Nonlinear modeling of concentrically loaded reinforced blockwork masonry columns

2004 ◽  
Vol 31 (6) ◽  
pp. 1012-1023 ◽  
Author(s):  
Hasan Orhun Köksal ◽  
Bilge Doran ◽  
Ayse Elif Ozsoy ◽  
Sema Noyan Alacali
Keyword(s):  
Finite Element ◽  
Yield Criterion ◽  
Nonlinear Modeling ◽  
Damage Model ◽  
Three Dimensional ◽  
Mesh Size ◽  
Simple Relation ◽  
Damage Parameter ◽  
Damage Models ◽  
Isotropic Damage

Since only a limited number of experimental and analytical studies have been carried out for the purpose of developing strength design procedures for reinforced blockwork masonry columns, there is a certain need for further studies that reflect material properties and behavior of blockwork masonry more closely. This paper deals with a nonlinear finite element modeling of the concentrically loaded reinforced blockwork masonry columns making use of both elasto-plastic and isotropic damage models. If the damage model is enriched with the introduction of a simple relation for the material damage parameter that accounts for the mesh size effect, three-dimensional finite element analyses of columns for the well-known experimental works in the literature are accomplished. Finally, the predictions from both the numerical analyses and the existing expressions for the ultimate load of the masonry columns are compared with the experimental results.Key words: compressive strength, reinforced blockwork masonry column, finite element method, Drucker-Prager yield criterion, isotropic damage theory.

Numerical model for composite patch repair of notched aluminum plates under impact loading

2021 ◽  
pp. 146442072098337
Author(s):  
Umut Caliskan ◽  
Recep Ekici ◽  
Ayse Yildiz Bayazit ◽  
M Kemal Apalak
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Composite Structures ◽  
Impact Damage ◽  
Damage Model ◽  
Three Dimensional ◽  
Patch Repair ◽  
Progressive Damage ◽  
Damage Models ◽  
Composite Patch

The damaged area for various structures can be effectively repaired using composite materials. With the effect of impact, damage can occur that cannot be clearly seen in the inner structure of a laminated composite. This can cause delamination and other damage modes in layered composite structures. In this study, three-dimensional dynamic progressive damage analysis was performed in adhesively bonded composite patch-repaired metal notched plates under impact loads to investigate the effect of external composite patch material and thickness. Three-dimensional Hashin damage models were used for the progressive damage model. A user-defined subroutine, VUMAT was written to transfer the damage models to finite element code. By writing a separate script in Python language that relates to the damage models, the weakness in the laminate of the composite patch was transferred to the finite element model with a different degradation model proposed. It was found that plastic deformations occurring after impact damage in the notched metal plates was prevented by the use of composite patches. While glass and carbon fiber exhibit similar behavior at lower impact velocities, the progress of damage is prevented by increasing patch thickness. These behaviors were confirmed by the numerical model and showed an advanced agreement with experimental results.

scholarly journals Simulating Progressive Damage of Notched Composite Laminates with Various Lamination Schemes

2017 ◽  
Vol 22 (2) ◽  
pp. 333-347 ◽  
Author(s):  
B. Mandal ◽  
A. Chakrabarti
Keyword(s):  
Finite Element ◽  
Composite Laminates ◽  
Constitutive Relations ◽  
Damage Model ◽  
Three Dimensional ◽  
Failure Criteria ◽  
Progressive Damage ◽  
Damage Models ◽  
Matrix Shear ◽  
Three Dimensional Finite Element

AbstractA three dimensional finite element based progressive damage model has been developed for the failure analysis of notched composite laminates. The material constitutive relations and the progressive damage algorithms are implemented into finite element code ABAQUS using user-defined subroutine UMAT. The existing failure criteria for the composite laminates are modified by including the failure criteria for fiber/matrix shear damage and delamination effects. The proposed numerical model is quite efficient and simple compared to other progressive damage models available in the literature. The efficiency of the present constitutive model and the computational scheme is verified by comparing the simulated results with the results available in the literature. A parametric study has been carried out to investigate the effect of change in lamination scheme on the failure behaviour of notched composite laminates.

Failure Predictions for DP Steel Cross-die Test using Anisotropic Damage

2011 ◽  
Vol 21 (5) ◽  
pp. 713-754 ◽  
Author(s):  
M. S. Niazi ◽  
H. H. Wisselink ◽  
T. Meinders ◽  
J. Huétink
Keyword(s):  
Strain Rate ◽  
Damage Evolution ◽  
Damage Model ◽  
Anisotropic Damage ◽  
Continuum Damage ◽  
Anisotropic Plasticity ◽  
Continuum Damage Model ◽  
Damage Models ◽  
Isotropic Damage ◽  
Failure Predictions

The Lemaitre's continuum damage model is well known in the field of damage mechanics. The anisotropic damage model given by Lemaitre is relatively simple, applicable to nonproportional loads and uses only four damage parameters. The hypothesis of strain equivalence is used to map the effective stress to the nominal stress. Both the isotropic and anisotropic damage models from Lemaitre are implemented in an in-house implicit finite element code. The damage model is coupled with an elasto-plastic material model using anisotropic plasticity (Hill-48 yield criterion) and strain-rate dependent isotropic hardening. The Lemaitre continuum damage model is based on the small strain assumption; therefore, the model is implemented in an incremental co-rotational framework to make it applicable for large strains. The damage dissipation potential was slightly adapted to incorporate a different damage evolution behavior under compression and tension. A tensile test and a low-cycle fatigue test were used to determine the damage parameters. The damage evolution was modified to incorporate strain rate sensitivity by making two of the damage parameters a function of strain rate. The model is applied to predict failure in a cross-die deep drawing process, which is well known for having a wide variety of strains and strain path changes. The failure predictions obtained from the anisotropic damage models are in good agreement with the experimental results, whereas the predictions obtained from the isotropic damage model are slightly conservative. The anisotropic damage model predicts the crack direction more accurately compared to the predictions based on principal stress directions using the isotropic damage model. The set of damage parameters, determined in a uniaxial condition, gives a good failure prediction under other triaxiality conditions.

Fracture simulations using edge-based smoothed finite element method for isotropic damage model via Delaunay/Voronoi dual tessellations

2021 ◽  
pp. 105678952110405
Author(s):  
Young Kwang Hwang ◽  
Suyeong Jin ◽  
Jung-Wuk Hong
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Voronoi Tessellation ◽  
Damage Model ◽  
Time Integration ◽  
Voronoi Cell ◽  
Smoothed Finite Element Method ◽  
Isotropic Damage ◽  
Edge Based ◽  
Element Method

In this study, an effective numerical framework for fracture simulations is proposed using the edge-based smoothed finite element method (ES-FEM) and isotropic damage model. The duality between the Delaunay triangulation and Voronoi tessellation is utilized for the mesh construction and the compatible use of the finite element solution with the Voronoi-cell lattice geometry. The mesh irregularity is introduced to avoid calculating the biased crack path by adding random variation in the nodal coordinates, and the ES-FEM elements are defined along the Delaunay edges. With the Voronoi tessellation, each nodal mass is calculated and the fractured surfaces are visualized along the Voronoi edges. The rotational degrees of freedom are implemented for each node by introducing the elemental formulation of the Voronoi-cell lattice model, and the accurate visualizations of the rotational motions in the Voronoi diagram are achieved. An isotropic damage model is newly incorporated into the ES-FEM formulation, and the equivalent elemental length is introduced with an additional geometric factor to simulate the consistent softening behaviors with reducing the mesh sensitivity. The full matrix form of the smoothed strain-displacement matrix is constructed for optimal use in the element-wise computations during explicit time integration, and parallel computing is implemented for the enhancement of the computational efficiency. The simulated results are compared with the theoretical solutions or experimental results, which demonstrates the effectiveness of the proposed methodology in the simulations of the quasi-brittle fractures.

scholarly journals Finite Element Simulation and Multi-Factor Stress Prediction Model for Cement Concrete Pavement Considering Void under Slab

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5294
Author(s):  
Bangyi Liu ◽  
Yang Zhou ◽  
Linhao Gu ◽  
Xiaoming Huang
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Concrete Slab ◽  
Three Dimensional ◽  
Mesh Size ◽  
Maximum Tensile Stress ◽  
Concrete Pavement ◽  
Slab Thickness ◽  
Void Size ◽  
Tensile Stresses

Uneven support as result of voids beneath concrete slabs can lead to high tensile stresses at the corner of the slab and eventually cause many forms of damage, such as cracking or faulting. Three-dimensional (3D) finite element models of the concrete pavement with void are presented. Mesh convergence analysis was used to determine the element type and mesh size in the model. The accuracy of the model is verified by comparing with the calculation results of the code design standards in China. The reliability of the model is verified by field measurement. The analysis shows that the stresses are more affected at the corner of the slab than at the edge. Impact of void size and void depth at the slab corner on the slab stress are similar, which result in the change of the position of the maximum tensile stress. The maximum tensile stresses do not increase with the increase in the void size for relatively small void size. The maximum tensile stress increases rapidly with the enlargement in the void size when the size is ≥0.4 m. The increments of maximum tensile stress can reach 183.7% when the void size is 1.0 m. The increase in slab thickness can effectively reduce maximum tensile stress. A function is established to calculate the maximum tensile stress of the concrete slab. The function takes into account the void size, the slab thickness and the vehicle load. The reliability of the function was verified by comparing the error between the calculated and simulated results.

Progressive fatigue behavior of single-lap bolted laminates under different tightening torque magnitudes

2020 ◽  
Vol 234 (10) ◽  
pp. 1303-1312
Author(s):  
M Feyzi ◽  
S Hassanifard ◽  
A Varvani-Farahani
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Damage Model ◽  
Three Dimensional ◽  
Bolted Joints ◽  
Element Analysis ◽  
Damage And Failure ◽  
Experienced Fatigue ◽  
Three Dimensional Finite Element

The present paper studies fatigue damage and life of single-lap bolted joints tightened with different torque magnitudes subjected to uniaxial load cycles. The adherends were constructed from E-glass/epoxy layers using a hand layup technique and assembled by 1.5, 3, and 8 N m of applied torques. Increasing the torque magnitude benefitted the final fatigue life of the joints so that the high-cycle fatigue life of the joint sample tightened with 8 N m was as high as 10 times that of the joint tightened with 1.5 N m. In the numerical section of this study, a three-dimensional finite element analysis was employed, and the impacts of applied torques were included in the progressive damage model to assess damage and failure in the bolted joints. For the joints tightened with higher torque levels, numerical results revealed higher fatigue lives but at the cost of more delamination at the vicinity of the hole. Laminate fracture surface was investigated through scanning electron microscopy and more cracking/damage progress was evidenced in matrix, fiber, and matrix–fiber interface as composite joints experienced fatigue cycles. Experimental life data of tested joints agreed with those anticipated through the use of finite element analyses indicating the developed model as an appropriate tool in evaluating the effects of applied torques on the fatigue fracture behavior of bolted laminates.

GENERALIZED FINITE ELEMENT METHOD FOR NONLINEAR THREE-DIMENSIONAL ANALYSIS OF SOLIDS

2008 ◽  
Vol 05 (01) ◽  
pp. 37-62 ◽  
Author(s):  
SERGIO PERSIVAL BARONCINI PROENÇA ◽  
IVAN FRANCISCO RUIZ TORRES
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dimensional Analysis ◽  
Damage Model ◽  
Three Dimensional ◽  
Generalized Finite Element Method ◽  
Good Tool ◽  
Selective Enrichment ◽  
Generalized Finite Element ◽  
Element Method

The Generalized Finite Element Method (GFEM) is employed in this paper for the numerical analysis of three-dimensional solids under nonlinear behavior. A brief summary of the GFEM as well as a description of the formulation of the hexahedral element based on the proposed enrichment strategy are initially presented. Next, in order to introduce the nonlinear analysis of solids, two constitutive models are briefly reviewed: Lemaitre's model, in which damage and plasticity are coupled, and Mazars's damage model suitable for concrete under increased loading. Both models are employed in the framework of a nonlocal approach to ensure solution objectivity. In the numerical analyses carried out, a selective enrichment of approximation at regions of concern in the domain (mainly those with high strain and damage gradients) is exploited. Such a possibility makes the three-dimensional analysis less expensive and practicable since re-meshing resources, characteristic of h-adaptivity, can be minimized. Moreover, a combination of three-dimensional analysis and the selective enrichment presents a valuable good tool for a better description of both damage and plastic strain scatterings.

Transient Thermal Analysis and Visco-Plastic Damage Model for Life Prediction of Turbine Components

2014 ◽  
Author(s):  
A. Staroselsky ◽  
T. J. Martin ◽  
B. Cassenti
Keyword(s):  
Finite Element ◽  
Life Prediction ◽  
Failure Modes ◽  
Damage Model ◽  
High Stress ◽  
Three Dimensional ◽  
Dissipated Energy ◽  
Linear Deformation ◽  
Three Dimensional Finite Element ◽  
Turbine Airfoils

This paper reports the process and computer methodology for a physics-based prediction of overall deformation and local failure modes in cooled turbine airfoils, blade outer air seals, and other turbomachinery parts operating in severe high temperature and high stress environments. The computational analysis work incorporated time-accurate, coupled aerothermal CFD with non-linear deformation thermal-structural FEM with a slip-based constitutive model, evaluated at real engine characteristic mission times and flight points for part life prediction. The methodology utilizes a fully-coupled elastic-viscoplastic model that was based on crystal morphology, and a semi-empirical lifing model introduced the use of dissipated energy to estimate the remaining part life in terms of cycles to failure. The method was effective for use with three-dimensional finite element models of realistic turbine airfoils using commercial finite element applications. The computationally predicted part life was calibrated and verified against test data for deformation and crack growth.

Three-Dimensional Thermo-Mechanical Finite Element Simulation for Casting Ladle Structure under Thermal Loadings

2008 ◽  
Vol 575-578 ◽  
pp. 1-6
Author(s):  
Shou Ju Li ◽  
Ying Xi Liu ◽  
He Yu
Keyword(s):  
Finite Element ◽  
Shell Structure ◽  
Yield Criterion ◽  
Three Dimensional ◽  
Element Model ◽  
Steel Shell ◽  
Casting Ladle ◽  
Lining Structure ◽  
Calculation Results ◽  
Von Mises

The finite element model of coupling the thermal field with structural analysis is proposed in order to analyze the thermo-stress of casting ladle structure. The thermal fields of casting ladle with refractory lining structure are computed according to the thermal properties of materials and boundary conditions. Numerical simulation shows that that computed outer temperatures of casting ladle agree with measured ones. The thermo-stress of casting ladle structure is simulated by taking thermal loadings as the loading conditions of the steel shell structure. Material behaviors were described by the Drucker–Prager plasticity model and Von Mises yield criterion. Calculation results of thermo-stress fields shows the outer shell structure is safety under the action of thermal loadings.

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