEM for nine different values of punch radius to the sheet thickness ratio have been compared. Considering forward FEM as a reference method, the average of calculated error in the presented model for prediction of thickness at the middle of punch radius zone is around half of that in the membrane model. In solving the studied problems, the presented model requires only slightly more computation time (around 2%) than the membrane inverse isogeometric model and much less computation time than forward FEM. Therefore, the presented method is a valuable inverse forming solver especially when the bending effects are significant.

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.

Sheet metal forming processes for manufacturing truncated cones can be divided into methods which use shape related tooling to produce the required form, for example, spinning and deep drawing, and processes that utilise kinematics to produce the required geometry, for example, roller, air and swivel bending. Such kinematic forming methods can achieve high degrees of forming flexibility but require process models to avoid elaborate trial and error approaches. For the incremental manufacture of cones, CNC swivel bending as yet lacks such a process model. In addition, with the current ‘state of the art’ processes, the manufactured cones exhibit geometric defects with respect to concentricity and skewing. In this study, the operation of a CNC bending machine fitted with an upper beam that can be inclined was investigated. The proposed inclination of the beam corresponds to the desired conical shape of the product. The machine was provided with a radial sheet feed mechanism (back-gauge) to feed material in even segments between bent corners thus avoiding geometric imperfections. A plasto-mechanic process model was developed to deliver the process parameters for swivel bending of specific conical geometries. The process model was validated by numerical simulations and practical bending experiments. Coarsely segmented conical shapes can be manufactured using the analytically calculated process parameters. For conical geometries, the process modifications of sequential swivel bending showed satisfactory improvements in the initial bending defects, that is, lack of concentricity and skewing. Compared with the target geometries, a tendency towards larger diameters remained in the experiments and is explained by the boundary conditions of the sequential process and if a larger number of bending increments is carried out. The present study delivers a first approach to determine the process parameters for the sequential operation of a swivel bending machine in order to provide relevant process parameters for the industrial production of conical components.