Fatigue limit

About: Fatigue limit is a(n) research topic. Over the lifetime, 20489 publication(s) have been published within this topic receiving 305744 citation(s). The topic is also known as: endurance limit & fatigue strength.

Surface modification of titanium, titanium alloys, and related materials for biomedical applications

Abstract: Titanium and titanium alloys are widely used in biomedical devices and components, especially as hard tissue replacements as well as in cardiac and cardiovascular applications, because of their desirable properties, such as relatively low modulus, good fatigue strength, formability, machinability, corrosion resistance, and biocompatibility. However, titanium and its alloys cannot meet all of the clinical requirements. Therefore, in order to improve the biological, chemical, and mechanical properties, surface modification is often performed. This article reviews the various surface modification technologies pertaining to titanium and titanium alloys including mechanical treatment, thermal spraying, sol–gel, chemical and electrochemical treatment, and ion implantation from the perspective of biomedical engineering. Recent work has shown that the wear resistance, corrosion resistance, and biological properties of titanium and titanium alloys can be improved selectively using the appropriate surface treatment techniques while the desirable bulk attributes of the materials are retained. The proper surface treatment expands the use of titanium and titanium alloys in the biomedical fields. Some of the recent applications are also discussed in this paper.

Fatigue of structures and materials

Abstract: Preface. Frequently used symbols, acronyms and units. 1. Introduction to Fatigue of Structures and Materials. Part 1: Introductory Chapters on Fatigue. 2. Fatigue as a Phenomenon in the Material. 3. Stress Concentrations at Notches. 4. Residual Stresses. 5. Stress Intensity Factors of Cracks. 6. Fatigue Properties of Materials. 7. The Fatigue Strength of Notched Specimens. Analysis and Predictions. 8. Fatigue Crack Growth. Analysis and Predictions. Part 2: Load Spectra and Fatigue Under Variable-Amplitude Loading. 9. Load Spectra. 10. Fatigue under Variable-Amplitude Loading. 11. Fatigue Crack Growth under Variable-Amplitude Loading. Part 3: Fatigue Tests and Scatter. 12. Fatigue and Scatter. 13. Fatigue Tests. Part 4: Special Fatigue Conditions. 14. Surface Treatments. 15. Fretting Corrosion. 16. Corrosion Fatigue. 17. High-Temperature and Low-Temperature Fatigue. Part 5: Fatigue of Joints and Structures. 18. Fatigue of Joints. 19. Fatigue of Structures. Design Procedures. Part 6: Arall and Glare, Fiber-Metal Laminates. 20. The Fatigue Resistance of the Fiber-Metal Laminates Arall and Glare. Subject index.

Toward a quantitative understanding of mechanical behavior of nanocrystalline metals

Abstract: Focusing on nanocrystalline (nc) pure face-centered cubic metals, where systematic experimental data are available, this paper presents a brief overview of the recent progress made in improving mechanical properties of nc materials, and in quantitatively and mechanistically understanding the underlying mechanisms. The mechanical properties reviewed include strength, ductility, strain rate and temperature dependence, fatigue and tribological properties. The highlighted examples include recent experimental studies in obtaining both high strength and considerable ductility, the compromise between enhanced fatigue limit and reduced crack growth resistance, the stress-assisted dynamic grain growth during deformation, and the relation between rate sensitivity and possible deformation mechanisms. The recent advances in obtaining quantitative and mechanics-based models, developed in line with the related transmission electron microscopy and relevant molecular dynamics observations, are discussed with particular attention to mechanistic models of partial/perfect-dislocation or deformation-twin-mediated deformation processes interacting with grain boundaries, constitutive modeling and simulations of grain size distribution and dynamic grain growth, and physically motivated crystal plasticity modeling of pure Cu with nanoscale growth twins. Sustained research efforts have established a group of nanocrystalline and nanostructured metals that exhibit a combination of high strength and considerable ductility in tension. Accompanying the gradually deepening understanding of the deformation mechanisms and their relative importance, quantitative and mechanisms-based constitutive models that can realistically capture experimentally measured and grain-size-dependent stress–strain behavior, strain-rate sensitivity and even ductility limit are becoming available. Some outstanding issues and future opportunities are listed and discussed.

Mechanical biocompatibilities of titanium alloys for biomedical applications.

Abstract: Young's modulus as well as tensile strength, ductility, fatigue life, fretting fatigue life, wear properties, functionalities, etc., should be adjusted to levels that are suitable for structural biomaterials used in implants that replace hard tissue. These factors may be collectively referred to as mechanical biocompatibilities. In this paper, the following are described with regard to biomedical applications of titanium alloys: the Young's modulus, wear properties, notch fatigue strength, fatigue behaviour on relation to ageing treatment, improvement of fatigue strength, fatigue crack propagation resistance and ductility by the deformation-induced martensitic transformation of the unstable beta phase, and multifunctional deformation behaviours of titanium alloys.

On the mechanical behaviour of titanium alloy TiAl6V4 manufactured by selective laser melting: Fatigue resistance and crack growth performance

Abstract: Direct manufacturing (DM), also referred to as additive manufacturing or additive layer manufacturing, has recently gained a lot of interest due to the feasibility of producing light-weight metallic components directly from design data. Selective laser melting is a very promising DM technique for providing near net shape components with relative high surface quality and bulk density. Still, process induced imperfections, i.e. micron sized pores and residual stresses upon processing, need to be considered for future application, e.g. in the aerospace and biomedical sectors. Moreover, fatigue loading is a critical scenario for such components and needs to be investigated thoroughly. Consequently, the current study aims at establishing sound microstructure–defect–property relationships under cyclic loading for a TiAl6V4 alloy processed by selective laser melting. Employing mechanical testing, hot isostatic pressing, electron microscopy and computer tomography it is shown that the micron sized pores mainly affect fatigue strength, while residual stresses have a strong impact on fatigue crack growth.