The stress concentrations that occur at inclusions due to thermal expansion and elastic modulus mismatch are discussed and the stress intensity factors at interface cracks that result from these stresses are calculated. It is shown that conservative failure prediction based on an equivalence between inclusion size and crack size is usually acceptable if the shear modulusμ or thermal expansion coefficientα for the inclusion is larger than the matrix values. If, however,μ andα are smaller for the inclusion than the matrix, extensive cracking can develop at the inclusions which may lead to premature failure. For this case the only effective methods for failure prediction are techniques which give directly the maximum stress intensity factor, i.e., proof testing and/or acoustic emission.

The role of inclusions in the fracture of ceramic materials

Adhesion of bioactive glass coating to Ti6Al4V oral implant

Assessment of relative efficacy of different materials in manufacture of archaeological ceramics; contribution of different materials and techniques to vessel durability. Potter's, user's, and scientist's viewpoints. Examines resistance to impact, thermal shock, etc. -- AATA

The use of materials science techniques in the study of pottery construction and use

Publisher Summary This chapter discusses the use of materials science techniques in the study of pottery construction and use. It focuses on the use of materials-science characterization studies in two other spheres of research: (1) assessment of the relative efficacy of different materials in the manufacture of archaeological ceramics and (2) the contribution of different materials and techniques to vessel durability as measured through simulated-use techniques. The assessment of the contribution of different materials and manufacturing techniques to the performance of archaeological ceramics has a long history in archaeological research. Only recently has an interest in the mechanical performance of ceramics begun to receive wider attention in the field due to growing concern with the broader socioeconomic context of the potter and use of pots as tools. The chapter presents a number of basic materials-science concepts and analytic approaches, particularly in the study of mechanical strength, reviews their use in archaeological studies of pottery production and use, and suggests directions for future research. Some of the techniques discussed in this chapter have been used widely by archaeologists; some have never been used by archaeologists. All have the potential to provide crucial answers to questions about the function of prehistoric ceramics and the technology and organization of ceramic production.

The Use of Materials Science Techniques in the Study of Pottery Construction and Use

In the present work the acoustic emission (AE) technique is applied to examine some aspects influencing concrete failure in compression. By monitoring a structure by means of the AE technique, it proves possible to detect the occurrence of stress-induced cracks. Cracking, in fact, is accompanied by the emission of elastic waves that propagate within the bulk of the material. These waves can be received and recorded by transducers applied to the surface of the structural elements. This technique can be used for diagnosing structural damage phenomena. The current paper presents a mixed experimental and theoretical approach to evaluate the energy density dissipated during compression at each value of strain. Through this method, the two semi-empirical Gutenberg–Richter (GR) laws, well-known in seismology, are verified, the fractal interpretation results of which are very close to the essence of the AE phenomenon. Furthermore, the mentioned approach allows the parameter of ‘magnitude’ to be identified, appear...

https://staff.polito.it/alberto.carpinteri/papers/CARPINTERI_2006_N.413_MCR.pdf

Richter's laws at the laboratory scale interpreted by acoustic emission

Acoustic emission testing has found many uses in recent years and new applications are constantly being uncovered. The interesting areas for application lie in failure prediction and the characterization of the microscopic processes of yielding and fracture, and the macroscopic processes of slow crack growth and onset of fast crack propagation. This paper has described these applications and emphasized that the total counts and count rate depend on the energy released per event and the density of events per unit of deformation. Where models are presented, they should be regarded as first order approximations which await confirmation.

A. S. Tetelman

Papers

Failure Prediction in Brittle Materials Using Fracture Mechanics and Acoustic Emission