New peak shear strength criteria for anisotropic rock joints

The fractal characteristics of a series of fractured AISI 4340 steel specimens were studied experimentally by means of vertical sections through the fracture surface. Extensive fractal data have been generated for both the fracture surfaces and their profiles. Fractal plots for the irregular profile curves differ significantly from those of the infinitely subdivisible curves with “self-similarity” as postulated by Mandelbrot. Instead of a linear fractal curve and constant fractal dimension D , we find a reversed sigmoidal curve (RSC) and variable D . Because of the inadequacies of the linear Richardson fractal equation, we have developed an alternative procedure whereby constant slopes β and γ are obtained from the RSCs for both profiles and surfaces respectively. Since a fractal equation for surfaces apparently does not exist, we propose one that parallels the Richardson equation for profiles. Slopes from the RSCs are related to the new constant fractal dimensions D β and D γ in the modified fractal equations for profiles and fracture surfaces. Some insight into the physical nature of the fractal dimension is afforded by its close similarity to fracture roughness parameters that have simple physical meanings. It is believed that the results of the extensive study may have general validity for the irregular complex curves and surfaces of nature.

https://popups.ulg.ac.be/0351-580x/index.php?id=2985&file=1&pid=2965

Fractals in fractography

Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities.

/pdf/dental-implant-systems-3fx6kzjx3z.pdf

Dental Implant Systems

Fractal analysis of topographic data by the patchwork method

https://pharmahub.org/resources/28/download/roughness_model_for_particle_adhesion.pdf

H.Y. Wen

Papers

Fractal-based characterization of surface texture