An Experimental Modelling and Numerical FE Analysis of Steel-Strip Ironing Process
This paper deals with analysis of steel strip ironing using experimental modelling and numerical FE simulation. Since both approaches are complementary to each other, numerous results were obtained that enable complete analysis of the processes with in deformation zone. Device for modelling of strip ironing has been developed for experimental testing. Die cone angle, holding force, contact friction conditions on the die and the punch side were varied, due to easily replace able working elements of the device. Friction coefficient values used in numerical FE simulations were determined based on measured values of forces on die and punch, as well as forming load on machine. Experimentally obtained results were confirmed by FE analysis that provided additional information about physics of the process itself within deformation zone. Presented research results point to coherent influences of process factors on tensile wall stress values, which represents key indicator for efficiency of forming, resulting in recommendations for efficient process management.
An experimental and numerical study of the wall ironing process of polymer coated sheet metal
In the traditional manufacturing process for metal food and beverage containers, a food contact-safe lacquer is sprayed onto the can before filling. This time consuming and therefore expensive process can be eliminated using a polymer coated sheet metal provided that the polymer will survive the manufacturing operations. The most critical stage in can making is the ironing process because of the large deformations that occur. This paper presents experimental and numerical results regarding the ironing process of polymer coated aluminium and polymer coated steel. A plane strain strip ironing device has been constructed to investigate the influence of the ironing reduction, velocity and die angle on the process forces and friction. Furthermore, an in-situ study of the displacement and strain fields has been performed in the strip ironing experiments using a digital image correlation technique. Simulations of the process have been performed using an arbitrary Lagrange Euler method based on an operator splitting procedure (OS-ALE). The constitutive behaviour of metal and polymer has been modelled with a generalised compressible Leonov model with a Bodner–Partom and an Eyring viscosity function, respectively. The experimental results are in good agreement with numerical simulations.
Neutron Residual Stress Measurements on Rail Sections for Different Production Conditions
Rail sectioning with subsequent neutron diffraction experiments has been used to assess residual stresses in the rails. In this study we present the results of neutron stress measurements performed at the NIST Center for Neutron Research (NCNR) on rail sections from rails that were produced under various conditions. Specifically, these are air-cooled, air-cooled and roller-straightened, head-hardened and head-hardened and roller-straightened. More significantly, a head-hardened and roller-straightened rail was also studied after service to elucidate evolution of the service-induced residual stresses. In the latter case both a transverse-cut slice and the central region of a 0.53 m long piece were studied. Measurements on this piece are the first in which triaxial stresses have been determined for an intact rail. Neutron strain measurements with 3×3×3 mm3 spatial resolution were successfully employed for transversally cut slices to verify the difference in the stress state depending on the production process. Although examination of slices allows determination of only two-dimensional stresses in the plane of the slice, additional measurements on obliquely-cut slices, which were also carried out, and utilization of FEM gives the possibility of reconstructing the full triaxial stress distribution. Together, these approaches provide a better understanding of rail fabrication and the possibility of improving the durability and safety of rails in the future.Copyright © 2004 by ASME