scholarly journals Surface Settlement Damage Model of Pile-Anchor Supporting Structure in Deep Excavation

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yuanxun Li ◽  
Wuyu Zhang ◽  
Ningshan Jiang ◽  
Hui Li
Keyword(s):  
Damage Mechanics ◽  
Damage Model ◽  
Surface Settlement ◽  
Skewed Distribution ◽  
Constitutive Relationship ◽  
Deep Excavation ◽  
Damage Development ◽  
Element Analysis ◽  
Undisturbed Soil ◽  
Damage Evolution Equation

In damage mechanics, the deep excavation of soil is a process of damage development, and soil failure can be considered a process of continuously transforming undisturbed soil to damaged soil. Therefore, this study considered the occurrence of soil damage during the pit excavation, established a soil damage model, damage evolution equation, and soil damage constitutive relationship, and then deduced a calculate model of the pile displacement under the consideration of soil damage. Based on the principle of the stratum loss method, the surface settlement around a deep excavated pit was assumed as a skewed distribution curve, and the surface settlement of the pile-anchor supporting pit was solved. Based on this established method, finite element analysis software was used to calculate the surface subsidence for a field case, and the numerical results were compared with monitoring data in the field. The results revealed that, to a certain extent, soil damage affected the distribution of surface settlement in excavated pits. With the development of soil damage, the mechanical properties of soil gradually decreased, which led to increased surface settlement and changes in the direction of the excavation pit. Because soil damage is an important factor causing surface settlement, it is meaningful to consider soil damage when calculating the surface settlement in the deep excavation of pits.

Cross-Ply Laminates under Static Three-Point Bending: A Numerical Development Model

2012 ◽  
Vol 498 ◽  
pp. 42-54 ◽  
Author(s):  
S. Benbelaid ◽  
B. Bezzazi ◽  
A. Bezazi
Keyword(s):  
Numerical Model ◽  
Damage Mechanics ◽  
Progressive Failure ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Failure Criteria ◽  
Continuum Damage ◽  
Damage Development ◽  
Element Analysis ◽  
Progressive Failure Analysis

This paper considers damage development mechanisms in cross-ply laminates using an accurate numerical model. Under static three points bending, two modes of damage progression in cross-ply laminates are predominated: transverse cracking and delamination. However, this second mode of damage is not accounted in our numerical model. After a general review of experimental approaches of observed behavior of laminates, the focus is laid on predicting laminate behavior based on continuum damage mechanics. In this study, a continuum damage model based on ply failure criteria is presented, which is initially proposed by Ladevèze. To reveal the effect of different stacking sequence of the laminate; such as thickness and the interior or exterior disposition of the 0° and 90° oriented layers in the laminate, an equivalent damage accumulation which cover all ply failure mechanisms has been predicted. However, the solution algorithm using finite element analysis which implements progressive failure analysis is summarized. The results of the numerical computation have been justified by the previous published experimental observations of the authors.

Modelling Damage of Composite Laminates with Different Stacking Sequences

2013 ◽  
Vol 698 ◽  
pp. 1-10
Author(s):  
S. Benbelaid ◽  
B. Bezzazi ◽  
A. Bezazi
Keyword(s):  
Composite Laminates ◽  
Damage Mechanics ◽  
Progressive Failure ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Failure Criteria ◽  
Continuum Damage ◽  
Damage Development ◽  
Numerical Application ◽  
Element Analysis

This paper considers damage development mechanisms in composite laminates subjected to tensile loading. The continuum damage mechanics is the most widely used approach to capture the non linear behaviour of laminates due to cracking. In this study, a continuum damage model based on ply failure criteria, which is initially proposed by Ladevèze has been extended to cover all plies failures mechanisms using an accurate numerical model to predict the equivalent damage accumulation. However, this model requires a reliable representation of the elementary damage mechanisms which can be produced in the composite laminate. To validate this model, a numerical application has been carried on the cross-ply laminates of type [0n/90m]s..A shear lag model was adapted to calculate the average stress of the 0° and 90° plies. The solution presented is obtained by using finite element analysis which implements progressive failure analysis. The effect of the stacking sequences has been done by varying the thickness of the 90° plies.

Nonlinear Analysis of RC Structures Using Isotropic Damage Model

2011 ◽  
Vol 21 (5) ◽  
pp. 647-669 ◽  
Author(s):  
Smitha Gopinath ◽  
J. Rajasankar ◽  
N. R. Iyer
Keyword(s):  
Damage Mechanics ◽  
Local Level ◽  
Damage Model ◽  
Coupled Model ◽  
Crack Model ◽  
Element Analysis ◽  
Directional Bias ◽  
Rc Structures ◽  
Isotropic Damage ◽  
As Stress

This article proposes a simple isotropic damage model within damage mechanics framework to represent the behavior of concrete in tension. Macroscopic evolution of tensile crack is considered as damage and is mathematically defined using an exponential function of tensile strain. A damage evolution law is formulated by applying strain equivalence principle to hyperbolic tension-softening curve. Value of damage variable is assumed theoretically to vary between ‘0’ and ‘1’ to denote uncracked and ruptured states, respectively. A smeared rotating crack model is coupled with damage formulation to simulate crack propagation effects in nonlinear finite element analysis of reinforced concrete (RC) structures. Many deficiencies of smeared crack model such as stress locking, mesh-induced directional bias, and instability in response computation for near-ultimate load are overcome using the coupled model. To verify the proposed model, nonlinear static response behavior of a RC beam is computed and compared with experimental and analytical results reported in literature. Effectiveness and applicability of the model to analyze practical structures are proved by analyzing a RC chimney. Nonlinear response of RC chimney is reviewed at global level while damage states of finite elements are studied at local level.

Influence of Aggregate Stiffness on Fracture-Mechanical Properties of Lime-Based Mortars

2013 ◽  
Vol 486 ◽  
pp. 289-294 ◽  
Author(s):  
Pavel Tesárek ◽  
Václav Nežerka ◽  
Pavel Padevět ◽  
Jakub Antoš ◽  
Tomáš Plachy
Keyword(s):  
Experimental Investigation ◽  
Finite Element ◽  
Damage Model ◽  
Element Model ◽  
Stress Concentrations ◽  
Damage Development ◽  
Element Analysis ◽  
Three Point Bending ◽  
Isotropic Damage ◽  
The Finite Element Model

Addition of relatively stiff aggregates into lime-based mortars is responsible for an increase of the effective mortar stiffness and stress concentrations around aggregates during mechanical loading. To observe the damage development during the three-point bending and splitting tests a 2D plane-stress nonlinear finite element analysis utilizing isotropic damage model was carried out and the results were validated against experimentally obtained data. The study revealed that the finite element model is able to capture the trends observed during the experimental investigation. The results of the numerical modeling and experimental investigation show the advantages of the use of relatively compliant crushed brick aggregates in ancient structures.

Damage Mechanics of Two-Dimensional Woven SiC/SiC Composites

1994 ◽  
Vol 116 (3) ◽  
pp. 403-407 ◽  
Author(s):  
Hui-Zu Shan ◽  
Philippe Pluvinage ◽  
Azar Parvizi-Majidi ◽  
Tsu-Wei Chou
Keyword(s):  
Experimental Data ◽  
Damage Mechanics ◽  
Damage Model ◽  
Ceramic Matrix Composites ◽  
Elastic Behavior ◽  
Two Dimensional ◽  
Compression Tests ◽  
Damage Development ◽  
Tension And Compression ◽  
Sic Composites

The paper reports an analysis and modeling of the damage behavior of two-dimensional woven SiC/SiC composites. The damage mechanics analysis originally developed by Ladeveze and coworkers for polymeric and C/C composites are adopted and extended for ceramic matrix composites. The experimental findings of the coauthors reported in a companion paper provides the data for analytical modeling. The damage model assumes quasi-isotropic elastic behavior of the undamaged SiC/ SiC composites as well as orthotropic damage development (e.g., matrix microcracking, interfacial debonding, and fiber fracture). The model utilize two damage variables which are determined from experimental data; and the constitutive relation takes into account the difference in damage development between tension and compression in the principal material directions. The validity of the theory is demonstrated by the prediction of damage evolution of a SiC/SiC specimen under four-point bend test based upon the experimental data of tension and compression tests. A finite element method coupled with damage is adopted for the flexural analysis. The predictions agree quite well with experimental results.

scholarly journals A Modified Fatigue Damage Model for High-Cycle Fatigue Life Prediction

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Meng Wang ◽  
Qingguo Fei ◽  
Peiwei Zhang
Keyword(s):  
Damage Mechanics ◽  
High Cycle Fatigue ◽  
Failure Process ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Cycle Fatigue ◽  
Damage State ◽  
Damage Evolution Equation ◽  
Metal Material ◽  
Python Language

Based on the assumption of quasibrittle failure under high-cycle fatigue for the metal material, the damage constitutive equation and the modified damage evolution equation are obtained with continuum damage mechanics. Then, finite element method (FEM) is used to describe the failure process of metal material. The increment of specimen’s life and damage state can be researched using damage mechanics-FEM. Finally, the lifetime of the specimen is got at the given stress level. The damage mechanics-FEM is inserted into ABAQUS with subroutine USDFLD and the Python language is used to simulate the fatigue process of titanium alloy specimens. The simulation results have a good agreement with the testing results under constant amplitude loading, which proves the accuracy of the method.

scholarly journals A continuum damage mechanics model for fatigue and degradation of fiber reinforced materials

2020 ◽  
Vol 54 (21) ◽  
pp. 2837-2852
Author(s):  
Jörg Hohe ◽  
Monika Gall ◽  
Sascha Fliegener ◽  
Zalikha Murni Abdul Hamid
Keyword(s):  
Damage Mechanics ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Material Model ◽  
Continuum Damage ◽  
Fiber Reinforced ◽  
Finite Element Program ◽  
Damage Evolution Equation ◽  
Fiber Reinforced Materials ◽  
Reinforced Materials

Objective of the present study is the definition of a continuum damage mechanics material model describing the degradation of fiber reinforced materials under fatigue loads up to final failure. Based on the linear elastic framework, a brittle damage model for fatigue conditions is derived, where the damage constitutes the only nonlinearity. The model accounts for damage effects by successive degradation of the elastic moduli. Assuming that material damage is driven by microplastic work, a stress-driven damage evolution equation is defined. For generality, a fully three-dimensional formulation on single ply level is employed. The model is implemented into a finite element program. In a validation against experimental data on filament-wound carbon fiber reinforced material, the model proves to provide a good numerical approximation of the damage during the cyclic loading history up to final material failure.

Physically based damage models for laminated composites

2003 ◽  
Vol 217 (3) ◽  
pp. 163-199 ◽  
Author(s):  
L N McCartney
Keyword(s):  
Composite Laminates ◽  
Damage Mechanics ◽  
Laminated Composites ◽  
Damage Model ◽  
Shear Loading ◽  
Analytical Models ◽  
Element Analysis ◽  
Plane Shear ◽  
Triaxial Loading ◽  
Physically Based

The computing power that is available for engineering calculation continues to grow at a dramatic pace. Engineers in industry want to have seamless models that can be used to design across the scale range from atoms to structures, including simulation of the manufacturing process. A limited aspect of this wish is the requirement to deal effectively with the progressive growth of microstructural damage in composites and its effect on both property degradation and the catastrophic failure event. This paper reviews progress that is being made at the National Physical Laboratory (NPL) with the development and validation of physically based damage growth models for laminated composites. The review includes: (a) prediction of undamaged ply properties determined from the properties of the fibre and the matrix, with emphasis on comparison of analytical models with each other, and with finite and boundary element solutions; (b) discussion of various stress transfer models, and their validation, that have been developed for application to the prediction of the properties of composite laminates having ply crack damage; (c) prediction of ply cracking in multiple-ply cross-ply laminates subject to triaxial loading (without shear) and bending; (d) prediction of ply cracking in general symmetric laminates subject to combined triaxial loading and in-plane shear loading; (e) consideration in a damage mechanics context of progressive ply crack formation in general symmetric laminates subject to thermal residual stresses and general in-plane loading, where an important new methodology is described that results from attempting to develop a continuum damage model from a physically based discrete ply cracking model based on energy concepts; (f) discussion of how the models might be integrated into finite element analysis (FEA) systems to enable strain softening in structures to be adequately modelled. The paper also includes statements concerning the status of the various models in relation to alternative approaches, and to model validation.

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