Jacques Luc Lamon

• Dr.
• Research Director at French National Centre for Scientific Research

This paper tackles the important issue of the flexural strength of continuous fiber-reinforced ceramic composite. Estimates of the flexural strength of 2D woven SiC/SiC composite are extracted from symmetric and asymmetric 3-point bending test results using three independent approaches: (1) the equations of elastic beam theory for homogeneous solid...

The present paper tackles the important issue of tensile ultimate strength of ceramic matrix composites, using a multiscale approach. The ultimate strength is investigated at the successive increasing length scales inherent to 2D woven SiC/SiC composites, i.e., single filaments, fibre tow, unidirectional composite (minicomposites), and 2D woven com...

: The present paper tackles the important issue of tensile ultimate strength of ceramic matrix composites, using a multiscale approach. The ultimate strength is investigated at the successive increasing length scales inherent to 2D woven SiC/SiC composites, i.e. single filaments, fiber tow, minicomposites reinforced with a single tow, and 2D woven...

The present paper investigates flaw strength distributions established using various flexural tests on batches of SiC bar test specimens, namely four-point bending as well as three-point bending tests with different span lengths. Flaw strength is provided by the elemental stress operating on the critical flaw at the fracture of a test specimen. Fra...

The present paper investigates flaw strength distributions established using various flexural tests on batches of SiC bar test specimens: 4-point bending as well as 3-point bending with different span lengths. Flaw strength is given by the elemental stress operating on the critical flaw at fracture of a test specimen. Fracture inducing flaws and th...

The present paper investigates the unexpected unstable failure observed commonly on fiber tows tensile-tested under strain-controlled loading, although the force on the fibers should theoretically be relaxed under controlled strain. A model of the reaction of the load train when the fibers break under strain-controlled conditions is proposed. The c...

The present paper investigates the failure of SiC and alumina-fiber-reinforced minicomposites in relation to the strength distributions of filaments, and the failure behavior of the reinforcing dry tows. The strength data are measured on single-filament, dry-tow and minicomposite specimens using tensile tests under commonly used test condition of s...

The present paper proposes a model of the specimen size effect on the critical flaw strength distribution in fiber tows for composite reinforcement. The model is based on the basic assumption of brittle fracture that the failure probability at a given strength increases with specimen size in the p-quantile vs. strength relation and on the normal di...

The tensile strength distributions of five types of silicon carbide (SiC) fiber, namely, Nicalon, Hi-Nicalon, Hi-Nicalon TypeS, Tyranno ZMI and Tyranno SA, were evaluated by monofilament and multifilament tow tensile testing with the estimated Weibull parameters being compared from each method. Whereas values for the Weibull scale parameter were fo...

The flaw strength data are determined using tensile tests on various fiber tow types including, SiC, carbon, glass, basalt and alumina. The plots of p-quintile vs. flaw strength data derived from experimental force-strain curves exhibit linearity. This indicates unambiguously that flaw strength is a Gaussian variate. The statistical distribution of...

The present paper investigates the static fatigue behavior of Hi-Nicalon fiber-reinforced SiC–SiC minicomposites at high temperatures in the 900–1200 °C range, and under tensile stresses above the proportional limit. The stress–rupture time relation was analyzed with respect to subcritical crack growth in filaments and fiber tow fracture. Slow crac...

Ceramics need to be reinforced because of their inherent brittleness and lack of reliability. Only continuous fibers are able to arrest the cracks through deflection at fiber/matrix interfaces. Only those fibers that can withstand the high temperatures required by composite processing (> 1000°C) without significant damage can be used. This chapter...

The present paper discusses the statistical features of static fatigue for E-glass multifilament tows in water. In such an aggressive environment, the glass fibres are sensitive to slow crack propagation from micron-sized flaws. Rupture and interrupted static fatigue tests under constant deformation in water, as well as tensile tests in inert envir...

SiC-based fibers are sensitive to delayed failure under constant load at high temperatures in air. Static fatigue at intermediate temperatures < 800 °C was attributed to slow crack growth from flaws located at the surface of fibers, driven by the oxidation of free carbon at grain boundaries. The present paper examines the static fatigue behavior of...

The influence of damage on thermal properties is an important issue for the design of reliable ceramic matrix composites for high temperature applications. This work is devoted to the experimental study of this influence on SiC/SiC minicomposite. This single tow reinforced composite is appropriate to investigating the damage mechanisms and thermal...

SiC/SiC composites reinforced with Hi-Nicalon S 3rd generation SiC fibers are promising candidates for high temperature aeronautical applications and fuel cladding in nuclear reactors. An original patented process was used to produce SiC/SiC tubular samples for dimensional and tensile mechanical characterizations. The process route is described in...

The content of the review covers, first, generalities on creep. Then, the creep of ceramics and fibres, that are key constituents of fibre-reinforced ceramic matrix composites (CMCs) are addressed. The general features of ceramic matrix composites that may influence the creep behaviour and creep rupture are discussed. Emphasis is placed on microstr...

: 2D woven SiC/SiC composites, with nanoscale-multilayered (PyC/SiC) n interphases, have been made via chemical vapour infiltration of a preform of either Nicalon or Hi-Nicalon fibres. The nanoscale-multilayered (PyC/SiC) n interphases consist of n successive PyC-SiC sequences. In the present paper n = 10 and the thickness of the PyC and SiC sublay...

Silicon carbide fibers combine structural and refractory properties making them good candidates for ceramic matrix composite reinforcement, driving their ultimate failure. The fractographic observation after tensile tests of various silicon carbide fibers, belonging to first, second or third generations, reveals the critical flaw location i.e. inte...

Being damage tolerant, the CMCs exhibit nonlinear deformations as a result of cracks that form in the matrix, in the interfaces, and in the fibers. The sequence of cracking modes displays several features that depend on the arrangement of fibers, the microstructure, and the respective properties of constituents. Being ceramic materials, the constit...

The paper investigates the damage and failure of fiber tows induced by slow crack growth activated by environment and applied load. The investigation is based on calculation of residual strengths and stress-lifetimes using models of slow crack growth on filaments and residual tensile behavior of fiber tows. This approach allows an exploration of be...

The term “size effects” designates the dependence of fracture resistance on the size of stressed volume or surface. The larger the size, the smaller the fracture resistance, since the probability that a severe flaw is present increases with size. As flaw severity depends on the stress state, the stress state contributes to size effects. The effect...

In those theories which consider flaws as physical entities, the expression of failure probability is derived from flaw density function. This function is the probability density function (pdf), or density, of a random variable characteristic of flaw severity. The following characteristics are generally used:

Any material can contain flaws, i.e. materials are never free of flaws. According to dictionaries, a flaw is “an imperfection, often concealed, that impairs soundness”. Here, a flaw is a heterogeneity that disrupts the theoretical order and introduces a discontinuity or a singularity. Flaws impede the working of materials and systems, as well as va...

The statistical parameters of interest in statistical-probabilistic approaches to fracture index the distribution of strength data, i.e. the flaw strengths for the physics-based models, or the strengths of the specimens for the Weibull model. These parameters can be regarded as characteristics of populations of flaws or specimens, and consequently,...

The statistical-probabilistic models of brittle failure find an important application to the design of components made up of brittle materials, as they allow predictive calculations of failure. They provide a decisive improvement over classical structure calculations by stress analysis. Failure probability is a quantitative and objective criterion...

In this chapter, the method of calculation of failure probability is applied to various loading cases. Both fundamental steps of statistical parameter estimation and failure probability calculation are conducted by using the finite element analysis of stress state and the postprocessor CERAM. Analytical approaches are given for comparison when they...

The name Wallodi Weibull (1887–1979) is associated with the domain of statistics on life data of systems and analysis of failures. Weibull was interested in problems of material strength, such as fatigue and failure of vacuum tubes. In 1939, he proposed a theory based on the elementary laws of probability, whose formulae may solve inconsistencies o...

The previous chapters addressed brittle fracture, which displays the following features: (1) the initiation of a crack from a defect causes the instantaneous breakdown of a solid, (2) crack initiation is the preponderant step as it coincides with the complete separation of the solid, (3) the crack propagates instantaneously through the solid and (4...

In these statistical-probabilistic theories, the severity of flaws is characterized by a critical stress.

The notion of effective volume (respectively, effective surface area) is useful for the comparison of fracture resistance under different stress states, loading modes or volume sizes. The effective volume is a probabilistically equivalent volume of material subjected to a uniform tensile stress. It represents the volume of material for which failur...

The failure properties of flax fibres were investigated using a tow behaviour-based approach that was developed on ceramic and glass fibres. The Weibull and normal strength distributions of filament failure strains and the true statistical parameters were extracted from the tensile curve of a tow test specimen made of several 100 of filaments. Tens...

The third generation of composite materials possesses a functional interphase between plies, which is reinforced by thermoplastic particles. Understanding the mechanism of matrix crack propagation through the interphase is an important prerequisite to the development of a robust code for the computation of damage resistance of cross ply laminates p...

Compressive tests involving buckling are known to be defect sensitive, nevertheless, to our knowledge, no inverse approach has been proposed yet to use this property for the localization and characterization of material defects. This is due to geometric imperfections, which greatly influence and even dominate the response of defective parts under c...

Flaws are the principal source of fracture in many materials, whether brittle or ductile, whether nearly homogeneous or composite. They are introduced during either fabrication or surface preparation or during exposure to aggressive environments (e. g. oxidation, shocks). The critical flaws act as stress concentrators and initiate cracks that propa...

This paper investigates local phenomena that govern the damage behaviour of laminated composites of third generation that possess a functional interphase between plies reinforced by thermoplastic particles. The effects of interphase parameters (thickness and mod-ulus) on the propagation of the matrix transverse crack and on the micro-delamination p...

Ceramic Matrix Composites (CMC) are very attractive for structural applications at high temperatures or under temperature gradients. For these reasons, the mechanical properties must be considered together with the thermophysical properties. The aim of this work is to demonstrate the thermal characterization capabilities of IR thermography in multi...

Woven SiC-based ceramic matrix composites (CMCs) are promising materials for several systems running at high temperatures. They provide excellent examples of microstructure–behavior relationships in long fiber-reinforced brittle matrices. Minicomposite test specimens represent an appropriate length scale for investigation of multidirectionally rein...

Several brittle inorganic fibers (including glass, SiC- or alumina- based fibers) are sensitive to slow crack growth activated by environment (water, high temperature air, etc.) in fatigue, so that failure can occur under stresses much smaller than the fracture stress. The delayed fracture of glass fibers has been investigated in a previous paper,...

Lesioned myocardial tissue can be replaced with innovative biological grafts. However, the strength of most biological grafts is initially not sufficient for left ventricular applications. Implants that mechanically support these grafts and gradually lose their function as the graft develops its strength are a possible solution. We are developing m...

The chapter examines failure characteristics of silicon carbide fibers and their performances at intermediate temperatures <1000°C. Behavior at higher temperatures when creep dominates has been discussed in previous papers and books on fibers or ceramic matrix composites. Focus is placed on features of fast fracture of single filaments and tows, on...

The interfacial domain is a physical entity that influences significantly composite mechanical behavior. It consists of a fiber matrix interface or an interphase bonded to the fiber and the matrix. This chapter discusses the main features of interfacial domain in CMCs, with respect to composite mechanical behavior, not only from a qualitative but a...

This book is a comprehensive source of information on various aspects of ceramic matrix composites (CMC). It covers ceramic and carbon fibers; the fiber-matrix interface; processing, properties and industrial applications of various CMC systems; architecture, mechanical behavior at room and elevated temperatures, environmental effects and protectiv...

This volume contains papers presented at seven international symposia held during the Materials Science & Technology 2013 Conference (MS&TM3), October 27-31, 2013 at the Palais des congress, in Montreal, Quebec, Canada. The symposia in this volume include: Innovative Processing and Synthesis of Ceramics, Glasses and Composites; Advances in Ceramic...

This paper proposes a new approach to the analysis of acoustic emission data. The energy of acoustic emission signals recorded at two sensors is used to evaluate real-time energy attenuation due to damage accumulation. The method is applied to acoustic emission data recorded during static fatigue tests at intermediate temperatures on ceramic matrix...

This work is devoted to the experimental study of the effect of mechanical damage on the thermal diffusivity of SiC/SiC minicomposite test specimens. This sample geometry is very useful for understanding the damage mechanisms and their effect on mechanical and thermal properties. Relations between constituent properties (fiber/matrix/interface) and...

A main purpose of this paper is to consider the possibility of predicting rupture time of CMC from damage evolution recorded by AE technique. The energy of acoustic emission signals recorded at two sensors is used to evaluate in real-time energy attenuation due to damage accumulation. In this study SiCf/[Si-B-C] composites are studied under static...

The present paper investigates fracture statistics for brittle fibers used for composite reinforcement. Large sets of failure strengths (500 to 1000 data) were produced using tensile tests on tows that contained either 500 or 1000 filaments. The statistical distributions of filament strengths were described using the normal distribution. The Weibul...

The advantageous properties of SiC/SiC composites, such as high-temperature strength; creep and corrosion resistances; low density; high toughness; resistance to shocks, fatigue, and damage; and reliability, make them ideal candidates for the replacement of metals and ceramics in many engineering applications involving loads, high temperatures, and...

Ceramic Matrix Composites (CMCs) are anticipated for use in aeronautical engines. Expected lifetimes in service conditions that are of thousands of hours are unattainable during laboratory tests. The objective of this paper is to propose an Acoustic Emission (AE) based approach to lifetime prediction for CMCs. The energy of AE sources is extracted...

This paper discusses the tensile resistance of an impact-damaged SiC/SiC based ceramic composite. As-received and impact-damaged specimens were subjected to static fatigue tests at 650°C and 450°C and to monotonous tensile tests at room temperature. Damage induced during the tensile and fatigue tests was characterized by the evolution of linear den...

Silicon carbide‐based fibers have been shown to be sensitive to delayed failure at temperatures Hi Nicalon SiC‐based filaments in the intermediate temperature range where creep is ineffective. Statistical distributions of rupture times under constant and identical stresses were determined from static fatigue tests on single filaments at 500°C and 8...

With contributed papers from the 2011 Materials Science and Technology symposia, this is a useful one-stop resource for understanding the most important issues in the processing and properties of advanced ceramics and composites. Logically organized and carefully selected, the articles cover the themes of the symposia: Innovative Processing and Syn...

Acoustic emission-based approach for lifetime prediction of CMCs during static fatigue tests at high temperature. Ceramic matrix composites (CMCs) are promising materials for high temperature structural applications, such as new generations of civil aircraft engines. Expected lifetimes under service conditions are of tens of thousands of hours, wh...

The present paper investigates glass fibre flaw size distributions. Two commercial fibre grades (HP and HD) mainly used in cement-based composite reinforcement were studied. Glass fibre fractography is a difficult and time consuming exercise, and thus is seldom carried out. An approach based on tensile tests on multifilament bundles and examination...

The present paper investigates large sets of ceramic fibre failure strengths (500 to 1000 data) produced using tensile tests on tows that contained either 500 or 1000 filaments. The probability density function was determined through acoustic emission monitoring which allowed detection and counting of filament fractures. The statistical distributio...

IntroductionMaterial and Experimental ProcedureResults and DiscussionConclusion Acknowledgement

The present paper investigates glass fibre flaw size distributions. Two commercial fiber grades (HP and HD) mainly used in cement-based composites reinforcement were studied. Glass fibre fractography is a difficult and time-consuming exercise, thus seldom carried out. An approach based on tensile tests on multifilament bundles and examination of fi...

The present paper proposes a method of virtual testing with a view to investigating the local response of tows within textile ceramic matrix composite (CMC) under various loading conditions. The method was developed on 2D woven SiC/SiC composites. It capitalizes on knowledge on mechanical damage phenomenology and data established in previous works....

IntroductionExperimental Procedure: AE Experiments and Description of the AE SignalPattern Recognition TechniquesResults and DiscussionConclusion Acknowledgments

Ceramics need to be reinforced because of their inherent brittleness and lack of reliability. Only continuous fibers are able to arrest the cracks through deflection at fiber-matrix interfaces. Only those fibers that can withstand the high temperatures required by composite processing (>. 1000. °C) without significant damage can be used. Efficiency...

Ceramic matrix composites (CMCs) are promising materials for high temperature structural applications, such as new generations of civil aircraft engines. Expected lifetimes under service conditions are of tens of thousands of hours, which make them unattainable using laboratory tests. Thus, the present paper proposes an approach to lifetime predict...

Many inorganic fibers are sensitive to subcritical crack growth activated by the environment. Failure occurs even though the applied stress is much smaller than the fracture stress. This mechanism has been extensively investigated on ceramics, glasses and glass fibers, essentially at room temperature, and has recently been shown in SiC-based fibers...

The present paper proposes a multiscale model of the mechanical behaviour of woven composite materials. The DMD model is based on a physical description of the reinforcement geometry of the material and the damage mechanisms. The model is applied to a woven-ceramic-matrix composite material and its predictive capabilities are investigated.