Nonlinear damage behaviour of concrete structures

2005 ◽  
Vol 32 (4) ◽  
pp. 765-774 ◽  
Author(s):  
Youcef Labadi ◽  
Naceur Eddine Hannachi
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Damage Model ◽  
Concrete Structures ◽  
Equivalent Strain ◽  
Experimental Results ◽  
Nonlinear Behaviour ◽  
Element Simulation ◽  
Isotropic Damage ◽  
Damage Law

Concrete structures are becoming more and more sophisticated and submitted to severe conditions, for example: high stresses and temperatures, cyclic loadings, earthquakes, etc. It is therefore necessary to simulate correctly the behaviour and damage of such structures. However, the behaviour of this material is among the most complex ones: various phenomena are observed experimentally, such as, loss of stiffness, irreversible strains, stiffness recovery and dissymmetric behaviour to mention a few. If all these effects are taken into consideration, it would lead to models that use numerous parameters. In this paper, a framework for damage mechanics of concrete is presented and used to simulate the nonlinear behaviour of concrete using finite element method (FEM). A relatively simple isotropic damage model, containing essentially no adjustable parameters is shown to produce results in remarkably good agreement with experimental results. Indeed, the damage law requires only the fracture energy to be completely defined. A special form of damage surfaces is constructed to illustrate the application of the model. A new damage criterion, defined as an equivalent strain norm, is proposed to take into consideration the dissymmetric behaviour of concrete. To verify the FEM program including the model, the predicted deformations are compared with experimental results and results from other nonlinear constitutive models.Key words: elasticity, quasi-brittle materials, damage, cracking, nonlinear behaviour, concrete modelling, finite element, simulation.

Finite Element Simulation of the Creep Behavior of 2.25Cr-1Mo-0.25V Steel Based on Continuum Damage Mechanics

2015 ◽  
Vol 750 ◽  
pp. 266-271 ◽  
Author(s):  
Yu Zhou ◽  
Xue Dong Chen ◽  
Zhi Chao Fan ◽  
Yi Chun Han
Keyword(s):  
Genetic Algorithm ◽  
Finite Element ◽  
Creep Behavior ◽  
Constitutive Equations ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Creep Damage ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Element Simulation

The creep behavior of 2.25Cr-1Mo-0.25V ferritic steel was investigated using a set of physically-based creep damage constitutive equations. The material constants were determined according to the creep experimental data, using an efficient genetic algorithm. The user-defined subroutine for creep damage evolution was developed based on the commercial finite element software ANSYS and its user programmable features (UPFs), and the numerical simulation of the stress distribution and the damage evolution of the semi V-type notched specimen during creep were studied. The results showed that the genetic algorithm is a very efficient optimization approach for the parameter identification of the creep damage constitutive equations, and finite element simulation based on continuum damage mechanics can be used to analyze and predict the creep damage evolution under multi-axial stress states.

Numerische Abbildung von Beton mit einem plastischen Schädigungsmodell – Grundlegende Untersuchungen zu Normalbeton und UHPC/Finite element simulation of concrete with a plastic damage model – Basic studies on normal strength concrete and UHPC

Bauingenieur ◽  
2015 ◽  
Vol 90 (06) ◽  
pp. 252-264 ◽  
Author(s):  
Dominik Kueres ◽  
Alexander Stark ◽  
Martin Herbrand ◽  
Martin Classen
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Damage Model ◽  
Normal Strength Concrete ◽  
Numerische Simulation ◽  
Plastic Damage ◽  
Element Simulation ◽  
Finite Elemente ◽  
Normal Strength ◽  
Basic Studies

Die numerische Simulation des Tragverhaltens von Beton- und Stahlbetonkonstruktionen mit nicht-linearen Finite-Elemente-Modellen gewinnt in der konstruktiven Ingenieurpraxis zunehmend an Bedeutung. In kommerziellen Finite-Elemente-Programmen stehen dem Anwender unterschiedliche Möglichkeiten zur Abbildung des Betonverhaltens in Form von plastischen Materialmodellen zur Verfügung. Zur Anwendung dieser Materialmodelle ist dabei in der Regel die Kenntnis des Betontragverhaltens unter einaxialer Druck- und Zugbeanspruchung erforderlich. Im vorliegenden Beitrag werden verschiedene Ansätze zur mathematischen Beschreibung dieser konstitutiven Beziehungen für Normalbeton und ultrahochfesten Beton (UHPC) vorgestellt und im Hinblick auf ihre Anwendbarkeit in plastischen Materialmodellen untersucht. Darauf aufbauend werden numerische Simulationen mit einem plastischen Schädigungsmodell unter Verwendung eines einheitlichen Parametersatzes durchgeführt und mit den Ergebnissen experimenteller Untersuchungen verglichen. Die Untersuchungen umfassen hierbei Materialprüfungen an Normalbeton und UHPC unter verschiedenen ein- und mehraxialen Spannungszuständen. Durch die Wahl geeigneter konstitutiver Beziehungen kann für die untersuchten Spannungszustände eine gute Übereinstimmung zwischen simuliertem und experimentell ermitteltem Betontragverhalten erreicht werden.

scholarly journals Determination of Forming Limits Based on Finite Element Simulations

2021 ◽  
Author(s):  
Fuhui Shen ◽  
Kai Chen ◽  
Junhe Lian ◽  
Sebastian Münstermann
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Tensile Tests ◽  
Finite Element Simulations ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Anisotropic Plasticity ◽  
Forming Limits ◽  
Dog Bone ◽  
Spatio Temporal

Two categories of experiments have been performed to obtain the experimental forming limits of a ferritic stainless steel from uniaxial to equibiaxial tension, including Nakajima tests and tensile tests of flat specimens with different geometries of the central hole as well as the notched dog bone. The plasticity behavior of the investigated material is described using an evolving non-associated anisotropic plasticity model, which is calibrated based on experimental results of uniaxial tensile tests along different loading directions. A damage mechanics model is calibrated and validated based on the global force and displacement response of tensile tests. Finite element simulations of the Nakajima tests and the tensile tests of various geometries have been performed using the anisotropic material model. A novel spatio-temporal method is developed to evaluate the forming limits under different stress states by quantitatively characterizing the plastic strain distribution on the specimen surface. The forming limits have been independently determined from finite element simulation results of tensile specimens and Nakajima specimens using the spatio-temporal evaluation method. The forming limits obtained from numerical simulations of these two types of experiments are in good agreement with experimental results.

Experimental and Numerical Analyses of a Head Arm Assembly of a Micro-Drive

2006 ◽  
Vol 326-328 ◽  
pp. 1585-1588
Author(s):  
B.J. Shi ◽  
Dong Wei Shu ◽  
J. Luo ◽  
Q.Y. Ng ◽  
J.H.T. Lau
Keyword(s):  
Finite Element ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Hard Disk Drives ◽  
Element Model ◽  
Information Storage ◽  
Experimental Results ◽  
Disk Drives ◽  
Element Simulation ◽  
Important Means

Hard disk drives (HDD) are now the most important means of information storage, and they continue to be made smaller in size, higher in capacity, and lower in cost. The dynamic performance of an HDD has been an increasingly important consideration for its design, as we move forward toward its consumer applications. The dynamic properties of the head arm assembly (HAA) of a micro-drive were investigated using both experimental and numerical techniques. A finite element model for studying the dynamic property of the HAA was created and modified according to the experimental results. Good correlation between the experimental results and those by finite element simulation was achieved.

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.

Numerical simulation of ductile fracture in polyethylene pipe with continuum damage mechanics and Gurson-Tvergaard-Needleman damage models

2019 ◽  
Vol 233 (12) ◽  
pp. 2455-2468
Author(s):  
Yi Zhang ◽  
P-Y Ben Jar ◽  
Shifeng Xue ◽  
Lin Li
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Constitutive Equations ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Experimental Testing ◽  
Monotonic Loading ◽  
Test Method ◽  
Strain Level ◽  
Element Simulation

A phenomenon-based hybrid approach of experimental testing and finite element simulations is used to describe the fracture behavior of pipe-grade polyethylene. The experimental testing adopts a modified D-split test method to stretch the pipe ring (notched pipe ring) specimens that have symmetric, double-edged flat notches along the pipe direction. Two series of experimental testing were conducted: (1) monotonic loading till fracture and (2) monotonic loading to a predefined strain level, keeping constant displacement for a period of time, and then unloaded. Crosshead speeds of 0.01, 1, and 100 mm/min were used in both series of tests. Likewise, two series of finite element simulation were conducted to establish the constitutive equations, either with or without considering damage evolution during the deformation process. The constitutive equation without the consideration of damage was established using results from the first series of experimental testing, and that with damage was inspired from the second series which showed the decrease in unloading modulus with the increase of crosshead speed or the predefined strain level. The results show that with the consideration of damage evolution, the constitutive equations enable the finite element simulation to determine the whole stress–strain relationship during both necking and fracture processes.

Eddy Current Testing Probe to Improve the Defect Detection Sensitivity of Metal Tube

2014 ◽  
Vol 945-949 ◽  
pp. 1987-1990
Author(s):  
Si Quan Zhang ◽  
Yu Liu ◽  
Hao Jun Xu ◽  
Chang Yin
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Defect Detection ◽  
Eddy Current ◽  
Experimental Results ◽  
Detection Sensitivity ◽  
Metal Tube ◽  
Current Testing ◽  
Element Simulation ◽  
Axial Defects

The structure of conventional bobbin probe was modified to improve the detection sensitivity of defects in metal tube. Based on the results of finite element simulation, several types of modified probes are fabricated and used to detect artificial defects in tube and the defect signals are acquired and analyzed. The simulation and experimental results verified that the modified eddy current probes are more sensitive to non-axial defects than conventional bobbin probe and can improve the reliability of tube inspection.

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