Papers by Keyword: Bending

Abstract: Air bending is a critical operation in the metalworking industry, where dimensional accuracy and process efficiency are essential to ensure product quality and economic viability. This work proposes an AI-driven design and optimization strategy which couples artificial intelligence, specifically artificial neural networks, with a quasi-random search algorithm for the metamodeling and optimization of the air bending process. An extensive simulation database was generated by varying geometrical, material, and process parameters, and neural-network-based metamodels were trained to predict the maximum punch force, maximum thickness reduction, and final bending angle, achieving high predictive accuracy with R² values exceeding 0.96. The metamodel was subsequently used to optimize process configurations by simultaneously minimizing the maximum punch force and the maximum thickness reduction while ensuring the target bending angle, leading on average to reductions of 46.7% in maximum force and 31.5% in thickness reduction compared to non-optimized cases. The results demonstrate that artificial intelligence provides an efficient and effective tool for the design and optimization of the bending process, significantly accelerating parameter selection while improving process quality and reducing manufacturing costs.

Abstract: A consistent kinematic method was developed to calculate a forming limit curve (FLC) for a material with thickness t^*₀ from a given FLC pertaining to a different thickness t₀ ≠ t^*₀. The developed method is based on the analysis of the bending strains introduced by the Nakajima test method. To calculate the required strains, an explicit and an implicit procedure are presented. In contrast to its implicit equivalent, the explicit method suffers from an intrinsic error which scales with the material’s gauge and can be quantified by considering the neutral case t^*₀ = t₀. Finally, the developed method predicts a linear relationship between and the material thickness, which is in line with practical experience.

Abstract: Tailored welded and patchwork blanks are commonly used in the automotive field to locally tailor the mechanical response of sheet metal components, but conventional manufacturing approaches often introduce structural discontinuities, corrosion-prone interfaces and limited formability. Additive deposition of local reinforcements offers a more flexible alternative, enabling material to be placed only where it provides the greatest structural benefit and reducing overall material usage and environmental impact. This work investigates the flexural behaviour of additively reinforced blanks through finite element simulations. A numerical model was developed in Abaqus to reproduce three-point bending tests on 22MnB5 sheets locally reinforced by the wire-laser additive deposition of a 316L stainless steel. Metallographic cross-sections were used to define the reinforcement geometry and penetration depth, micro-hardness profiles to define the extent of the heat affected zone, and plastometric characterisation to obtain local mechanical properties. The simulations demonstrate that the proposed numerical model reliably reproduces the experimentally observed flexural behaviour of wire-laser additively reinforced blanks. The numerical force-displacement response is consistent with the experimental one, and within this agreement the increase in bending strength obtained with minimal added material is confirmed.

Abstract: Accurate prediction of forming behavior in dry textile reinforcements requires constitutive models that capture both in-plane and out-of-plane deformation mechanisms. This work presents the development and validation of advanced bending models for unidirectional non-crimp fabrics (UD-NCFs) that exhibit two distinct characteristics: side-dependent behavior arising from asymmetric stitching and glass fiber backing, and nonlinear behavior characterized by decreasing bending stiffness with increasing curvature. Based on cantilever bending tests with optical moment–curvature measurement, five mathematical formulations (piecewise linear, polynomial, power law, logarithmic, and exponential) used to describe the moment-curvature relation were systematically evaluated using the coefficient of determination R². The piecewise linear and logarithmic models achieved the highest accuracy, with R² values approaching unity across all fiber orientations and bending directions. These models were implemented in ABAQUS/Explicit via the VUGENS user subroutine and validated through virtual cantilever tests, demonstrating good agreement with experimental deflection curves within the standard deviation bands. Application to hemispherical forming simulations revealed significant differences in wrinkle prediction between linear and nonlinear models. While the classical linear model based on Peirce predicted a single pronounced wrinkle in fiber direction, the nonlinear models captured additional wrinkles in the transverse direction and wider wrinkle patterns in fiber direction. Side-dependent models exhibited slightly increased wrinkle amplitudes compared to non-side-dependent models, particularly in fiber direction. The developed framework allows for a more accurate virtual process design than the current state of the art for composite forming operations by accounting for the side-dependent and nonlinear bending characteristics of UD-NCF materials.

Abstract: This study was prepared on the bending and buckling analyses of the 2D honeycomb structure beam with a pocket section on it. In the study, two different materials,PLA and ABS, were selected to be examined for the beam. The aim of the study was to determine the buckling modes and critical buckling loads of lattice beams using numerical methods. Besides, bending analyses were conducted. As a result of bending analyses, the displacement (u_y), equivalent von Mises stress (σ_von), shear stress (τ_xy) and normal stress (σ_yy) behaviours for two different materials were obtained. It was determined that the ABS material deformed more than the PLA material beam. In this direction, important findings were obtained for understanding the bending and buckling behavior of lattice beams.

Abstract: The choice of materials for mechanical or civil engineering applications depends on both structural and mechanical characteristics. The latter is more important as the material is intended to support loads that force it to undergo both transverse and longitudinal deformations. The aim of this study is to analyze the three-point bending behavior in the specimen condition of virgin or recycled polyethylene/eucalyptus fiber composites. However, two types of composites were formulated, and bending tests were carried out to determine the deformation characteristics following an applied stress. The elastic modulus E, which characterizes the stiffness or flexibility of the material, was discussed and the results compared between virgin and recycled LDPE matrix composites. Virgin low-density polyethylene (LDPE_V) matrix composites showed better flexural strength than recycled matrix (LDPE_R) composites. On the other hand, Charpy impact strength showed that recycled low-density polyethylene (LDPE_R) matrix composites had better impact strength than virgin low-density polyethylene (LDPE_V) matrix composites.

Abstract: This research improves the mechanical properties of laminates in ship hulls made of glass fiber reinforced plastics (GFRP) with the design of auxetic sheets, to take advantage of the property in their geometry to reduce the damage energy due to surface impacts absorbed by the laminate. 3D printing of second generation auxetic components to produce modified specimens. Laboratory reproductions of mechanical damage were compared with those of specimens extracted from a ship under construction. The mechanical properties of the bending and tensile tests demonstrated that the insertion of the core in the laminate protected the matrix from damaged energy, prolonging its useful life. Comparative results are presented, which will allow GFRP hull designers to insert auxetic sheet cores into their design. Mechanical tests allowed us to compare the progress of delamination.

Abstract: Plasma and TIG arc welding they are similar welding processes for the base of plasma welding is tig welding. The main purpose of this paper to come to a detailed conclusion based on a comparative analysis of both welding processes. The analysis is done steel bars each applied with the particular welding technique either plasma or tig welding. The principles of each welding procedure are discussed on how they welding is carried out, the mechanics and the technological functions of the welding devices are also discussed. The time required to complete a weld, the amount of current used. Impact on the steel is investigated caused by each welding processes. The welded joints are tested for bending and how much they elongate when under bending stress. The welded joints are done as butt welds for both of the grouped steel bars. These welding processes are used in industries where precision is of great importance like aerospace, design of industrial machinery, ship construction and Petro chemical industries. The concluded results of this paper will be of great contribution to the manufacturing industries because they would be able to know which welding process is best for which particular case or both must be used in order to achieve an ideal outcome. Keywords: Plasma and Tungsten inert gas TIG welding arc, tensile mild Steel bars, bending, butt weld, Amount of current, elongation.

Abstract: Increasing usage of the high-strength steels in structural design requires deeper understanding of the residual manufacturing stresses effect on the product service fatigue life. The bending forming process is being examined in this work. High cycle fatigue testing of the specimens before and after the bend shaping is performed by means of the vibrational fatigue method. The manufacturing residual and the fatigue tests stress fields are estimated by means of finite element analysis. The similarity principle is used to compare the fatigue curves constructed for the specimens with different geometries based on their local stress field concentration. A comparison with reference work is provided to support the similarity premise. The implementation of the mean stress correction for the residual stress is evaluated. The goal of this work is to demonstrate a methodological integration of the finite element analysis throughout manufacturing and fatigue testing for accurizing design life estimations. It may also serve as an end-to-end review and provide an outline for similar projects.

Abstract: This study examines the potential to customize the bending and transverse shear behavior of aluminum honeycomb sandwich panels by introducing sinusoidal perturbations to their cell walls. Finite element analysis is used to investigate the effect of varying the amplitude and frequency of the introduced perturbations on the flexural and transverse shear stiffness and strength of perturbed aluminum cores. Results show that increasing the amplitude and frequency of the perturbations generally decreases the flexural and transverse shear stiffness and yield strength. Local deformations in the perturbed cores indicate that imposing perturbations encouraged the development of localized deformations in the curved cell walls, which increased the perturbed cores' compliance. The transverse shear and flexural responses at the highest frequencies and amplitudes exhibited a very smooth and compliant behavior compared to the unperturbed cores. The response of the perturbed cores can be attractive for applications involving impact energy mitigation, as they demonstrate an enhanced capacity to reduce and limit the force transmitted through them.