Sheet Bending Research Articles

Methane Adsorption and Transport in Tortuous Slit-like Nanochannels: A Molecular Simulation Study.

Tortuosity is a crucial characteristic of porous materials, such as the shale matrix where shale gas is stored. The presence of tortuous nanochannels significantly affects the adsorption and transport of nanoflows. In this research, we use molecular dynamics simulation (MD) to study the adsorption and transport properties of shale gas (methane) in a curved slit-like nanochannel constructed from bent graphene sheets. Our findings reveal that the curvature of the tortuous channel influences methane adsorption: convex surfaces exhibit stronger adsorption, while concave surfaces exhibit weaker adsorption; the discrepancy is amplified by the nanoflow. Additionally, nanoflow velocity is heterogeneously distributed within the curved channel, with higher tangential flow velocities observed near the entrance and the outer surface. We also identify a "bouncing effect", where the nanoflow not only moves tangentially along the channel but also bounces between the inner and outer walls. Furthermore, methane in narrower channels exhibits higher tangent flow velocity and higher bouncing frequency but smaller flux, whereas larger curvature results in shorter channel length and smaller tortuosity, but the transport tangent velocity and flux are both reduced. The findings of this study can help in the better understanding of shale gas nanoflow properties in tortuous media and provide insights for simulating more general nonstraight nanoflows.

Springback behavior after air bending of pre-strained AA 6016-T4 sheets: Influence of dislocation density and backstress on model accuracy

Predicting springback in sheets of aluminum alloys is challenging, particularly for complex strain path deformation used to form the material. This paper presents experimental and modeling results for air bending of AA 6016-T4 sheet material. Prior to bending, pre-strains were applied to the specimens in uniaxial tension, plane-strain tension, and biaxial tension. Specimens were then cut from the pre-strained material and were subjected to air bending using three different bend angles in a v-die, after which springback was measured. It was found that greater levels of pre-strain result in larger springback magnitudes, and that the biaxial pre-strained specimens generally exhibited greater springback than the others. A CPFE – EPSC model with phenomenological backstress component in the hardening law was used to predict springback magnitude across the different pre-strain paths, pre-strain levels, and imposed air bend angles. It was observed that the more significant the strain path change, as was seen in the case of biaxial tension pre-strain followed by bending, the greater the influence of backstress on model accuracy, owing to the activation of new slip systems. When backstress was excluded from the model, a 3.2 % prediction error in springback angle was observed in the worst case, versus an error of 0.8 % when backstress was included. Backstress was correlated to more rapid dislocation density development on both the tensile surface of the sheet, and also through the thickness, after the strain path change. On the other hand, for the case of plane-strain pre-strain followed by bending, dislocation density development was more gradual and the backstress impact on model prediction was less significant, with the same slip systems active during both pre-strain and bending. Therefore, it is seen that the influence of backstress on accuracy springback modeling in AA 6016-T4 varies significantly depending on the strain path. Thus, the use of a phenomenological backstress law within the CPFE-EPSC framework is seen to be an accurate and efficient approach for modeling springback after strain path changes that can occur during industrial forming applications.

Radially patterned morphogenesis of murine hair follicle placodes ensures robust epithelial budding.

The bending of simple cellular sheets into complex three-dimensional (3D) forms requires developmental patterning cues to specify where deformations occur, but how positional information directs morphological change is poorly understood. Here, we investigate how morphogen signaling and cell fate diversification contribute to the morphogenesis of murine hair placodes, in which collective cell movements transform radially symmetric primordia into bilaterally symmetric tubes. Through live imaging and 3D volumetric reconstructions, we demonstrate that Wnt and Shh establish radial patterns of cell fate, cell morphology, and movement within developing placodes. Cell fate diversity at different radial positions provides unique and essential contributions to placode morphogenesis. Further, we show that downstream of radial patterning, gradients of classical cadherin expression are required for efficient epithelial rearrangements. Given that the transformation of epithelial discs into 3D tubes is a common morphological motif used to shape diverseorgan primordia, mechanisms of radially patterned morphogenesis are likely highly conserved across evolution.

Investigating the effect of MXene reinforcement on the mechanical and vibrational behaviour of honeycomb core sandwich composite structures

Honeycomb core sandwich composite panels are now being employed in various industries and possess huge potential owing to the fact that they provide almost similar properties as that of traditional metallic materials with substantial reduction in weight and are extremely corrosion resistant. MXene nanosheets have caught attention of the scientific community owing their extraordinary physical, chemical and mechanical properties. In the present work, the effect MXene reinforcement on the bending and vibrational behaviour of honeycomb cored sandwich composite structures has been investigated using experimentation and finite element (FE) modeling. The honeycomb cored sandwich plates were fabricated and samples were tested via three-point bending and vibration test under various testing conditions. The SEM images revealed that the MXene nanosheets were well dispersed within the epoxy matrix when their mixture was prepared and the homogenous dispersion was also maintained in the fabricated honeycomb core. Also, the MXene and glass fibres were found to be well bonded with the matrix. As far as bending behaviour is concerned, the sandwich structure containing MXene reinforced honeycomb core displayed superior load bearing capacity and exhibited higher values of core shear strength and face sheet bending strength at all testing temperatures. Furthermore, the reinforcement of MXene resulted in an increase in the natural frequency for all the considered modes irrespective of the end conditions. For instance, the natural frequency of the honeycomb core sandwich composite plate at first mode increased by 5.5 % and 10.2 % under CFFF and CFCF boundary conditions, respectively, upon addition of MXene.

Manually directional splitting of in-situ intact igneous rocks into large sheets

This paper presents a directional large-area rock fracturing method. The method had distinctive features compared with other common fracturing methods. The area of the fracturing surface could reach 10–500 m2. The fractured rock was sheet-like in shape, with a thickness of 6–8 cm. The main fracturing tools and procedures used were described in the paper. This paper analysed the reason for controllable and directional (also mode-I) rupturing in rock from the view of fracture mechanics. Counter-intuitively, the fracturing surface of the rock sheet had an angle (approximately 25°) to the loading direction (i.e., the orientation of the maximum principal compressive stress). The rupture behavior was controlled by the relationship between the load and the geometric boundary of the rock. It is found that the fracturing surface can suddenly and rapidly propagate after a certain strike by calculating the energies of the rock sheet. The striking energy could be converted into elastic strain energy, which accumulates in a very-slightly bent rock sheet step by step until exceeds the bearing limit of rock sheet. Most of the stored elastic strain energy was subsequently released in the form of splitting energy, leading to rock fracturing. This study provides insights into the occurrence of tectonic earthquakes.

Bending of bimetallic steel sheet on three-roll mills in the production of large diameter tubes

Bending of bimetallic steel sheet on three-roll mills in the production of large diameter tubes

Bending of Sheet Metal (st37) Using 90 Degree to Estimate Blank Dimensions

Several factors must be considered whendesigning parts that are being made by bending. Theprimary factor is minimum radius and angle of bending thatcan be bent successfully without metal cracking. Lowcarbon steel metal (st37), manufactured by Libyan Iron andsteel Company, was used in this study. Various bendingprocesses by Vee die for different radii and calculatethickness were conducted and bending zones were tested tofind the mean radius and calculate the bending allowance.These calculations depend upon the inner bend radius andthickness of the sheet metal. The thickness was reduced andthe neutral axis were moved up in the direction ofcompression side. Form the values of reduction in thicknessand different radii of bending a chart was drawn. Anotherchart was drawn to minimums the process of trial and errorfor estimating the blank length of the bending sheet metal.Form these charts, the initial blank sizes can be determined,so that products can bend without loss and crack in thematerial. As a result time and material can be saved. Theresults of the present study can have practical applicationsfor this material (st37) which is in common use by theLibyan industry.

Technology Updates on Plate Bending Machines with Hydraulic Systems

The swift progression of industrial technology has profoundly influenced the manufacturing sector, especially in the domain of sheet metal manipulation. Hydraulic plate bending machines hold a pivotal role in contemporary production due to their precision in shaping sheet metal components. This study aims to elevate the versatility and efficiency of hydraulic plate bending machines through innovative modifications. Key components underwent substantial alterations, including punch substitution, installation of dual punch locking plates, and integration of a pressure gauge. An evaluation ensued to determine the optimal parameters duration and force requisite for bending sheet metals ranging from 1 mm to 4 mm in thickness, aimed at assessing machinery efficacy. Test outcomes unveiled the modified machine's adeptness in accurately bending sheets of varying thicknesses, affirming its intended functionality. Moreover, the machine's enhanced adaptability allowed for seamless interchangeability of punches with diverse sizes and shapes. These empirical findings provide invaluable insights for enterprises striving to streamline manufacturing processes and boost overall productivity. Notably, this study highlights the pivotal role of technological advances in hydraulic plate bending machines, offering firms an efficient avenue to cater to diverse sheet metal shaping demands, thereby amplifying productivity and adaptability in industrial operations.

Experimental and model investigation of spreading characteristics of the liquid sheet formed by jet impinging on a circular plane

The focus of this paper is on the spreading characteristics of the liquid sheet formed by jet impinging on a circular plane. The liquid sheet is studied in two parts: the liquid film that spreads radially on the circular plane, and the free liquid sheet after leaving the circular plane, the former determines the initial thickness and velocity of the latter. Experimental results show that, for the liquid film on the circular plane part, as the jet velocity increases, the liquid film thickness increases due to the film velocity loss caused by the inelastic collision. The liquid film thickness is positively correlated with the jet radius and negatively correlated with the circular plane radius. Liquid viscosity slows the spreading of liquid film, forms the boundary layer, and thickens the liquid film. The surface tension inhibits the velocity loss due to the inelastic collision. For the free liquid sheet part, surface tension and gravity promote the bending of the liquid sheet. The larger the initial momentum of the liquid sheet leaving the circular plane, the larger the maximum spreading range of free liquid sheet reaching the equator. As for the theoretical model, a film velocity correction coefficient reflecting collision loss is introduced to improve the radial spreading theory of the liquid film on a solid surface, and a streamline function is assumed to solve the momentum integral equation of free liquid sheet. The predicted streamline agrees well with the experimental data.

Warm Air Bending of AZ31B Sheets Based on an Online Local Contact Heating Method

Abstract Warm forming holds significant potential in shaping challenging materials due to its comprehensive advantages compared to cold and hot forming. Effective heating is crucial for precise warm forming processes. This study explored an innovative warm air bending technique employing an online local contact heating method. Heat transfer during the preheating stage and the air bending of AZ31B sheets were investigated through experiments and finite element analysis at temperatures ranging from room temperature (24 °C) to 250 °C, considering the thermomechanical coupling effect. The results indicate a significant increase in the bending center angle, advancing from 69.8 deg to more than 119 deg as the heating temperature rises from room temperature to 250 °C. Fractures were effectively eliminated when the sheet heating temperatures exceeded 150 °C. Simultaneously, as the localized heating temperature increases, a corresponding decrease in the rebound angle is observed, reducing from 10.6 deg to 2.3 deg. The findings validate the feasibility of warm air bending using online local contact heating in industrial applications, with regard to forming quality and production efficiency.

A Study on the Laser Bending of AISI303 Stainless Steel Sheets under Active Heat Control Temperature

A Study on the Laser Bending of AISI303 Stainless Steel Sheets under Active Heat Control Temperature

Experimental Measurement of the Stress Gradient in a Bent Sheet

Stress gradients were experimentally measured in a 316 stainless steel sheet after bending with a press brake. Two different tool radii and three different bend angles were used to produce plastically bent sheets. Microhardness tests were performed across the thickness of the bent sheet, and a correlation between microhardness and strength was experimentally determined and was used to obtain the stress gradient. The position of the experimentally determined neutral plane correlated well with theory. Theoretical calculations of the stress gradient were made using a power law constitutive equation along with a simple mechanics analysis of plastic bending. Four of the six bending experimental conditions had reasonable correlation with the theoretical calculations. Ideas for improving this experimental method are discussed.

Multi-sensor-based process monitoring and quality assessment during laser forming of novel titanium foam to prevent cellular structure damage

Titanium foam finds its application in different fields like battery electrodes, heat exchangers, biological prosthetics, and lightweight structures for aeronautical parts. However, the inherent property of the foam to fail during mechanical loading conditions poses a challenge in providing final shape to these materials for practical applications. The present work investigates forming of Titanium foam (Ti Foam) using inline process monitoring for achieving controlled foam deformation while maintaining its quality without failure. Infrared (IR) pyrometer and laser-based displacement sensor were used to monitor the foam deformation behavior and thermal signature. The monitoring data were used to understand the process mechanism of laser forming. The bending mechanism within the foam was analysed with respect to solid sheet bending process. The correlation of the achieved bending angles, was attempted with the process parameters for surface, microstructural, elemental, and phase transformation. A critical analysis of Ti foam behavior, like surface melting, in situ oxidation, phase transformation, and formation of nano-structures on foam surface was addressed based on process parameter combinations. Micro-computed tomography (μCT) was carried out to investigate the pore deformation mechanism. Metallurgical characterisations for foam surface and phase analysis were carried out using X-ray photoelectron spectroscopy (XPS) and tunneling electron microscopy (TEM) to determine the chemical and crystallographic states of the laser-formed surface.

Folding of a growing hyperelastic sheet in a viscous fluid

Understanding the growth-induced deformation of soft materials in viscous environments is important for a variety of problems in nature and engineering. Here, we focus on the fluid–structure interaction of a hyperelastic sheet growing in an incompressible Newtonian fluid in the Stokes flow regime. We develop a computational framework for simulating this problem, where the isogeometric boundary integral method is used with the Kirchhoff–Love shell formulation and elastic–plastic decomposition of the deformation gradient tensor. We quantify the relative effects of the growth rate, the sheet bending rigidity, and the fluid viscosity on the fold formation and development of the growing sheet. Our results suggest that the viscous resistance to in-plane deformation promotes fold formation, whereas the viscous resistance to out-of-plane deformation suppresses fold development. We also investigate the effects of the thickness and aspect ratio of the rectangular sheet. Finally, we compare the growth- and prestrain-induced deformations to find a common behavior of sheets under viscous environments.

Effect of Process Parameters on Bend Angle during Underwater Laser Bending of SS304 Sheet

Effect of Process Parameters on Bend Angle during Underwater Laser Bending of SS304 Sheet

Experimental investigation, statistical modeling and optimization of laser bending process of perforated sheets

In this work, the laser bending process of perorated sheets is performed experimentally using a CO2 laser machine with maximum power of 120 W. Perforated sheets made of stainless steel 304 with a thickness of 2 mm are irradiated by laser beam in order to bend along a straight line. The effects of LOP (90–114 W), laser scanning speed (1–3 mm/s) and number of irradiations (10–20) on the bending angle of laser bent perforated sheets are examined using design of experiments based on response surface methodology. It is concluded from the obtained results that the bending angle of laser bent perforated sheet is increased with increasing in the laser output power and number of irradiations. In addition, it is proved that with increasing the laser scanning speed, the bending angle of bent sheet is decreased. Also, optimization of input variables shows that for achieving the maximum value of bending angle in laser bent perforated sheet the laser output power, laser scanning speed and number of irradiations should be adjusted as 114 Watts, 1 mm/s and 20, respectively.

Bending of sheets and profiles on a four-roll machine for rocket bodies, pipe and frame products. Part 13

A theory of stamping is developed taking into account the anisotropy and hardening of the workpiece. The parameters of the strain-stress state of the workpiece are calculated using the example of bending a conical tube on a rolling machine or in a die. CAD/CAE modeling is used to study deformations, stresses and forces acting on the workpiece from rolls or die tools. The criteria for the formation of cracks, low accuracy and excessive springback of the part after processing are determined, and recommendations for their elimination are given. Keywords:stamping, workpiece, anisotropy, bending of a conical tube, rolling machine, die, CAD/CAE modeling dr_zharkov_v_a@mail.ru

Analytical description of adjustment of rolls for manufacturing parts from elastic sheet material

The object of research is the process of bending sheet material, taking into account its springiness. When manufacturing sheet parts by bending from a completely elastic sheet, its shape is completely restored after the deformation stops, unlike an elastic sheet. Thus, when producing cylindrical parts by drawing between three rolls, the resulting radius of the cylindrical part will be larger than the calculated one. This phenomenon is evaluated by the coefficient of springing – the ratio of the calculated radius to the one obtained after partial expansion. When manufacturing conical parts, this approach cannot be applied, because the value of the radius is variable. The article applies the theory of surface bending from differential geometry. The curvature of the line on the surface has two components - normal and geodesic. When the surface is bent, the normal component changes, while the geodesic component remains unchanged. The magnitude of the normal component depends on the angle between the origin of the cone and its axis. So, for a cone with a base of radius R and an angle of 20°, the normal curvature is 0.94/R, and the geodesic curvature is 0.34/R. For cylindrical parts, the geodesic curvature of the cross-section (circle) is zero, so it is not necessary to take it into account. Usually, adjustment of rolls for the production of conical parts is carried out experimentally. The difference of the proposed approach lies in the elimination of this problem thanks to the decomposition of the curvature of the base of the cone into two components. This allows to calculate the settings of the rolls and thereby reduce their adjustment time. The parameters of the rolls and their mutual placement are calculated for the production of conical parts of the required size, taking into account their springiness. The field of application of the obtained results is the production of parts by bending flat metal sheet blanks

Effect of the individual layer thickness and relative blanking clearance on micro-blanking for Cu/Nb multilayer composite sheets

In this study, two types of Cu/Nb multilayer composite sheets with individual layer thicknesses of 11.11 μm and 0.35 μm, respectively, were first prepared and then tested by micro-blanking. The results show that the sheets of 0.35 μm exhibit higher ultimate tensile and shear strengths, and greater elongation, compared to those with an individual layer thickness of 11.11 μm. The sheet with an individual layer thickness of 11.11 μm achieves optimal blanking accuracy at a relative blanking clearance of 7%. Additionally, when the relative blanking clearance is 3%, it exhibits a significant proportion of smooth areas on the shear surface. Investigation of the shear surface at different ratios of punch stroke to sheet thickness (h/t) reveals that the Cu/Nb multilayer composite sheet experiences significant extrusion and bending during the micro-blanking process. Furthermore, the laminated structure exhibits remarkable continuity and deformation mobility, delaying crack formation. This study provides theoretical support for the plastic micro-blanking technology of multilayer composite.

Improving Press Bending Production Quality through Finite Element Simulation: Integration CAD and CAE Approach

Efficient operations and output of outstanding quality distinguish superior manufacturing sectors. The manufacturing process production of bending sheet metal is a form of fabrication in the industry of manufacture in which the plate is bent using punches and dies to the angle of the work design. Product quality is influenced by plate material selection, which includes thickness, type, dimensions, and material. Because no prior research has concentrated on this methodology, this research aims to determine V-bending capacity limits utilizing the press bending method. The inquiry employed finite element analysis (FEA), along with Solidworks was the tool of choice to develop drawings of design and simulations. The ASTM E290 standard guides this study. The software in this package may combine CAD (Computer-Aided Design) and CAE (Computer-Aided Engineering) without requiring extra design applications. This study tested SPCC and SPHC plate materials with five thickness variations. The findings embrace the number of failure risks associated with press bending exhibited on the von Mises stress diagram, which is directly proportional to showing the thickness limit of each material type throughout the bending process. The study's findings lay the groundwork for improving manufacturing quality by lowering the number of faulty goods produced by trial and error. Because the maximum allowable die width is 12 mm, the thickness limit of the press bending process is 2 mm. However, due to the greater intensity of the SPCC material, it has a reduced defect rate compared to SPHC material.