bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical Models for Railway Track Structural Analysis Based on Numerical and Experimental Data
Authors: Maria Rafaela Bezerra de Macedo Ribeiro  , Manoel Ricardo Siqueira Filho  , José Antônio Fontes Santiago
Published: January 2025

Since the 19th century, mechanistic models based on the theory of elasticity have been developed to structurally analyze the permanent way. In this context, the Winkler model considers the rail as a beam infinitely supported on an elastic base, from which the analytical solutions derived presented in this research were compared with numerical and experimental results, from operational data recorded in the Carajás Railway. The software Matlab and SAP 2000 were used to develop the analytical and numerical models, respectively. The comparison considered the loading scenarios for a wheel, with the bogie and the coupling region between wagons, and evaluating the influence of the superposition of effects. The results obtained in both the analytical and numerical models proved to be reliable in the real structural representation of the permanent way.
Vibrations induced by railway traffic: from environmental impact assessment to exploration in new railway projects
Authors: Aires Colaço  , Ana Ramos  , Pedro Alves Costa
Published: January 2025

Prediction and control of ground-borne vibrations are one of the largest environmental challenges for railway exploration in urban areas. Nowadays, there is a shift at global level, in which investment in rail transport takes precedence over other transportation options, in a final attempt to drastically reduce CO2 emission. The expansion and improvement of the railway network, associated with the high standards of comfort required by modern societies, requires the assessment and mitigation of the environmental impact induced by the implementation of such infrastructures in nearby buildings, more specifically in their inhabitants and in the operation of sensitive equipment. Using a recently completed railway line in Porto, Portugal, as a case study, this paper aims to provide insights into the numerical studies conducted during the environmental impact assessment phase concerning vibrations induced by railway traffic. Additionally, it discusses the results from the experimental measurement campaign carried out after the line's construction to validate the assumptions made during the design phase regarding expected vibration levels.
Applicability of inverse analysis to obtain the tensile behavior of bamboo bioconcretes
Authors: Kaliel Gomes Andrade  , Eduardo de Moraes Rego Fairbairn  , Magno Teixeira Mota  , Vanessa Maria Andreola
Published: January 2025

In view of the difficulties in obtaining traction laws in the experimental field, it is of the utmost importance to adopt alternative tools to overcome this problem. Thus, this work is a brief manual for obtaining tensile laws using numerical modeling, which describes the steps for obtaining them, from defining the fixed parameters of the numerical model to characterizing the material's tensile mechanical behavior. The DIANA® software was used to run the numerical simulations and the numerical model calibration was based on average results of experimental curves. The target material for this study is a new bamboo bioconcretes developed by researchers at COPPE/UFRJ. The results show that the traction laws developed through inverse analysis using numerical modeling are highly accurate compared to experimental responses. The calibration of the numerical model makes a significant contribution to the quality of the results. Among the evaluated tensile models, the ones that best reproduce the experimental behavior of the bamboo bioconcrete are the multilinear and exponential models.
Numerical Analysis of Semi-Buried Cisterns Constructed with Precast Cementitious Plates
Authors: Hidelbrando José Farkat Diógenes  , João Paulo de Barros Cavalcante  , Ronald Lopes Silva  , Rosa Cristina Cecche Lintz
Published: January 2025

Semi-buried cisterns formed by cementitious plates represent an important solution for water harvesting and storage in arid and semi-arid regions, being fundamental to ensure water security and combat water scarcity, as presented in the governmental program One Million Cisterns. Therefore, this study proposes to explore preliminary strategies of numerical modeling using finite element methods, employing Abaqus Simulia software. The objective is to analyze in detail the structural behavior of these cisterns, aiming to optimize their design and performance. The adopted methodology involves a literature review to support the numerical modeling and subsequently compare the results with traditional analytical methods. The preliminary results indicate a promising possibility of reducing the horizontal reinforcement of the walls compared to the technical recommendations of the current agencies. Thus, preserving safety and durability conditions while implying constructions with lower costs, thereby promoting the social development of the served communities. Therefore, this study represents a significant advancement in the understanding and optimization of semi-buried cisterns, emphasizing their importance and potential to address challenges related to water storage.
Numerical analysis of the beam-column connection stiffness in precast concrete with welded steel angle
Authors: Felipe Melo Carvalho  , Augusto Teixeira de Albuquerque  , Marcelo Silva Medeiros Júnior  , Antônio Macário Cartaxo de Melo
Published: January 2025

The use of precast elements in civil construction has the main advantag of expediting the structures construction process, as well as increased technological control of the materials used. Despite this, precast structures presente a discontinuity in the connections between the elements, such as between beam and column. This has become an important object of study, where we seek to improve the continuity of these regions, ensuring better distribution of loads and increasing the stiffness of the connection. Therefore, the objective of this study is to analyze, using numerical methods, the stiffness of the beam-column connection in precast concrete using a steel angle welded to the beams and column. To achieve this goal, the structure will be modeled using the Finite Element Method. A structural system composed of two beams and a column with the steel angle welded to the elements in the connection region. The angle is employed to assure a level of continuity in the connections between structural elements and increase its rigidity hence creating a with semi-rigid condition. The result of the numerical model will be verified with a proposed analytical model, considering the existence of a spring in the connection that guarantees the increased stiffness, reducing rotation in the support. From the rotation predicted in the numerical model, we can estimate the rotational stiffness and apply it to the analytical model for comparison and validation. In the numerical model, 4 analyzes will be carried out, the first analysis wont have the welded angle. The other three analyzes will be carried out with the welded angle, changing the weld area on the column and beams. Finally, the results are expected to demonstrate that the application of the welded angle on the beam and column presents better performance for semi-rigid connection, bringing greater rigidity to the connection, reducing the existing rotation and achieving a better redistribution of loads, thus ensuring a lower maximum positive bending moment for the beam. It is also expected that angles with larger weld areas guarantee greater rigidity for the connection than those with smaller weld areas.
Buckling of columns with top and distributed loading using Rayleigh's method: assessment of two cases of boundary conditions
Authors: Ana Paula Freitas Borges  , Alexandre de Macêdo Wahrhaftig  , Moshe Eisenberger
Published: January 2025

The problem of buckling in compressed parts has been the subject of study by many researchers due to the importance that these structural elements have for different areas of engineering. The compressive capacity of columns can be quantified using the so-called critical buckling load. The first studies date back to the work of Euler and Greenhill that began in the 18th century. Other contributions have been made since then. One of the most relevant for this field of study is the Rayleigh solution formulated to understand the vibration of elastic systems, whose equations can be directly used in determining the critical buckling load. The central feature of this method is the possibility of associating continuous systems with an equivalent system with a single degree of freedom. The Rayleigh method is used to define the critical buckling load of two columns under the simultaneous action of concentrated and distributed load along their length. Prismatic section parts are evaluated considering two boundary conditions. The values suggested in the literature are compared to the current results.
Parametric Study of Pile Installation Using a Numerical Approach with Material Point Method
Authors: Nuno Henrique Albuquerque Pires  , Jennifer Mikaella Ferreira Melo  , Mávyla Sandreya Correia Tenorio  , Beatriz Ramos Barboza  , João Paulo Lima Santos  , João Paulo Lima Santos  , Fabio Sawada Cutrim  , Rafael Dias
Published: January 2025

In engineering, problems dealing with rigid structures that penetrate the ground are common. A better understanding of the installation process of these bodies can be obtained through numerical studies. Each technique has its own advantages and challenges, and the choice of the appropriate method depends on the specific geotechnical conditions. The main objective of this work is to conduct a parametric study of pile installation by impact driving using a prototype numerical model in order to analyze the behavior of these structures when penetrating the soil. This will enable the construction of more complex numerical models that simulate impact problems, such as driving a conductor casing in oil well projects or installing monopiles in the construction of wind turbines. To achieve the established objectives, the Anura3D is employed, an open source simulator based on Material Point Method (MPM). The parametric study is carried out considering a non-cohesive soil, modeled by Mohr-Coulomb. Additionally, the pile is treated as a rigid body. The parametric study conducted in this work provides valuable insights into optimizing engineering projects, enhancing its efficiency and effectiveness .
Improving accuracy of parametric surrogate model for turbidity currents using diffusion-based super-resolution
Authors: Adriano Cortes  , Ruan Felipe de Sousa e Silva  , Roberto Machado Velho  , Gabriel Freguglia Barros  , Fernando Alves Rochinha  , Alvaro Luiz Gayoso de Azeredo Coutinho
Published: January 2025

Turbidity currents are a sort of density-driven flow carrying particles that are generated between fluids with small density differences. They also are a mechanism responsible for the deposition of sediments on a seabed. A deep understanding of this phenomenon may help geologists on strategic knowledge in oil exploration. We simulate such currents using a stabilized finite element formulation in a Eulerian-Eulerian framework.This brings the challenge of a high computational cost for the evaluation of the high-fidelity model. We thus use a surrogate model composed of one linear (Proper Orthogonal Decomposition) and one non-linear (Autoencoder) reduction [1,2]. Once the surrogate is trained for a set of parameters with data generated by the high-fidelity model, one can use such a surrogate model for predicting the dynamics for unseen values of the parameter.Denoising Diffusion Probabilistic Models (DDPM) [3] is the method behind SOTA generative AI algorithms with very good performance in tasks like super-resolution. Based on such usage of diffusion for generative AI, the authors in [4] developed a framework for flow field reconstruction using a super-resolution task. Such a diffusion model is trained only using high-resolution data, without a pairing between low and high-resolution data, common in other techniques in the area.The present work aims to use the dataset of high-fidelity parametric simulations of turbidity currents for training both the surrogate and the diffusion model for the super-resolution task. The goal is: using the trained super-resolution model, improve the fields predicted by the reduced model for unseen points of the parametric space.[1] - M. Cracco et al., Deep learning-based reduced-order methods for fast transient dynamics, Arxiv Preprint 2212.07737, 2022.[2] - S. Fresca and A. Manzoni, POD-DL-ROM: Enhancing deep learning-based reduced order models for nonlinear parametrized PDEs by proper orthogonal decomposition, Comput. Methods Appl. Mech. Engrg., 2022.[3] - J. Ho, A. Jain and P. Abbeel, Denoising Diffusion Probabilistic Models, arXiv: 2006.11239, 2020.[4] - D. Shu, Z. Li, A. Barati Farimani, A physics-informed diffusion model for high-fidelity flow field reconstruction, Journal of Computational Physics, Volume 478, 2023
Uncertainty quantification analysis in porous media using differential evolution McMC method with selection (DESk)
Authors: Michel Antonio Tosin Caldas  , Marcio R. Borges
Published: January 2025

Reservoir rocks display high spatial variability hydraulic properties. In general, this variability can not be deterministically described, and therefore, geostatistical methods come into place to approach the problem from a stochastic perspective. In particular, Markov chain Monte Carlo methods are often used on those applications. The most significant difficulty in using McMC methods for flow problems in porous media is related to the large stochastic dimension of the fields, which leads to low acceptance rates. Adaptive McMC methods have been a strong ally on this matter. Among them, differential evolution-based Markov chain Monte Carlo methods showed promising results. These methods exchange information among multiple chains running in parallel. Thus, improving its acceptance rate is not something as well explored in the literature. Additionally, to reduce the stochastic dimension of the problem, neural network techniques have become pretty popular as an alternative to using classical Karhunen-Loève expansion (KLE) to generate permeability fields. This work generates the proposed fields through variational autoencoders (VAE). A novel differential evolution Markov chain Monte Carlo with selection mechanisms (DESk) is proposed for solving a Bayesian inference problem involving a single fluid flow in a heterogeneous media. The scheme combines the faster convergence characteristic from the DE, which is improved by selection steps. The results showed that DESk performed better than the standard DE strategy for different selection pressures.
Numerical nonlinear structural analysis of a timber truss roof under fire condition
Authors: Caroline Aparecida Ferreira  , Jackson da Silva Rocha Segundo  , Ricardo Azoubel da Mota Silveira  , Luís Henrique Aragão Alves de Queiroz  , Ígor José Mendes Lemes  , Rafael Cesário Barros  , Dalilah Pires Maximiano
Published: January 2025

As greenhouse gases continue to rise and environmental impact reduction gains global attention, timber buildings have emerged as a vital asset in the pursuit of a sustainable future. Throughout history, timber has been linked to fire as a flammable material, and there have been numerous reports of out-of-control fires that highlight the importance of fire safety. Hence, the primary goal of this study is to assess the fire resistance of a timber truss roof. As the temperature rises, changes occur in the physical and mechanical characteristics of the timber members, causing the loss of the strength capacity and rigidity of part or the entire truss. Therefore, this research aims to explore the SAFIR computer program to carry out the following analyses: thermal analysis of the timber cross-section; and the structures thermo-mechanical analysis. By conducting the first analysis, it becomes possible to calculate the temperature field of timber members cross-section in a transient regime, while also obtaining information about the degradation of material properties. The second analysis provides the displacements, internal forces, critical time, and/or critical temperature of the timber truss during collapse. The numerical results obtained here were compared and validated with those from the literature (experimental results). The truss collapse time predicted by SAFIRs model was quite similar to the one observed in the laboratory. The developed numerical methodology allows for more realistic studies of timber elements or systems, enabling designs based on safety, economy, and sustainability.
Study of the behavior and resistance of the U shear connector consisting of cold formed profile
Authors: Lívia Cristina Lopes Sousa  , Jerfson Moura Lima  , Gregório Sandro Vieira
Published: January 2025

The use of composite beams leads to economical solutions for use in building and bridge structures, for example, due to the combined action between the steel beam and the concrete slab, providing greater stiffness and flexural resistance than when considering the work isolated from materials. However, as they are two materials with different behaviors, mechanical devices are needed that are capable of ensuring that their elements work together. Such devices are called shear connectors, whose function is to resist the horizontal forces that develop at the steel-concrete interface, avoiding the physical separation of these components and ensuring their joint action. The U shear connector made up of a cold-formed profile is a low-cost alternative connector, however, more studies to understand its mechanical behavior need to be developed. The analysis of the mechanical behavior of a shear connector is carried out by carrying out the push-out test, standardized by Eurocode-4 (2004). Another possibility is the use of numerical modeling. Numerous researchers have used numerical modeling to study the behavior of shear connectors and obtained satisfactory results. The numerical model, which must be calibrated and validated by the experimental model, presents as its main advantage the possibility of carrying out a parametric variation for the analysis of the connector without the need to spend time and materials, that is, numerous parameters can be varied in the test, such as thickness of the connector profile or its properties, among other test parameters, only with the computational cost involved, which proves to be advantageous when compared with the experimental cost related to the push-out test. In this sense, this work aims to numerically simulate the mechanical behavior of U-shaped shear connectors consisting of a cold-formed profile. The developed numerical model will be calibrated and validated, and applied for a parametric analysis to evaluate the connector resistance, where the thickness and length of the connector, in addition to the concrete resistance, will be the main parameters studied.
Reliability Analysis of the Simplified Punching Shear Resistance Model of Eurocode 2:2004 in Different Column Positions on Flat Slabs
Authors: José Caio Couto Bezerra Carneiro  , Luiz Eduardo Gonçalves de Mattos  , André Teófilo Beck
Published: January 2025

The use of coefficients in structural design is a strategy aimed at providing adequate levels of safety for buildings, avoiding excessive conservatism. The effectiveness of these coefficients depends on mathematical models that approximately capture the real behavior of the structure, considering the random nature of resistance and load variables. In this context, the proper definition of coefficients is even more crucial in resistance models that do not have an analytical formulation, such as empirical models. An example of an ultimate limit state whose model is empirical is the punching shear phenomenon, which occurs in flat reinforced concrete slabs. Despite the notable accuracy among normative models to assist in the development of these phenomena, some are based on simplifications that can result in high levels of conservatism or even insecurity when compared to more refined models. In EUROCODE 2:2004, there is the possibility of omitting the analysis of moments in the slab-to-column connection in punching shear design, considering only the axial force. For this purpose, a coefficient is applied to the applied stress to compensate for this simplification, depending on the position of the column in plan: corner, center, or edge. Therefore, this research aims to evaluate the reliability, through the First Order Reliability Method, of slab-to-column connections subjected to punching shear, using the EUROCODE 2:2004 simplification for design and employing an error model in the reliability analysis based on stress estimates derived from Fourier series. The research aims to assess whether the reliability indices of these connections demonstrate adequate levels of safety, using as reference the target reliability indices of other recognized standards, such as ACI 318 (2019) and CEB-FIP/MC (2010).
Applications of topology optimization considering physical nonlinearity
Authors: Matheus Barbosa Moreira Cedrim  , Eduardo Nobre Lages  , Aline da Silva Ramos Barboza
Published: January 2025

Topology optimization is a powerful computational tool that assists designers in determining efficient structural configurations. In civil engineering, most applications are still limited to the field of theoretical/computational analysis. This limitation restricts the scope and applications of topology optimization concepts for practical problems. Extensive research has focused on topology optimization using isotropic material with linear elastic behavior. However, there is a paucity of studies comparing linear and nonlinear material behaviors, highlighting a research gap in result analysis and structural application fields. For concrete structures, in particular, there is generally a deeply nonlinear behavior, including effects such as cracking, creep, and shrinkage. Therefore, it becomes a challenge to realistically optimize this type of material. This study investigates the applications of topology optimization for evaluating the structural behavior of beams considering the physical nonlinearity of the material. Using the ABAQUS® software and the SIMP method, a finite element numerical analysis is conducted to determine the density distribution in a design domain. The obtained results of the optimized models are compared, and it is observed that the presence of plastic deformations influences relevant aspects of structural behavior. This study contributes to the dissemination of the use of nonlinear constitutive models, highlighting the potential of the concept of optimization-assisted design.
Robust topology optimization of trusses with automatic grouping of cross-sections
Authors: Lorran Ferreira Oliveira  , Adeildo Soares Ramos Júnior
Published: January 2025

The ground structure method is a topology optimization strategy that tends to generate complex structural solutions to structural optimization problems. One of the main causes of this complexity is the large number of different cross-sections present in the topologies optimized by this method, in which the solutions obtained often have dozens of bars with different cross-sections. This excessive diversity of cross-sections makes the solutions obtained impractical for the manufacture and assembly of real structures, which require standardized cross-sections for economic and constructive viability. Therefore, in order to improve the workflow during the design stage, we propose the development of a strategy that allows the number of cross-sectional areas available to be restricted during the optimization process. The proposed method acts independently of the number of members present in the initial structure and ensures that the optimized solution has a predefined number of cross-sections with equal areas. To do this, an initial optimization is carried out to obtain an ordered vector of optimized design variables with a higher tolerance. From this ordering, the groupings of members that will be associated with the same design variable are defined, which generates a new optimization problem with a reduced number of design variables. The material of the structure is again redistributed among the members and the new optimization problem is solved. Structures were optimized with a robust compliance minimization formulation that introduces uncertainty in the loading directions. This formulation naturally increases the complexity of the final structure compared to a nominal formulation. As a result, simpler topologies are obtained that benefit the construction process by reducing the number of elements with different cross-sections in the structure. Numerical examples are presented to demonstrate the efficiency of the strategy developed.
Active suspension using a PID controller with an inerter device
Authors: Carlos Vinicius da Silva Martins  , Michele Karine Rodrigues de Andrade  , SUZANA MOREIRA AVILA
Published: January 2025

This article is dedicated to a thorough investigation of the behavior of an active suspension system that incorporates the PID controller in a vehicle quarter, adding an inerter component to the system. Through comprehensive analysis of a variety of track profiles, the active suspension system demonstrates its ability to precisely control wheel movements, with the primary aim of improving passenger comfort and vehicle handling. By using the PID controller in conjunction with track sensors, the system is able to continuously evaluate road conditions, identifying the most effective movements to optimize the driving experience. The PID controller, incorporating proportional, integral, and derivative components, plays a fundamental role in minimizing error, integrating corrections, and adjusting response time as needed. The inerter, an innovative mechanical device with two terminals, is introduced to provide inertia without adding mass to the system, utilizing the difference in angular acceleration between the terminals. To validate and compare the performance of the active suspension system with and without the inerter, detailed simulations are conducted using the powerful tools of MATLAB and Simulink. The inclusion of the inerter in the active suspension system, along with the PID controller, aims to enhance the overall effectiveness of the system, even if it results in a slight increase in manufacturing costs. However, the substantial benefits in terms of passenger comfort and vehicle safety fully justify this additional investment. This approach represents a significant advancement in the field of automotive suspension systems, offering an ideal balance between performance, cost, and user satisfaction.
Dynamic Analysis of Plates Subjected to Explosive Loading: Comparison Between SDOF and FEM Models
Authors: Rodrigo Bird Burgos  , Mayara Machado Martins  , Ana Waldila De Queiroz Ramiro Reis
Published: January 2025

With the global increase in explosive events, arising from armed conflicts and/or accidental occurrences, a thorough analysis of the dynamic behavior of structures under this type of load becomes important. The explosive phenomenon causes an overpressure (positive) wave with a subsequent underpressure (negative) phase, which is often disregarded. Moreover, recent studies have highlighted that this negative phase can generate displacements and stresses as relevant as the ones from the positive phase only. This work investigates simply supported plates subjected to explosive loading considering the membrane effect (laterally immovable condition) which introduces nonlinearities in the model. Due to the problems mathematical complexity, these nonlinear dynamic analyses are usually performed using complicated finite element models. In this way, a software called DYNAblast was developed using a simpler approach based on a Single Degree of Freedom (SDOF) analytical model which incorporates the von Karman plate theory. Dynamic analyses were carried out in DYNAblast to understand the influence of the positive and negative phases of the blast loads, as well as the contribution of the membrane energy of the plate. Numerical models implemented in ABAQUS software were used for the validation of DYNAblast results, with excellent agreement.
Multiobjective Optimization of Steel and Concrete Composite Slabs via NSGA algorithm
Authors: Isabela Maia  , Elcio Cassimiro Alves  , Adenilcia Fernanda Grobério Calenzani
Published: January 2025

With the expansion of the civil construction sector, composite steel and concrete slabs with incorporated shapes have become increasingly common due to their ease of execution and the elimination of shoring. However, optimization studies focusing on this type of structural element are still limited. The objective of this study is to propose a formulation for the multi-objective optimization of composite steel and concrete slabs, considering both the phases before and after concrete curing. Objective functions will be established to minimize CO2 emissions and slab costs, as well as to maximize the load-bearing capacity of the slab for a given span. To address this optimization problem, the NSGA algorithm implemented in the Matlab platform will be used. Comparative analyses will be conducted between examples from the literature utilizing single-objective optimization and those employing multi-objective optimization to validate the proposed formulation. Additionally, new problem instances will be examined to identify the key factors that influence the final solution.
A double-hybrid finite element formulation for Stokes flows using a divergence-free approximation space
Authors: Philippe Devloo  , Giovane Avancini  , Carlos Puga  , Nathan Shauer
Published: January 2025

This paper presents a study of Stokes flows using a fully-hybrid finite element formulation. Incompressibility appears in Stokes differential equations as an additional constraint that enforces the velocity field to be divergence-free. A straightforward option to discretise those kind of problems would be to use a space of vector functions that includes the divergence-free constraint. When using standard De Rham compatible $H(/text{div},\Omega) - L^2(\Omega)$ spaces a scalar $H^1(\Omega)$ space is used as a Lagrange multiplier to enforce the divergence-free condition weakly. In recent developments, the research group at LabMeC developed $H(\text{div})$ approximation spaces derived from $H(\text{Curl})$ spaces whose divergence is constant. This work demonstrates that this pair, that also satisfies the De Rham sequence, can be used to approximate the velocity and pressure fields, respectively. This approach greatly reduces the number of global degrees of freedom. In previous work, $H(\text{div})$ spaces, which automatically guarantee continuity of the normal components, were combined with a Lagrange multiplier space to enforce the tangent velocity weakly. The Lagrange multiplier is associated with a shear stress applied between elements. In this contribution, a second hybridization is applied to the shear stress approximation, leading to a Lagrange multiplier associated with the tangent velocity. Condensing internal degrees of freedom leads to an element stiffness matrix that is positive definite with a single pressure Lagrange multiplier enforcing the incompressibility. Examples are presented to test and verify the developed numerical methodology.
Elastostatic analysis using the boundary element method and the Aifantis gradient elasticity theory
Authors: Fabio Carlos da Rocha  , Leslie Darien Pérez Fernández  , Julián Bravo Castillero  , Maria do Socorro Martins Sampaio
Published: January 2025

The increasing use of micro and nano-scale structures has sparked interest in theories incorporating the effect of scale since the classical continuum theory has limitations in capturing effects that depend on size. Therefore, three-dimensional elastostatic microstructure modeling is carried out in this work using the boundary element method (BEM).To account for microstructural effects, the simplified gradient theory proposed by Aifantis, a particularization of Mindlin's general theory, was employed. A variational argument was established to determine the governing equations and boundary conditions for the problem. This argument explains the fundamental solution of gradient elasticity, and the integral contour representation is constructed with the aid of the reciprocal identity. Curved triangular elements of Proriol spectral functions were used to approximate the geometry and the physical parameters for the discretization of the BEM. The presented formulation yielded results consistent with other analyses in the literature.
Modifying the refined zigzag theory to incorporate functional gradation into the bending analysis of laminated beams
Authors: Maria do Socorro Martins Sampaio  , Joseph Richard Santana Rodrigues  , Fabio Carlos da Rocha  , Leslie Darien Pérez Fernández  , Julián Bravo Castillero
Published: January 2025

Extensive research has been conducted in the field of composite materials, particularly in laminated composites. However, laminated composites often face challenges such as stress concentration at interfaces due to the sharp differences in properties between layers. This study proposes an approach to mitigate stress concentrations in laminated composites using functionally graded materials (FGM). FGM is achieved by gradually varying properties across the thickness of each beam layer, employing the power law in conjunction with the rule of mixtures. The modeling is based on the refined zigzag theory (RZT), with an additional introduction of the sublayers to capture the functional gradient. The analysis involves deriving the zigzag function for FGM, which is referred to as modified RZT. Subsequently, the kinematic model is applied based on the principle of minimum total energy to derive the Euler equation and its associated boundary conditions. For analytical resolution, the Navier procedure is employed. The results obtained for displacement and tension fields are compared with other formulations from the literature, demonstrating alignment and validation of the proposed method.
Static Mechanical Analysis of Nanobeams Reinforced with Graphene Nanoplatelets Using Modified Couple Stress Theory
Authors: Elyakim Aguiar Santana  , Leonardo Fellipe Prado Leite  , Fabio Carlos da Rocha  , Leslie Darien Pérez Fernández  , Julián Bravo Castillero  , Maria do Socorro Martins Sampaio
Published: January 2025

Composite materials are fundamental in contemporary engineering, standing out for their ability to combine different raw materials to create new materials with superior properties. Graphene, characterized by its flat two-dimensional (2D) carbon monolayer structure with a thickness of 0.34 nm, has aroused considerable interest due to its remarkable mechanical, thermal, and electrical properties. In particular, graphene derivatives, such as graphene nanoplatelets (GNP) and carbon nanotubes (CNT), have been widely explored as reinforcements in composites. Compared to CNT, GNP offers a more economical alternative and a greater surface area, available in various sizes, from nanometers to micrometers. Micro- and nanoscale composites serve as models for assessing material performance in multiple industries, such as automobiles, aviation, medicine, and construction, especially in cases where experimental methods are costly. Modeling and simulation techniques are employed to mitigate the costs associated with experimentation, from quantum mechanics to continuum mechanics. This work proposes a variational formulation to model the static mechanical behavior of nanobeams reinforced with graphene nanoplatelets. The micromechanical constitutive model modified Couple Stress, coupled with high-order beam kinematics, is developed to obtain the governing equations and their boundary conditions. The Navier procedure is utilized to develop an analytical solution to the problem. The results are compared with the literature, and the proposed model is proven accurate.
A study on Physics-Informed Neural Networks parameters influences in solid mechanics problems.
Authors: Flávio Valberto Barrionuevo Rodrigues  , Paulo de Mattos Pimenta
Published: January 2025

In recent years, Physics-Informed Neural Networks (PINNs) have introduced a novel approach to solving partial differential equations (PDEs) using deep learning techniques. Despite the promising results and rapid advancements in the field, there is a lack of more accurate studies concerning properties related to modeling choices within the deep learning framework, especially, but not exclusively, in solid mechanics problems. In this study, we aim to explore whether the neural network architecture, activation function, optimizer, and sampling method can influence the accuracy of results and training speed for solid mechanics problems. We will focus on elasticity and hyperelasticity problems in 1D, 2D, and 3D dimensions to lay the groundwork for more complex investigations.
A study on the representation of local effects in low order models for thin-walled rod members
Authors: Marcos Pires Kassab  , Eduardo de Morais Barreto Campello  , Adnan Ibrahimbegovic
Published: January 2025

This work aims to explore alternatives to represent local effects, such as local buckling and plasticity, in low order models for thin-walled rod members. The discussion is carried out on a theoretical-numerical level, and illustrative examples are provided. The techniques that are explored stem from two different approaches: (i) direct enrichment of the rod kinematics and (ii) multiscale methods. Direct enrichment of low order kinematics usually leads to models with optimal computational cost, while still at the downside of having lower-order (still limited) kinematics. Models derived from the Generalized Beam Theory (GBT) are an example of such an approach. Multiscale methods, in turn, rely on results of higher-order theories (e.g., shells and 3D solids) to improve the performance of the lower-order model. The associated computational cost and accuracy vary widely with the imposed coupling level between the different scales. It is possible to have models ranging from full coupling at run-time  the so-called strong coupling multiscale method  to no coupling at all  the higher-order models are used only to compute meaningful mechanical quantities that are passed on to the low order model at some point. The work is an on-going development of a PhD research by the first author, and the results provided so far are only partial.
Strategies for the development of finite elements for non-prismatic frames
Authors: Aline dos Santos Alves Gesteira  , Luiz Fernando Martha  , Rodrigo Bird Burgos
Published: January 2025

Non-prismatic structural elements, often referred to as beams with variable cross-sections, constitute a special class of slender structures. These types of structures capture the interest of engineers and architects due to their ability to optimize geometry to meet specific needs, such as weight reduction, material consumption, environmental impact, and costs. Despite the advantages that engineers can gain from using non-prismatic structural elements, modeling these structures poses non-trivial challenges, resulting in inaccuracies that may compromise the benefits offered by such structures. Taking this into consideration, this work presents an innovative approach to obtain the displacement solution for non-prismatic beams, obtaining the elastic stiffness matrix through the virtual work principle, using the kinematics of Timoshenko's theory. This proposed formulation is independent of bar discretization to achieve an analytical result. This is due to the absence of considering any additional approximations beyond those already contained in the analytical idealization of bar behavior, resulting in a nearly natural discretization of the structure.
Three-dimensional finite-volume theory for elastic stress analysis in solid mechanics
Authors: Marcelo Vitor Oliveira Araujo  , Romildo dos Santos Escarpini Filho  , Márcio André Araújo Cavalcante  , Arnaldo do Santos Júnior  , Eduardo Nobre Lages
Published: January 2025

The finite-volume theory is a powerful numerical technique for structural analysis in solid mechanics and has emerged as an alternative to the finite-element method. The finite-volume theory is an equilibrium-based approach that employs surface-averaged tractions and displacements acting on the faces of a subvolume. In addition, this theory employs the equilibrium equations at the subvolume level and continuity conditions between adjacent subvolumes along subvolume faces. The finite-volume theory has been successfully used for two-dimensional structural analyses. However, in the context of three-dimensional solid mechanics analysis, this numerical technique has encountered instability problems related to the interpretation between adjacent subvolumes' faces. These problems result in the singularity of the global stiffness matrix, which has delayed the publication of a three-dimensional version of the finite-volume theory for continuum elastic structures. These numerical instability problems can be solved by employing a modified stiffness matrix, where the Tikhonov regularization method is used to artificially add minimal stiffness in the main diagonal of the global stiffness matrix. This contribution proposes the stress analysis of three-dimensional continuum elastic structures by the finite-volume theory, where problems with analytical solutions are employed for verification.
Young's modulus identification via finite element model updating using full-field data from a 3-point bending test
Authors: Arthur Mota Goncalves  , Igor Paganotto Zago  , Rafael Vargas  , Rodrigo Bresciani Canto  , Ricardo Afonso Angélico
Published: January 2025

High-temperature applications usually require refractory materials because of their thermal and physical properties. The mechanical design of structures with these materials demands their elastic properties to be well known. However, evaluating these data at high temperatures through common experimental methods such as strain gauges, not only generally furnishes single-point measurements but may also become impossible at higher temperatures due to the required contact with the specimen. Non-intrusive image-based techniques are thus welcome to overcome these limitations, allowing full-field displacement and strain measurements, calculated from images gathered with cameras placed far from the sample. In this context, the article aims to assess the Young's modulus of a refractory material by combining Digital Image Correlation (DIC) and a Finite Element Model Updating (FEMU) approach. DIC allows the computation of the displacement field over a region of interest for each loading level (i.e., acquired picture), enabling different parameter evaluations from a single test. Pictures are gathered through a camera setup in a three-point bending test, and the DIC analysis is performed in MATLAB with the Correli framework. The identification problem is modeled using the finite element software Abaqus and its Scripting Interface in Python. A sensitivity analysis is performed to ensure the successful identification of parameters. Then, the elastic parameters are iteratively updated until computational results match the experimental displacement field and the resultant reaction forces (FEMU-UF). Both displacement and force residue involving the comparison of the computational model and experimental results are discussed. It is shown that the richness of full-field measurements is helpful to identify different parameters from a single experiment.
A hybrid FEM-Kriging approach for fatigue assessment of a steel pipe riser from field-measured motions
Authors: Bernardo Donni de Sena  , Ludimar Lima de Aguiar  , Marcos André Duarte Martins  , Fabrício Nogueira Corrêa  , Breno Pinheiro Jacob
Published: January 2025

The establishment of monitoring systems for Floating Production Units motions provides an important input needed for real-time assessment of riser fatigue through Finite Element Method analysis. Standard practice relies on these simulations to obtain the loads required to calculate fatigue life along the riser, however, it is a CPU-intensive approach which makes it difficult to achieve results in real-time. Since interest often lies on few critical points on the riser, such as 1st weld and TDP, the number of outputs of is vastly reduced, making surrogate models an interesting and cost-effective alternative. Previous work such as DAMASCENO (2020) has shown Kriging to be a good choice for time series prediction, yielding adherent results for outputs such as forces and moments by having vessel motions as inputs. This method requires a short FEM simulation (~600 s) to train the models that will expand the output time-series to full 3,600 s duration, which will be shown to be far less CPU intensive. A case study for a SCR connected to a semi-submersible platform is presented, evaluating fatigue life from 5715 hours worth of data from the year of 2018 through both methods. Analysis of the obtained results yields additional tools which correlate damage to vessel motions, which are then used to prioritize sea states and evaluate the most cost-effective FEM and Kriging combination.
Analysis of Inertial Influence and Damping of Mooring Lines on Fatigue Damage
Authors: Christie de Vilhena Prata Machado  , Fabricio Nogueira Corrêa  , Magnus Carvalho de Vilhena Prata  , Breno Pinheiro Jacob
Published: January 2025

The high demand for oil has driven its exploration into increasingly deeper water depths, which required significant scientific and technological advancements. In this context, the floating production and offshore system is a type of platform, based on ship, anchored by mooring lines arranged by chains/steel cables and polyester cables with the objective to restrict the platforms movements in a design region. Offshore platforms are exposed to environmental loads of waves, wind, and currents, which are responsible for generating hull motions and tension variation in the mooring lines. This tension history, in turn, is directly associated with fatigue failure of the lines. Despite efforts to estimate the fatigue life of mooring lines to ensure their integrity throughout the platforms operation, premature failures in the mooring system have been observed over the past decades. This serves as an alert that the fatigue damage estimated during the design phase may be less than the actual damage occurring in the field. Several factors influence the initial estimation of fatigue life, for instance, the analysis method used to represent the lines behavior, such as quasi-static and dynamic analysis. The first one, that ignore the inertial and damping effects, was widely used in design of mooring lines in the 90s and the beginning of this century due its low computational cost, while the dynamic analysis, that represents rigorously the mooring line dynamic behavior, is used increasingly nowadays. The use of these two different approaches can affect the fatigue damage. Therefore, the present work aims to evaluate the influence of the inertia and damping of moorings in the fatigue damage, comparing the quasi-static and dynamic approaches studied with a floating unit numerical model, with 910m water depth, that uses a conventional catenary mooring system. In this way, a critical analysis is carried out based on the comparison between the fatigue life resulting from the two forms of analysis.