Most ceramics show an increase of the crack growth resistance during crack propagation (R-curve behaviour). Reasons for such behaviour are bridging effects between opposite crack surfaces, phase transformations around the tip of a crack, and development of micro-cracking zones.This booklet predominantly deals with the bridging behaviour and the discussion of the observed effects in terms of the fracture mechanics weight function procedure.
This book is an evidence-based update on recent most significant advances in dental ceramics, specifically related to the relationships between composition, microstructure and mechanical behavior. Readers will find an introduction to the chemistry of dental ceramics as well as information about the technological progress and practical requirements restorative materials need to satisfy for long-lasting structural integrity. The book uses mechanistic approaches to address failure mechanisms from controlled experiments thus providing the tools for the application of sound research methodologies in the field. It is targeted for researcher and dentists interested in the field of dental ceramic materials and fracture mechanics.
Most storage materials exhibit phase changes, which cause stresses and, thus, lead to damage of the electrode particles. In this work, a phase-field model for the cathode material NaxFePO4 of Na-ion batteries is studied to understand phase changes and stress evolution. Furthermore, we study the particle size and SOC dependent miscibility gap of the nanoscale insertion materials. Finally, we introduce the nonlocal species concentration theory, and show how the nonlocality influences the results.
Fracture of storage particles is considered to be one of the major reasons for capacity fade and increasing power loss in Li-ion batteries. In this work, we tackle the problem by merging a coupled model of mechanical stress and diffusion of Li-ions with a phase field description of an evolving crack. The novel approach allows us to study the evolution of the Li concentration together with the initiation and growth of a crack in an arbitrary geometry and without presuming a specific crack path.
Bioceramics are an important class of biomaterials. Due to their desirable attributes such as biocompatibility and osseointegration, as well as their similarity in structure to bone and teeth, ceramic biomaterials have been successfully used in hard tissue applications. In this book, a team of materials research scientists, engineers, and clinicians bridge the gap between materials science and clinical commercialization providing integrated coverage of bioceramics, their applications and challenges. The book is divided into three parts. The first part is a review of classes of medical-grade ceramic materials, their synthesis and processing as well as methods of property assessment. The second part contains a review of ceramic medical products and devices developed, their evolution, their clinical applications and some of the lessons learned from decades of clinical use. The third part outlines the challenges to improve performance and the directions that novel approaches and advanced technologies are taking, to meet these challenges. With a focus on the dialogue between surgeons, engineers, material scientists, and biologists, this book is a valuable resource for researchers and engineers working toward long-lasting, reliable, customized biomedical ceramic and composites devices. - Edited by a team of experts with expertise in industry and academia - Compiles the most relevant aspects on regulatory issues, standards and engineering of bioceramic medical devices as inspired by commercial and clinical needs - Introduces bioceramics, their evolution and applications in hard tissue engineering and medical devices
This work furthers the overall understanding of a 3w-measurement, by considering previously unexamined macroscopic influence factors within measurement by Finite Element simulations (FES). Moreover, new measuring configurations are developed to determine (an)isotropic thermal conductivities of nanoscale samples. Since no analytic solutions are available for these configurations, a new evaluation methodology is presented to determine emergent thermal conductivities by FES and Neural Networks.
Water diffusing into silica surfaces gives rise for several effectson diffusion behaviour and mechanical properties. Water added to silica glass increases its specific volume so that the silica expands near the surface. Mechanical boundary conditions give rise for compressive “swelling stresses”. This fact provides a tool for the interpretation of many experimental observations from literature.
Water diffusing into silica surfaces gives rise for several effects on diffusion behaviour and mechanical properties. In a preceding booklet, we focused on diffusion and fiber strengths and deformations which were obtained by water soaking under external loading. In the present booklet we deal with results and interpretations of strength increase in the absence of applied stresses.
The main objective of this work is to significantly deepen the understanding of the material and the structural behaviour of continuous-discontinuous SMC composites, following a holistic approach to investigate microscopic aspects, macroscopic mechanical behaviour as well as failure evolution at the coupon, structure and component level. In addition, criteria to evaluate the effect of hybridisation are introduced and modelling approaches are presented and discussed.
Custom built setups were developed to investigate micro samples during quasistatic and cyclic testing in tension, compression and bending. Micro molded CuAl10Ni5Fe4-samples showed similar fatigue behavior compared to macroscopic samples due to both the sample size and microstructure being scaled down with the manufacturing process. Results from cyclic three-point bending tests on micro molded 3Y-TZP suggested that a minimum crack extension is necessary to develop cyclically degradable shielding.
