scholarly journals THE EXPERIMENTAL AND NUMERICAL STUDY OF THE FORCES DURING THE INCREMENTAL FORMING OF TITANIUM SHEETS

2021 ◽  
Vol 23 (1) ◽  
pp. 5-10
Author(s):  
E.V. Markova ◽  
◽  
A.M. Al Darabseh ◽  
I.E. Daba’bneh ◽  
A.R. Ahmed ◽  
...  
Keyword(s):  
Incremental Forming ◽  
Numerical Study ◽  
Experimental Tests ◽  
Force Sensor ◽  
Thin Sheets ◽  
Forming Force ◽  
Elastoplastic Deformations ◽  
Machining Center ◽  
Forming Tools ◽  
Component Force

Incremental forming is a rapid prototyping process that allows sheets to be formed without using forming tools, using a numerically controlled machine tool. A wide variety of shapes can be generated with this process. The objective of this work is to study through experimental tests and numerical simulations the behavior of ASTM grade 2 titanium during incremental point forming (SPIF). A Spinner MFG850 machining center from ISET in JENDOUBA coupled to a multi-component force sensor FN7325 was used for the forming of thin sheets by this process. As the diameter of the punch and its incremental movement are parameters having a direct effect on the forming force, tests with diameters of the punches dp varying between 10 and 15 mm and various paths made up of circular movements in the horizontal plane have been carried out experimentally. Numerical simulation is carried out in large elastoplastic deformations with ABAQUS/explicit. Comparisons of the evolution of the forming force for different values of the diameter of the punch dp and of the displacement step ∆zare carried out.

scholarly journals Force Prediction for Incremental Forming of Polymer Sheets

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1597 ◽  
Author(s):  
Gustavo Medina-Sanchez ◽  
Alberto Garcia-Collado ◽  
Diego Carou ◽  
Rubén Dorado-Vicente
Keyword(s):  
Numerical Model ◽  
Specific Energy ◽  
Incremental Forming ◽  
Low Cost ◽  
Single Point ◽  
Experimental Tests ◽  
Element Model ◽  
Forming Force ◽  
Polymer Sheets ◽  
Metal Sheets

Incremental sheet forming (ISF) is gaining attention as a low cost prototyping and small batch production solution to obtain 3D components. In ISF, the forming force is key to define an adequate setup, avoiding damage and reducing wear, as well as to determine the energy consumption and the final shape of the part. Although there are several analytical, experimental and numerical approaches to estimate the axial forming force for metal sheets, further efforts must be done to extend the study to polymers. This work presents two procedures for predicting axial force in Single Point Incremental Forming (SPIF) of polymer sheets. Particularly, a numerical model based on the Finite Element Model (FEM), which considers a hyperelastic-plastic constitutive equation, and a simple semi-analytical model that extends the known specific energy concept used in machining. A set of experimental tests was used to validate the numerical model, and to determine the specific energy for two polymer sheets of polycarbonate (PC) and polyvinyl chloride (PVC). The approaches provide results in good agreement with additional real examples. Moreover, the numerical model is useful for accurately predicting temperature and thickness.

Formability and Surface Quality of Incrementally Formed Grade 1 Titanium Thin Sheets

2016 ◽  
Vol 716 ◽  
pp. 99-106 ◽  
Author(s):  
Antonio Formisano ◽  
Luca Boccarusso ◽  
Luigi Carrino ◽  
Massimo Durante ◽  
Antonio Langella ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Surface Quality ◽  
Manufacturing Process ◽  
Flexible Manufacturing ◽  
Incremental Forming ◽  
Experimental Tests ◽  
Thin Sheets ◽  
Contact Conditions ◽  
Complex Components

The incremental forming of titanium alloy sheets combines the advantages of this advanced flexible manufacturing process, that allows to produce complex components without using dedicated tools, with the interesting properties of the material under consideration. In this study, thin sheets of grade 1 titanium were incrementally formed to evaluate their formability and surface quality by varying the tool-sheet contact conditions. Experimental tests and surface analyses highlight dependence on the contact conditions of the surface quality rather than of the formability. Moreover, they emphasize that the tool-sheet contact conditions mainly affect the repeatability of the process due to the occurrence of galling.

Numerical Investigation of Ductile Fracture in Pipelines Under Complex Loading Using a Phenomenological Damage Model

2021 ◽  
Author(s):  
Iago S. Santos ◽  
Diego F. B. Sarzosa
Keyword(s):  
Ductile Fracture ◽  
Mechanical Response ◽  
Numerical Study ◽  
Damage Model ◽  
Stress Triaxiality ◽  
Numerical Procedure ◽  
Complex Loading ◽  
Experimental Tests ◽  
Compact Tension ◽  
Axial Tensile

Abstract This paper presents a numerical study on pipes ductile fracture mechanical response using a phenomenological computational damage model. The damage is controlled by an initiation criterion dependent on the stress triaxiality and the Lode angle parameter, and a post-initiation damage law to eliminate each finite element from the mesh. Experimental tests were carried out to calibrate the elastoplastic response, damage parameters and validate the FEM models. The tested geometries were round bars having smooth and notched cross-section, flat notched specimens under axial tensile loads, and fracture toughness tests in deeply cracked bending specimens SE(B) and compact tension samples C(T). The calibrated numerical procedure was applied to execute a parametric study in pipes with circumferential surface cracks subjected to tensile and internal pressure loads simultaneously. The effects of the variation of geometric parameters and the load applications on the pipes strain capacity were investigated. The influence of longitudinal misalignment between adjacent pipes was also investigated.

scholarly journals Simulation of incremental forming processes of a pyramidal ring made of two materials

2018 ◽  
Vol 19 (3) ◽  
pp. 313
Author(s):  
Masood Ghassabi ◽  
Milad Salimi ◽  
Mohammad Haghpanahi
Keyword(s):  
Feed Rate ◽  
Rotational Speed ◽  
Incremental Forming ◽  
Thickness Distribution ◽  
Single Point ◽  
Dimensional Accuracy ◽  
Cnc Machine ◽  
Forming Force ◽  
Forming Process ◽  
Dimensional Precision

Incremental forming is one of the most well-known forming processes for complex and asymmetric parts. This method uses a CNC machine, simple forming tool, and a die. This study focused on effects of some parameters such as the material, feed rate, pitch, rotational speed and movement strategy of tool on the dimensional precision, forming force, thickness distribution and fracture in the welding area. The results showed that single point incremental forming (SPIF) led to a better thickness distribution with lower tool force, whereas two-point incremental forming led to better dimensional accuracy. Rotational speed does not have any significant impact on the forming process while decreasing the feed rate partially reduced the forming force. According to the results, although dimensional precision in double point incremental forming is better than SPIF, when it comes to the thickness distribution, forming force, and economic issues, SPIF is in favor. The results also showed that by connecting two materials, different parameters for the two materials could be investigated simultaneously in one simulation process.

Determination of the Shear Modulus of Orthotropic Thin Sheets With the Anticlastic-Plate-Bending Experiment

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Nengxiu Deng ◽  
Yannis P. Korkolis
Keyword(s):  
Shear Modulus ◽  
Numerical Study ◽  
Pure Shear ◽  
High Strength Steels ◽  
High Strength ◽  
Elastoplastic Material ◽  
Plate Bending ◽  
Thin Sheets ◽  
Principal Stresses ◽  
Advanced High Strength Steels

The shear modulus of orthotropic thin sheets from three advanced high-strength steels (AHSS) is measured using the anticlastic-plate-bending (APB) experiment. In APB, a thin square plate is loaded by point forces at its four corners, paired in opposite directions. It thus assumes the shape of a hyperbolic paraboloid, at least initially. The principal stress directions coincide with the plate diagonals, and the principal stresses are equal and opposite. Hence, at 45 deg to these, a state of pure shear exists. A finite element (FE) study of APB is reported first, using both elastic and elastoplastic material models. This study confirms the theoretical predictions of the stress field that develops in APB. The numerical model is then treated as a virtual experiment. The input shear modulus is recovered through this procedure, thus validating this approach. A major conclusion from this numerical study is that the shear modulus for these three AHSS should be determined before the shear strain exceeds 2 × 10−4 (or 200 με). Subsequently, APB experiments are performed on the three AHSS (DP 980, DP 1180 and MS 1700). The responses recorded in these experiments confirm that over 3 × 10−4 strain (or 300 με) the response differs from the theoretically expected one, due to excessive deflections, yielding, changing contact conditions with the loading rollers and, in general, the breaking of symmetry. But under that limit, the responses recorded are linear, and can be used to determine the shear modulus.

Dynamic Hybrid Modeling of the Vertical Z Axis in a High-Speed Machining Center: Towards Virtual Machining

2007 ◽  
Vol 129 (4) ◽  
pp. 780-788 ◽  
Author(s):  
Giovanni Tani ◽  
Raffaele Bedini ◽  
Alessandro Fortunato ◽  
Claudio Mantega
Keyword(s):  
High Speed ◽  
Experimental Tests ◽  
Pneumatic System ◽  
Mechanical Structure ◽  
Virtual Machining ◽  
Feed Drive ◽  
Machining Center ◽  
Dynamic Hybrid ◽  
Five Axis ◽  
Machine Head

This paper describes the modeling and simulation of the Z axis of a five axis machining center for high-speed milling. The axis consists of a mechanical structure: machine head and electro-mandrel, a CNC system interfaced with the feed drive, and a pneumatic system to compensate for the weight of the vertical machine head. These subsystems were studied and modeled by means of: (1) finite element method modeling of the mechanical structure; (2) a concentrated parameter model of the kinematics of the axis; (3) a set of algebraic and logical relations to represent the loop CNC-Z feed drive; (4) an equation set to represent the functioning of the pneumatic system; and (5) a specific analytical model of the friction phenomena occurring between sliding and rotating mechanical components. These modeled subsystems were integrated to represent the dynamic behavior of the entire Z axis. The model was translated in a computer simulation package and the validation of the model was made possible by comparing the outputs of simulation runs with the records of experimental tests on the machining center. The firm which promoted and financed the research now has a virtual tool to design improved machine-tool versions with respect to present models, designed by traditional tools.

scholarly journals Numerical Study of Branched Turboprop Inlet Ducts Using a Multiple Block Grid Procedure

1991 ◽  
Author(s):  
Anil K. Tolpadi ◽  
Mark E. Braaten
Keyword(s):  
Numerical Solutions ◽  
Numerical Study ◽  
Three Dimensional ◽  
Separated Flow ◽  
Experimental Tests ◽  
Spherical Particles ◽  
Branch Duct ◽  
Pressure Losses ◽  
Overlapping Grids ◽  
Inlet Duct

An important requirement in the design of an inlet duct of a turboprop engine is the ability to provide foreign object damage protection. A possible method for providing this protection is to include a bypass branch duct as an integral part of the main inlet duct. This arrangement would divert ingested debris away from the engine through the bypass. However, such an arrangement could raise the possibility of separated flow in the inlet, which in turn can increase pressure losses if not properly accounted for during the design. A fully elliptic three-dimensional body-fitted computational fluid dynamics (CFD) code based on pressure correction techniques has been developed that has the capability of performing multiple block grid calculations compatible with present day turboshaft and turboprop branched inlet ducts. Calculations are iteratively performed between sets of overlapping grids with one grid representing the main duct and a second grid representing the branch duct. Both the grid generator and the flow solver have been suitably developed to achieve this capability. The code can handle multiple branches in the flow. Using the converged flow field from this code, another program was written to perform a particle trajectory analysis. Numerical solutions were obtained on a supercomputer for a typical branched duct for which experimental flow and pressure measurements were also made. The flow separation zones predicted by the calculations were found to be in good agreement with those observed in the experimental tests. The total pressure recovery factors measured in the experiments were also compared with those obtained numerically. Within the limits of the grid resolution and the turbulence model, the agreement was found to be fairly good. In order to simulate the path of debris entering the duct, the trajectories of spherical particles of different sizes introduced at the inlet were determined.

scholarly journals Numerical Study on Crack Distributions of the Single-Layer Building under Seismic Waves

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Fenghui Dong ◽  
Zhipeng Zhong ◽  
Jin Cheng
Keyword(s):  
Seismic Waves ◽  
Numerical Study ◽  
Single Layer ◽  
Experimental Tests ◽  
Masonry Structure ◽  
Original Model ◽  
Dynamic Responses ◽  
Masonry Structures ◽  
Reinforced Masonry ◽  
Longitudinal Cracks

This paper conducts a numerical simulation of the antiseismic performance for single-layer masonry structures, completes a study on crack distributions and detailed characteristics of masonry structures, and finally verifies the correctness of the numerical model by experimental tests. This paper also provides a reinforced proposal to improve the antiseismic performance of single-layer masonry structures. Results prove that the original model suffers more serious damage than the reinforced model; in particular, longitudinal cracks appear on bottoms of two longitudinal walls in the original model, while these cracks appear later in the reinforced model; a lot of cracks appear on the door hole of the original model, and no crack appears in the reinforced model till the end of seismic waves; seismic damage of walls in the reinforced model is obviously lighter than that in the original model; dynamic responses at all observed points of the reinforced masonry are obviously less than those of the original model. Strains at all positions of the reinforced model are obviously smaller than those of the original model. From macroscopic and microscopic perspectives, the computational results prove that the reinforced proposal proposed in this paper can effectively improve the antiseismic performance of the masonry structure.

Analysis of Flangeability by Single-Stage SPIF and Press-Working in AA7075-O Sheet

2020 ◽  
pp. 1-17
Author(s):  
Marcos Borrego ◽  
Domingo Morales-Palma ◽  
Carpóforo Vallellano
Keyword(s):  
Deformation Process ◽  
Failure Modes ◽  
Forming Limit Diagram ◽  
Experimental Tests ◽  
Single Stage ◽  
Forming Limit ◽  
Flange Forming ◽  
Conventional Press ◽  
Forming Tools ◽  
Hole Flanging

Abstract Recently, the research interest of hole-flanging has turned from conventional press-working to SPIF as a viable process for small- and medium-sized batches. Both technologies have been studied separately using different approaches and, therefore, most studies cannot be easily compared. Besides, some studies that measured the formability in SPIF using the classical Limiting Forming Ratio (LFR) showed conflicting results that still need to be clarified. Under these circumstances, the aim of this work is to provide a better understanding of the deformation process and the material formability in hole-flanging by critically comparing both forming processes. To this end, a series of experimental tests on AA7075-O sheet of 1.6-mm thickness by press-working and single-stage SPIF, using forming tools with different profile radii, are analysed. The material formability and flange geometry are compared and discussed in detail. The process limits are analysed by using both the Forming Limit Diagram (FLD) and the LFR. The failure modes by necking and fracture are clearly identified and assessed on both processes along with the influence of the bending induced by the tools during the flange forming. Results conclude that the LFR is not an adequate parameter to compare formability between processes other than press-working and, accordingly, two additional variables based on either the flange height or the average thickness reduction are proposed to successfully analyse flangeability.

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