Modeling the creep behavior of GRFP truss structures with Positional Finite Element Method

Abstract

This paper presents the development of a formulation, based on Positional Finite Element Method, to describe the viscoelastic mechanical behavior of space trusses. The numerical method used was chosen due to its efficiency in the applications concerning nonlinear numerical analyses. The formulation describes the positional variation over time under constant stress state (creep). The objective is to provide a way to quantify the creep behavior for space truss structures and thus contribute to the encouragement of GFRP usage in such structural components. Time-dependent behavior of such materials is one the most important factors for their use in design of structures, demanding studies about the deformations expected within the operational life of the structural systems. To perform this study, the proposed methodology considers a standard solid rheological model to describe stress-strain time-dependent law. This model is implemented in the formulation for quantify the total strain energy. The effects of the model parameters in the mechanical response of the structure with accentuated geometric nonlinearity were presented. In this analysis, it was possible to identify the influence of the elastic and the viscous moduli on the creep response. Model calibration was performed using test data obtained from literature and a GFRP transmission line tower cross-arm was simulated to predict the evolution of displacements under real operational loads. From the results, it was possible to observe a fast evolution of displacements due to the creep effect in the first 7,500 h. This increase was close to 0.6% in relation to the displacement obtained in the elastic behavior. The presented methodology provided a simple and efficient way to quantify the creep phenomenon in viscoelastic GFRP composites truss structures, as can be seen in the developed analyses.

Influence of Retardation Time on Viscoelastic Behavior of Plane Beams Modeled by the Nonlinear Positional Formulation of the Finite Element Method

“…Different numerical formulations have been developed to analyze the viscoelastic behavior of solid materials, as demonstrated in the works of Chen [1], Aköz and Kadioǧlu [2], Beijer and Spoormaker [3], Zheng et al [4], Mesquita and Coda [5], Galucio et al [6], Bottoni et al [7], Payette and Reddy [8], Panagiotopoulos et al [9], Latorre and Montáns [10], dos Santos Becho et al [11], Carniel et al [12], Oliveira and Leonel [13], Pascon and Coda [14], Rabelo et al [15], and Fernandes et al [16]. is interest is due to the need for modeling behavior of unconventional materials and the more complex and realistic analyzes of structures and structural components.…”

“…us, structural engineering aims to address the demands for technological advances in the most diverse areas, such as infrastructure, civil construction, mechanical industry, aerospace industry, and others. Part of these studies are related to the analyses of structures with viscoelastic behavior adopting stress-strain relation deduced from rheological models, as demonstrated in the works of Aköz and Kadioǧlu [2], Mesquita and Coda [5], Panagiotopoulos et al [9], dos Santos Becho et al [11], Carniel et al [12], Oliveira and Leonel [13], Pascon and Coda [14], Rabelo et al [15], and Fernandes et al [16]. ese rheological models are schematic representations that combine elastic and viscous elements to obtain a physical interpretation of stress-strain relationships.…”

“…It is worth mentioning that part of these studies uses the positional formulation of the finite element method to describe the viscoelastic behavior, as demonstrated in the works of dos Santos Becho et al [11], Pascon and Coda [14], Rabelo et al [15], and Fernandes et al [16]. e use of such a formulation is justified by the capacity and simplicity of its application in the analysis of nonlinear problems as highlighted in Coda and Greco [17] and Greco and Coda [18].…”

Dynamic Instability in Shallow Arches under Transversal Forces and Plane Frames with Semirigid Connections

“…The strain energy function of the considered body (framed elements) is considered to be stored at the reference volume of the body (V) and E represents the material longitudinal elasticity modulus. An engineering strain measure ( ) can be used to calculate the strain energy, as presented in Rabelo et al [21]. The damping contribution (Ka) in the energy functional (Π) is implicit.…”

Biomechanics of pollen pellet removal by the honey bee

“…At the high speed of 5.0 mm s −1 , the average force and work done were both significantly higher in trials that left residue. Fracture can occur in viscoelastic materials at both high and low stresses if the stress is applied over enough time [25]. Therefore, the force to remove the pellets at the low speed of 0.76 mm s −1 may not depend on whether or not residue was left because the time elapsed was sufficient to fracture the pellet.…”