Deformation Modes and Lip Fracture During Hole Flanging of Circular Plates of Anisotropic Materials

1977 ◽  
Vol 99 (3) ◽  
pp. 738-748 ◽  
Author(s):  
W. Johnson ◽  
N. R. Chitkara ◽  
H. V. Minh
Keyword(s):  
Plastic Anisotropy ◽  
Orthotropic Materials ◽  
Circular Plates ◽  
Anisotropic Behavior ◽  
Plastic Properties ◽  
Different Depths ◽  
Instability Strain ◽  
Strain Paths ◽  
Hole Flanging ◽  
Deformation Modes

An experimental investigation was carried out to determine the deformation leading to failure of the hole periphery in the hole flanging process using a conical punch. Circular plates of various hole sizes and of different materials were tested to different depths of punch penetration and the lip strain paths as well as the variation of thickness around the periphery of the lip were studied. In all cases, failure of the plate was due to lip fracture and the onset of lip instability was determined from the examination of the secondary surface texture of the lip of the plate during various stages of lip deformation. The instability strain in the hole flanging process was then calculated and it was found to be influenced by the process geometry and the plastic properties of the material. Hill’s model of plastic anisotropy for orthotropic materials was applied to a plane stress case to predict the variation of thickness around the periphery of the lip and the results were compared with experimental data. The influence of the anisotropic behavior of the material on the direction of lip fracture was also investigated.

Hole flanging and punching of circular plates with conically headed cylindrical punches

1973 ◽  
Vol 8 (3) ◽  
pp. 228-241 ◽  
Author(s):  
W Johnson ◽  
N R Chitkara ◽  
A H Ibrahim ◽  
A K Dasgupta
Keyword(s):  
Elementary Theory ◽  
Experimental Results ◽  
Circular Plates ◽  
Simple Analysis ◽  
Neck Formation ◽  
Fracture Development ◽  
Hole Flanging ◽  
Deformation Modes

To investigate the mechanics of the hole-flanging process, the quasi-static drifting and punching of thin circular plates with conically headed cylindrical punches was carried out for different materials. The deformation modes of the defected plates and the loads associated with them at different stages of punch penetration were obtained and the results are analysed by use of an elementary theory. The neck characteristics in the flange formation, which are of basic types—lip, petal and plug—were found to be dependent on punch semi-angle, material, and size of the initial hole in the plate. The change-over from lip to petal mode and the stage at which fracture occurs were studied. A simple analysis that predicts some features of neck formation, the onset of plugging and features of fracture development is also given and results obtained by its use are compared with experimental results.

Development of Combined Machining Modes, Investigation of Mechanical Properties and Structure of Deformed Semi-Finished Products from Alloy 01417

2020 ◽  
Vol 992 ◽  
pp. 498-503
Author(s):  
S. Sidelnikov ◽  
D. Voroshilov ◽  
M. Motkov ◽  
M. Voroshilova ◽  
V. Bespalov
Keyword(s):  
Mechanical Properties ◽  
Rare Earth Metals ◽  
Electrophysical Properties ◽  
Intermediate Annealing ◽  
Plastic Properties ◽  
Bar Rolling ◽  
Annealing Temperatures ◽  
Continuous Ingot ◽  
The Wire ◽  
Deformation Modes

The article presents the results of studies on the production of wire with a diameter of 0.5 mm from aluminum alloy 01417 with a content of rare-earth metals (REM) in the amount of 7-9% for aircraft construction needs. The deformation modes, the experimental technique and equipment for the implementation of the proposed technology described. The wire was obtained by drawing and bar rolling with subsequent drawing from a rod with a diameter of 5 mm, obtained previously using the process of combined rolling-extruding (CRE) from a continuous ingot with a diameter of 12 mm, cast in an electromagnetic mold (EMM). The wire obtained by the presented technology was subjected to 4 different heat treatment modes with annealing temperatures from 350 to 500 °C and holding time of 1 h in the furnace to achieve mechanical and electrophysical properties corresponding to TS 1-809-1038-2018. The level of strength and plastic properties obtained in the course of research required only one intermediate annealing. The microstructure of the wire was investigated and the modes were revealed that made it possible to obtain the required level of mechanical properties and electrical resistivity, satisfying TS 1-809-1038-2018.

Locking and Stability of 3D Woven Composite Reinforcements

2014 ◽  
Vol 611-612 ◽  
pp. 292-299 ◽  
Author(s):  
Sylvain Mathieu ◽  
Philippe Boisse ◽  
Nahiene Hamila ◽  
Florent Bouillon
Keyword(s):  
Finite Element ◽  
Strain Energy ◽  
Constitutive Law ◽  
Element Formulation ◽  
Woven Composite ◽  
Anisotropic Behavior ◽  
Stabilization Procedure ◽  
Bias Extension ◽  
Deformation Modes ◽  
Composite Reinforcements

3D woven composite reinforcements preforming simulations are an unavoidable step of composite part processing. The present paper deals with thick composite fabric behavior modelling and issues arising during the numerical simulation of preforming. After the description of the independent deformation modes of initially orthotropic reinforcements, a physically motivated and invariant based hyperelastic strain energy density is introduced. This constitutive law is used to show the limitations of a classical finite element formulation in 3D fabric simulations. Tension locking is highlighted in bias extension tests and a reduced integration hexahedral finite element with specific physical hourglass stabilization is proposed. Instabilities due to the highly anisotropic behavior law, witnessed in bending dominated situations, are exposed and a stabilization procedure is initiated.

scholarly journals Specific Cutting Forces of Isotropic and Orthotropic Engineered Wood Products by Round Shape Machining

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2575 ◽  
Author(s):  
Giacomo Goli ◽  
Rémi Curti ◽  
Bertrand Marcon ◽  
Antonio Scippa ◽  
Gianni Campatelli ◽  
...  
Keyword(s):  
Cutting Forces ◽  
Medium Density Fiberboard ◽  
Laminate Veneer Lumber ◽  
Scientific Basis ◽  
Wood Products ◽  
Orthotropic Materials ◽  
Machining Parameters ◽  
Cutting Coefficients ◽  
Round Shape ◽  
Different Depths

The set-up of machining parameters for non-ferric materials such as wood and wood-based materials is not yet defined on a scientific basis. In this paper, a new rapid experimental method to assess the specific cutting coefficients when routing isotropic and orthotropic wood-based materials is presented. The method consists of routing, with different depths of cut, a given material previously machined to a round shape after having it fixed on a dynamometric platform able to measure the cutting forces. The execution of subsequent cuts using different depths of cut allows the calculation of the specific cutting coefficients. With the measurement being done during real routing operations, a method to remove machine vibrations was also developed. The specific cutting coefficients were computed for the whole set of grain orientations for orthotropic materials and as an average for isotropic ones. The aim of this paper is to present and validate the whole method by machining selected materials such as Polytetrafluoroethylene—PTFE (isotropic), Medium Density Fiberboard—MDF (isotropic), beech Laminate Veneer Lumber—LVL (orthotropic) and poplar LVL (orthotropic). The method and the proposed analysis have been shown to work very effectively and could be used for optimization and comparison between materials and processes.

scholarly journals Identification of Anisotropic Yield Criterion Parameters from a Single Biaxial Tensile Test

2014 ◽  
Vol 611-612 ◽  
pp. 1710-1717 ◽  
Author(s):  
Shun Ying Zhang ◽  
Lionel Leotoing ◽  
Dominique Guines ◽  
Sandrine Thuillier
Keyword(s):  
Tensile Test ◽  
Yield Criterion ◽  
Biaxial Test ◽  
Anisotropic Behavior ◽  
Yield Model ◽  
Plane Stress Condition ◽  
Cruciform Specimen ◽  
Biaxial Tensile Test ◽  
Biaxial Tensile ◽  
Strain Paths

The present work deals with the calibration strategy of yield functions used to describe the plastic anisotropic behavior of metallic sheets. In this paper, Bron and Besson yield criterion is used to model the plastic anisotropic behavior of AA5086 sheets. This yield model is flexible enough since the anisotropy is represented by 12 parameters (4 isotropic parameters and 8 anisotropic parameters in plane stress condition) in the form of two linear fourth order transformation tensors. The parameters of this anisotropic yield model have been identified from a single dedicated cross biaxial tensile test. It is shown, from finite element simulations, that the strain distribution in the center of the cruciform specimen is significantly dependent on the yield criterion. Moreover, this cross biaxial test involves a large range of strain paths in the center of the specimen. The calibration stage is performed by means of an optimization procedure minimizing the gap between experimental and numerical values of the principal strains along a specified path in the gauge area of the cruciform specimen. It is shown that the material parameters of Bron and Besson anisotropic yield model can be determined accurately by a unique biaxial tensile test.

scholarly journals Effects of plastic anisotropy on localization in orthotropic materials: new explicit expressions for the orientation of localization bands in flat specimens subjected to uniaxial tension

2020 ◽  
Author(s):  
Jose Rodriguez-Martinez ◽  
Oana Cazacu
Keyword(s):  
Uniaxial Tension ◽  
Theoretical Investigation ◽  
Plastic Anisotropy ◽  
Orthotropic Materials ◽  
Uniaxial Tensile ◽  
Experimental Measurements ◽  
Plastic Localization ◽  
Metallic Sheet ◽  
First Time ◽  
Explicit Expressions

This paper presents a theoretical investigation on the inception of plastic localization bands in specimens taken from orthotropic metallic sheets, and subjected to uniaxial tension. For the first time, it is shown that the orientations of the localization bands can be obtained directly from experimental measurements of the uniaxial tensile flow stresses and Lankford coefficients (r-values) of the metallic sheet.

scholarly journals Dynamic cylindrical cavity expansion in orthotropic porous ductile materials

2020 ◽  
Author(s):  
Jose Rodriguez-Martinez ◽  
Alvaro Vaz-Romero ◽  
Tiago dos Santos
Keyword(s):  
Theoretical Model ◽  
Shock Waves ◽  
Cylindrical Cavity ◽  
Plastic Anisotropy ◽  
Cavity Expansion ◽  
Expansion Velocity ◽  
Ballistic Performance ◽  
Plastic Properties ◽  
Cylindrical Cavity Expansion ◽  
Anisotropic Porous Medium

This paper investigates the steady-state elastoplastic fields induced by a pressurized cylindrical cavity expanding dynamically in an anisotropic porous medium. For that task, we have developed a theoretical model which: (i) incorporates into the formalism developed by Cohen and Durban (2013b) the effect of plastic anisotropy using the constitutive framework developed by Benzerga and Besson (2001) and (ii) uses the artifical viscosity approach developed by Lew et al. (2001) to capture the shock waves that emerge at high cavity expansion velocities. We have shown that while the development of the shock waves is hardly affected by the material anisotropy, the directionality of the plastic properties does have an effect on the elastoplastic fields that evolve near the cavity. The importance of this effect is strongly dependent on the cavity expansion velocity, the initial porosity and the strain hardening of the material. In addition, the theoretical model has been used in conjunction with the Recht and Ipson (1963) formulas to assess the ballistic performance of porous anisotropic targets against high velocity perforation.

scholarly journals Influence of the Processing of Magnesium Alloys AZ31 and ZE10 on the Sheet Formability at Elevated Temperature

2011 ◽  
Vol 473 ◽  
pp. 335-342 ◽  
Author(s):  
Lennart Stutz ◽  
Jan Bohlen ◽  
Gerrit Kurz ◽  
Dietmar Letzig ◽  
Karl Ulrich Kainer
Keyword(s):  
Elevated Temperatures ◽  
Plastic Anisotropy ◽  
Production Costs ◽  
Processing Route ◽  
Forming Limit ◽  
Rolled Sheet ◽  
Strain Paths ◽  
Twin Roll Cast ◽  
Hot Rolled ◽  
Twin Roll

The substitution of conventional materials such as aluminium alloys and steels with the lightest structural metal magnesium and its alloys can yield significant weight saving in the transportation industry and hence, reduce vehicle weight and greenhouse gas emissions. Producing magnesium sheets by conventional hot rolling is expensive due to the large number of rolling passes to final gauge and annealing steps at elevated temperatures between the rolling passes. Twin roll casting is a well established processing route for aluminium sheets which can reduce the necessary rolling passes to a bare minimum to reduce the production costs. This process is receiving increasing attention for the production of magnesium sheets. This study reveals first hand results of sheet metal forming experiments on magnesium sheets rolled from twin roll cast strip as well as conventional DC cast slabs. Two different alloys, AZ31 (Mg-3Al-1Zn-Mn) and rare earth element containing ZE10 (Mg-1Zn-RE) were investigated. It is known that these alloys show significant differences in the microstructure development during conventional rolling as a result of recrystallisation. For hot rolled AZ31, distinct textures are formed with the majority of basal planes oriented in the sheet plane and hence, unfavourably for basal slip. Conventionally rolled ZE10 commonly shows a much weaker texture. Forming limit diagrams are presented and discussed with respect to the initial texture of the sheets. Strain response to various strain paths and plastic anisotropy are evaluated. Results of twin roll cast sheets are compared with conventionally hot rolled sheet of the same alloys. Competitive formability can be achieved at 200°C for all tested sheets. While conventionally rolled sheets show a generally higher formability than their twin roll cast counterparts, ZE10 outperforms AZ31 for both processing routes.

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