Resumo em Inglês:

Abstract This study investigates the mechanical properties of reed straw under axial and radial compression using Micro-CT scanning, Mimics inverse reconstruction, and finite element analysis. Key findings reveal that nodal features play a crucial role in maintaining structural stability by providing radial constraints on the straw's outer bark and pith core. The internal vascular bundles, distributed unevenly with varying sizes, significantly influence the straw's mechanical performance. Under axial compression, the maximum stress recorded was 64.59 MPa, while radial compression yielded a maximum stress of 1.17 MPa. Stress concentrations typically occurred at the nodes, which are identified as the most vulnerable points prone to failure. These insights into the mechanical response of reed straw under compression provide valuable references for biomimetic design and applications in bio-materials.

Resumo em Inglês:

Abstract Materials subjected to moderate/large strains that exhibit similar tension and compression trends on the stress-strain diagram have several applications. Inspired by this aspect of this diagram, we have found appropriate to incorporate a same tension and compression trend on the strain-stretching curve of these materials. Because previous literature lacks strain measures with this property, this study intends to obtain this using a strain tensor belonging to a recently introduced strain measure family, the Generalized Hyperbolic Sine (GHS) strain tensor, which has significantly improved the behavior of the Seth-Hill family toward measures with better physical consistency. One uses the positional formulation of the finite element method to obtain expressions for any Lagrangian work conjugate stress-strain pair. Thereafter, this pair is employed in Hooke’s law to obtain the constitutive equation. The derivatives of the strain tensors with respect to the deformation gradient are written directly in the global directions and do not explicitly depend on the derivatives of the right stretch tensor with respect to the deformation gradient. Finally, the aforementioned model is used to perform 3D simulations of compressible bodies, including a comparison with a typical result of a polymer foam obtained from literature. The numerical results demonstrate excellent agreement with the analytical results, showing that a reconciliation of the stress-strain diagram of a Hooke-like material with its strain-stretching curve is numerically feasible.

Resumo em Inglês:

Abstract Most studies, standards, and codes on wind pressure distributions commonly disregard the influence of the flexibility of structures. Nevertheless, in the case of tensile-membrane structures, their flexibility cannot be ignored, so this study presents the results of numerical simulations evaluating wind pressure coefficient distributions on tensile-membrane structures, accounting for fluid-structure interaction (FSI) choosing the most common geometry: the hyperbolic paraboloid. Various curvature configurations, wind incidence directions, and structural models (both open and enclosed) were analyzed. The FSI solution involves a two-way partitioned simulation between Computational Fluid Dynamics, Computational Structural Dynamics and through a coupling system that culminates in the derivation of final pressure coefficient distributions. Results indicate that pressure coefficients obtained for rigid models underestimate those obtained by the FSI methodology, which accounts for deformations altering the interaction between the fluid and membrane.