Crushing strength

FIG. 20-79 Effect of pelleting pressure on axial crushing strength of compacted calcite particles of different sizes demonstrating existence of a critical yield pressure. Inset shows the effect of hardness on critical yield pressure. [Benhow, Enlargement and Compaction of Particulate Solids, Stanley-Wood (ed.), Butteixooiihs, 169 (1.9S3),]... 

Fig. 17.2. Tests which measure the fracture strengths of ceramics, (a) The tensile test measures the tensile strength, CTj. (b) The bend test measures the modulus of rupture, o , typically 1.7 x CTj. (<) The compression test measures the crushing strength, a, typically 15 x...

Figure 26.6 shows that the transverse crushing strength (T varies roughly as... 

For the two explosive loading systems used, the initial pressure wave into the powder is relatively low, varying from perhaps 1.5-4 GPa. In such cases the most relevant compression characteristic of the powder compact is its crush strength , i.e., the pressure required to compress the porous compact to solid density. In the simulations, this strength can be varied over a wide range with the P-a model. The wavespeed of the initial waves was modeled on the basis of shock-compression data on rutile at densities from 44% to 61% of solid density [74T02]. 

The influence of crush strength on mean-bulk temperature achieved in one-dimensional compression of powders has been extensively investigated... 

Fig. 6.8. The peak mean-bulk temperatures predicted in one-dimensional numerical simulation are investigated for powder compacts of different crush strengths. For the explosive loadings of the Bear fixtures, no difference in temperature is predicted for crush strengths up to about 2 GPa. This value is about that of the initial loading wave into the samples. Above that pressure the crush strength has a strong effect on temperature. The predicted behavior can be understood in terms of the various loading paths.

Interest in the use of syntactic foam as a shock attenuator led to studies of its static and dynamic mechanical properties. Particularly important is the influence of loading rate on stiffness and crushing strength, since oversensitivity of either of these parameters can complicate the prediction of the effectiveness of a foam system as an energy absorber. 

Rocksloh K, Rapp F-R, Abu Abed S, Mueller W, Reher M, Gauglitz G, Schmidt PC. Optimization of crushing strength and disintegration time of a high dose plant extract tablet by neural networks. Drug Dev Ind Pharm 1999 25 1015-25. 

With increasing particle size, the SA/V ratio and hence the reaction rate decreases, which is unfavourable, while the pressure drop, the crushing strength, and the manufacturing costs also decrea.se, which is favourable. At the same overall particle diameter the diffusion length decreases in the order ... 

Sphere> pellet > trilobe > hollow extrudate > wagon wheel/ minilith The definitive catalyst size selection will be a compromise between high reaction rate (small partiele, exotic shape), low pressure drop (large particle, exotic shape), large crushing strength... 

Granular and extruded carbon supports are stable to hydrothermal conditions as measured by crush strength unlike silica or alumina. There are certain metal oxides, such as mtile titania that are also stable. The data shown in Figure 34.5 shows the retention of original crush strength following 24 h soak in pH adjnsted... 

Figure 34.5. Crush strength of various supports after soaking for 24 h at 200°C in pH adjusted water.

Fig. 27 Methods of evaluating tablet crushing strength (a) bending or flexure strength (b) diametrical compression. (From Ref. 145.)...

Comparative reports in the literature confirm the necessity of employing some calibration procedure if results from testers are to be compared or reduced to actual units of force. This is particularly true where the information is being used to determine relationships between crushing strength to other tablet properties. 

One might anticipate that the crushing strength (F) of a tablet is a function of the pressure (P) employed during its compaction [134]. For example the following relationship may hold true ... 

The crushing strength of pipes should also be tested. There have been examples where pipes in landfills have actually collapsed and thus forced the site to stop operating. The ASTM D241241 is used to measure the strength of pipe materials. 

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