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38th International Conference on Advanced Ceramics and Composites (ICACC), Daytona Beach, FL, JAN 26-31, 2014; International audience; The low density and the high tensile strength of Ceramic Matrix Composites (CMC) make them a good technical solution to design aeronautical structural components. To fully understand damage mechanisms and be able to design components, its behavior has to be analyzed during fatigue tests. The aim of the present study is to compare behavior of this composite under static and cyclic loading. Tests are realized under the same conditions of temperature and maximal load levels in order to determine the effects of cycles on the sequence of damage mechanisms. Hence the evolution of mechanical parameters is analyzed. Nevertheless the complexity of mechanisms and duration of tests make the use of complementary damage indicators necessary. Different approaches based on acoustic emission can be taken into consideration in order to quantify damage along the tests. In this case the analysis of acoustical energy is studied by comparing to the evolution of strain energy. This method enables to point out different damage levels during tests.

Mechanical Behavior and Performance of Ceramics and Composites Symposium during the 36th International Conference and Exposition on Advanced Ceramics and Composites (ICACC), Daytona Beach, FL, JAN 22-27, 2012; International audience; 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 degrees C and 450 degrees C and to monotonous tensile tests at room temperature. Damage induced during the tensile and fatigue tests was characterized by the evolution of linear density of acoustic emission events (AE) during unloading-reloading cycles. Results of tensile tests at room temperature show the material impact insensitivity and the analysis of AE signals has demonstrated efficiency for proper investigation of damage evolution in the impacted specimens. During fatigue at 450 degrees C, 650 degrees C and under 80 MPa, both impact-damaged and as-fabricated samples survived 1000 hours. Residual strengths indicated insensitivity to impact damage. At 650 degrees C, damage evolution seemed to slow down from matrix self-healing.

Mechanical Behavior and Performance of Ceramics and Composites Symposium / 35th International Conf and Exposition on Advanced Ceramics and Composites, Daytona Beach, FL, JAN 23-28, 2011; International audience; The control of damage is a key factor for the durability and reliability of parts in service. Sound identification of damage mechanisms and kinetics is an important issue with a view to predicting remaining lifetime. For that purpose, analysis of acoustic emission (AE) is an interesting and powerful tool. Damage of fiber reinforced ceramic matrix composites involves several phenomena at various length scales including matrix cracking, fiber debonding, fiber failures. The objective of the present paper is to propose a quantitative approach to damage identification based on signal analysis by pattern recognition. An unsupervised classification method was used to differentiate the signals generated during reference fatigue tests performed on C/SiC samples at high temperature. Each class of signals was then associated to relevant damage mode. A library of signals was then used to identify the damage modes generated during fatigue tests performed at various temperatures (supervised classification method).