DOCSLIB.ORG

Evaluation of Formability and Determination of Flow

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Evaluation of Formability and Determination of Flow EVALUATION OF FORMABILITY AND DETERMINATION OF FLOW STRESS CURVE OF SHEET MATERIALS WITH DOME TEST THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Ji You Yoon Graduate Program in Mechanical Engineering The Ohio State University 2012 Master's Examination Committee: Taylan Altan, Advisor Jerald Brevick Copyright by Ji You Yoon 2012 Abstract Determination of flow stress curve of sheet material is important for designing stamping process efficiently. Entering accurate flow stress curve to FE simulations is necessary to obtain reliable results from simulations. Furthermore, in most Advanced High Strength Steels (AHSS), material properties may vary from coil to coil and that can affect to product quality. The dome test is a material test to evaluate formability and determine the flow stress curve of the sheet materials. The dome test is a biaxial test which consequently achieves greater maximum true strain without localized necking compared to that of uniaxial tensile test. As a result, the flow stress curve obtained from the dome test can be determined up to larger strains than in tensile test. This reduces possible errors from extrapolation of flow stress curve obtained from tensile test. FE simulations are performed in order to understand the deformation process in the dome test and to develop database for computer program, PRODOME, (MATLAB). With PRODOME, flow stress curve is calculated (determining K and n values in Hollomon’s Law (σ=Kεn)) by inputting dome test outputs of punch force vs. stroke. It is calculated by using inverse analysis method. From the dome test, JAC 590R (t = 1.6 mm), JAC 780 TRIP (thickness = 1.0 mm) and Al 6022 (t = 1.0 mm) are tested. Lubrication system is developed from the dome test. With lubrication system, samples are evaluated how much they deviate from the apex of the dome by having percentage error they have in the flow stress curve. ii Dedication This document is dedicated to my parent, my sister and friends iii Acknowledgements Thanks God, I barely finish my study without Your help and Your strength that comes from You. To be able to accomplish this study, I have been supported and supervised by many people that God sent to me. To my family, I cannot express my gratitude enough. I am indebted to my family and my friends who helped me a lot during my school period. I believe that I would not be able to name everyone separately and to thank for everything that they did for me, however, I would like to express a few words of thanks from the bottom of my heart. I would like to express my deepest gratitude to: Prof. Taylan Altan for his great support and his valuable suggestions which make me strong to step up beyond my deficiency. His intellectual support, advice and guidance make me possible to accomplish this research works. I thank my committee member Dr. Jerald Brevick for support. I thank my colleagues of the CPF, Eren Billur, Dr. Hyun-Sung Son, Soumya Subramonian, Tingting Mao, Xi Yang, Adam Groseclose, Niranjan Rajagopal for their assistance. I also want to express great thanks to HRA, Jim Dykeman and Ben Flocken for their support. Specially, I would like to thank my parents and my sister for their endless encouragement, inspiration, advice and support. I would like to thank all those too numerous to mention here, who have assisted and encouraged to complete of my work. iv Vita February 2006 ............................................ Se-Hwa Girls’ High School 2010 ........................................................... B.S. Mechanical Engineering, Hanyang University 2011 to present .............................................. Graduate Research Associate, Department of Mechanical Engineering, The Ohio State University Fields of Study Major Field: Mechanical Engineering v Table of Contents Abstract ................................................................................................................... ii Dedication .............................................................................................................. iii Acknowledgements ................................................................................................ iv Vita .......................................................................................................................... v CHAPTER 1 INTRODUCTION ............................................................. 1 CHAPTER 2 BACKGROUND ............................................................... 3 2.1 Uniaxial Tensile Test .................................................................... 4 2.2 Biaxial Tension Test ................................................................... 16 2.2.1 Cupping tests ......................................................................... 16 2.2.2 Limiting Dome Height (LDH) Test ....................................... 17 2.2.3 Bulge Test .............................................................................. 20 2.2.4 Dome Test (extension of LDH test) ....................................... 24 CHAPTER 3 OBJECTIVES AND APPROACH .................................. 25 3.1 Objectives .................................................................................... 25 3.2 Approach ..................................................................................... 25 CHAPTER 4 INVERSE ANALYSIS METHODOLOGY .................... 30 vi CHAPTER 5 EXPERIMENTAL WORK AND RESULTS ................. 33 5.1 Experiments and Tooling ............................................................ 33 5.2 Test Procedure ............................................................................. 34 5.3 Output from the Dome Tests ....................................................... 35 5.4 Test Parameters and Selection of Materials ................................ 36 5.5 Test Results ................................................................................. 39 CHAPTER 6 FE SIMULATIONS ......................................................... 41 6.1 Simulation Parameters ................................................................ 41 6.2 Computer Program “PRODOME” Using MATLAB ................. 43 6.2.1 General concepts of computer program using MATLAB ..... 43 6.2.2 Running the PRODOME ....................................................... 44 CHAPTER 7 RESULTS AND DISCUSSION ...................................... 47 7.1 Determination K and n Values of the Sheet Materials ................ 47 7.2 Anisotropy Correction ................................................................. 48 7.3 Comparison of the Flow Stress Curves ....................................... 49 7.3.1 Tensile test vs. dome test ....................................................... 49 7.3.2 VPB test vs. Dome test from DEFORM and PAMSTPMP ... 51 7.4 Zero Point Adjustment ................................................................ 53 7.5 Lubrication System ..................................................................... 55 vii 7.5.1 Preliminary Evaluation Lubricant Test .................................. 55 7.5.2 Measurement of angle of fractures ........................................ 56 CHAPTER 8 SUMMARY AND CONCLUSIONS .............................. 64 REFERNECES ..................................................................................................... 68 APPENDIX A: Lubricants list .............................................................................. 72 APPENDIX B: Evaluation lubricant tests for high formability material (JSC 270F, t = 0.8 mm) ................................................................................................. 73 viii List of Tables Table 1. Dome test experiment matrix [Dykeman 2011, POSCO 2012].............. 33 Table 2. Material properties evaluated by tensile test provided by Honda ........... 37 Table 3. Test parameters of the dome test ............................................................ 38 Table 4. K & n values and of the materials with isotropic assumption ( = 1) ........................................................................................................................... 47 Table 5. Normal anisotropy of the materials (provided by Honda) ...................... 49 Table 6. Determined parameters from VPB test (w/o considering anisotropy), DEFORM and PAMSTAMP ................................................................................ 52 ix List of Figures Figure 1. Tensile test specimen, according to ASTM E8 [Altan 2012, ASTM 2011] ....................................................................................................................... 4 Figure 2. Schematic of a fixture used in a tensile test [Altan 2012] ....................... 5 Figure 3. The schematic of the force vs. elongation curve obtained from tensile test [Altan 2012] ..................................................................................................... 5 Figure 4. Engineering stress vs. engineering strain curve [Kalpakjian 2008] ........ 7 Figure 5. Comparison stress vs. strain curve between engineering state and true state [Hosford 2007] ............................................................................................... 8 Figure 6. True stress and true strain curve of Al 1100-O, plotted on log-log scale [Hosford 2007, Altan 2012] .................................................................................... 9 Figure 7. Some of the flow curve equations used in plastic deformation studies [Marciniak 2002, Altan 2012]: (a)
Load more

Recommended publications
  • An Experimental and Modeling Study of the Viscoelastic Behavior Of
    ð þ1 t An Experimental and Modeling rðÞ¼t re þ rsðÞexp À ds (1) Study of the Viscoelastic Behavior 0 s of Collagen Gel In Eq. (1), re is the equilibrium stress, and r(s) is the relaxation time distribution function with relaxation time s. Viscoelastic biomaterials likely contain a continuous spectrum Bin Xu of relaxation time constants [5]. While Eq. (1) can be well fitted with a few exponential terms, the fitting may provide little infor- Haiyue Li mation relevant to the characterization of intrinsic material prop- erties [6]. In the present study, the time-dependent distribution spectrum r(s) of collagen gel is obtained through numerical Department of Mechanical Engineering, inverse Laplace transform. Investigating the spectrum in terms of Boston University, the number of peaks, time constants, and peak intensity was found 110 Cummington Mall, to appropriately demonstrate the main properties of viscoelastic Boston, MA 02215 behaviors [7,8]. The intensity of the peak reflects the amount of dissipated energy during relaxation. The number of peaks and time constants are often correlated with specific molecular archi- Yanhang Zhang1 tectures; as a result it can be used as an approach to understand the structural behavior of biomaterials, as well as a useful tool to Associate Professor distinguish materials [9,10]. Department of Mechanical Engineering, In this study, the relaxation time distribution spectrum is Department of Biomedical Engineering, obtained from stress relaxation data by means of inverse Laplace Boston University, transform. This spectrum is employed to understand the mecha- 110 Cummington Mall, nisms of stress relaxation in collagen network.
    [Show full text]
  • Design of Forming Processes: Bulk Forming
    1 Design of Forming Processes: Bulk Forming Chester J. Van Tyne Colorado School of Mines, Golden, Colorado, U.S.A. I. BULK DEFORMATION atures relative to the melting point of the metal. Hot working occurs at temperatures above tJllerecrystalliza- Bulk defonnation is a metal-fonning process where the tion temperature of the metal. There is a third temper- defonnation is three-dimensional in nature. The pri- ature range, warm working, which is being critically mary use of the tenn bulk deformation is to distinguish it examined due to energy savings and is, in some cases, from sheet-fonning processes. In sheet-forming opera- used by industries. tions, the defonnation stressesare usually in the plane of the sheet metal, whereas in bulk defonnation, the 1. Cold Working Temperatures defonnation stresses possess components in all three Cold working usually refers to metal deformation that is coordinate directions. Bulk defonnation includes metal carried out at room temperature. Th,~ phenomenon working processes such as forging, extrusion, rolling, associated with cold work occurs wht:n the metal is and drawing. deformed at temperatures that are about 30% or less of its melting temperature on an absolute temperature scale. During cold work, the metal ,~xperiences an II. CLASSIFICATION OF DEFORMATION increased number of dislocations and elltanglement of PROCESSES these dislocations, causing strain hardening. With strain hardening, the strength of the metal increases with The classification of deformation processescan be done deformation. To recrystallize the metal, ;i thermal treat- in one of several ways. The more common classification ment, called an anneal, is often needed. During anneal- schemes are based on temperature, flow behavior, and ing, the strength of the metal can be drastically reduced stressstate.
    [Show full text]
  • Application of Forming Limit Diagram and Yield Surface Diagram to Study Anisotropic Mechanical Properties of Annealed and Unannealed Sprc 440E Steels S.P
    INTERNATIONAL CONFERENCE ON RECENT ADVANCEMENT IN MECHANICAL ENGINEERING &TECHNOLOGY (ICRAMET’ 15) Journal of Chemical and Pharmaceutical Sciences ISSN: 0974-2115 APPLICATION OF FORMING LIMIT DIAGRAM AND YIELD SURFACE DIAGRAM TO STUDY ANISOTROPIC MECHANICAL PROPERTIES OF ANNEALED AND UNANNEALED SPRC 440E STEELS S.P. Sundar Singh Sivam, M. Gopal, S.Venkatasamy, Siddhartha Singh Department of Mechanical Engineering, SRM University, Kancheepuram District, Kattankulathur- 603203, Tamil Nadu, India *Corresponding author: Email: [email protected] ABSTRACT Sheet metal forming is a vital operation in the manufacturing of a number of automobile components. The quality of the formed component depends largely on the formability of the sheet metal. In the present study, the formability of SPRC440E steel sheets by deep drawing have been characterized and the forming limit diagram (FLD’s) have been experimentally determined by conducting punch stretching experiments on unannealed and annealed SPRC440E sheets using a double acting hydraulic press. Formability observed from FLD’s has been correlated with microstructure, mechanical properties and formability parameters. From the experimental results, it has been found that the sheets have a favorable grain size and mechanical properties to meet the requirements of good formability for annealed SPRC 440E steel. It is also confirmed by Erichsen cupping test. It was also observed that metal stretchability increases with increasing value of strain hardening exponent (n) and drawability increases with increasing value of normal anisotropy (rm) value. It is well known that FLD and anisotropic properties of a substance sensitively depends upon its yield surface diagram. Therefore a suitable yield criterion is chosen to describe the plastic behavior and predict the nature of FLD of SPRC440E.
    [Show full text]
  • Mechanical Characterisation of Hydrogels for Tissue Engineering
    CHAPTER 12 Mechanical Characterisation of Hydrogels for Tissue Engineering Applications M. Ahearne*, Y. Yang and K-K Liu Summary ydrogels have been extensively investigated for use as constructs to engineer tissues in-vitro. Among the principal limitations with using hydrogels for engineering tissues are their poor mechanical H characteristics. Many techniques exist to measure the mechanical properties of hydrogels but few allow non-destructive monitoring of these propertie s under cells culture conditions. Two recently developed techniques shall be discussed in detail in the current chapter. Thin hydrogels have been clamped around their outer edge and deformed using a spherical load. The time-dependent deformation has been measured in-situ using a long focal distance microscope connected to a CCD camera and the deformation displacement has been used with a theoretical model to quantify the mechanical and viscoelastic properties of the hydrogels. For thicker hydrogels, optical coherence tomography has been used to measure the time-dependent depth of indentation caused by a spherical load on top of the hydrogel. Hertz contact theory has been applied to calculate the hydrogels mechanical properties. The mechanical and viscoelastic properties of several different hydrogel materials were examined. The principal advantages of these techniques have over conventional mechanical characterisation techniques are that the measurement can be performed on cell-seeded hydrogels and under sterile conditions while allowing non-destructive, in-situ and real-time examination of the changes in mechanical properties. KEYWORDS: Hydrogel, Mechanical characterisation, Indentation, Viscoelastic, Optical coherence tomography. *Correspondence to: Tel.: +44 (0)1782 555227. Fax: +44 (0)1782 717079. E-mail address: [email protected].
    [Show full text]
  • System for the Application of Hydrostatic Pressure and Mechanical Strain to Cell Cultures Justin Bacaoat Clemson University, [email protected]
    Clemson University TigerPrints All Theses Theses 12-2018 System for the Application of Hydrostatic Pressure and Mechanical Strain to Cell Cultures Justin Bacaoat Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_theses Recommended Citation Bacaoat, Justin, "System for the Application of Hydrostatic Pressure and Mechanical Strain to Cell Cultures" (2018). All Theses. 2966. https://tigerprints.clemson.edu/all_theses/2966 This Thesis is brought to you for free and open access by the Theses at TigerPrints. It has been accepted for inclusion in All Theses by an authorized administrator of TigerPrints. For more information, please contact [email protected]. SYSTEM FOR THE APPLICATION OF HYDROSTATIC PRESSURE AND MECHANICAL STRAIN TO CELL CULTURES A Thesis Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Master of Science Bioengineering by Justin Bacaoat December 2018 Accepted by: Jiro Nagatomi, PhD, Committee Chair William Richardson, PhD Ken Webb, PhD ABSTRACT Pressure and stretch are two of the primary forces that result in mechanotransductory events which regulate certain aspects of human health and disease. Laboratory systems such as the commercially available Flexercell® system and a variety of custom-made setups are currently used in research to systematically apply stretch and hydrostatic pressure independently, or in conjunction to cell and tissue cultures. However, these systems do not allow for the decoupling of pressure and stretch under the same culture conditions. The present study aims to design, fabricate, and calibrate a device that can apply pressure and stretch simultaneously, as well as independently to cells in culture.
    [Show full text]
  • Identification of Strain Rate-Dependent Mechanical Behaviour of DP600 Under In-Plane Biaxial Loadings Wei Liu, Dominique Guines, Lionel Leotoing, Eric Ragneau
    Identification of strain rate-dependent mechanical behaviour of DP600 under in-plane biaxial loadings Wei Liu, Dominique Guines, Lionel Leotoing, Eric Ragneau To cite this version: Wei Liu, Dominique Guines, Lionel Leotoing, Eric Ragneau. Identification of strain rate-dependent mechanical behaviour of DP600 under in-plane biaxial loadings. Materials Science and Engineering: A, Elsevier, 2016, 676, pp.366 - 376. 10.1016/j.msea.2016.08.125. hal-01394743 HAL Id: hal-01394743 https://hal.archives-ouvertes.fr/hal-01394743 Submitted on 9 Nov 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Identification of strain rate-dependent mechanical behaviour of DP600 under in-plane biaxial loadings Wei LIU(1), Dominique GUINES(2), Lionel LEOTOING(2), Eric RAGNEAU(2) Corresponding author : Dominique GUINES, [email protected] (1)School of Materials Science and Engineering, Wuhan University of Technology (WHUT), China (2)Université Européenne de Bretagne, INSA-LGCGM-EA 3913, 20 Av. des Buttes de Coësmes, CS 70839, 35708 Rennes Cedex 7, France Abstract: The rate-dependent hardening behaviour of dual phase DP600 steel sheet is investigated by means of in-plane biaxial tensile tests, in an intermediate strain rate range (up to 20s-1) and for large strains (up to 30% of equivalent plastic strain) at room temperature.
    [Show full text]
  • Large-Strain Hyperelastic Constitutive Model of Envelope Material Under Biaxial Tension with Different Stress Ratios
    materials Article Large-Strain Hyperelastic Constitutive Model of Envelope Material under Biaxial Tension with Different Stress Ratios Zhipeng Qu 1,*, Wei He 2,3, Mingyun Lv 1 and Houdi Xiao 1 1 School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China; [email protected] (M.L.); [email protected] (H.X.) 2 AVIC Special Vehicle Research Institute, Jingmen 448035, China; [email protected] 3 College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China * Correspondence: [email protected]; Tel.: +86-010-82338116 Received: 13 August 2018; Accepted: 12 September 2018; Published: 19 September 2018 Abstract: This paper reports the biaxial tensile mechanical properties of the envelope material through experimental and constitutive models. First, the biaxial tensile failure tests of the envelope material with different stress ratio in warp and weft directions are carried out. Then, based on fiber-reinforced continuum mechanics theory, an anisotropic hyperelastic constitutive model on envelope material with different stress ratio is developed. A strain energy function that characterizes the anisotropic behavior of the envelope material is decomposed into three parts: fiber, matrix and fiber–fiber interaction. The fiber–matrix interaction is eliminated in this model. A new simple model for fiber–fiber interaction with different stress ratio is developed. Finally, the results show that the constitutive model has a good agreement with the experiment results. The results can be used to provide a reference for structural design of envelope material. Keywords: envelope material; biaxial tension; constitutive model; stress ratio 1. Introduction The stress of stratospheric airship envelope material usually comes from two or more directions in practical application; thus, it is necessary to test envelope material by biaxial or multiaxial tension.
    [Show full text]
  • Characterization and Sensitivity Analysis of Hyperelastic Materials in Biaxial Tension Lowell Smoger
    Rochester Institute of Technology RIT Scholar Works Theses Thesis/Dissertation Collections 10-8-2010 Characterization and sensitivity analysis of hyperelastic materials in biaxial tension Lowell Smoger Follow this and additional works at: http://scholarworks.rit.edu/theses Recommended Citation Smoger, Lowell, "Characterization and sensitivity analysis of hyperelastic materials in biaxial tension" (2010). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by the Thesis/Dissertation Collections at RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. CHARACTERIZATION AND SENSITIVITY ANALYSIS OF HYPERELASTIC MATERIALS IN BIAXIAL TENSION By Lowell M. Smoger Submitted in partial fulfillment of the requirement for the Master of Science In Mechanical Engineering Dr. Elizabeth DeBartolo _______________________ Department of Mechanical Engineering (Thesis Advisor) Dr. Risa J. Robinson _______________________ Department of Mechanical Engineering (Committee Member) Dr. Kathleen Lamkin-Kennard _______________________ Department of Mechanical Engineering (Committee Member) Dr. Mario Gomes _______________________ Department of Mechanical Engineering (Committee Member) Dr. Wayne Walter _______________________ Department of Mechanical Engineering (Department Representative) KATE GLEASON COLLEGE OF ENGINEERING ROCHESTER INSTITUTE OF TECHNOLOGY October 8th 2010 Permission
    [Show full text]
  • Metal Forming Process
    METAL FORMING PROCESS Unit 1:Introduction and concepts Manufacturing Processes can be classified as i) Casting ii) Welding iii) Machining iv)Mechanical working v) Powder Metallurgy vi)Plastic Technology etc., In Mechanical working Process the raw material is converted to a given shape by the application of external force. The metal is subjected to stress.It is a process of changing the shape and size of the material under the influence of external force or stress.Plastic Deformation occurs. Classification of Metal Working Processes 1. General classification i. Rolling ii. Forging iii. Extrusion iv. Wire Drawing v. Sheet Metal Forming 2. Based on Temperature of Working i. Hot Working ii. Cold Working iii. Warm Working 3. Based on the applied stress i. Direct Compressive Stress ii. Indirect Compressive Stress iii. Tensile Stress iv. Bending Stress v. Shear Stress Classification of Metal Working based on temperature. Hot working: It is defined as the mechanical working of metal at an elevated (higher) temperature above a particular temperature. This temperature is referred to RCT(Re Crystallization Temperature). Cold Working: It is defined as the mechanical working of metal below RCT. Warm Working: It is defined as the mechanical working of metal at a temperature between that of Hot working and Cold Working. Ingot is the starting raw metal for all metal working process. Molten metal from the furnace is taken and poured into metallic moulds and allowed to cool or solidify. The cooled solid metal mass is then taken out of the mould. This solid metal is referred to as Ingot.This Ingot is later on converted to other forms by mechanical working.
    [Show full text]
  • 2. Technology Metal Forming
    2. Technology Metal Forming Technology: Metal Forming • Metal forming includes a large group of manufacturing processes in which plastic deformation is used to change the shape of metal work pieces • Plastic deformation: a permanent change of shape, i.e., the stress in materials is larger than its yield strength • Usually a die is needed to force deformed metal into the shape of the die Metal Forming • Metal with low yield strength and high ductility is in favor of metal forming • One difference between plastic forming and metal forming is Plastic: solids are heated up to be polymer melt Metal: solid state remains in the whole process 4 groups of forming techniques: • Rolling, • Forging & extrussion, • Wire drawing, • Deep drawing. Bars shaping vs. Sheets shaping Rolling Flat (plates) rolling Cross rolling slant rolling (for tubes production) Forging & extrussion Macroetched structure of a hot forged hook (a) Relative forgability for different metals and alloys. This information can be directly used for open die forgings. (b) Ease of die filling as a function of relative forability and flow stress/forging pressure – applicable to closed die forging Wire drawing In and conventional wire drawing process, the diameter of a rod or wire is reduced by pulling it through a conical die Illustration of some drawing operations: (a) conventional wire drawing with circular cross-section; (b) wire drawing with rectangular cross-section, using so-called ‘Turk’s’ head; (c) drawing using a floating mandrel. Sheet metal forming Equi-biaxial streching using a clamped sheet and a hemispherical punch (left) and a schematic of an industrial strech-forming operation (right).
    [Show full text]
  • Prediction and Reduction of Defects in Sheet Metal Forming Dissertation
    PREDICTION AND REDUCTION OF DEFECTS IN SHEET METAL FORMING DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University Ali Fallahiarezoodar M. S. Graduate Program in Industrial and Systems Engineering The Ohio State University 2018 Dissertation Committee: Taylan Altan, Advisor Farhang Pourboghrat Jerald Brevick Copyright by Ali Fallahiarezoodar 2018 ABSTRACT Sheet metal forming as process of forming a metal blank into a useful part is a major metal forming process. The overall objective of the sheet metal forming process is to form the part within the required tolerances without any defects. Defects in sheet metal forming appeared as tearing, necking, wrinkling, and springback. In the last decade, the advanced high strength steels (AHSS) and high strength aluminum alloys are increasingly used in automotive industry to satisfy the demands for improved safety, fuel efficiency and low-emission of greenhouse gas. However, in general, in high strength materials, low formability and high springback are observed. Therefore, forming of these materials is more challenging than normal mild steels. Several parameters affect the quality of the final part. Blank and tool material, friction and lubrication, and process parameters such as forming speed and temperature can significantly affect the result. Determination of material properties and formability is necessary for tooling and process design. The common methods for determination of material properties required for designing and simulating the sheet metal forming process are reviewed. Also, forming limit diagram as an indication of material formability is studied. The limitations of the forming limit diagram are presented and a practical method for developing the forming limit diagram is presented.
    [Show full text]
  • Sheet-Metal Forming Processes and Equipment Ch 16 Sheet-Metal Forming
    Hail University College of Engineering Department of Mechanical Engineering Sheet-Metal Forming Processes and Equipment Ch 16 Sheet-Metal Forming Products made of sheet metals are all around us. They include a very wide range of consumer and industrial products, such as beverage cans, cookware, file cabinets, metal desks, appliances, car bodies, trailers, and aircraft fuselages there are numerous processes employed for making sheet-metal parts. However; the term pressworking or press forming is used commonly in industry to describe general sheet-forming operations, because they typically are performed on presses using a set of dies. Examples of sheet-metal parts. (a) Stamped parts. (b) Parts produced by spinning. Sheet-Metal Forming Low-carbon steel is the most commonly used sheet metal because of its low cost and generally good strength and formability characteristics More recently developed alloys, such as TRIP and TWIP steels, have become popular for automotive applications because of their high strength; they are well suited for providing good crash protection in a lightweight design. Aluminum is the most common material for such sheet-metal applications as bevera beverage cans, packaging, kitchen utensils, and applications where corrosion resistance is a concern Most manufacturing processes involving sheet metal are performed at room temperature. Hot stamping is occasionally performed in order to increase formability and decrease forming loads on machinery. Typical materials in hot-stamping operations are titanium alloys and various high-strength steels. TABLE 16.1 General Characteristics of Sheet-metal Forming Processes (in alphabetic order) Shearing Before a sheet-metal part is made, a blank of suitable dimensions first is removed from a large sheet (usually from a coil) by shearing.
    [Show full text]