Buckling and Post-buckling Behaviour of Prismatic Aluminium Columns Submitted to a Series of Compressive Loads

Abstract

The buckling and post-buckling behaviour of prismatic aluminium columns from stocky to very slender shapes is investigated. The unconventional, in terms of buckling tests, displacement control of compressive load and a series of loadings provided an enhanced insight into the buckling process. A phenomenon of buckling load drop has been detected in columns of intermediate slenderness, reaching over 20% of the load early critical value. This newly observed occurrence resembles finite disturbance instability, which until recently was commonly believed to only appear in cases of thin walled cylindrical shells, but not columns. The observation is in contradiction to predicted results from the elasto-plastic buckling models of Engesser or Shanley, with constant or growing values of load during the post-buckling process. Further tests on columns of intermediate slenderness, with strain gauges glued at node and anti-node locations of the buckled profiles, revealed that even minute buckling results in fields of highly non-symmetric residual microplastic strain. The results of the present study indicate that running column buckling tests under displacement control is worthy of being adopted as common practice. The envelope of column post-buckling states can be conveniently determined. This information will in turn allow for the quick and reliable estimation of the safety of a column, which has undergone accidental or deliberate damage in the form of limited buckling when under operational load.

Buckling Analysis and Stability of Compressed Low‐Carbon Steel Rods in the Elastoplastic Region of Materials

“…By solving it, the formula for calculating critical force/ stress was developed by Leonard Euler [9,12]:…”

“…e geometrical and material characteristics of the carbon steel (S235) columns with various grades are presented in Table 1. A diagram depicting the stress-strain relationship for carbon steel is constructed in Figure 4(a) according to Table 1, and a diagram depicting the slenderness ratio of critical stresses (equation (2)) for carbon steel is constructed in Figure 4(b), Curve 1 [9,15,21,28].…”

“…A prismatic (rectangular) steel column was studied as a sample that is depicted in Figure 1. e study of the buckling behavior of prismatic (rectangular) compressed elements is a relevant step towards understanding and assessing the reliability of more complex structures [9].…”

“…e linear elastic Euler model of a prismatic simply supported rod is still the fundamental tool for studying buckling stability [9,10].…”

“…In a similar way, several empirical models, for instance, Engesser's [7,13,14], are proposed in the literature to experimentally characterize the elastic-plastic and plastic buckling. Later, Shanley [9,15] o ered a di erent approach for de ning the buckling process with its semiempirical design equation.…”