BEND RADIUS (R/T) EFFECTS ON STRESS IN S355 SHEET BENDING: ELASTIC VS. ELASTOPLASTIC FINITE ELEMENT ANALYSIS

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  • TITLE: BEND RADIUS (R/T) EFFECTS ON STRESS IN S355 SHEET BENDING: ELASTIC VS. ELASTOPLASTIC FINITE ELEMENT ANALYSIS
  • AUTHOR(S): G. Irsel
  • ABSTRACT: In this study, the effects of bend radius on stress concentration and permanent deformation in sheet metal geometries were numerically investigated using both elastic and elastoplastic material models. Static analyses were conducted in ANSYS for ST52 (S355) steel plates with a constant thickness of 4 mm and various inner bend radii (R = 2, 4, 6, 8 mm). The material behavior was defined by a Multilinear Isotropic Hardening (MISO) model calibrated from tensile test data. Results showed that as the bend radius increased, the maximum equivalent stress decreased almost linearly. The mean stress was 390 MPa, with a standard deviation of 6.98 MPa and a strong negative correlation between R and stress (r = −0.994). The regression equation σ = −2.73R + 403.3 (MPa) indicates a stress drop of approximately 2–3 MPa per mm radius increase. Elastic models produced unrealistic stresses exceeding the material’s ultimate strength (≈ 670 MPa), while the MISO-based elastoplastic model realistically captured post-yield strain hardening and stiffness reduction. The activation of Large Deflection significantly improved deformation prediction under geometric nonlinearity, and Force Convergence evaluation confirmed stable and accurate nonlinear solutions. These results demonstrate that reliable FE analysis of sheet bending requires both plasticity modeling and geometric nonlinearity for physically meaningful stress prediction.
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  • DOWNLOAD: Vol72-2026.pdf
  • HOW TO CITE THIS ARTICLE: G. Irsel. BEND RADIUS (R/T) EFFECTS ON STRESS IN S355 SHEET BENDING: ELASTIC VS. ELASTOPLASTIC FINITE ELEMENT ANALYSIS. Journal of the Technical University of Gabrovo. 72 (2026).