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Open access Aug 2026

Theoretical and Numerical Study on Buckling Analysis of Cylindrical Shell Structures by Galerkin and Finite Element Methods

The structural instability of cylindrical shells has long attracted scholarly attention due to its inherently nonlinear response and extensive engineering relevance. Although numerous investigations have examined buckling phenomena arising from individual loading modes such as axial compression or pure torsion, the complex behavior of shells subjected to simultaneous torsional and axial actions remains comparatively underexplored. In this study, an integrated approach combining theoretical formulations and finite element analyses is employed to comprehensively characterize the buckling responses of cylindrical shells under coupled torsional–axial loading conditions. The theoretical framework is developed using Donnell’s shell theory and solved through the Galerkin approximation. The predicted results exhibit strong agreement with finite element simulations. It is demonstrated that the buckling evolution of cylindrical shells under combined loading markedly differs from that produced by a single load component. Specifically, shells under torsion with minor compression display a stable deformation mode, whereas higher compression induces a transition toward a diamond-shaped buckling pattern. Such findings elucidate the coupled torsion–compression/tension effects governing buckling instabilities in cylindrical shells, offering valuable insight for the design of load-responsive foldable and origami-inspired structures driven by combined mechanical actions.

Unknown authors · 0 citations
Open access Aug 2026

Influence of lattice-core geometry on the mechanical performance of FDM-printed PETG sandwich panels: an experimental, computational, and statistical investigation

This study aims to find the impact of lattice-core geometry on the tensile and flexural properties of FDM-printed PETG-sandwich panels. Six core profiles (namely square, circular, elliptical, octagonal, pentagonal and hexagonal) were fabricated under controlled parameters of the FDM and tested based on ASTM D638 and D790. The pentagonal core resulted in the highest flexural strength (23.2 MPa), peak load (322 N), and the hexagonal core in the highest tensile strength (24.8 MPa). The variation in tensile and flexural strength was highly explained by core geometry (93.4% and 93.8% respectively) (ANOVA, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p<0.001$$\end{document}). The Taguchi S/N ratio evaluation demonstrated that both tensile and flexural performances exhibit comparable high sensitivity to core geometry variations (a relative difference of approximately 2.5%). A flexural strength was predicted by an elastic–plastic FEA model created in ABAQUS/CAE, with an error margin of 4.1% when compared to experimental results. These PETG panels experienced a strength loss of 12–16% but a 58–63% increase in ductility when compared to PLA + panels with the same core topology, demonstrating that core topology dictates performance across the evaluated thermoplastic matrices. The results will be useful for quantitatively suggesting the topology for FDM-fabricated sandwich structures.

A. Ogaili, Abdul-Rasool Kareem Jweri, S. Amin et al. · 0 citations
Preprint Jul 2026

Numerical and experimental framework for bending elasticity of highly flexible slender structures

Slender structures are highly flexible, spanning several orders of magnitude in length scale. Their deformation depends on the slenderness of their cross sections, highlighting that the elasticity and geometry of structures are intrinsically coupled. The deformation of the cross-section becomes significant, particularly when tubes and pipes are subjected to bending, known as the Brazier instability. Although the bending performance of slender structures is quantified experimentally using a canonical three-point bending test, their numerical counterparts remain under-explored because complex contact mechanics must be implemented in simulations. In this study, we develop a computational framework to simulate experimental three-point bending tests using a hybrid material point method (hybrid-MPM) approach, which integrates Lagrangian finite element and Eulerian finite difference frameworks. We adapt our framework to elastic tubes and tape springs as canonical examples that exhibit characteristic bending deformation in which the cross-sectional and lengthwise bending are coupled. The predictions of numerical simulations are validated against desktop experiments and classical theory. The excellent agreement between the simulation and the experiments implies that the hybrid-MPM framework provides a robust computational framework for predicting the large deformation of structures involving complex contact, such as soft robots and deployable structures.

Shunsuke Nomura, Satsuki Shibuya, Isamu Hashiguchi et al. · 0 citations
Aug 2026

Plastic behavior of foam-filled hexagonal core sandwich beams

Analytical modeling and numerical simulations are employed in this study to examine the plastic behavior of fully clamped foam-filled hexagonal core sandwich beams (FHCSBs) under transverse loading. A yield criterion is developed for the FHCSB cross-section by considering the combined strength contributions of the folded plates and the metallic foam filler. By coupling this criterion with the associated flow rule, an analytical model is developed to predict the large-deflection behavior of FHCSB, specifically accounting for the interaction between bending and axial stretching. To verify the theoretical framework, numerical calculations using Abaqus/Explicit software are performed. The results show that the analytical predictions for post-yield response match the numerical results for both mid-span and offset loading cases. Additionally, a parametric study investigates how face-sheet thickness, foam strength, and cell inclination angle influence the structural performance. The analysis indicates that face-sheet thickness is the primary factor determining the membrane hardening rate, whereas the hexagonal core configuration offers a stable cushioning effect during early-stage deformation. This analytical approach provides an effective tool for assessing the load-carrying capacity and energy absorption of FHCSB structures.

Yiming Cao, Xilin Luo, Yao Wang et al. · 0 citations
Open access Aug 2026

Finite Element Analysis of the Stiffness of a Plug-in Device Connection with a Modified Stiffener

Modular steel construction offers significant advantages in fabrication efficiency, installation speed, and structural adaptability; however, the performance of inter-module connections remains a critical concern, particularly under lateral loading conditions. This study aimed to evaluate the mechanical behavior and stiffness characteristics of a modified plug-in device connection incorporating a U-shaped stiffener with bolted stiffener-to-column connections. The research employed finite element analysis using ANSYS Mechanical. Numerical models were first validated against previous experimental studies using two reference connections, SC1 and SC2, before analyzing the modified model, SC_Mod. The validation results showed differences of 7% and 9% between the numerical and experimental results, confirming the acceptable accuracy of the developed models. The SC_Mod connection achieved an initial translational stiffness of 21,500.46 kN/m and rotational stiffness of 26,739.38 kNm/rad. Compared with SC1, the translational and rotational stiffness increased by 243% and 163%, respectively, while increases of 127% and 82% were observed relative to SC2. The modified connection reached a maximum load of 633.5 kN, with yielding occurring at approximately 22.6 mm deformation and failure occurring at 120.39 mm. These findings demonstrated that the bolted U-shaped stiffener configuration substantially improved connection stiffness, load transfer capacity, ductility, and constructability, making it a promising alternative for steel modular building connections while preserving the practical advantages of modular construction systems.

Unknown authors · 0 citations
Jul 2026

Global flange buckling strength prediction of I-stiffened laminated composite FRP box-beams using ANN

The utilisation of stiffened fibre-reinforced polymer (FRP) box-beams is highly advantageous for lightweight bridge structures; however, their design is computationally intensive due to anisotropy and buckling sensitivity. This study presents a computationally efficient artificial neural network (ANN) model for predicting the global flange buckling strength of stiffened laminated composite FRP box-beams subjected to lateral loading. A comprehensive database was generated using validated finite element analysis (FEA) considering fibre orientation, stiffener geometry, and orthotropic stiffness effects. Five governing parameters (αsf, CEIw, D1/D2, (EA)fs/(EA)fp, and βsf) derived from laminate theory and stiffened panel mechanics were used as ANN inputs. Among the evaluated models, the Bayesian regularised ANN achieved an average prediction error of 3.01% and a maximum error of 4.77%, while reducing computation time from approximately 300 s (FEA) to less than 0.01 s per prediction. The proposed model provides a reliable surrogate tool for design optimisation of composite box-beams.

Dhamodharavadhani S, Kanimozhi Suguna S, Anbarasu M et al. · 0 citations