Prediction of plastic instability and forming limits in sheet metal forming

Download

index.pdf

Date

2010

Author

Şanay, Berkay

Metadata

Show full item record

Item Usage Stats

182
views

74
downloads

The Forming Limit Diagram (FLD) is a widely used concept to represent the formability of thin metallic sheets. In sheet metal forming processes, plastic instability may occur, leading to defective products. In order to manufacture defect free products, the prediction of the forming limits of sheet metals is a very important issue. FLD’s can be obtained by several experimental, empirical and theoretical methods. However, the suitability and the accuracy of these methods for a given material may vary. In this study, FLD’s are predicted by simulating Nakazima test using finite element software Pam-Stamp 2G. Strain propagation phenomenon is used to evaluate the limit strains from the finite element simulations. Two different anisotropic materials, AA2024-O and SAE 1006, are considered throughout the study and for each material, 7 different specimen geometries are analyzed. Furthermore, FLD’s are predicted by theoretical approaches namely; Keeler’s model, maximum load criteria, Swift-Hill model and Storen-Rice model. At the end of the study, the obtained FLD’s are compared with the experimental results. It has been found that strain propagation phenomenon results for SAE 1006 are in a good agreement with the experimental results; however it is not for AA2024-O. In addition, theoretical models show some variations depending on the material considered. It has been observed that forming limit prediction using strain propagation phenomena with FE method can substantially reduce the time and cost for experimental work and trial and error process.

Subject Keywords

Mechanical engineering.

URI

http://etd.lib.metu.edu.tr/upload/12612486/index.pdf
https://hdl.handle.net/11511/19978

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Development of a shell finite element for large deformation analysis of laminated composites Yıldız, Tuba; Darendeliler, Haluk; Department of Mechanical Engineering (2008) The objective of the present work is to investigate the behavior of laminated fiber -reinforced polymer matrix composite shell structures under bending load with the help of a modified finite element computer code which was previously developed for the analysis of pseudo-layered single material shells. The laminates are assumed to be orthotropic and the formulation is adapted to first order shear deformation theory. The aim is to determine the large deformation characteristics numerically, and to predict th...
Design of a touch trigger probe for a coordinate measuring machine Karuç, Emre; Dölen, Melik; Department of Mechanical Engineering (2007) Coordinate Measuring Machines (CMMs) have been widely used in industry in order to determine the form / dimensional tolerances of workpieces with very complicated geometrical shapes. Therefore, CMM is an important tool during the manufacturing and quality control phases. Workpiece to be measured on a CMM is probed via touch trigger probe through its stylus tip. In other words, by virtue of the touch trigger probes CMM can acquire the dimensional data of the workpiece that is to be measured. Therefore the pr...
Analysis of single phase convective heat transfer in microchannels with variable thermal conductivity and variable viscosity Gözükara, Arif Cem; Güvenç Yazıcıoğlu, Almıla; Department of Mechanical Engineering (2010) In this study simultaneously developing single phase, laminar and incompressible flow in a micro gap between parallel plates is numerically analyzed by including the effect of variation in thermal conductivity and viscosity with temperature. Variable property solutions for continuity, momentum and energy equations are performed in a coupled manner, for air as a Newtonian fluid. In these analyses the rarefaction effect, which is important for the slip flow regime, is taken into account by imposing slip veloc...
Analysis of thin walled open section tapered beams using hybrid stress finite element method Akman, Mehmet Nazım; Oral, Süha; Department of Mechanical Engineering (2008) In this thesis, hybrid stress finite element is formulated for the analysis of the isotropic, thin walled, open section beams with variable cross sections. The beam element has two nodes each having seven degrees of freedom. Assumption of stress field is sufficient to determine the element stiffness matrix. Axial, flexural and torsional effects are taken into account in the analysis. The methodology can be applied both to the tapered and the uniform beams. Throughout this study, firstly element cross-sectio...
Numerical analysis of ablation process on a two dimensional external surface Aykan, Fatma Serap; Dursunkaya, Zafer; Department of Mechanical Engineering (2005) The thermal response analysis of an ablative material on a two dimensional external surface is performed. The method is applied to both rectangular and cylindrical coordinate systems, where rectangular coordinate system is used for comparison with results available in literature. The current study solves the decomposition of the material at high temperatures by using the nth order Arrhenius equation but excludes the removal of char from the surface due to mechanical erosion or phase change and considers tha...

Citation Formats

B. Şanay, “Prediction of plastic instability and forming limits in sheet metal forming,” M.S. - Master of Science, Middle East Technical University, 2010.