Finite element analysis of sided coined-bead technique in precision V-bending process

The U-bending process is a common sheet-metal forming process widely employed to fabricate sheet parts like channels, beams, and frames of various sizes applied in almost all industrial fields. In recent years, the precision requirements are increased on the U-bent parts. To achieve these requirements, in this study, the effects of part geometry on the spring-back/spring-go feature including work piece length, U-channel width, punch and die radii, and work piece thickness, were investigated by using the finite element method (FEM) and laboratory experiments. The FEM simulation results clearly revealed the influence of part geometry on spring-back/spring-go feature via the changes of stress distribution analyses on the bending allowance zone, the bottom of bent part, and the U-leg of bent part. Specifically, the part geometry affected on the bending characteristic on the bending allowance zone, as well as it affected on the spring-back feature. In addition, the part geometry also affected on the formation of reversed bending characteristic on the bottom and U-leg of bent parts, as well as it affected on the spring-go feature. The bending angle could be achieved by compensating these bending and reversed bending characteristics. Therefore, to meet the required bending angle, the suitable design of part geometry was strongly considered to maintain the balancing of the bending and reversed bending characteristics. The laboratory experiments were carried out to validate the accuracy of the FEM simulation results. The FEM simulation results showed good agreement with the experimental results with reference to the bending angle and bending force.

Investigation of the V-bending process with the effect of V-grooving insert geometries is performed through finite element analysis within ANSYS LS-DYNA. Different V-groover geometries are tested to evaluate the effect on the final bent angle and bent radius of the sheet metal part, with the objective of obtaining the minimized bent angle and bent radius results. It is also observed that the corner radius of the V-groover has a major influence on the bent angle and bent radius. Due to the removal of material in the bending region, which reduced the bending resistance, an increase in the corner radius results in a decrease in both the bent angle and radius. The shape of V-groover also affects the bending results, with variations in geometries leading to variations in both bent angle and radius. When the cutting cross-sectional area is kept constant, the bent angle shows minimal variation, while the bent radius steadily increases with the V-groover angle, reaching its maximum at 90 degrees.

Finite Element Analysis and Experimental Investigations on Laser Bending of AISI304 Stainless Steel Sheet

Forming of the titanium elements by bending

Rotary bending is able to bend sheets with various bending radii and angles by controlling forming conditions. The effects of applied radial force and rotary angle on bending radius and angle are clarified to realize and a precise rotary bending system. The bending radius is determined by applied force and bending angle is determined by applied radial pressure and rotary angle. The feedback bending system for rotary bending is developed in that the bending conditions are determined by the previous measured value of bend sheets.

Background/Aim. In implant prosthetics, there is an increasing use of materials that, with their mechanical characteristics, can alleviate the negative consequences of implant stress. The aim of this study was to conduct a comparative analysis of stress distribution and deformation of implant-supported telescopic systems and surrounding structures made of different materials using the finite element method. Methods. The 3D finite element models were prepared using the SolidWorks program (SolidWorks 2018, Concord, MA, USA). Two models of telescopic crowns with the characteristics of polyetherether-ketone (PEEK) polymer and cobalt-chromium (Co-Cr) alloy faceted with feldspar ceramics were used. The models were loaded with an axial force of 150 N in the region of the central fossa. The analysis of stress and strain distribution was per-formed by the finite element method in the Ansys software (ANSYS Workbench 16; Ansys Inc., Pittsburg, PA, USA). Results. Implant-supported telescopic crowns made of PEEK polymer significantly reduced stress in the implant and abutment neck area compared to the conventional Co-Cr crown veneered ceramic. At the level of bone structure, both models showed a concentration of stress at the level of the cortical bone, while the trabecular bone was significantly less exposed to stress. Under the same conditions, the degree of deformation of the secondary telescopic crown was more pronounced in models with PEEK polymer characteristics. Conclusion. Owing to their mechanical characteristics, PEEK polymers can be the materials of choice in the fabrication of superstructures on implants. Given that this in vitro study was accompanied by limitations, further research is needed to confirm the superior role of PEEK material in implant prosthetics.

Considering the advantages of the press process as compared to the machining process, the making good utilization of work piece materials and the saving of production time, the Press machine associated with press form tooling is increasingly served for complicated shape parts production. The sheet-extrusion is the most important metal-forming process, which controls the material flow to fulfil the extruded shape. By using this process, the complicated extruded-shape parts could be manufactured without the machining process. Owing to the piping defect, however, the complicated extruded-shape parts are limited in the sheet-extrusion process. In this study, the finite element method (FEM) is used to investigate the piping feature. In addition, a relationship between extruded shape and piping defect is also examined. The laboratory experiments are performed to validate the accuracy of FEM simulation results. Based on the stress distribution and velocity analysis, the relationship between extruded shape and piping defect could be clearly identified. Furthermore, The FEM simulation results show good agreement with the experimental results with reference to the extruded shape and piping defect.

Interaction of low-frequency axisymmetric ultrasonic guided waves with bends in pipes of arbitrary bend angle and general bend radius

Cover glass in commercial handheld devices is now evolving from flat (2D) to curved (3D) shapes. For example, some commercial devices have utilized sled-shape cover glass,[1] which partially covers long edges of the device. According to the patents published by key handheld manufacturers,[2, 3] we can expect more variety of 3D shaped cover glass for handheld devices in the market. In this study, we have focused on the reliability of 3D cover glass when it is dropped to a rigid surface. The key parameters under study are the corner/edge bend radius and angle of the cover glass, which determines the 3D shape of the cover glass. To achieve this goal, we developed a finite element model to simulate the drop[4-13] of a handheld device with 3D-shaped glass. The model uses explicit algorithm to simulate the high speed impact on the device during the drop test. The glass performance was evaluated based on contact force between the glass and the ground and maximum principal stress in the glass. We showed that to avoid severe damage because of first impact between the glass and the ground, the bend angle of 3D glass has to be in the range between 0 and 45°. For drop angles of 45° and higher, with the proposed glass bend angle, the impact can be taken over by the edge of the back cover of the device. In addition, we showed that optimum glass bend radius is in the range of 3.8 mm and larger. This is required to reduce stress in glass because of impact. The approach and conclusions from the current study can serve as a general guideline to improve the 3D cover glass reliability of a handheld device.

The development of intracranial internal carotid artery (ICA) stenoses may be associated with the morphology of the siphon. The aim is to quantitatively characterize the geometry of ICA, and develop a classifier of the ICA shape in relation to the location and incidence of stenoses. The ICA geometry from 74 subjects was analyzed by means of image-based computational techniques. The siphon was split into two bends, and was described in terms of curvature radius, radius of vessel, angle of bending, and length. Differences of geometry between ICA classes were assessed in control group, consisted of 30 subjects without stenoses. In stenosed group, the association between the ICA classes and the incidence of stenoses were investigated and validated by hemodynamic simulation. The curvature radius and angle of the posterior bend were significantly different between ICA classes, as well as the angle between the two bends. An innovative classifier was developed with the three geometric parameters. The ICA classification was found associated with the incidence of stenoses at the siphon. Geometric factors relative to the ICA were correlated with the location and incidence of stenoses at the siphon. The present work has potential implications in the quest for hemodynamic factors contributing to the initiation and progression of intracranial ICA stenoses.

3D explicit finite element analysis of tensile failure behavior in adhesive-bonded composite single-lap joints

Precision and efficiency constitute the main challenges in minimally invasive surgeries. Current endoscopic robotic system limitations have been sought for innovative design and optimization strategies. Moreover, the use of flexible surgical robots in high-speed flows such as cavitation flows is a problem that needs to be solved. To address these issues, the design optimization of a tendon-driven endoscopic robot based on hydrodynamic cavitation is presented in this study. The flexible part of the robot was analyzed using the Finite Element Method (FEM), where fluid–structure interactions and material mechanical properties were considered which led to the fabrication of a prototype. Employing the shadow-graphy technique, sprays emerging from the endoscopic robot were imaged at various bending angles and fluid pressures to examine carefully flow cone angle change effects. Subsequently, the results from the experiments involving ex vivo human cervix and uterus myoma tissues were included. Thermal conditions and mass transfer rates were measured according to variations in applied pressure, bending angle enabling quantitative assessment of heat diffusion and material removal efficiency at the tissue interface. This study focuses on the continuum endoscopic robots operating at high flow rates and presents an optimal working area via a prototype. Tissue experiments demonstrated that superficial endometrial ablation increased proportionally with the bending angle of the robot in both cervix and myoma tissues, which are characterized by their dense and resilient structure. The results highlight the interconnected dynamics of cone angle, flow pressure, and tissue ablation during robot bending. In short, this study presents guidelines for future studies on the design optimization of continuum robots for high-flow rate applications. • A tendon-driven flexible robot was fabricated according to simulation parameters. • Finite Element Method (FEM) simulations were performed with fluid–structure interactions. • The change in cone angle was determined under different bending angles and fluid pressures. • Ablated tissue area is proportional to robot bending angle and flow cone angle in dense tissues. • The device does not cause significant temperature differences during ablation.

The VDA238-100 standard for tight radius bending (v-bending) of sheet materials has received widespread acceptance with automotive suppliers and material producers to characterize local formability. However, the test fixture and tooling in the v-bend test standard is not amenable to direct strain measurement and the operator cannot terminate the test at the onset of crack initiation as the outer bend surface is not visible. Consequently, fracture is identified using a load threshold and the bend angle estimated from an analytical formula based upon the punch displacement and tooling geometry. Bend angles are not directly transferable and must be interpreted relative to the sheet thickness and bend radius unlike a strain measurement. By obtaining an in-situ strain measurement on the surface using digital image correlation (DIC), the plane strain fracture limit can be accurately identified at the onset of cracking and remove ambiguity in translating the bend angles to practical forming operations and simulations. A novel inverted VDA test frame was developed to incorporate DIC strain measurement during the bend test and a variety of advanced high strength sheet materials were evaluated. It was observed that the VDA bend test creates a homogeneous strain state of plane strain across the width of the sample along with a proportional strain path to fracture without necking that is ideal for fracture characterization. A correlation is developed to relate the bend angle with the major strain for the materials considered and accounts for the sheet thickness and bend radius. A comparison of the bend angle obtained using the formula in the VDA standard based on the punch displacement was in very good agreement with manual measurements and an algorithm to measure the bend angle using DIC analysis was developed.

As a hydraulic lifting pipeline structure widely used in deep-sea oil, gas transportation, and sediment dredging projects, the pipeline configuration is related to the improvement of transportation efficiency and pipeline safety. Particularly, the bending section consumes the most energy and withstands severe erosion. Understanding and predicting the conveying characteristics of two-phase flow in bends is therefore crucial. In this study, CFD-DEM (computational fluid dynamics-discrete element method) simulation method is employed to calculate various cases, considering five parameters: pipeline bending radius and angle, conveying velocity, particle diameter, and concentration, to explore the influence of these parameters on pressure drop and erosion rate of pipeline and result in a data set of hundreds of cases. Based on this data set, seven machine learning models are trained to predict pressure drop and erosion rate, respectively. To enhance model accuracy, the stacking method in ensemble learning is employed to combine multiple models with good performance. Additionally, the Optuna and SHAP (SHapley Additive exPlanation) methods are utilized to optimize hyperparameters and explain the degree to which parameters impact the predictions. The result demonstrates that pressure drop is almost unaffected by bending radius, while erosion rate initially decreases and then increases with bending angle, and both increase with other parameters. Among the evaluated models, artificial neural network, XGBoost, and random forest all demonstrate high prediction accuracy. The stacking model further improves the accuracy, with mean absolute error improving by 21.7% and 32.2%, and the SHAP method demonstrated good interpretability, which is basically consistent with CFD-DEM results.

Design of Process Parameters in Wiping Z-bending Process using Statistical Analysis Technique