scholarly journals Nonlinear Finite Element Modelling for Reinforced Concrete Beams Retrofitted with FRP in Bending

2019 ◽  
pp. 1-20
Author(s):  
Ihab Samir Abdou Ibrahim Mattar
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Material Properties ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Material Models ◽  
Bond Model ◽  
Modelling Procedure ◽  
Sheet Width

For the purpose of simulating the behaviour of reinforced concrete (R.C)[1] beams retrofitted with fibre-reinforced polymers/plastics (FRP)[2] in bending, a finite element (FE)[3] modelling procedure has been developed throughout this paper. The FE software package ABAQUS CAE 6.11-3 was used. The data required for such modelling process are boundary conditions, geometric and material properties. Non-available material properties are obtained through experimentally verified numerical material models. FRP isotropic and orthotropic material models are compared; both models nearly yielded similar results. Also, perfect bond model and cohesive zone model for the interface between concrete and FRP have been compared. Unlike the perfect bond model, the cohesive zone model captured the debonding. The modelling procedure was validated through its application to R.C beams retrofitted with FRP in bending. The FE model results were compared to experimental results where both results were highly correlated. Such results include load-deflection curves and cracking pattern. The effect of sheet width and number of FRP layers is emphasized through performing a parametric study. Increasing sheet width is only effective at longer sheet lengths regarding increasing both; stiffness and load carrying capacity. Upon increasing the number of FRP layers, only shifting of the yielding point of reinforcement was noticed.

Examination of the Transferability of CTOA From Small-Scale DWTT to Full-Scale Pipe Geometries Using a Cohesive Zone Model

2020 ◽  
Author(s):  
Chris Bassindale ◽  
Xin Wang ◽  
William R. Tyson ◽  
Su Xu
Keyword(s):  
Finite Element ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Element Model ◽  
Full Scale ◽  
Opening Angle ◽  
Small Scale ◽  
Zone Model ◽  
Pipe Model ◽  
Good Agreement

Abstract In this work, the cohesive zone model (CZM) was used to examine the transferability of the crack tip opening angle (CTOA) from small-scale to full-scale geometries. The pipe steel STPG370 was modeled. A drop-weight tear test (DWTT) model and pipe model were studied using the finite element code ABAQUS 2017x. The cohesive zone model was used to simulate crack propagation in 3D. The CZM parameters were calibrated based on matching the surface CTOA measured from a DWTT finite element model to the surface CTOA measured from the experimental DWTT specimen. The mid-thickness CTOA of the DWTT model was in good agreement with the experimental value determined from E3039 and the University of Tokyo group’s load-displacement data. The CZM parameters were then applied to the pipe model. The internal pressure distribution and decay during the pipe fracture process was modeled using the experimental data and implemented through a user-subroutine (VDLOAD). The mid-thickness CTOA from the DWTT model was similar to the mid-thickness CTOA from the pipe model. The average surface CTOA of the pipe model was in good agreement with the average experimental value. The results give confidence in the transferability of the CTOA between small-scale specimens and full-scale pipe.

Finite Element Simulation of Delamination in Carbon Fiber/Epoxy Laminate Using Cohesive Zone Model: Effect of Meshing Variation

2019 ◽  
Vol 964 ◽  
pp. 257-262
Author(s):  
Victor D. Waas ◽  
Mas Irfan P. Hidayat ◽  
Lukman Noerochim
Keyword(s):  
Finite Element ◽  
Carbon Fiber ◽  
Cohesive Zone ◽  
Composite Laminate ◽  
Cohesive Zone Model ◽  
Critical Force ◽  
Zone Model ◽  
Interface Elements ◽  
Dcb Specimen ◽  
Carbon Fiber Epoxy

Delamination or interlaminar fracture often occurs in composite laminate due to several factors such as high interlaminar stress, stress concentration, impact stress as well as imperfections in manufacturing processes. In this study, finite element (FE) simulation of mode I delamination in double cantilever beam (DCB) specimen of carbon fiber/epoxy laminate HTA/6376C is investigated using cohesive zone model (CZM). 3D geometry of DCB specimen is developed in ANSYS Mechanical software and 8-node interface elements with bi-linear formulation are employed to connect the upper and lower parts of DCB. Effect of variation of number of elements on the laminate critical force is particularly examined. The mesh variation includes coarse, fine, and finest mesh. Simulation results show that the finest mesh needs to be employed to produce an accurate assessment of laminate critical force, which is compared with the one obtained from exact solution. This study hence addresses suitable number of elements as a reference to be used for 3D simulation of delamination progress in the composite laminate, which is less explored in existing studies of delamination of composites so far.

Crack Growth Modelling in the Silicon Nitride Ceramics by Application of the Cohesive Zone Approach

2013 ◽  
Vol 592-593 ◽  
pp. 193-196
Author(s):  
Vladislav Kozák ◽  
Zdeněk Chlup
Keyword(s):  
Finite Element ◽  
Silicon Nitride ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Interface Elements ◽  
Practical Applications ◽  
Damage Models ◽  
Cohesive Models ◽  
Finite Element Package

Specific silicon nitride based materials are considered according to certain practical requirements of process, the influence of the grain size and orientation on the bridging mechanisms was found. Crack-bridging mechanisms can provide substantial increases in toughness coupled with the strength in ceramics. The prediction of the crack propagation through interface elements based on the fracture mechanics approach and cohesive zone model is investigated and from the amount of damage models the cohesive models seem to be especially attractive for the practical applications. Using cohesive models the behaviour of materials is realized by two types of elements. The former is the element for classical continuum and the latter is the connecting cohesive element. Within the standard finite element package Abaqus a new finite element has been developed; it is written via the UEL (users element) procedure. Its shape can be very easily modified according to the experimental data for the set of ceramics and composites. The new element seems to be very stable from the numerical point a view. The shape of the traction separation law for three experimental materials is estimated from the macroscopic tests, JR curve is predicted and stability of the bridging law is tested.

scholarly journals Finite Element Multibody Simulation of a Breathing Crack in a Rotor with a Cohesive Zone Model

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Rugerri Toni Liong ◽  
Carsten Proppe
Keyword(s):  
Finite Element ◽  
Crack Closure ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Fe Model ◽  
Multibody Simulation ◽  
Closure Model ◽  
Breathing Mechanism ◽  
Cracked Shaft

The breathing mechanism of a transversely cracked shaft and its influence on a rotor system that appears due to shaft weight and inertia forces is studied. The presence of a crack reduces the stiffness of the rotor system and introduces a stiffness variation during the revolution of the shaft. Here, 3D finite element (FE) model and multibody simulation (MBS) are introduced to predict and to analyse the breathing mechanism on a transverse cracked shaft. It is based on a cohesive zone model (CZM) instead of linear-elastic fracture mechanics (LEFM). First, the elastic cracked shaft is modelled by 3D FE. As a second step, the 3D FE model of the shaft is transferred into an MBS model in order to analyze the dynamic loads, due to the crack, and the inertia force acting during rotation at different rotating speeds. Finally, the vibration responses in the centroid of the shaft obtained from MBS have been exported into FE model in order to observe the breathing mechanism. A bilinear crack closure model is proposed. The accuracy of the bilinear crack closure model and the solution techniques have been demonstrated by a comparison with the corresponding results of previous publications.

Multiscale Model to Study the Effect of Interfaces in Carbon Nanotube-Based Composites

2005 ◽  
Vol 127 (2) ◽  
pp. 222-232 ◽  
Author(s):  
S. Namilae ◽  
N. Chandra
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Finite Element ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Interfacial Region ◽  
Model Parameters ◽  
Zone Model ◽  
Pullout Tests ◽  
Nanoscale Interfaces

In order to fully harness the outstanding mechanical properties of carbon nanotubes (CNT) as fiber reinforcements, it is essential to understand the nature of load transfer in the fiber matrix interfacial region of CNT-based composites. With controlled experimentation on nanoscale interfaces far off, molecular dynamics (MD) is evolving as the primary method to model these systems and processes. While MD is capable of simulating atomistic behavior in a deterministic manner, the extremely small length and time scales modeled by MD necessitate multiscale approaches. To study the atomic scale interface effects on composite behavior, we herein develop a hierarchical multiscale methodology linking molecular dynamics and the finite element method through atomically informed cohesive zone model parameters to represent interfaces. Motivated by the successful application of pullout tests in conventional composites, we simulate fiber pullout tests of carbon nanotubes in a given matrix using MD. The results of the pullout simulations are then used to evaluate cohesive zone model parameters. These cohesive zone models (CZM) are then used in a finite element setting to study the macroscopic mechanical response of the composites. Thus, the method suggested explicitly accounts for the behavior of nanoscale interfaces existing between the matrix and CNT. The developed methodology is used to study the effect of interface strength on stiffness of the CNT-based composite.

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