Transactions on Modelling and Simulation vol 10, 1995 WIT Press, ISSN X
|
|
- Heather Evans
- 6 years ago
- Views:
Transcription
1 Parameters controlling the numerical simulation validity of damageable composite toughness testing S. Yotte, C. Currit, E. Lacoste, J.M. Quenisset Laboratoire de Genie Meanique - IUT 'A\ Domaine Universitaire, Talence cedex, France Abstract Assuming that CMC's toughness can be assessed through crack growth resistance curves, a procedure of testing has been proposed. Despite various approximations which are pointed out, the use of the finite element method is shown to be helpful to define the specimen shape and loading conditions. More particularly, an initial procedure based on the CT test is modified to prevent various perturbations related to brinelling effects or compressive damage and to generate steady state crack propagations. 1. introduction Ceramic matrix composites are now well known for their quasi damageable elastic behaviour. This fact renders difficult their toughness characterisation through an intrinsic characteristic. As a matter of fact a damage zone whose size and shape depend on the specimen type and loading conditions develops in front of the macrocrack during toughness tests. As a consequence the stress intensity factor K commonly used for characterising brittle or quasi brittle materials cannot be considered anymore as a representative fracture parameter. An energetical approach seems to be more suitable so that the energy release rate G can be chosen for assessing the ability of the material to dissipate its energy during the propagation of a process zone consisting in mic roc racking and in fibre/matrix sliding and friction. Due to the difficulty of determining intrinsic toughness characteristics, CMC's toughness requires the standardisation of a procedure usable with every type of materials. One objective of the procedure is the development of a state of propagation giving rise to a plateau on the R curve. Providing we propose specimen shapes and conditions of loading which prevent any interaction between the propagating damage zone and the specimen edges, the G values related to R curve plateau could be considered as an acceptable representation of CMC's toughness. The choice of a method among various testing procedures can be guided either by performing experimental tests which is time and material consuming or by simulating the toughness tests with the help of
2 738 Computational Methods and Experimental Measurements numerical approaches. Although the exactitude of such computations of process zone growth is questionable, the approximate results are able to drive a choice of procedure. The aim of the present contribution is to point out the various sources of uncertainties related to the numerical aspects of a procedure determination. First the conditions of obtaining CMC's crack growth resistance curves are investigated prior to the presentation of the parameters controlling the validity of numerical tests. Then, an analysis of the loading conditions in relation with specimen shapes allows the procedure initially based on a CT test (figure 1), to be proposed. Figure 1 : CT test 2. Determination of CMC crack growth resistance curves R curve in term of crack growth release rate G can be obtained in the case of quasi linear elastic CMC's with the following equation [1] : G = (p2/2b)dc/da (1) where P is the applied load, B the specimen width, C the specimen compliance which is the displacement obtained for a unit load, and a the crack length which defines the fracture area in the case of brittle materials. Relation (1) shows that the main difficulty in the calculation of G versus a can be related to the determination of a which is not precisely defined. Crack length definition In the case of CMC materials, crack growth occurs by propagating a damage zone made of numerous microcracks and fibre/matrix debonding rather than an undeniable crack. Various studies have attempted to measure a macrocrack length from microscopic observation but the uncertainties assigned to the crack length values are very significant while the 3C/9a values and as a consequence G are very sensitive to a. Thus a determination of a through a crack growth calibration curve has been preferred, and requires focusing on the methods of calibration. Compliance calibration The calibration of compliances versus crack length can be performed either by loading specimens with various notch lengths in the elastic domain or by computing with a finite element programme specimen compliances, with material characteristics derived from tensile and shear tests. In the latter case, the numerical approach of compliance can be performed by varying either a notch length or an ideal crack length from the initial notch as illustrated in figure 2. On the one hand, the first case which corresponds to the conditions of experimental calibrations, allows a validation of the numerical approach, while on the other hand, the second case satisfies the need of a calibration curve corresponding to an ideal crack. The results reported in figure 2 point out significant deviations between the two calibration curves as already noted elsewhere [2]. Thus after validating the computation with various notch lengths, the use of calibration curves computed with crack lengths has allowed equivalent crack length a to be
3 Computational Methods and Experimental Measurements 739 determined and 3C/3a to be derived providing we are able to measure precisely the load displacement. notch length variation^ crack length Figure 2 : Compliance curves in the case of notch length increase and crack length increase Load displacement measurement In addition to the need of measuring load displacements for equivalent crack length determination, 8 is an important parameter of the energy balance resulting from the use of the equation (1). In order to avoid taking into account in the energy balance, the dissipation induced by brinelling effects occurring in the vicinity of the load application point, load displacements have been measured at a point located slightly under the pin holes both for the experimental and the numerical tests. All the precautions previously noticed can be considered as essential requirements whatever the type of specimen and loading conditions expected to be used to ensure a good interlaboratory reproductibility. 3. Numerical simulation of a process zone development The aim of numerical simulated tests consists in the assessment and representation of the damage zone development while saving experiments and
4 740 Computational Methods and Experimental Measurements more particularly expensive composite consumption. They enable various problems to be pointed out in relation with the specimen shape and the loading conditions. Damage model The simulation is based on a damageable elastic model of the composites. The effect of damage is depicted by a decrease of the elastic constants [3]. Although such an approximate approach of constitutive laws already used by many authors, is rather simple and could be more realistic with more sophisticated models, it has been assumed to be sufficient for the purpose of the study all the more so since the related CMC's exhibit some variability in properties. The programme schematically illustrated in figure 3 is made with the f.e. code MODULEF. [ Mesh X K Materials^ properties j jf (Displacemtmt applied to thesp>ecimen ]^_ C Increment oh ^ J^ "1 displacement! ^ V (Stress in every elements ^^ (Determination of ^ J ^ the new properties J A <Stress deviationv^.or. > First iteration/^ /"Damage in all the"\ 1 elements J yes _^ Figure 3: Flowchart of the test numerical simulation of the D D easy convergence <r difficulty of convergence <7 Figure 4 : Influence of the material behaviour on the numerical convergence
5 Computational Methods and Experimental Measurements 741 The material characteristics of each element vary with the local state of stress, which is calculated through an iterative procedure, allowing the material damage to be increased or decreased during each iteration. Some difficulties of convergence arise when the D-a curvature is small and negative as illustrated in figure 4. For instance a material such as C/SiC composite, whose damage behaviour can be represented by a damage curve exhibiting this feature, induces a longer calculation time. Although the unicity of the resulting process zone development has not been established the stability of the solution for different mesh and loading increments has been considered as a first argument of validation. The deviations of the elastic properties versus stress level were derived from tensile tests performed on unnotched specimens. It is noteworthy that these properties concern loading conditions for which the principal axes correspond to the orthotropic axes of the materials while the finite element programme treats each element in the material orthotropic axes rather than in each element principal axes of loading. However, the analysis of the first results shows a test for which the damage occurs mainly in the vicinity of the ligament that is the specimen symmetry axis where the loading principal axes are the orthotropic axes of the material. Also this result shows that the only case of interference between damage zone and specimen edges are related to a correspondence between the axes. Thus, the deviations between loading and material axes are expected to induce only small errors. Rupture criterion A major difficulty related to numerical simulation is the stress state that causes the occurrence of local fractures. As an accurate fracture criterion is not available, the fracture is assumed to happen when the maximum stress value is reached in one direction of stress. This assumption is not a source of error since fractures develop in the direction perpendicular to the ligament, for which the stresses are the most significant compared to other directions. The difficulties could arise in the case of macrocrack bifurcation for which the validity of the result is questionable and has to be checked. First results In spite of these approximations in the numerical simulation, the correlation between the plateau of the R curves and the stabilisation of the damage zone has been established. It is worthy of note that the damage does not extend anymore toward the two symmetric specimen edges after the macrocrack initiation, but it develops along the ligament toward the specimen backedge (figure 5). i microcrack tmm damage zone Figure 5 : Damage zone extension during a CT test
6 742 Computational Methods and Experimental Measurements The macrocrack initiation can be distinguished from R curves as schematically illustrated in figure 6 : the plateau of R curves corresponds to the macrocrack growth that is the fibre fracture. The transitory part of the R curves before the plateau, corresponds to the development of the damage zone by matrix microcracking. G A fdamage zone development macrocrack appearance crack length Figure 6 : Schematic of an R curve illustrating a damage zone development and a steady state macrocrack growth The previously described numerical simulation of toughness tests is able to generate informations similar to observations derived from experimental tests while saving CMC materials. However experimentation cannot be avoided since the constitutive laws representative of CMC's behaviour are only approximate and do not depict material damage in the vicinity of macrocrack tips. In contrast complementary indications can be expected from elastic analyses of toughness tests. 4 Analysis of the loading mode During the numerical simulation of tests, the complexity of phenomena involved in the development of damage zones renders difficult the analysis of the loading mode in the vicinity of the singularity. With this goal, it is easier and sufficient to visualise the distribution of stress or specimen deformations with the help of a mere elastic approach. The isostatic lines show what can be the influence of the loading conditions on the development of the damage zone independently of the damage material behaviour. isostatic lines related _ damage zone isostatic lines related damage zone Figure 7 : Isostatic lines with the damage zone related to the same test before macrocracking initiation.
7 Computational Methods and Experimental Measurements 743 Comparisons between the indications derived from both the elastic analyses and numerical test simulations show that the damage zone begins to develop in the direction of the isostatic lines. This correlation allows an interaction of damage zones with specimen edges to be prevented thanks to an adjustment of the loading conditions. As an example it has been possible to shift from the configuration illustrated in figure 7a toward that of figure 7b. Pointing out the deformation of the specimen helps to understand this distribution of the isostatic lines and to modify the specimen geometry for a better stress distribution. From the isostatic lines the contribution of bending and tension to the loading can be assessed depending on for instance the notch length as shown in figure 8. Figure 8 : Tensile bending repartition for a test with grips ; this curve is obtained by comparing the load distribution on the nodes along the ligament: Since the tensile/bending contribution tends to prevent damage zone/specimen edge interaction, as schematically illustrated in figure 9, such elastic analyses constitute guides for the definition of a test procedure prior to numerical simulations and experimental investigations. - a- -b- Figure 9 : Influence of the loading conditions on the damage zone shape : a : in the case of a tensile dominated test; b : in the case of a bending dominated test. The contribution of (1) the objectives of a toughness test concerning the steady state growth of a damage zone in thin or thick plates without any specimen edge interaction, and (2) the indications derived from the previous numerical approaches, gave rise to evolutions of the test procedure initially based on a CT configuration. 5. Evolution of the test The first chosen specimen was identical to that defined by the ASTM 399 standard, (specimen 1, figure 10) but the small material thickness caused damages around the pin holes. As a consequence steel grips were added to
8 744 Computational Methods and Experimental Measurements distribute applied loads (specimen 2, figure 10), but lateral buckling and compression appeared at the backedge of specimens, mainly due to the grips stiffness. Preventing these phenomena leads to extend the glued grip all around the unnotched edges (specimen 3, figure 10). Then a study of the influence of the distance between the centre of the pin hole and the position of the notch tip shows the influence of the loading position and allowed the bending contribution to be adjusted in the conditions of loading. It shows that shifting the pin holes ahead of specimens tends to restrict the risks of damage zone/specimen interaction (specimen 4, figure 10). 1C} v/v \ \ N f S S S S N ) \ ' N X \ f*s S S S S 4f S S SV c) specimen 1 specimen 2 specimen 3 specimen 4 Conclusion steel grips k\v CMC material to be tested Figure 10 : Evolution of test conditions The need for comparing CMC's toughness and the difficulty of obtaining an intrinsic characteristic of toughness for damageable materials leads to search for a testing procedure allowing a steady state propagation of macrocracks and related damage zone. Such an approach of toughness would not be necessary if representative constitutive laws of the concerned materials could be identified, which requires a large amount of testing. However the availability of some CMC's approximate constitutive laws have allowed numerical simulation of toughness tests to be performed. Despite many approximations and a lack of precision, which were investigated, such approaches completed by elastic analyses are able to guide the design of a testing procedure. As an example the evolution of a CT test has been described and has pointed out the main criteria to be satisfied for generating steady state crack propagations that is plateaux on the related R curves whose corresponding G values could be used as comparative data. References 1. Bouquet, M., Birbis J. M. & Quenisset J. M. Toughness assessment of ceramic matrix composites, Composites Science and Technology, 1990, 37, Kachanov Y. N., Time of the rupture process under creep conditions, Izv. Akad. Nauk S.S.R. Otd. Tekh Nauk, 1958, 8, Rouillon, M.H. Resistance a la propagation de fissure de materiaux composites ceramiques SiC/C/SiC 2D, PhD thesis, Caen University, France 1993.
DEVELOPMENT OF TEST GUIDANCE FOR COMPACT TENSION FRACTURE TOUGHNESS SPECIMENS CONTAINING NOTCHES INSTEAD OF FATIGUE PRE-CRACKS
Transactions, SMiRT-23 Division II, Paper ID 287 Fracture Mechanics and Structural Integrity DEVELOPMENT OF TEST GUIDANCE FOR COMPACT TENSION FRACTURE TOUGHNESS SPECIMENS CONTAINING NOTCHES INSTEAD OF
More informationFracture mechanics fundamentals. Stress at a notch Stress at a crack Stress intensity factors Fracture mechanics based design
Fracture mechanics fundamentals Stress at a notch Stress at a crack Stress intensity factors Fracture mechanics based design Failure modes Failure can occur in a number of modes: - plastic deformation
More informationAbstract. 1 Introduction
Contact analysis for the modelling of anchors in concrete structures H. Walter*, L. Baillet** & M. Brunet* *Laboratoire de Mecanique des Solides **Laboratoire de Mecanique des Contacts-CNRS UMR 5514 Institut
More informationCalculation of Damage-dependent Directional Failure Indices from the Tsai-Wu Static Failure Criterion
Van Paepegem, W. and Degrieck, J. (3. alculation of Damage-dependent Directional Failure Indices from the sai-wu Static Failure riterion. omposites Science and echnology, 63(, 35-3. alculation of Damage-dependent
More informationSKIN-STRINGER DEBONDING AND DELAMINATION ANALYSIS IN COMPOSITE STIFFENED SHELLS
SKIN-STRINER DEBONDIN AND DELAMINATION ANALYSIS IN COMPOSITE STIFFENED SHELLS R. Rikards, K. Kalnins & O. Ozolinsh Institute of Materials and Structures, Riga Technical University, Riga 1658, Latvia ABSTRACT
More informationTHE ROLE OF DELAMINATION IN NOTCHED AND UNNOTCHED TENSILE STRENGTH
THE ROLE OF DELAMINATION IN NOTCHED AND UNNOTCHED TENSILE STRENGTH M. R. Wisnom University of Bristol Advanced Composites Centre for Innovation and Science University Walk, Bristol BS8 1TR, UK M.Wisnom@bristol.ac.uk
More informationMechanics of Earthquakes and Faulting
Mechanics of Earthquakes and Faulting Lectures & 3, 9/31 Aug 017 www.geosc.psu.edu/courses/geosc508 Discussion of Handin, JGR, 1969 and Chapter 1 Scholz, 00. Stress analysis and Mohr Circles Coulomb Failure
More information3D Finite Element analysis of stud anchors with large head and embedment depth
3D Finite Element analysis of stud anchors with large head and embedment depth G. Periškić, J. Ožbolt & R. Eligehausen Institute for Construction Materials, University of Stuttgart, Stuttgart, Germany
More informationTHE BEHAVIOUR OF REINFORCED CONCRETE AS DEPICTED IN FINITE ELEMENT ANALYSIS.
THE BEHAVIOUR OF REINFORCED CONCRETE AS DEPICTED IN FINITE ELEMENT ANALYSIS. THE CASE OF A TERRACE UNIT. John N Karadelis 1. INTRODUCTION. Aim to replicate the behaviour of reinforced concrete in a multi-scale
More informationMechanics of Earthquakes and Faulting
Mechanics of Earthquakes and Faulting www.geosc.psu.edu/courses/geosc508 Surface and body forces Tensors, Mohr circles. Theoretical strength of materials Defects Stress concentrations Griffith failure
More informationAdhesive Joints Theory (and use of innovative joints) ERIK SERRANO STRUCTURAL MECHANICS, LUND UNIVERSITY
Adhesive Joints Theory (and use of innovative joints) ERIK SERRANO STRUCTURAL MECHANICS, LUND UNIVERSITY Wood and Timber Why I m intrigued From this to this! via this Fibre deviation close to knots and
More informationInterlaminar fracture characterization in composite materials by using acoustic emission
5th International Symposium on NDT in Aerospace, 13-15th November 2013, Singapore Interlaminar fracture characterization in composite materials by using acoustic emission Ian SILVERSIDES 1, Ahmed MASLOUHI
More informationDiscrete Element Modelling of a Reinforced Concrete Structure
Discrete Element Modelling of a Reinforced Concrete Structure S. Hentz, L. Daudeville, F.-V. Donzé Laboratoire Sols, Solides, Structures, Domaine Universitaire, BP 38041 Grenoble Cedex 9 France sebastian.hentz@inpg.fr
More informationLecture #7: Basic Notions of Fracture Mechanics Ductile Fracture
Lecture #7: Basic Notions of Fracture Mechanics Ductile Fracture by Dirk Mohr ETH Zurich, Department of Mechanical and Process Engineering, Chair of Computational Modeling of Materials in Manufacturing
More informationElastic-Plastic Fracture Mechanics. Professor S. Suresh
Elastic-Plastic Fracture Mechanics Professor S. Suresh Elastic Plastic Fracture Previously, we have analyzed problems in which the plastic zone was small compared to the specimen dimensions (small scale
More informationFracture Mechanics, Damage and Fatigue Non Linear Fracture Mechanics: J-Integral
University of Liège Aerospace & Mechanical Engineering Fracture Mechanics, Damage and Fatigue Non Linear Fracture Mechanics: J-Integral Ludovic Noels Computational & Multiscale Mechanics of Materials CM3
More informationFracture Mechanics, Damage and Fatigue Linear Elastic Fracture Mechanics - Energetic Approach
University of Liège Aerospace & Mechanical Engineering Fracture Mechanics, Damage and Fatigue Linear Elastic Fracture Mechanics - Energetic Approach Ludovic Noels Computational & Multiscale Mechanics of
More informationA FINITE ELEMENT MODEL TO PREDICT MULTI- AXIAL STRESS-STRAIN RESPONSE OF CERAMIC MATRIX COMPOSITES WITH STRAIN INDUCED DAMAGE
A FINITE ELEMENT MODEL TO PREDICT MULTI- AXIAL STRESS-STRAIN RESPONSE OF CERAMIC MATRIX COMPOSITES WITH STRAIN INDUCED DAMAGE Daxu Zhang and D. R. Hayhurst School of Mechanical, Aerospace and Civil Engineering,
More informationLecture 4 Honeycombs Notes, 3.054
Honeycombs-In-plane behavior Lecture 4 Honeycombs Notes, 3.054 Prismatic cells Polymer, metal, ceramic honeycombs widely available Used for sandwich structure cores, energy absorption, carriers for catalysts
More informationOpen-hole compressive strength prediction of CFRP composite laminates
Open-hole compressive strength prediction of CFRP composite laminates O. İnal 1, A. Ataş 2,* 1 Department of Mechanical Engineering, Balikesir University, Balikesir, 10145, Turkey, inal@balikesir.edu.tr
More informationMixed-Mode Fracture Toughness Determination USING NON-CONVENTIONAL TECHNIQUES
Mixed-Mode Fracture Toughness Determination USING NON-CONVENTIONAL TECHNIQUES IDMEC- Pólo FEUP DEMec - FEUP ESM Virginia Tech motivation fracture modes conventional tests [mode I] conventional tests [mode
More informationNUMERICAL MODELLING OF COMPOSITE PIN- JOINTS AND EXPERIMENTAL VALIDATION
NUMERICAL MODELLING OF COMPOSITE PIN- JOINTS AND EXPERIMENTAL VALIDATION Fabrice PIERRON*, François CERISIER*, and Michel GRÉDIAC** * SMS/ Département Mécanique et Matériaux, École Nationale Supérieure
More informationModule 5: Failure Criteria of Rock and Rock masses. Contents Hydrostatic compression Deviatoric compression
FAILURE CRITERIA OF ROCK AND ROCK MASSES Contents 5.1 Failure in rocks 5.1.1 Hydrostatic compression 5.1.2 Deviatoric compression 5.1.3 Effect of confining pressure 5.2 Failure modes in rocks 5.3 Complete
More informationTHE MUTUAL EFFECTS OF SHEAR AND TRANSVERSE DAMAGE IN POLYMERIC COMPOSITES
THE 19 TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS THE MUTUAL EFFECTS OF SHEAR AND TRANSVERSE DAMAGE IN POLYMERIC COMPOSITES L.V. Smith 1 *, M. Salavatian 1 1 School of Mechanical and Materials
More informationPlane Strain Test for Metal Sheet Characterization
Plane Strain Test for Metal Sheet Characterization Paulo Flores 1, Felix Bonnet 2 and Anne-Marie Habraken 3 1 DIM, University of Concepción, Edmundo Larenas 270, Concepción, Chile 2 ENS - Cachan, Avenue
More informationDirect Comparison of Anisotropic Damage Mechanics to Fracture Mechanics of Explicit Cracks
Direct Comparison of Anisotropic Damage Mechanics to Fracture Mechanics of Explicit Cracks John A. Nairn Wood Science and Engineering, Oregon State University, Corvallis, OR 97330, USA Tel: +1-541-737-4265
More informationCOMPARISON OF COHESIVE ZONE MODELS USED TO PREDICT DELAMINATION INITIATED FROM FREE-EDGES : VALIDATION AGAINST EXPERIMENTAL RESULTS
COMPARISON OF COHESIVE ZONE MODELS USED TO PREDICT DELAMINATION INITIATED FROM FREE-EDGES : VALIDATION AGAINST EXPERIMENTAL RESULTS A. Uguen 1, L. Zubillaga 2, A. Turon 3, N. Carrère 1 1 Laboratoire Brestois
More informationEvolution of Tenacity in Mixed Mode Fracture Volumetric Approach
Mechanics and Mechanical Engineering Vol. 22, No. 4 (2018) 931 938 c Technical University of Lodz Evolution of Tenacity in Mixed Mode Fracture Volumetric Approach O. Zebri LIDRA Laboratory, Research team
More informationG1RT-CT A. BASIC CONCEPTS F. GUTIÉRREZ-SOLANA S. CICERO J.A. ALVAREZ R. LACALLE W P 6: TRAINING & EDUCATION
A. BASIC CONCEPTS 6 INTRODUCTION The final fracture of structural components is associated with the presence of macro or microstructural defects that affect the stress state due to the loading conditions.
More informationLinear Elastic Fracture Mechanics
Measure what is measurable, and make measurable what is not so. - Galileo GALILEI Linear Elastic Fracture Mechanics Krishnaswamy Ravi-Chandar Lecture presented at the University of Pierre and Marie Curie
More informationImpact and Crash Modeling of Composite Structures: A Challenge for Damage Mechanics
Impact and Crash Modeling of Composite Structures: A Challenge for Damage Mechanics Dr. A. Johnson DLR Dr. A. K. Pickett ESI GmbH EURO-PAM 99 Impact and Crash Modelling of Composite Structures: A Challenge
More informationOn characterising fracture resistance in mode-i delamination
9 th International Congress of Croatian Society of Mechanics 18-22 September 2018 Split, Croatia On characterising fracture resistance in mode-i delamination Leo ŠKEC *, Giulio ALFANO +, Gordan JELENIĆ
More informationFinite element analysis of diagonal tension failure in RC beams
Finite element analysis of diagonal tension failure in RC beams T. Hasegawa Institute of Technology, Shimizu Corporation, Tokyo, Japan ABSTRACT: Finite element analysis of diagonal tension failure in a
More informationStatic and Time Dependent Failure of Fibre Reinforced Elastomeric Components. Salim Mirza Element Materials Technology Hitchin, UK
Static and Time Dependent Failure of Fibre Reinforced Elastomeric Components Salim Mirza Element Materials Technology Hitchin, UK Introduction Fibre reinforced elastomers are used in many applications,
More informationMassachusetts Institute of Technology Department of Mechanical Engineering Cambridge, MA 02139
Massachusetts Institute of Technology Department of Mechanical Engineering Cambridge, MA 02139 2.002 Mechanics and Materials II Spring 2004 Laboratory Module No. 6 Fracture Toughness Testing and Residual
More informationModule III - Macro-mechanics of Lamina. Lecture 23. Macro-Mechanics of Lamina
Module III - Macro-mechanics of Lamina Lecture 23 Macro-Mechanics of Lamina For better understanding of the macromechanics of lamina, the knowledge of the material properties in essential. Therefore, the
More informationUniversity of Sheffield The development of finite elements for 3D structural analysis in fire
The development of finite elements for 3D structural analysis in fire Chaoming Yu, I. W. Burgess, Z. Huang, R. J. Plank Department of Civil and Structural Engineering StiFF 05/09/2006 3D composite structures
More informationCrack Tip Plastic Zone under Mode I Loading and the Non-singular T zz -stress
Crack Tip Plastic Zone under Mode Loading and the Non-singular T -stress Yu.G. Matvienko Mechanical Engineering Research nstitute of the Russian Academy of Sciences Email: ygmatvienko@gmail.com Abstract:
More informationAVOIDING FRACTURE INSTABILITY IN WEDGE SPLITTING TESTS BY MEANS OF NUMERICAL SIMULATIONS
Damage, Avoiding fracture Fracture instability and Fatigue in wedge splitting tests by means of numerical simulations XIV International Conference on Computational Plasticity. Fundamentals and Applications
More informationDAMAGE MODEL FOR CONCRETE INCLUDING RESIDUAL HYSTERETIC LOOPS: APPLICATION TO SEISMIC AND DYNAMIC LOADING
Fracture Mechanics of Concrete Structures Proceedings FRAMCOS-3 AEDIFICA TIO Publishers, D-79104 Frei burg, Germany DAMAGE MODEL FOR CONCRETE INCLUDING RESIDUAL HYSTERETIC LOOPS: APPLICATION TO SEISMIC
More informationMMJ1133 FATIGUE AND FRACTURE MECHANICS A - INTRODUCTION INTRODUCTION
A - INTRODUCTION INTRODUCTION M.N.Tamin, CSMLab, UTM Course Content: A - INTRODUCTION Mechanical failure modes; Review of load and stress analysis equilibrium equations, complex stresses, stress transformation,
More informationNUMERICAL MODELLING OF THE WEDGE SPLITTING TEST IN ROCK SPECIMENS, USING FRACTURE-BASED ZERO-THICKNESS INTERFACE ELEMENTS
Numerical modelling of the Wedge Splitting Test in rock specimens, using fracture-based zero-thickness interface elements XIII International Conference on Computational Plasticity. Fundamentals and Applications
More informationAn orthotropic damage model for crash simulation of composites
High Performance Structures and Materials III 511 An orthotropic damage model for crash simulation of composites W. Wang 1, F. H. M. Swartjes 1 & M. D. Gan 1 BU Automotive Centre of Lightweight Structures
More informationFCP Short Course. Ductile and Brittle Fracture. Stephen D. Downing. Mechanical Science and Engineering
FCP Short Course Ductile and Brittle Fracture Stephen D. Downing Mechanical Science and Engineering 001-015 University of Illinois Board of Trustees, All Rights Reserved Agenda Limit theorems Plane Stress
More informationModelling the nonlinear shear stress-strain response of glass fibrereinforced composites. Part II: Model development and finite element simulations
Modelling the nonlinear shear stress-strain response of glass fibrereinforced composites. Part II: Model development and finite element simulations W. Van Paepegem *, I. De Baere and J. Degrieck Ghent
More informationCracked concrete structures under cyclic load
Cracked concrete structures under cyclic load Fabrizio Barpi & Silvio Valente Department of Structural and Geotechnical Engineering, Politecnico di Torino, Torino, Italy ABSTRACT: The safety of cracked
More informationA NEW METHODOLOGY FOR THE CHARACTERIZATION OF MODE II FRACTURE OF PINUS PINASTER WOOD
5th International Conference on Mechanics and Materials in Design REF: A0604.009 (Invited Paper) A NEW METHODOLOY FOR THE CHARACTERIZATION OF MODE II FRACTURE OF PINUS PINASTER WOOD M.F.S.F. de Moura 1*,
More informationMechanics of Materials Primer
Mechanics of Materials rimer Notation: A = area (net = with holes, bearing = in contact, etc...) b = total width of material at a horizontal section d = diameter of a hole D = symbol for diameter E = modulus
More informationComputational Analysis for Composites
Computational Analysis for Composites Professor Johann Sienz and Dr. Tony Murmu Swansea University July, 011 The topics covered include: OUTLINE Overview of composites and their applications Micromechanics
More informationOutline. Tensile-Test Specimen and Machine. Stress-Strain Curve. Review of Mechanical Properties. Mechanical Behaviour
Tensile-Test Specimen and Machine Review of Mechanical Properties Outline Tensile test True stress - true strain (flow curve) mechanical properties: - Resilience - Ductility - Toughness - Hardness A standard
More informationBRIDGING LAW SHAPE FOR LONG FIBRE COMPOSITES AND ITS FINITE ELEMENT CONSTRUCTION
Proceedings of ALGORITMY 2012 pp. 353 361 BRIDGING LAW SHAPE FOR LONG FIBRE COMPOSITES AND ITS FINITE ELEMENT CONSTRUCTION VLADISLAV KOZÁK AND ZDENEK CHLUP Abstract. Ceramic matrix composites reinforced
More informationFracture Mechanics, Damage and Fatigue: Composites
University of Liège Aerospace & Mechanical Engineering Fracture Mechanics, Damage and Fatigue: Composites Ludovic Noels Computational & Multiscale Mechanics of Materials CM3 http://www.ltas-cm3.ulg.ac.be/
More informationINFLUENCE OF A WELDED PIPE WHIP RESTRAINT ON THE CRITICAL CRACK SIZE IN A 90 BEND
18th International Conference on Structural Mechanics in Reactor Technology (SMiRT 18) Beijing, China, August 7-12, 25 SMiRT18-G8-5 INFLUENCE OF A WELDED PIPE WHIP RESTRAINT ON THE CRITICAL CRACK SIZE
More informationCHAPTER 3 EXPERIMENTAL STUDY
Experimental Study 42 CHAPTER 3 EXPERIMENTAL STUDY 3.1. INTRODUCTION The experimental study that has been carried out in this thesis has two main objectives: 1. Characterise the concrete behaviour in mode
More information5 ADVANCED FRACTURE MODELS
Essentially, all models are wrong, but some are useful George E.P. Box, (Box and Draper, 1987) 5 ADVANCED FRACTURE MODELS In the previous chapter it was shown that the MOR parameter cannot be relied upon
More informationALGORITHM FOR NON-PROPORTIONAL LOADING IN SEQUENTIALLY LINEAR ANALYSIS
9th International Conference on Fracture Mechanics of Concrete and Concrete Structures FraMCoS-9 Chenjie Yu, P.C.J. Hoogenboom and J.G. Rots DOI 10.21012/FC9.288 ALGORITHM FOR NON-PROPORTIONAL LOADING
More informationMULTISCALE AND MULTILEVEL ANALYSIS OF COMPOSITE STRUCTURES WITH BOLTED JOINTS
MULTISCALE AND MULTILEVEL ANALYSIS OF COMPOSITE STRUCTURES WITH BOLTED JOINTS F.-X. Irisarri, J.-F. Maire* and N. Carrere ONERA, 9 av. de la Division Leclerc, 930 Châtillon, France francois-xavier.irisarri@onera.fr,
More informationPREDICTING ISSUES OF SCALE IN NUCLEAR GRAPHITE COMPONENTS. Introduction
PREDICTING ISSUES OF SCALE IN NUCLEAR GRAPHITE COMPONENTS Gareth B. Neighbour and Matt Holt University of Hull, Cottingham Road, United Kingdom, HU6 7RX Introduction Polygranular graphite is used as a
More informationThe Accuracy of Characteristic Length Method on Failure Load Prediction of Composite Pinned Joints
, June 30 - July 2, 2010, London, U.K. The Accuracy of Characteristic Length Method on Failure Load Prediction of Composite Pinned Joints O. Aluko, and Q. Mazumder Abstract An analytical model was developed
More informationStandard Test Methods for Plane-Strain Fracture Toughness and Strain Energy Release Rate of Plastic Materials 1
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards,
More informationQUESTION BANK Composite Materials
QUESTION BANK Composite Materials 1. Define composite material. 2. What is the need for composite material? 3. Mention important characterits of composite material 4. Give examples for fiber material 5.
More informationStandard Test Methods for Plane-Strain Fracture Toughness and Strain Energy Release Rate of Plastic Materials 1
Designation: D 5045 99 AMERICAN SOCIETY FOR TESTING AND MATERIALS 100 Barr Harbor Dr., West Conshohocken, PA 19428 Reprinted from the Annual Book of ASTM Standards. Copyright ASTM Standard Test Methods
More informationEFFECT OF THE TEST SET-UP ON FRACTURE MECHANICAL PARAMETERS OF CONCRETE
Fracture Mechanics of Concrete Structures Proceedings FRAMCOS-3 AEDIFICATIO Publishers, D-79104 Freiburg, Germany EFFECT OF THE TEST SET-UP ON FRACTURE MECHANICAL PARAMETERS OF CONCRETE V. Mechtcherine
More informationFRACTURE MECHANICS FOR MEMBRANES
FRACTURE MECHANICS FOR MEMBRANES Chong Li, Rogelio Espinosa and Per Ståhle Solid Mechanics, Malmö University SE 205 06 Malmö, Sweden chong.li@ts.mah.se Abstract During fracture of membranes loading often
More informationNumerical Analysis of Composite Panels in the Post-Buckling Field taking into account Progressive Failure
Copyright c 007 ICCES ICCES, vol.1, no.3, pp.93-98, 007 Numerical Analysis of Composite Panels in the Post-Buckling Field taking into account Progressive Failure C. Bisagni 1 Summary The research here
More informationSTRENGTH AND STIFFNESS REDUCTION OF LARGE NOTCHED BEAMS
STRENGTH AND STIFFNESS REDUCTION OF LARGE NOTCHED BEAMS By Joseph F. Murphy 1 ABSTRACT: Four large glulam beams with notches on the tension side were tested for strength and stiffness. Using either bending
More informationLecture #8: Ductile Fracture (Theory & Experiments)
Lecture #8: Ductile Fracture (Theory & Experiments) by Dirk Mohr ETH Zurich, Department of Mechanical and Process Engineering, Chair of Computational Modeling of Materials in Manufacturing 2015 1 1 1 Ductile
More information5. STRESS CONCENTRATIONS. and strains in shafts apply only to solid and hollow circular shafts while they are in the
5. STRESS CONCENTRATIONS So far in this thesis, most of the formulas we have seen to calculate the stresses and strains in shafts apply only to solid and hollow circular shafts while they are in the elastic
More informationMulti-scale digital image correlation of strain localization
Multi-scale digital image correlation of strain localization J. Marty a, J. Réthoré a, A. Combescure a a. Laboratoire de Mécanique des Contacts et des Strcutures, INSA Lyon / UMR CNRS 5259 2 Avenue des
More informationFRACTURE MECHANICS TEST METHODS
DEVELOPMENT AND EVALUATION OF FRACTURE MECHANICS TEST METHODS FOR SANDWICH COMPOSITES Dan Adams Department of Mechanical Engineering University it of Utah Salt Lake City, UT AMTAS A t 2012 M ti AMTAS Autumn
More informationCracking in Quasi-Brittle Materials Using Isotropic Damage Mechanics
Cracking in Quasi-Brittle Materials Using Isotropic Damage Mechanics Tobias Gasch, PhD Student Co-author: Prof. Anders Ansell Comsol Conference 2016 Munich 2016-10-12 Contents Introduction Isotropic damage
More informationTransactions on Modelling and Simulation vol 9, 1995 WIT Press, ISSN X
Elastic-plastic model of crack growth under fatigue using the boundary element method M. Scibetta, O. Pensis LTAS Fracture Mechanics, University ofliege, B-4000 Liege, Belgium Abstract Life of mechanic
More informationFracture mechanics analysis of arc shaped specimens for pipe grade polymers
Fracture mechanics analysis of arc shaped specimens for pipe grade polymers Pemra Özbek, Christos Argyrakis and Patrick Leevers Department of Mechanical Engineering, Imperial College London, London SW7
More informationAfter lecture 16 you should be able to
Lecture 16: Design of paper and board packaging Advanced concepts: FEM, Fracture Mechanics After lecture 16 you should be able to describe the finite element method and its use for paper- based industry
More informationCritical applied stresses for a crack initiation from a sharp V-notch
Focussed on: Fracture and Structural Integrity related Issues Critical applied stresses for a crack initiation from a sharp V-notch L. Náhlík, P. Hutař Institute of Physics of Materials, Academy of Sciences
More informationComparison between a Cohesive Zone Model and a Continuum Damage Model in Predicting Mode-I Fracture Behavior of Adhesively Bonded Joints
Copyright 2012 Tech Science Press CMES, vol.83, no.2, pp.169-181, 2012 Comparison between a Cohesive Zone Model and a Continuum Damage Model in Predicting Mode-I Fracture Behavior of Adhesively Bonded
More informationIMECE CRACK TUNNELING: EFFECT OF STRESS CONSTRAINT
Proceedings of IMECE04 2004 ASME International Mechanical Engineering Congress November 13-20, 2004, Anaheim, California USA IMECE2004-60700 CRACK TUNNELING: EFFECT OF STRESS CONSTRAINT Jianzheng Zuo Department
More informationFRACTURE OF CRACKED MEMBERS 1. The presence of a crack in a structure may weaken it so that it fails by fracturing in two or more pieces.
Aerospace Structures Fracture Mechanics: An Introduction Page 1 of 7 FRACTURE OF CRACED MEMBERS 1. The presence of a crack in a structure may weaken it so that it fails by fracturing in two or more pieces.
More informationInfluence of impact velocity on transition time for V-notched Charpy specimen*
[ 溶接学会論文集第 35 巻第 2 号 p. 80s-84s (2017)] Influence of impact velocity on transition time for V-notched Charpy specimen* by Yasuhito Takashima** and Fumiyoshi Minami** This study investigated the influence
More informationInitiation de fissure dans les milieux fragiles - Prise en compte des contraintes résiduelles
Initiation de fissure dans les milieux fragiles - Prise en compte des contraintes résiduelles D. Leguillon Institut Jean le Rond d Alembert CNRS/UPMC Paris, France Parvizi, Garrett and Bailey experiments
More informationPrediction of Delamination Growth Behavior in a Carbon Fiber Composite Laminate Subjected to Constant Amplitude Compression-Compression Fatigue Loads
Prediction of Delamination Growth Behavior in a Carbon Fiber Composite Laminate Subjected to Constant Amplitude Compression-Compression Fatigue Loads J. Raju 1*, D.S. Sreedhar 2, & C.M. Manjunatha 1 1
More informationNonlocal computational methods applied to composites structures
Nonlocal computational methods applied to composites structures Norbert Germain, Frédéric Feyel, Jacques Besson To cite this version: Norbert Germain, Frédéric Feyel, Jacques Besson. Nonlocal computational
More informationLaboratory 4 Bending Test of Materials
Department of Materials and Metallurgical Engineering Bangladesh University of Engineering Technology, Dhaka MME 222 Materials Testing Sessional.50 Credits Laboratory 4 Bending Test of Materials. Objective
More informationMechanical modelling of SiC/SiC composites and design criteria
Mechanical modelling of SiC/SiC composites and design criteria F. Bernachy CEA, DEN/DMN/SRMA/LC2M, Gif-sur-Yvette, France L. Gélébart CEA, DEN/DMN/SRMA/LC2M, Gif-sur-Yvette, France J. Crépin Centre des
More informationStructural behaviour of traditional mortise-and-tenon timber joints
Structural behaviour of traditional mortise-and-tenon timber joints Artur O. Feio 1, Paulo B. Lourenço 2 and José S. Machado 3 1 CCR Construtora S.A., Portugal University Lusíada, Portugal 2 University
More informationNUMERICAL AND EXPERIMENTAL STUDY OF FAILURE IN STEEL BEAMS UNDER IMPACT CONDITIONS
Blucher Mechanical Engineering Proceedings May 2014, vol. 1, num. 1 www.proceedings.blucher.com.br/evento/10wccm NUMERICAL AND EXPERIMENTAL STUDY OF FAILURE IN STEEL BEAMS UNDER IMPACT CONDITIONS E. D.
More informationInfluence of fibre proportion and position on the machinability of GFRP composites- An FEA model
Indian Journal of Engineering & Materials Sciences Vol. 12, October 2005, pp. 443-450 Influence of fibre proportion and position on the machinability of GFRP composites- An FEA model D Abdul Budan* Department
More informationPLANES OF WEAKNESS IN ROCKS, ROCK FRCTURES AND FRACTURED ROCK. Contents
PLANES OF WEAKNESS IN ROCKS, ROCK FRCTURES AND FRACTURED ROCK Contents 7.1 Introduction 7.2 Studies On Jointed Rock Mass 7.2.1 Joint Intensity 7.2.2 Orientation Of Joints 7.2.3 Joint Roughness/Joint Strength
More informationMODELING OF THE WEDGE SPLITTING TEST USING AN EXTENDED CRACKED HINGE MODEL
Engineering MECHANICS, Vol. 21, 2014, No. 1, p. 67 72 67 MODELING OF THE WEDGE SPLITTING TEST USING AN EXTENDED CRACKED HINGE MODEL Tomáš Pail, Petr Frantík* The present paper describes a semi-analytical
More informationA FINITE ELEMENT MODEL FOR SIZE EFFECT AND HETEROGENEITY IN CONCRETE STRUCTURES
A FINITE ELEMENT MODEL FOR SIZE EFFECT AND HETEROGENEITY IN CONCRETE STRUCTURES Roque Luiz Pitangueira 1 and Raul Rosas e Silva 2 1 Department of Structural Engineering -Federal University of Minas Gerais
More informationEffective stress assessment at rectangular rounded lateral notches
Focussed on characterization of crack tip fields Effective stress assessment at rectangular rounded lateral notches Enrico Maggiolini, Roberto Tovo, Paolo Livieri University of Ferrara Enrico.maggiolini@unife.it,
More informationEnhancing Prediction Accuracy In Sift Theory
18 TH INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS Enhancing Prediction Accuracy In Sift Theory J. Wang 1 *, W. K. Chiu 1 Defence Science and Technology Organisation, Fishermans Bend, Australia, Department
More informationESCOLA POLITÉCNICA DA UNIVERSIDADE DE SÃO PAULO BOLETIM TÉCNICO PEF-EPUSP. Título:
ESCOLA POLITÉCNICA DA UNIVERSIDADE DE SÃO PAULO BOLETIM TÉCNICO PEF-EPUSP Título: STUDY OF CRACK PROPAGATION IN THE SPECIMEN RECOMMENDED BY RILEM TC 16 BASED ON LINEAR ELASTIC FRACTURE MECHANICS LUIZ EDUARDO
More informationTransactions on Engineering Sciences vol 6, 1994 WIT Press, ISSN
A computational method for the analysis of viscoelastic structures containing defects G. Ghazlan," C. Petit," S. Caperaa* " Civil Engineering Laboratory, University of Limoges, 19300 Egletons, France &
More informationTensile stress strain curves for different materials. Shows in figure below
Tensile stress strain curves for different materials. Shows in figure below Furthermore, the modulus of elasticity of several materials effected by increasing temperature, as is shown in Figure Asst. Lecturer
More informationCOMPARISON BETWEEN 2D AND 3D ANALYSES OF SEISMIC STABILITY OF DETACHED BLOCKS IN AN ARCH DAM
COMPARISON BETWEEN 2D AND 3D ANALYSES OF SEISMIC STABILITY OF DETACHED BLOCKS IN AN ARCH DAM Sujan MALLA 1 ABSTRACT The seismic safety of the 147 m high Gigerwald arch dam in Switzerland was assessed for
More informationFREE EDGE DELAMINATION ONSET CRITERION
FREE EGE ELAMINATION ONSET CRITERION G. MARION now, 2, formerl 3, R. HARRY 2, and F. LECUYER MEYSYS, 29 rue J. Rostand, 9873 ORSAY CEEX, FRANCE 2 Laboratoire de Génie Mécanique, IUT Bordeaux I, 3345 TALENCE
More informationFinite element analysis of longitudinal debonding between fibre and matrix interface
Indian Journal of Engineering & Materials Sciences Vol. 11, February 2004, pp. 43-48 Finite element analysis of longitudinal debonding between fibre and matrix interface K Aslantaş & S Taşgetiren Department
More informationDetermination of Stress Intensity Factor for a Crack Emanating From a Rivet Hole and Approaching Another in Curved Sheet
International OPEN ACCESS Journal Of Modern Engineering Research (IJMER) Determination of Stress Intensity Factor for a Crack Emanating From a Rivet Hole and Approaching Another in Curved Sheet Raghavendra.
More informationNUMERICAL INVESTIGATION OF DELAMINATION IN L-SHAPED CROSS-PLY COMPOSITE BRACKET
NUMERICAL INVESTIGATION OF DELAMINATION IN L-SHAPED CROSS-PLY COMPOSITE BRACKET M.Gümüş a*, B.Gözlüklü a, D.Çöker a a Department of Aerospace Eng., METU, Ankara, Turkey *mert.gumus@metu.edu.tr Keywords:
More information