Finite element simulation of slender thin-walled box columns by implementing real initial conditions

2018

Engineering Structures

Finite element models for elastic thin-walled rectangular hollow section (RHS) struts with pre-defined local and global geometric imperfections are developed within the commercial package Abaqus. A unified local imperfection measurement based on equal local bending energy is proposed. The effects of imperfect cross-section profiles, imperfection wavelength in the longitudinal direction and the degree of imperfection localization on the ultimate load and equilibrium path are investigated and the most severe imperfection profiles are determined. A parametric study on the wavelength of the most severe local imperfection profile is conducted and a semi-empirical equation to approximate the corresponding wavelength is proposed. Moreover, an equation to calculate the global buckling load of thin-walled RHS struts with tolerance level doubly-symmetric cross-section local imperfections is proposed.

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Section: Introductionmentioning

confidence: 97%

Sensitivity of elastic thin-walled rectangular hollow section struts to manufacturing tolerance level imperfections

2018

Engineering Structures

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“…material and cross-section properties, manufacturing methods and handling [24]. They are essentially random variables and measured imperfection data have demonstrated that they are far removed from the linear buckling modes [25,26,16]. More importantly, several studies have demonstrated that the local eigenmode with the lowest load may not even represent the most severe imperfection profile anyway [27,28,29,30,31].…”

Section: Introductionmentioning

confidence: 99%

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

2019

Structures

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.

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“…Even though the elastic post-buckling behaviour of purely local buckling and purely global buckling are strongly and weakly stable respectively [5,6], the interaction of these two modes may lead to a profound change in the nonlinear behaviour, especially in the cases when these are triggered practically simultaneously [7,8,9,10,11,12,13]. Moreover, such members exhibiting mode interaction have been demonstrated to be very sensitive to geometric imperfections; a tiny imperfection can lead to a significant erosion in the load-carrying capacity [14,15,16,17,18,19,20,21,22].…”

Section: Introductionmentioning

confidence: 99%

“…Owing to the development of computational methods as well as the popularity of general-purpose finite element (FE) packages with powerful modelling and solution functions, the FE method has been adopted to investigate the inelastic behaviour of thin-walled box-section columns exhibiting mode interaction [3,18,31,27]. Experimental results have been used to calibrate and verify the FE models.…”

Section: Introductionmentioning

confidence: 99%

Local–global mode interaction in thin-walled inelastic rectangular hollow section struts part 1: Nonlinear finite element analysis

2019

Thin-Walled Structures