Mean strength

Kraft Process. The dominant chemical wood pulping process is the kraft or sulfate process. The alkaline pulping Hquor or digesting solution contains about a three-to-one ratio of sodium hydroxide, NaOH, and sodium sulfide, Na2S. The name kraft, which means strength in German,... 

Most ceramics (as we have seen) contain flaws holes and cracks left by processing, cracks caused by thermal stress, corrosion or abrasion. Even if there are no cracks to start with, differences in elastic moduli between phases will nucleate cracks on loading. And most of these flaws have a size which is roughly that of the powder particles from which the ceramic was made. If the flaw size can be reduced, or if samples containing abnormally large flaws can be detected and rejected, the mean strength of the ceramic component is increased. 

Increase mean strength (increasing size, using stronger materiais)... 

The Burchell model s prediction of the tensile failure probability distribution for grade H-451 graphite, from the "SIFTING" code, is shown in Fig. 23. The predicted distribution (elosed cireles in Fig. 23) is a good representation of the experimental distribution (open cireles in Fig. 23)[19], especially at the mean strength (50% failure probability). Moreover, the predicted standard deviation of 1.1 MPa con ares favorably with the experimental distribution standard deviation of 1.6 MPa, indicating the predicted normal distribution has approximately the correct shape. 

Pauling (1929) introduced the concept of mean strength of the bond (Si) as a ratio of the valence with coordination number. He also formulated the principle of electrostatic valence, which establishes that the sum of the mean bond strengths for a given coordination polyhedron (P) coincides with the valence state—i.e.. 

Type of admixture in 270 kg m Mean strength (N mm Standard deviation (N mm... 

Gives long fibers, therefore strong paper (kraft means strength in Swedish and German). 

Type of admixture in Mean strength Standard deviation... 

Consider a fiber that follows the strength distribution given by Eq. (10.2). We can obtain an expression for the mean strength as follows ... 

Substituting the value of =()8+ l)/j8, we have the mean strength given by... 

From the standard deviation and mean strength, we can arrive at the following expression for the coefficient of variation, /t, for this distribution... 

Term Mean strength Weibull modulus Pellet density ... 

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