Force and Microstructure Variation of SLM Prepared AlMgSc Samples during Three-Point Bending

Lightweight parts manufactured by metal selective laser melting (SLM) are widely applied in machinery industries because of their high specific strength, good energy absorption effect, and complex shape that are difficult to form by mechanical machining. These samples often serve in three-dimensional stress states. However, previous publications mainly focused on the unidirectional tensile/compressive properties of the samples. In this paper, AlMgSc samples with different geometric parameters were prepared by the SLM process, and the variation of force and microstructure during three-point bending were systematically investigated. The results demonstrate that the deformation resistance of these samples has good continuity without mutation in bending, even for brittle materials; the bending force-displacement curves exhibit representative variation stages during the entire bending process; the equivalent bending strength deduced from free bending formula is not applicable when compactability is less than 67%. The variations of grain orientation and size of the three representative bending layers also show regularity.

Investigation on the Influence of Weld Position on the Deformation Behavior of Welded Tube During Free Bending Process

The non-uniform distribution of the mechanical properties of welded tube would affect the plastic deformation behavior of tube during the free bending process. To explore the influence of weld position on the forming quality and axis dimensional accuracy of welded tube, the free bending experiment and numerical simulation of welded tube were conducted in this paper. First, the principle of free bending was theoretical deduced and the stress distribution of bent tube was analyzed. Then the hardness test and uniaxial tensile test were conducted to obtain the mechanical properties of weld zone and parent zone of welded tube. The material strength in the weld zone of welded tube is significantly higher than that in the parent zone. Finally, the free bending experiment and numerical simulation with different weld position were carried out, and the influence of weld position on the bending radius, cross-sectional distortion and wall thickness of bent tube was discussed. All these findings advance the insight into the free bending deformation behavior of welded tube and help to improve the forming quality of welded tube and facilitate the application of free bending technology in welded tube.

Study on the Iterative Compensation Method for Continuous Varying Curvature Free Bending

The parts formed by the bending process not only have high precision of appearance dimension but also have good performance. In recent years, enterprises have put forward higher requirements for the forming process and product quality. Therefore, a new method for iterative compensation of bending springback with certain generality is proposed for continuous curvature bending. The purpose of this study is to take curvature as an iterative parameter and make the shape size reach the expected value through the finite compensation. On the basis of establishing this iterative compensation mechanism, the convergence of curvature iteration in the general free bending process is proved. The reliability of the proposed iterative compensation method in the bending process engineering application is verified by combining simulation with experiment. The two materials of 304 stainless steel and ST12 cold rolled steel were studied, and the two-dimensional plane stress-strain model Abaqus cantilever beam was established by using finite element software. The bending forming simulation was carried out based on the above iterative compensation mechanism. Finally, through the bending experiments of four models, the feasibility of the iterative compensation mechanism of curvature in the continuous curvature plane bending process is verified, and different models are selected to clarify that the method has the characteristics of generality, that is, it will greatly improve the flexibility of the bending process in industrial applications without the limitation of material types and mechanical models.

Influence of the electromagnetic field pressure on the free bending of the straight side

Bending is the operation of forming or changing the angles between the parts of the workpiece or giving it a curved shape and in the mean time is the most difficult and timeconsuming operation of the technological process of manufacturing parts from profiles. Aircraft bending parts of the following nomenclature are obtained as profiles: frames, ribs, stringers, linings and brackets. Profile parts are responsible for their intended purpose; therefore, high requirements are placed on the accuracy of their dimensions and the preservation of the crosssection shape. The process of bending profiles has its own characteristics, which are due to the shape of the profile section; the first feature is the presence of vertical shelves, significantly loaded and deformed due to large distances from the neutral axis of the bent section, the second is the mismatch of the bending plane with the main axes of inertia of the section, which causes oblique bending and twisting of the part. When analyzing the bending process of extruded profiles, it should be borne in mind that the neutral layer of the workpiece coincides with the line that passes through the centers of gravity of the sections. When using the hypothesis of planar sections of the plot of deformations and stresses in the stretched and compressed zones do not have a mutually reflected form. It is very important how the profile is oriented in the bending plane. Different orientation of the profile, even the simplest cross-section (for example, angular), gives a qualitatively different picture of the deformed state.

Investigating Fracture Failure in Origami-based Sheet Metal Bending

Origami-based sheet metal (OSM) bending is a promising new die-free folding technique for sheet metal. OSM bending principle is based on deforming the material along a pre-defined fold line, which is determined using material discontinuity (MD) produced by laser or waterjet cutting. The objective of this work is to study and evaluate the fracture in OSM bending under the influence of various MD types, kerf-to-thickness (k/t) ratios, and sheet thicknesses. The research goal is to provide information on selecting an optimized k/t ratio and type of MD that allows for fracture-free bending. Four different ductile fracture criteria (DFC) are used and calibrated from experimental data to forecast fracture. The DFC calibration is used to produce a set of critical damage values (CDV) for assessing the possibility of fracture in the OSM bending. In addition, the study provides fracture evaluation using finite element analysis (FEA) integrated with experimental cases for a broader range of OSM bending parameters and MDs. The results demonstrated that an MD with a higher k/t ratio is less likely to fracture during the OSM bending, whereas a higher sheet thickness increases the possibility of fracture. Furthermore, the study identifies the k/t ratio limit that ensures successful bending without fracture and categorizes MD types into two groups based on fracture likelihood. The fracture in the first group is dependent on the limiting k/t ratio, whereas the possibility of fracture in the second group is independent of the k/t ratio due to its topology.