Influence of the cold work effects in perforated rack columns under pure compression load

Abstract

This paper analyses the influence of residual stresses and strain hardening due to the cold rollforming process on the load carrying capacity of perforated rack columns. First of all, a residual strain distribution of the manufacturing process is obtained via a finite element analysis and then it is introduced in the model as initial state to carry out a nonlinear buckling analysis. Two different methodologies to introduce the residual strain pattern are presented in order to reproduce the local stress effects because of perforations. Moreover, the changes of the mechanical properties of the material by strain hardening are evaluated through experimental tests and its influence on the rack column behaviour is investigated. The results obtained agree well with experimental tests and show a method to predict the load carrying capacity of perforated rack column taking into account the effects of the cold roll-forming process.

Residual stresses in cold-formed steel members: Review of measurement methods and numerical modelling

“…However, the prediction of residual stresses is hard to tackle due to some reasons: (i) information from manufacturers is not easy to obtain; (ii) real machines consist of many complex rolling stations; and the influence of other secondary processes can be significant, e.g. coiling [56], flattening [34] or pre-punching [170]. Roll forming is an especially complex process for modelling purposes in comparison to press braking; the progressive bending throughout the stations implies a three-dimensional deformation pattern so longitudinal effects can be critical.…”

Distortional Influence of Pallet Rack Uprights Subject to Combined Compression and Bending

“…The true stress-strain relationship ( Figure 14) for both materials (flat and corner regions) used in the finite element model follows the experimental curves obtained in Section 2.1. It is also possible to obtain the strength enhancement of corner areas through the finite element analysis of the roll-forming process done in COPRA analysing the equivalent plastic strain or curved regions and introducing the residual equivalent plastic strain in ANSYS modes as initial state with similar results [15]. The residual elastic and plastic strain (not the equivalent plastic strain) pattern is extended on a geometrically perfect upright, without any initial geometrical imperfection (the imperfection generated in COPRA analysis has been neglected).…”

“…The residual longitudinal stresses obtained due to the manufacturing process can be seen in Figure 13. More details about COPRA simulation as well as the characteristics and methodology to define this pattern are explained in [15].…”

Industrial storage system continuous perforated uprights: a combined design proposal

“…A detail of roll forming is shown in Figure 2. Bonada, Pastor, Roure, & Casafont (Bonada et al, 2015) made a study of the influence of the cold-work effects on uprights under pure compression load. The mechanical properties change due to cold work depends on the parameters like corner radius, steel grades and thickness.…”

“…Global buckling is characterized by instability due to lateral displacements along the element length due to flexural, torsional, or flexural-torsional buckling. More information on the instability modes can be found at (Bonada et al, 2015;C D Moen & Schafer, 2011;Neiva, Sarmanho, Faria, Souza, & Starlino, 2018;Pastor et al, 2013;Ribeiro, 2006;Silva, L. S.;Simões, R.;Gervásio, H.;Vellasco, P.;Lima, 2016).…”