Bending Line Research Articles

The effect of mechanical behavior on bendability of ultrahigh-strength steel

Bendability is an important property of ultrahigh-strength steels since the typical applications of such materials include structures manufactured by air-bending. Conventional methods to evaluate bendability, such as the bending test according to the standard VDA-238 or the conventional tensile test do not provide sufficient information to evaluate bendability of ultrahigh-strength steels due to the average nature of the material response in these tests. In this study, the mechanical properties were determined using thin tensile specimens cut from the surface of the sheet and the evaluation of bendability was carried out using frictionless bending tests. The results of the experiments and FE-modelling presented in this paper reveal that the mechanical properties of the sheet surface have a significant impact on bendability. Novel ultrahigh-strength steel with better work-hardening capacity at the surface caused by a layer of relatively soft ferrite and lower bainite has good bendability, especially when the bend line is aligned transverse to the rolling direction. Microstructural investigations reveal that in a conventional steel with a relatively hard surface microstructure, the deformation localizes into shear bands that eventually lead to fracture, but similar shear banding was not present in the novel steel surface. This can be attributed to the better work-hardening capacity which delays the onset of shear localization and fracture.

Nanocellulose-reinforced phenol-formaldehyde resin for plywood panel production

The search for new technologies to improve adhesives and the properties of reconstituted wood panels is constant, and nanotechnology is a tool for this purpose. The aim of this study is investigating the effect of adding nanocellulose in the formulation of the adhesive phenol-formaldehyde on the physico-mechanical properties of Pinus taeda plywood panels. Three ratios of nanofibrillated cellulose (NFC) were added to the adhesive formulation used to produce plywood panels: 0,026 %, 0,038 % or 0,064 %. The panels were tested according to the European standards; apparent density, resistance to parallel and perpendicular flexure and glue line shear strength were determined after 6 hours of boiling and after the boiling cycle for the 1st glue line (face) and 2nd line (core). The use of NFC in the adhesive caused an increase of viscosity and reduction of the gel time of the adhesive. The apparent density of the panels was not influenced by the addition of NFC, but the properties of parallel bending, perpendicular flexing and glue line shear were sensitive to the addition of NFC. The NR2 treatment (0,038 % NFC) presented the best results in the mechanical tests

Research of high strength steels bending

The article deals with the issues of obtaining high-strength steels. A conclusion about the effect of the temperature on the steel was drawn based on the research of the microstructure. To check the effect of the welding process on the steel under study, the hardness of the weld and the zone of thermal influence were measured. The weld was checked by X-ray television control for defects in the weld joint.To analyze the possibility of free bending with local heating experiments on tempering samples were conducted in order to identify its optimum temperature at which no cracking occurs in the steels after bending. Bending experiments were carried out after local heating.A comparison of the results of measuring the hardness of the weld, as well as samples obtained after tempering and local heating of the bending line were made. Graphs of the drop in hardness of the studied steel depending on the tempering temperature, as well as the drop in hardness as it moves away from the local heating line, are constructed. Bending experiments with compression of high-strength steels were performed using a substrate material.The samples obtained during the experiments were examined by X-ray for defects in the bending line. The value of compressive stresses acting on bent sample is calculated.

Effect of Electric Current Pulse Type on Springback, Microstructure, Texture, and Mechanical Properties During V-Bending of AA2024 Aluminum Alloy

AbstractThe present work focused on the effect of the electric current pulse type on the springback, microstructure, texture, and mechanical properties during the V-bending process of AA2024 aluminum alloy. In order to investigate this effect, three different forming conditions including conventional V-bending and electrically assisted V-bending with square and sinusoidal pulses were considered. The results indicated that the amount of springback significantly decreased from 45.5 deg (for the sample formed via conventional V-bending) to 24 deg by applying the sinusoidal pulse. Microstructural observations revealed lower stored energy in the samples formed by electric current pulses which resulted in larger grain size compared with the samples formed without electric pulses. In addition, the result showed that the intensity of the 〈111〉||BLD (bend line direction) fiber texture reduced after applying electric current pulses, whereas it was very strong in the sample formed without electric pulses. It was suggested that the electric current pulses led to change the slip plane of the dislocations from {111} to {110} through cross slip. The applying electric current pulses decrease the ultimate tensile strength (UTS) from 471.1 MPa (for the conventional tensile test) to 448.0 and 426.7 MPa for the square and sinusoidal pulses, respectively. On the other hand, the electric pulses improved the formability of the AA2024 alloy owing to the activation of more slip systems, inhibition of dislocation pinning, the promotion of dislocation movement, and the acceleration of restoration mechanisms.

An analytical inverse analysis to determine equi-biaxial tensile properties of strain-hardening UHPFRC from ring-on-ring test

The equi-biaxial tensile properties of strain-hardening UHPFRC are determined and investigated based on an original analytical inverse analysis of results from ring-on-ring tests. First, the analytical inverse analysis method is developed based on the elastic slab bending and yield line theories. Using this method, a new objective criterion for the determination of the elastic limit stress of strain-hardening UHPFRC is provided, and a point-by-point inverse analysis is used to obtain the strain value at the end of hardening. This method reduces uncertainties regarding assumptions and avoids any iterative procedures. The inverse analysis results are put into perspective with experimental evidence, particularly based on DIC measurements. Moreover, the uniaxial tensile properties are also derived from the inverse analysis of 4PBT results and compared with the equi-biaxial tensile properties from the proposed inverse analysis. The inverse analysis results show a 18% lower elastic limit stress, and almost equivalent tensile strength of UHPFRC subjected to equi-biaxial stresses, compared with the corresponding values from uniaxial stress. Moreover, a relatively small equi-biaxial strain at the end of hardening is highlighted.

Investigation of Fluid-Structure Interaction Induced Bending for Elastic Flaps in a Cross Flow

With the recent increase in the design of light and flexible structures, numerical investigations of fluid and structure together play a significant role in most engineering applications. Therefore, the current study presents an examination of fluid-structure interaction involving flexible structures. The problem is numerically solved by a commercial software ANSYS-Workbench. Two-way coupled three-dimensional transient simulations are carried out for the flexible flaps of different thicknesses in glycerin for a laminar flow and Reynolds number ranging from 3 < Re < 12. The bending line of the flaps is compared with experimental data for different alignments of the flaps relative to the fluid flow. The study reports the computation of the maximum tip-deflection and deformation of flaps fixed at the bottom and mounted normal to the flow. Additionally, drag coefficients for flexible flaps are computed and flow regimes in the wake of the flaps are presented. As well, the study gives an understanding on how the fluid response changes as the structure deforms and the model is appropriate to predict the behavior of thick and comparatively thinner flaps. The results are sufficiently encouraging to consider the present model for analyzing turbulent flow processes against flexible objects.

P‐125: Influence of Line Shape on the Durability of Bending Lines on Flexible OLED Panels

Experiments were conducted to test the durability of bending line with different shapes on the bending area of 5.85 inch flexible OLED panel. Results showed that Z shape lines owned the best performance. Additionally, other shapes were further discussed.

Desain dan Analisis Alat Bending V Sistem Hidro Pneumatik

The design of the pneumatic hydro system V bending tool serves as an alternative tool for bending plates replacing the manual bending method which is widely used in the industrial community, especially machining workshop workshops today. In this design the hydraulic jack bender is driven by a pneumatic cylinder so that the workload of the operator is lighter. As for the results of this design and analysis, a V bending tool with 750 mm frame height, 650 mm frame width, 150 mm hydraulic stroke length, and 5 mm diameter spring pull wire are obtained. In addition, the punch angle is 85o and the punch radius is 1.5 mm while the die angle is 85o, the width of the V die is 33 mm and the bending line capacity is 300 mm. The punch and die material chosen is steel AISI 1045.

Biaxial flexural response of Strain-Hardening UHPFRC circular slab elements

The biaxial flexural response of strain-hardening UHPFRC circular slab element is investigated experimentally and analytically using the ring-on-ring test. The Digital Image Correlation (DIC) technology is applied to capture the 3D full-field of strain and deflection of the tensile surface through the whole loading process. Based on DIC analysis, a quasi-elastic limit is determined additionally to characterize the flexural response of UHPFRC under biaxial stress condition. The random and uniform distribution of matrix discontinuities in UHPFRC in the quasi-elastic domain, as well as multiple fictitious crack formation in hardening domain, is highlighted. In addition, ring-on-ring test and Four-Point Bending Test (4PBT) results are compared with special emphasis on flexural strength and characteristics of matrix discontinuity development. The results show higher ultimate flexural strength and energy absorption capacity at ultimate limit from the ring-on-ring test, and almost same flexural strength at the quasi-elastic limit for both tests. Finally, a simplified inverse analysis is proposed for the ring-on-ring test based on the elastic slab bending and yield line theories. The calculation results indicate a 19% lower tensile elastic limit stress of the UHPFRC, while an almost equivalent value of tensile strength is obtained from the ring-on-ring test, compared with the 4PBT results.

Bending technology of high strength steel sheets and tools for its realization

The article proposes and theoretically justifies a method for bending high-strength steels with compression. The technology allows to get parts from high-strength steels without cracks along the bending line. In the case of bending according to the proposed method, the deformation is carried out by the combined action of longitudinal and lateral forces. Equitations are derived showing the stress distribution over the cross section in the deformation zone. The article proposes and theoretically justifies a method for bending high-strength steels with compression. The technology allows you to get parts from high-strength steels without cracks along the bending line. In the case of bending according to the proposed method, the deformation is carried out by the action of longitudinal and transverse forces. Equitations were derived for finding the longitudinal compressive force at which the neutral layer in the workpiece moves to the outer surface based on the equations of stress distribution. Equitations are derived for finding the moment created by the longitudinal compressive force, as well as the moment formed by the action of compressive stresses, which made it possible to derive the equation for the external bending moment during bending with compression. Equitation is derived for finding the shoulder of the force action creating an external bending moment. Equitation is derived for finding the force of the punch for bending with compression.

An experimental and analytical model for force prediction in sheet metal forming process using perforated sheet and origami principles

In this work, we present a model for origami-based sheet metal (OSM) folding that can predict the required bending force. OSM folding is enabled by introducing bending features along the bending line, named material discontinuity (MD). Firstly, the introduced analysis in this work developed a bending setup for OSM that does not require a die then introduced a method to analytically derive the bending force for a regular sheet without any added folding features. The analytical approach is followed using an experimental setup identical to the developed OSM bending configuration. Secondly, the OSM bending experiment is conducted to measure the required bending force and to identify which parameters influence the OSM bending force significantly. Finally, an empirical model is proposed considering the analytical force in the first step and the influencing parameters defined in the second step. Regression analysis is carried out using one portion of experimental force measurement to determine the coefficients of the proposed empirical model. The other measurement set is used to validate the prediction model. The validation results of the proposed prediction model show good agreement between the developed prediction model and the experiment results. The prediction model provided a shape factor that represents the topology of each bending feature, as well.

Neutralization Line Decoupling Tri-Band Multiple-Input Multiple-Output Antenna Design

A pair of tri-band multiple-input-multiple-output (MIMO) antennas with high isolation is investigated in this paper. The proposed antenna consists of two monopole antenna elements with an edge to edge spacing of 4 mm ( $0.03~\lambda _{0}$ at 2.3 GHz). The monopole antenna element chose the bending line structure that can operate in tri-band and realize miniaturization. To achieve compact dimension and high isolation, symmetrical distribution layout is adopted to decouple the low frequency band, the U-shaped neutralization line (NL) contacting with two microstrip lines, and it can to improve the isolation in high frequency band, and the inverted U-shaped NL contacting with two radiation patch can decoupling in the middle frequency band. And then study the envelope correlation coefficient is lower, and the radiation pattern in operation bands is quasi-omnidirectional. It indicates that the antenna has obtained a satisfactory diversity performance within the whole operation bands which can be a good candidate for some portable MIMO applications.

Desain Konstruksi Press Tool Sebagai Alat Bending Bentuk V Dengan Garis Bending Max. 300mm

Nowadays, the process of metal forming in the machining industry and welding workshop is developing very rapidly especially in the plate bending process. The bending process is the formation of metals which generally use plates or rods of both ferrous and non-ferrous metal materials by bending, which in the bending process will cause stretching or stretching on the neutral plane axis along the bending area and produce a straight bend line. The use of appropriate technology machines has been widely used to increase productivity, efficiency, and effectiveness in the production process for community businesses, especially those in the regions. One of the appropriate technologies that might be applied in the bending process is a hydraulic jack press that is equipped with a press tool. Press tool is one type of product forming, cutting and bending tools from the basic material of sheet plates whose operations are using a press tool. The results of the design of press tool bending tool V have a length of 300 mm bending line, 33 mm bending width, 110 mm spring height, free step distance of 19 mm. The punch angle used is 85⁰ with the punch radius used is 1.5 mm while the die angle is 85⁰. The selected punch and die material is Steel AISI 1045 HV HR.

Refinement to the Existing Analytical Methods of Analysis of Buried Pipelines due to Strike-Slip Faulting

Analytical methods presented to analyze the buried steel pipelines at strike-slip fault crossing use the Euler-Bernoulli beam theory. The cross-section of a buried pipe that is completely surrounded by soil cannot rotate freely and would not be remained perpendicular to the bending line after deformation. So it would be better to take into consideration a rotation between the cross-section and the bending line. The developed model improves the existing methodologies by using the Timoshenko beam theory and considering the shear deformations as a refinement to the existing methodologies. The proposed model results are compared with the results of an existing analytical model and it is found that the maximum bending and axial strains decrease with taking into consideration the shear deformations. Furthermore, it is shown that the difference between the results of models increases with an increase in the burial depth.

Designing and Manufacturing the Press Tool of Air Bending V Brake

Nowadays, the metal forming process in the welding machinery and machinery industry is developing very rapidly, especially in the bending process. The buckling process is a metal formation which generally uses sheet plates or rods from both ferrous and non-ferrous metals by bending, which in the bending process will cause a stretching or stretching on the neutral axis of the field along the bending area and producing a straight bending line. Appropriate technology machines have been widely used to increase productivity, efficiency, and effectiveness in the production process for community efforts. One of the appropriate technologies that can be applied in buckling is a tool equipped with a press tool. Press tool is one type of tool for the formation, cutting and bending of products from the base material of sheet plates whose operation uses a press machine. In this study, a V brake bending tool has been produced which has a capacity that is bending line length 300 mm, bending width 33 mm, spring height 110 mm, free step distance 19 mm, spring load received 263,820 N and material capacity that can be bent is a thickness of 3 mm, the punch angle used is 85⁰ with a punch radius used which is 1.5 mm while the die angle is 85⁰

Calibration based on ray-tracing for multi-line structured light projection system.

Multi-line Structured Light Projection System (MSLPS) is widely used with the advantages of high-contrast stripes and high robustness in high-speed dynamic reconstruction in comparison with Phase Modulation System (PMS). However, existing calibration methods are either sophisticated or low-accuracy in large visual field application because the bending of line structured light plane caused by lens distortion is inevitable and projector calibration is necessary. Therefore, in this paper, we present an accurate and robust calibration method based on ray-tracing, which establishes accurate relationship between subpixel coordinates of each bending line structured light plane and 3D coordinates based on camera coordinate system without projector calibration. As long as placing a checkerboard at random positions, MSLPS can be calibrated and hence is more suitable in practical application. Experimental results demonstrated that, compared with existing line structured light strategies, the proposed method could achieve more accurate and robust 3D reconstruction and the calibration process is simpler and easier to implement.

Analysis of material behaviour and shape defect compensation in the flexible roll forming of advanced high strength steel

Roll forming is a fast and low-cost forming process with the ability to form a wide range of materials, especially advanced high-strength steels (AHSS) that have limited ductility. However, roll forming is only able to form constant cross-sections along the longitudinal direction of the component, while many automotive components are more complex in shape. Flexible Roll Forming (FRF) uses rolls that have the ability to translate or rotate during production, enabling the manufacture of a part that has a variable cross-section potentially useful for the automotive industry.Deakin University is equipped with a flexible forming facility that can prototype parts with variable cross-sections. The machine has been developed, patented and manufactured by dataM Sheet Metal Solutions GmbH. Deakin’s Flexible Forming Facility (DFFF) consists of a single forming stand with two opposing robotic arms connected to forming rolls. The flexibly controlled arms form the clamped sheet along a CNC defined bend line while the sheet remains clamped. This facility is capable of creating changes in the cross-section in both width and depth along the part. Moreover, the Deakin facility can form the part in both forwards and backwards directions along the longitudinal dimension of the part. In contrast, conventional FRF facilities use multiple stands of forming rolls, and the forming sequence occurs in a single direction along the part.The first part of this study compares material deformation in the DFFF in contrast to that of the conventional FRF setup. This study will determine the similarities and differences in the final formed part between DFFF and the forming conditions in conventional FRF. The second step of the study is to investigate the forming properties of the final part when the part has variable depth. An experimental part formed on DFFF was compared to a numerical analysis using COPRA RF FEA to investigate the material flow and the forming defects. The results show that the major shape error is wrinkling. A new forming concept using a blank holder tool was analysed, and it shows promising results in regard to wrinkling reduction.

Comparison of the miniaturization efficiency of the coupler using the bends of quarter-wave segments

This article analyzes the efficiency of micropolice bending line for minaturization compared to artificial transmission lines. Simple bending of the line allows reducing the area of the coupler only by no more than 50%, this is due to the limited space inside the coupler. While the artificial transmission lines can provide a reduction in the area of more than 60%.

Theoretical and Experimental Free Vibration Analysis of a Loaded Curved Beam With Moving Boundaries

The present article theoretically and experimentally investigates free vibration characteristics of generalized curved beams with moving boundaries. The dynamic behavior is characterized about deformed configuration, attained under different concentrated loads, and rigidly connected to the midpoint of the beam. The coupled static and dynamic analysis of the geometric nonlinear problem is decomposed into two parts: the static problem dealing with large deformed configuration and the dynamic problem dealing with small amplitude free vibration of the deformed configuration beam. The analysis is carried out incrementally in embedded curvilinear coordinate frames using variational principle. The governing equation of the static problem is derived for a combined effect of bending and center line extension. The governing equation for free vibration is derived at the particular configuration of the updated beam geometry, using Hamilton's principle. The comparison between the numerical and experimental results successfully validates the proposed semi-analytical model and leads toward some meaningful observations.

Modelling of the Calendering Process of NMC‐622 Cathodes in Battery Production Analyzing Machine/Material–Process–Structure Correlations

The shift in the transport sector from internal combustion engines to battery‐powered electric vehicles and the continued demand for portable applications increases the need for batteries in the coming years. To optimize battery technologies, it is essential to fully understand the production process and the associated parameters as well as their influence on the chemical processes within the cell. At the Institute for Machine Tools and Industrial Management (iwb), extensive knowledge of the calendering process is gathered including the investigation of the displacement behavior for both the calender rolls and the bearing, as well as the adhesion strength. The process parameters such as roll temperature and velocity, structure parameters (e. g., coating thickness, adhesion strength), and machine behavior parameters (displacement and bending line) are investigated using three calender models. The achieved porosities are verified via porosity consistency measurements. Based on the collected data, qualitative machine/material–process–structure models are built up. Scanning electron microscopy (SEM) and light microscopy support the relations made. In addition, a connection between vertical displacement and line load is established.