Study of Influence of Residual Stresses on Crack Propagation in Particulate Ceramic Composites

2016 ◽  
Vol 258 ◽  
pp. 178-181 ◽  
Author(s):  
Zdeněk Majer ◽  
Luboš Náhlík ◽  
Kateřina Štegnerová ◽  
Pavel Hutař ◽  
Raúl Bermejo
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Element Model ◽  
Ceramic Composites ◽  
Particulate Composites ◽  
Micro Cracks ◽  
Dimensional Finite Element ◽  
Density Factor ◽  
Energy Density Factor

The aim of the present work is to analyze the influence of residual stresses in the particulate ceramic composite on the crack propagation. The crack propagation direction was estimated using Sih’s criterion based on the strain energy density factor. A two-dimensional finite element model was developed for determination of crack path. The residual stresses resulting from the mismatch of coefficients of thermal expansion during the fabrication process of the composite were implemented to the computational model. The effect of the particles shape on the crack propagation was investigated. Conclusions of this paper can contribute to a better understanding of the propagation of micro-cracks in particulate composites in the field of residual stresses.

Estimation of the Crack Behaviour in the Compressive Layer of the Alumina-Zirconia Ceramic Laminate

2014 ◽  
Vol 627 ◽  
pp. 41-44
Author(s):  
Luboš Náhlík ◽  
Bohuslav Máša ◽  
Pavel Hutař
Keyword(s):  
Crack Propagation ◽  
Direct Method ◽  
Zirconia Ceramic ◽  
Finite Element Models ◽  
Linear Elastic ◽  
Dimensional Finite Element ◽  
Density Factor ◽  
Elastic Fracture ◽  
Energy Density Factor ◽  
Good Agreement

This paper deals with a description of the crack behaviour in the layered alumina-zirconia ceramic laminate. The main aim is to investigate the crack behaviour in the compressive layer. The crack propagation was investigated on the basis of linear elastic fracture mechanics. Two dimensional finite element models were developed in order to obtain a stress distribution around the crack tip. The stress intensity factors were computed numerically employing the direct method. The change in the crack propagation direction was estimated using criterion based on the strain energy density factor. Sharp crack deflection in the compressive layer was predicted by mentioned approach. The determined crack behaviour is qualitatively in a good agreement with experimental observations.

The Role of Residual Stresses in Particulate Composite with Glass Matrix

2015 ◽  
Vol 665 ◽  
pp. 173-176 ◽  
Author(s):  
Zdeněk Majer ◽  
Luboš Náhlík ◽  
Pavel Hutař
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Crack Propagation ◽  
Glass Matrix ◽  
Particulate Composite ◽  
Element Model ◽  
Propagation Path ◽  
Particulate Composites ◽  
Stress Criterion ◽  
Finite Element Software

The particulate composites with glass matrix are widely used in many engineering applications. The mismatch of coefficients of thermal expansion during the fabrication process usually causes the presence of the residual stresses around particles. The influence and the understanding of the effects of residual stresses on the material response is required. The main aim of the present paper was to create a two-dimensional finite element model to analyze the influence of residual stresses on micro-crack behavior of glass and ceramics-based particulate composites. The maximum tangential stress criterion (MTS) was used to predict the direction of the micro-crack propagation. The modelled material was a kind of Low Temperature Co-fired Ceramics (LTCC) containing alumina particles embedded in a glass matrix. The influence of the micro-crack length and magnitude of loading on the micro-crack propagation path were investigated. The finite element software ANSYS was used. Conclusions of this paper can contribute to a better understanding of the propagation of micro-cracks in particulate composites in the field of residual stresses.

Description of Strengthening Mechanism in Layered Ceramic Composites

2015 ◽  
Vol 665 ◽  
pp. 93-96 ◽  
Author(s):  
Kateřina Štegnerová ◽  
Luboš Náhlík ◽  
Pavel Hutař
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Ceramic Composite ◽  
Strengthening Mechanism ◽  
Ceramic Composites ◽  
Zirconia Ceramic ◽  
Linear Elastic ◽  
Density Factor ◽  
Elastic Fracture ◽  
Layered Ceramic

The aim of this paper is to describe specific crack behaviour in the layered alumina-zirconia ceramic composite with strong interfaces and its strengthening mechanism. Different coefficients of thermal expansion of individual constituents of ceramic composite cause high residual stresses inside the layers during the sintering process. Compressive residual stresses can significantly influence the crack propagation through the laminate hereby improve the resistance of the material to the crack propagation. Estimation of crack behaviour in laminate was performed assuming the validity of linear elastic fracture mechanics using the criterion based on the strain energy density factor derived by Sih. This paper describes the strengthening mechanism in layered ceramic composites and prediction of their failure which contributes to better understanding of the fracture behaviour of the layered ceramic composites.

Residual Lifetime Determination of Low Temperature Co-Fired Ceramics

2016 ◽  
Vol 713 ◽  
pp. 266-269
Author(s):  
Zdeněk Majer ◽  
Kateřina Štegnerová ◽  
Pavel Hutař ◽  
Martin Pletz ◽  
Raul Bermejo ◽  
...  
Keyword(s):  
Low Temperature ◽  
Residual Stresses ◽  
Crack Propagation ◽  
Crack Growth ◽  
Subcritical Crack Growth ◽  
Particulate Composite ◽  
Ceramic Materials ◽  
Ceramic Composites ◽  
Residual Lifetime ◽  
Density Factor

The effect of subcritical crack growth is nowadays intensively studied mainly in relation to the strength of ceramic materials. The main aim of the contribution is to describe behavior of micro-crack propagating in the Low Temperature Co-fired Ceramics (LTCC) under subcritical crack growth (SCCG) conditions. The micro-crack behavior is significantly influenced by residual stresses developed in the LTCC due to different coefficients of thermal expansion of individual components. Two-dimensional numerical model was developed to simulate micro-crack propagation through the composite. The micro-crack propagation direction was determined using Sih’s criterion based on the strain energy density factor and the micro-crack path was obtained. The residual lifetime of the specific ceramic particulate composite (LTCC) was estimated on the basis of experimental data. The paper contributes to a better understanding of micro-crack propagation in particulate ceramic composites in the field of residual stresses.

Influence of the Interface and Residual Stresses on the Apparent Fracture Toughness of Layered Ceramic Composites Based on Alumina-Zirconia

2014 ◽  
Vol 606 ◽  
pp. 209-212
Author(s):  
Luboš Náhlík ◽  
Bohuslav Máša ◽  
Pavel Hutař
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Ceramic Composites ◽  
Layered Composites ◽  
Material Interfaces ◽  
Linear Elastic ◽  
Apparent Fracture Toughness ◽  
Elastic Fracture ◽  
Layered Ceramic ◽  
Good Agreement

This paper deals with the fracture behaviour of layered ceramic composite with residual stresses. The main goal is to investigate the effect of residual stresses and material interfaces on crack propagation by more complex 3D finite element models. The crack behaviour was described by analytical procedures based on linear elastic fracture mechanics (LEFM) and generalized LEFM. The influence of laminate composition with residual stresses on critical values for crack propagation through the laminate interfaces was also determined. Good agreement has been found to exist between numerical results and experimental data. The results obtained can be used for a design of new layered composites with improved resistance against crack propagation.

Cyclic and Residual Stresses Generated in the UHMWPE Component of Total Knee Replacements During the Walking Cycle

1999 ◽  
Author(s):  
Raghu N. Natarajan
Keyword(s):  
Residual Stresses ◽  
Failure Modes ◽  
Contact Region ◽  
Three Dimensional ◽  
Knee Kinematics ◽  
Element Model ◽  
Clear Understanding ◽  
Dimensional Finite Element ◽  
Total Knee ◽  
Three Dimensional Finite Element

Abstract Fatigue due to cyclic stresses is one of the predominant failure modes seen in retrieved tibial polyethylene components. There is no clear understanding of the influence of knee kinematics on wear seen in retrieved samples. Magnitude, direction and location of the contact load at the tibial surface were taken from the measurement obtained from gait analysis of a patient with a total knee replacement and was input into a three dimensional finite element model of a tibial component. The analyses showed that stress fluctuations and stress reversals occur both on the surface and just below the surface in the posterior region of the component. Residual stresses were produced due to plastic deformation in the posterior contact region of the component.

Investigation of Residual Stress Development During Swage Autofrettage, Using Finite Element Analysis

2009 ◽  
Author(s):  
Michael C. Gibson ◽  
Amer Hameed ◽  
John G. Hetherington
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Axial Stress ◽  
Slope Angle ◽  
Subsequent Development ◽  
Element Model ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Reverse Yielding

Swaging is one method of autofrettage, a means of pre-stressing high-pressure vessels to increase their fatigue lives and load bearing capacity. Swaging achieves the required deformation through physical interference between an oversized mandrel and the bore diameter of the tube, as it is pushed through the tube. A Finite Element model of the swaging process was developed, in ANSYS, and systematically refined, to investigate the mechanism of deformation and subsequent development of residual stresses. A parametric study was undertaken, of various properties such as mandrel slope angle, parallel section length and friction coefficient. It is observed that the axial stress plays a crucial role in the determination of the residual hoop stress and reverse yielding. The model, and results obtained from it, provides a means of understanding the swaging process and how it responds to different parameters. This understanding, coupled with future improvements to the model, potentially allows the swaging process to be refined, in terms of residual stresses development and mandrel driving force.

Lifetime Assessment of Particulate Ceramic Composite with Residual Stresses

2017 ◽  
Vol 754 ◽  
pp. 107-110
Author(s):  
Luboš Náhlík ◽  
Zdeněk Majer ◽  
Kateřina Štegnerová ◽  
Pavel Hutař
Keyword(s):  
Residual Stresses ◽  
Crack Propagation ◽  
Mechanical Loading ◽  
Ceramic Composite ◽  
Subcritical Crack Growth ◽  
Particulate Composites ◽  
Time To Failure ◽  
Complex Load ◽  
Composite Surface

A micro-crack propagation in particulate ceramic based composite was studied using finite element method (FEM). Subcritical crack growth (SCG) was numerically simulated under complex load conditions (mechanical loading and loading by internal residual stresses). The effect of residual stresses on the crack propagation was studied. Two-dimensional computational model of particulate ceramic composite with material properties corresponding to low temperature co-fired ceramics (LTCC) was developed. The results indicate that the presence of residual stresses significantly reduces values of stress intensity factor in the vicinity of composite surface and the direction of residual stresses around the particles contributes to the micro-crack deflection from the particles. The time to failure of the composite under mechanical loading was determined. Results obtained contribute to a better understanding of the role of residual stresses during micro-crack propagation in ceramic particulate composites.

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