scholarly journals Scale Effects in Orthotropic Composite Assemblies as Micropolar Continua: A Comparison between Weak- and Strong-Form Finite Element Solutions

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 758 ◽  
Author(s):  
Lorenzo Leonetti ◽  
Nicholas Fantuzzi ◽  
Patrizia Trovalusci ◽  
Francesco Tornabene
Keyword(s):  
Finite Element ◽  
Scale Effects ◽  
Kinematic Model ◽  
Elastic Response ◽  
Actual Behavior ◽  
Orthotropic Composite ◽  
Additional Degree ◽  
Micropolar Continua ◽  
Orthotropic Composites ◽  
Micropolar Materials

The aim of the present work was to investigate the mechanical behavior of orthotropic composites, such as masonry assemblies, subjected to localized loads described as micropolar materials. Micropolar models are known to be effective in modeling the actual behavior of microstructured solids in the presence of localized loads or geometrical discontinuities. This is due to the introduction of an additional degree of freedom (the micro-rotation) in the kinematic model, if compared to the classical continuum and the related strain and stress measures. In particular, it was shown in the literature that brick/block masonry can be satisfactorily modeled as a micropolar continuum, and here it is assumed as a reference orthotropic composite material. The in-plane elastic response of panels made of orthotropic arrangements of bricks of different sizes is analyzed herein. Numerical simulations are provided by comparing weak and strong finite element formulations. The scale effect is investigated, as well as the significant role played by the relative rotation, which is a peculiar strain measure of micropolar continua related to the non-symmetry of strain and work-conjugated stress. In particular, the anisotropic effects accounting for the micropolar moduli, related to the variation of microstructure internal sizes, are highlighted.

Virtual trabecular bone models and their mechanical response

2008 ◽  
Vol 222 (8) ◽  
pp. 1185-1195 ◽  
Author(s):  
F E Donaldson ◽  
P Pankaj ◽  
A H Law ◽  
A H Simpson
Keyword(s):  
Finite Element ◽  
Trabecular Bone ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Elastic Response ◽  
Anatomical Site ◽  
Virtual Samples ◽  
Micro Level ◽  
Architectural Characteristics

The study of the mechanical behaviour of trabecular bone has extensively employed micro-level finite element (μFE) models generated from images of real bone samples. It is now recognized that the key determinants of the mechanical behaviour of bone are related to its micro-architecture. The key indices of micro-architecture, in turn, depend on factors such as age, anatomical site, sex, and degree of osteoporosis. In practice, it is difficult to acquire sufficient samples that encompass these variations. In this preliminary study, a method of generating virtual finite element (FE) samples of trabecular bone is considered. Virtual samples, calibrated to satisfy some of the key micro-architectural characteristics, are generated computationally. The apparent level elastic and post-elastic mechanical behaviour of the generated samples is examined: the elastic mechanical response of these samples is found to compare well with natural trabecular bone studies conducted by previous investigators; the post-elastic response of virtual samples shows that material non-linearities have a much greater effect in comparison with geometrical non-linearity for the bone densities considered. Similar behaviour has been reported by previous studies conducted on real trabecular bone. It is concluded that virtual modelling presents a potentially valuable tool in the study of the mechanical behaviour of trabecular bone and the role of its micro-architecture.

Elastic-Plastic Finite Element Simulation and Fatigue Life Prediction for Beam and Elbow Under Cyclic Loading

2007 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Plastic Strain ◽  
Kinematic Hardening ◽  
Kinematic Model ◽  
Cyclic Plastic ◽  
Hardening Models ◽  
Critical Location ◽  
Cyclic Plastic Strain

Work hardening and Bauschinger effects on plastic deformation and fatigue life for a beam and an elbow under cyclic loading are examined using finite element analysis (FEA). Three typical material plastic hardening models, i.e. isotropic, kinematic and combined isotropic/kinematic hardening models are adopted in the FEA calculations. Based on the FEA results of cyclic stress and strain at a critical location and using an energy-based fatigue damage parameter, the fatigue lives are predicted for the beam and elbow. The results show that (1) the three material hardening models determine similar stress at the critical location with small differences during the cyclic loading, (2) the isotropic model underestimates the cyclic plastic strain and overestimates the fatigue life, (3) the kinematic model overestimates the cyclic plastic strain and underestimates the fatigue life, and (4) the combined model predicts the intermediate cyclic plastic strain and reasonable fatigue life.

Large elastic deformation of micromorphic shells. Part II. Isogeometric analysis

2019 ◽  
Vol 24 (12) ◽  
pp. 3753-3778 ◽  
Author(s):  
Amir Norouzzadeh ◽  
Reza Ansari ◽  
Mansour Darvizeh
Keyword(s):  
Finite Element ◽  
Elastic Deformation ◽  
Isogeometric Analysis ◽  
Constitutive Relations ◽  
Kinematic Model ◽  
Benchmark Problems ◽  
Element Analysis ◽  
Deformation Problem ◽  
Macro Scale ◽  
Large Elastic Deformation

In Part I of this study, a variational formulation was presented for the large elastic deformation problem of micromorphic shells. Using the novel matrix-vector format presented for the kinematic model, constitutive relations, and energy functions, an isogeometric analysis (IGA)-based solution strategy is developed, which appropriately estimates the macro- and micro-deformation field components. Due to the capability of constructing exact geometries and the powerful mesh refinement tools, IGA can be successfully applied to solve the equilibrium equations with dominant nonlinear terms. It is known that different types of locking phenomena take place in the conventional finite element analysis of thin shells based on low-order elements. Non-standard finite element models with mixed interpolation schemes and additional degrees of freedom (DOFs) or the ones used the high-order Lagrangian shell elements which require high computational costs, are the available solutions to tackle locking issues. The present 16-DOFs IGA is found to be efficient because of possessing a good rate of convergence and providing locking-free stable responses for micromorphic shells. Such a conclusion is found from several comparative studies with available data in the well-known macro-scale benchmark problems based on the classical elasticity as well as the corresponding numerical examples studied in nano-scale beam-, plate-, cylindrical shell- and spherical shell-type structures on the basis of the micromorphic continuum theory.

scholarly journals Numerical analysis of castellated beams with oval openings

2018 ◽  
Vol 195 ◽  
pp. 02008
Author(s):  
Yanuar Setiawan ◽  
Ay Lie Han ◽  
Buntara Sthenly Gan ◽  
Junaedi Utomo
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Main Idea ◽  
Element Model ◽  
Steel Beams ◽  
Good Representation ◽  
Actual Behavior ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
The Web

The use of castellated beams has become more popular in the last two decades. The main idea for the use of these types of steel beams is to reduce their self-weight by providing openings in the web of wide flange (WF) or I sections. Numerous research on castellated beams has been conducted, the majority of the studies aimed to optimize the opening size and the shape configuration of the openings. A numerical analysis of castellated beams with oval openings was performed in this study. The sections under investigation had variations in the height-to-length ratios of the beam. The Do to D and b to Do ratios were kept at a constant. The D value was defined as the height of the beam, while Do is the height of the opening, and b is the width of the opening. The numerical analysis was performed by the finite element analysis using the STRAND7 software. The numerical model was further validated to the experimental data. The results showed that the developed finite element model resulted in a very good representation to the actual behavior of the sections.

The Numerical Simulation of Effective Elastic Response for WC-Co Cemented Carbide

2015 ◽  
Vol 1096 ◽  
pp. 417-421
Author(s):  
Pei Luan Li ◽  
Zi Qian Huang
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Theoretical Model ◽  
Material Properties ◽  
Cemented Carbide ◽  
Elastic Response ◽  
The Finite Element Method ◽  
Simulation Results ◽  
Element Method

By the use of finite element method, this paper predicts the effects of the shapes of reinforcements with different ductility (Co) on the effective elastic response for WC-Co cemented carbide. This paper conducts a comparative study on the material properties obtained through theoretical model, numerical simulation and experimental observations. Simulation results indicate that the finite element method is more sophisticated than the theoretical prediction.

Study of a curved continuous composite box girder bridge

1993 ◽  
Vol 20 (1) ◽  
pp. 107-119 ◽  
Author(s):  
S. F. Ng ◽  
M. S. Cheung ◽  
H. M. Hachem
Keyword(s):  
Finite Element ◽  
Structural Response ◽  
Shell Element ◽  
Elastic Response ◽  
Box Girder ◽  
Girder Bridges ◽  
Bridge Model ◽  
Box Girder Bridge ◽  
Girder Bridge ◽  
Critical Sections

To better understand the behaviour of curved box girder bridges in resisting eccentric design truck loads, and the influence of plan curvature on the structural response, a model study was conducted at the University of Ottawa. In this study, the elastic response of a curved composite box girder bridge model was evaluated experimentally and confirmed analytically using the finite element method. Analytical predictions of both vertical displacements and normal stresses at critical sections compared fairly well with those evaluated experimentally. The isoparametric thin shell element employed in the analysis proved to be versatile and provided an accurate representation of the various structural components of a curved box girder bridge. Despite the eccentric nature of the applied OHBDC design truck loads and the bridge plan curvature, it was evident that in resisting the applied live loads, the girders at critical sections share equal proportions of the applied bending moments. Key words: bridge, curved, cellular, composite, eccentric loads, static, linear, experimental, finite element.

Effects of Structure and Property Variations Within Hierarchal Biomineralized Composites Using Finite Element Methods

2016 ◽  
Author(s):  
Matt Nelms ◽  
Ken Livi ◽  
Bryan Crawford ◽  
A. M. Rajendran ◽  
Wayne Hodo
Keyword(s):  
Finite Element ◽  
High Strength ◽  
Elastic Response ◽  
Science And Engineering ◽  
Structure And Property ◽  
Alligator Gar ◽  
Flaw Tolerance ◽  
Delamination Resistance ◽  
Abalone Shell ◽  
Atractosteus Spatula

Biological materials (biomaterials) have had a marked increase in interest from the material science and engineering community due to unique characteristics and properties that are typically sought after in traditional engineering materials. During the last few decades, research on biomineralized composites such as abalone shell, fish armor, turtle shell, and human bone revealed that those biological systems possess a carefully arranged multilayered composite structure. Unlike metals, ceramics, and traditional composite materials; biomineralized composites often possess enhanced characteristics such as, penetration resistance high toughness, flaw tolerance energy dissipation, damage mitigation, and delamination resistance all while achieving high strength-to-weight ratios. In this research experimentally driven finite element modeling was used to investigate the elastic response for the biocomposite structure. The Atractosteus spatula (Alligator gar) was used as the model structure for determining the elastic properties.

scholarly journals On the Effect of Unit-Cell Parameters in Predicting the Elastic Response of Wood-Plastic Composites

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Fatemeh Alavi ◽  
Amir Hossein Behravesh ◽  
Abbas S. Milani ◽  
Davoud Karimi
Keyword(s):  
Finite Element ◽  
Modulus Of Elasticity ◽  
Strain Curve ◽  
Unit Cell ◽  
Elastic Response ◽  
Geometrical Parameters ◽  
Uniaxial Test ◽  
Cell Parameters ◽  
Plastic Composite ◽  
The Difference

This paper presents a study on the effect of unit-cell geometrical parameters in predicting elastic properties of a typical wood plastic composite (WPC). The ultimate goal was obtaining the optimal values of representative volume element (RVE) parameters to accurately predict the mechanical behavior of the WPC. For each unit cell, defined by a given combination of the above geometrical parameters, finite element simulation in ABAQUS was carried out, and the corresponding stress-strain curve was obtained. A uniaxial test according to ASTM D638-02a type V was performed on the composite specimen. Modulus of elasticity was determined using hyperbolic tangent function, and the results were compared to the sets of finite element analyses. Main effects of RVE parameters and their interactions were demonstrated and discussed, specially regarding the inclusion of two adjacent wood particles within one unit cell of the material. Regression analysis was performed to mathematically model the RVE parameter effects and their interactions over the modulus of elasticity response. The model was finally employed in an optimization analysis to arrive at an optimal set of RVE parameters that minimizes the difference between the predicted and experimental moduli of elasticity.

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