Fracture strength woods

Stanley-Wood, N. Sarrafi, M. (1988) Variations in, and relationships of surface area, internal angle of friction and compact diametral fracture strength with degree of compaction. Particle Particle Systems Characterisation, 5(4), 186-192. 

The word "composites" has a modern ring. But using the high strength of fibres to stiffen and strengthen a cheap matrix material is probably older than the wheel. The Processional Way in ancient Babylon, one of the lesser wonders of the ancient world, was made of bitumen reinforced with plaited straw. Straw and horse hair have been used to reinforce mud bricks (improving their fracture toughness) for at least 5000 years. Paper is a composite so is concrete both were known to the Romans. And almost all natural materials which must bear load - wood, bone, muscle - are composites. 

Wood Density (Mg m- j Young s modulus IGPol Strength (MPaj II to grain Fracture toughness (MPa m j ... 

Even plastics with fairly linear stress-strain curves to failure, for example short-fiber reinforced TSs (RPs), usually display moduli of rupture values that are higher than the tensile strength obtained in uniaxial tests wood behaves much the same. Qualitatively, this can be explained from statistically considering flaws and fractures and the fracture energy available in flexural samples under a constant rate of deflection as compared to tensile samples under the same load conditions. These differences become less as the... 

Gindl, W., Muller, U., and Teischinger, A., Transverse Compression Strength and Fracture of Spruce Wood Modified by Melamine-Formaldehyde Impregnation of Cell Walls, Wood and Fiber Science, Vol. 35, No. 2, 2003, pp. 239-246. 

In this chapter, an overview of performance characterization of FRP-wood bonded interfaces by conventional and fracture mechanics tests [4- 7] is presented. Modified ASTM standard tests (ASTM D2559 and D905) are first used to study the service performance and shear strength of the bond under moisture and/or mechanical loads, and then a contoured or tapered double cantilever beam specimen [8] is used to evaluate the fracture toughness of bonded interfaces under dry and wet conditions and cyclic loading. 

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