Materials science toughness

The first detailed book to describe the practice and theory of stereology was assembled by two Americans, DeHoff and Rhines (1968) both these men were famous practitioners in their day. There has been a steady stream of books since then a fine, concise and very clear overview is that by Exner (1996). In the last few years, a specialised form of microstructural analysis, entirely dependent on computerised image analysis, has emerged - fractal analysis, a form of measurement of roughness in two or three dimensions. Most of the voluminous literature of fractals, initiated by a mathematician, Benoit Mandelbrot at IBM, is irrelevant to materials science, but there is a sub-parepisteme of fractal analysis which relates the fractal dimension to fracture toughness one example of this has been analysed, together with an explanation of the meaning of fractal dimension , by Cahn (1989). 

Hill, R. G., Wilson, A. D. Warrens, C. P. (1989). The influence of poly(acrylic acid) molecular weight on the fracture toughness of glass-ionomer cements. Journal of Materials Science, 24, 363-71. 

Figure 5.28 Stress-strain diagram showing (1) modulus, (2) yield strength, (3) ultimate tensile strength, (4) ductility, and (5) toughness. Note the use of proof stress in determination of yield stress. Reprinted, by permission, from J. F. Shackelford, Introduction to Materials Science for Engineers, 5th ed., p. 190. Copyright 2000 by Prentice-Hall, Inc.

X. Li, PR. Moulinie, and J.P. Mason, Thermoplastic molding composition having improved toughness at low temperatures and surface appearance, US Patent 7524898, assigned to Bayer Material Science LLC (Pittsburgh, PA), April 28, 2009. 

Rice, R.W., Wu, C.C. and Mckinney, K.R., Fracture and fracture toughness of stoichiometric Mg A1204 crystals at room temperature , Journal of Materials Science, 1996 31 1353-60. 

Applying fracture mechanics techniques to characterize brittle materials has become an important subfield of materials science, and a reasonable understanding of the relation between toughness, composition, and microstructure is available. Silicate glasses have toughness values of 0.7-1,0 MPam, alumina ceramics values of 4-5 MPam, and glass ceramics values of 1-4 MPam, (the fracture toughness of metals is often > 50 MPam "),... 

What does this mean to all of us assembled here First, a recognition needs to exist that in all practical situations materials science is a tough ball game - it cannot remain a phenomenological art if we are expected to warranty the performance. 

Jancar, J. Dibenedetto, A.T.(1995). Failure mechanics in ternary composites of polypropylene with inorganic fillers and elastomer inclusions Part II Fracture toughness. Journal of Materials Science, 30(9), 2438-2445, ISSN 1573-4803. 

Y.-W. Bao, C.-C. Liu, J.L. Huang, "Effects of residual stresses on strength and toughness of particle-reinforced TiN/Si3N4 composite Theoretical investigation and FEM simulation, Materials Science Engineering A, 434, 250-258, (2006). 

Hilling, W. B. Annual Review of Materials Science, Vol. 17 341-383, 1987, Strength and Toughness of Geramic Matrix Gomposites http //www.geo2tech.com/tech.html... 

It has been shown in various studies that biological materials can reach impressive architectures and mechanical properties by smart hierarchical assembly and interface design/ Yet, examples of successful transfer of the principles underlying such natural architectures into bio-inspired materials are still rather scarce. Designing materials that combine stiffness, toughness, and strength, as well as reach reasonable dimensions as one can find in nature, is still one of the major challenges in materials science and... 

Hing, R, Groves, G. W. (1972) The strength and fracture toughness of polycrystalline magnesium oxide containing metallic particles and fibres . Journal of Materials Science, 7 427-34. 

The fractal dimension as a quantitative measure of the irregularity of the objects may be applied in various fields of materials science. It has been shown that the self-similarity over two orders of magnitude occurs for fracture surfaces of tempered steel and alumina. A linear relation between the fractal dimension and fracture toughness for these materials was also proposed. 

Atkins, A. G., Intermittent bonding for high toughness/high strength composites. Journal of Materials Science, 1975. 10(5) 819-823. 

Chiang, C. R., Prediction of the fracture toughness of fibrous composites. Journal of Materials Science, 2000. 35(12) 3161-3166. 

B. Avishan, S. Yazdani, and S. H. Nedjad, "Toughness variations in nanostructured bainitic steels". Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing, 548, 2012 pp. 106-111. 

Hsieh, T.H., Kinloch, A.J., Masania, K., Lee, J.S., Taylor, A.C., Sprenger, S., 2010b. The toughness of epoxy polymers and fibre composites modified with rubber microparticles and silica nanoparticles. Journal of Materials Science 45, 1193—1210. 

Xu, S.A., Wang, G.T., Mai, YW., 2013. Effect of hybridization of liquid rubber and nanosilica particles on the morphology, mechanical properties, and fracture toughness of epoxy composites. Journal of Materials Science 48, 3546—3556. 

K. M. Liang, Evaluation by Indentation of Fracture Toughness of Ceramic Materials, J. of Materials Science, 25, p.207-214, (1990). 

During the last 30 years, advances in material science have led to the development of synthetic materials that have unique properties for medical applications. Metals, ceramics, polymers, composites are the main classes of synthetic biomaterials. Metals and their alloys have been used in various forms as implants and for hard tissue repair (e.g., dental implants, joint replacement, fracture plates, screws, pins). They are mechanically strong, tough and ductile. They can be readily fabricated and sterilised. However, they may corrode in the biological media, their densities are high and their mechanical properties mismatch with bone, which may result undesirable destruction of the surrounding hard tissues. 

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