Sensitivity to local imperfections in inelastic thin-walled rectangular hollow section struts

Abstract

Mass efficient inelastic thin-walled rectangular hollow section (RHS) struts practically always fail in a combination of local-global interactive buckling and material nonlinearity while also exhibiting high sensitivity to initial imperfections. Nonlinear finite element (FE) models for inelastic thin-walled RHS struts with pre-defined local and global geometric imperfections are developed within the commercial package Abaqus. Using a unified local imperfection measurement based on equal local bending energy, the effects of imperfect cross-section profiles, imperfection wavelength and the degree of localization in the longitudinal direction on the ultimate load and the nonlinear equilibrium path are investigated for four characteristic length struts at different material yielding stress levels. The corresponding most severe imperfection profiles are determined and are found to be qualitatively different to the linear eigenmodes in all cases. Moreover, it is found that the most severe purely periodic imperfections may be used to provide a safe approximation of the ultimate load when the corresponding amplitude is constrained to the manufacturing tolerance level. An extensive parametric study on the wavelength of the most severe periodic imperfection profile is conducted and a relationship for this is proposed in terms of the normalized local slenderness, which compares excellently with the FE results.

Numerical Prediction of Local Instability in Double Corrugated Profiles

“…Because of the complicated profile shape (deep corrugations on the surface), an indirect method for detection of buckling and local instabilities formation was employed. The method is based on the observation of equilibrium path nonlinearities in the phase II pre-buckling elastic range instead of the classic approach [22][23][24][26][27][28][29][30] that relies on the determination of the plastic hinges' geometry. Phase I is a pre-buckling elastic range and ends when the yield strength f y = 337 MPa is achieved, transiting to the phase II pre-buckling elastoplastic range.…”

“…The knowledge about the local instability formation mechanism is useful for predicting the entire structure's stability and load-carrying capacity and particularly useful for spotting the nature and place of damage. Scientific studies on the subject [26][27][28][29] have made a significant contribution to the development of science and technology, but they are usually related to flat-walled profiles of regular geometry. Determination of the failure mechanism becomes more complicated with irregular geometry such as the double-corrugated one.…”

“…Determination of the failure mechanism becomes more complicated with irregular geometry such as the double-corrugated one. Therefore, the search for buckling mechanisms carried out with classical methods [22][23][24][26][27][28][29][30] is difficult in the case of double-corrugated profiles.…”

Effects of spring action of a non-rigid body stamped from 30KhGSA steel sheet on the accuracy of machining

“…The study of deformations of box complexes with the graph theory showed satisfactory agreement between the experimental results and numerical calculations for the values of the horizontal and vertical deflection of the wall, as well as for the experimental, calculated and numerical characteristics of the bending moment, and not only for closed but also unclosed box profiles [7]. Local defects additionally increase the sensitivity of profiles of a rectangular hollow section to the creation of a shape error [8].…”

The effect of porosity distributions on post-buckling of imperfect nanocomposite plate by TSDT

“…and Farsi, M [25]. Shen, J. and Wadee, M.A [26] probed the local and global geometric imperfections effect on mechanical behaviour of inelastic thin-walled rectangular hollow struts by nonlinear finite element (FE) models.…”