Compressibility, mechanical

R.A. Graham, Solids Under High-Pressure Shock Compression Mechanics, Physics and Chemistry, Springer-Verlag, New York, 1993. 

It has been a persistent characteristic of shock-compression science that the first-order picture of the processes yields readily to solution whereas second-order descriptions fail to confirm material models. For example, the high-pressure, pressure-volume relations and equation-of-state data yield pressure values close to that expected at a given volume compression. Mechanical yielding behavior is observed to follow behaviors that can be modeled on concepts developed to describe solids under less severe loadings. Phase transformations are observed to occur at pressures reasonably close to those obtained in static compression. 

Joshi A et al (2006) Functional compressive mechanics of a PVA/PVP nucleus pulposus replacement. Biomaterials 27(2) 176-184... 

In this the refrigerant vapor is compressed mechanically. Two-stage motor compressors are used mostly in freeze-drying systems. This compressor is installed in a screwed-on housing together with an electric motor. 

Rheological Properties. Rheological studies show that ammonia affects the compressive mechanical behavior of wood to a much higher extent than the tensile behavior (55,16). Since the compression strength is highly dependent on lignin content,... 

Mechanical Pressure This pressure is exerted by the punches of the ultrasound-assisted tableting machine. This is the main compression mechanism when low ultrasonic energies are employed (below 25 J in the mixtures studied by... 

Brodholt J. P. (2000) Pressure-induced changes in the compression mechanism of aluminous perovskite in the Earth s mantle. Nature 407, 620-622. 

Methods to determine compression behavior can be either static (dead load) or based on constantly increasing compression. Several methods for the determination of volume-reduction mechanisms due to compression or compaction have been presented in the literature the most relevant ones are described in the following sections. Compression mechanisms can be approached from different tests such as the Brazilian test, uniaxial confined compression test, cubical triaxial tester, HHP method, and the unconfined... 

Yan et al. (2001), studied how bulk density of instant nonfat milk, spray-dried coffee, and freeze-dried coffee was affected by HHP processing times, particle size, and water activity. The experimental curves for each powder in Figure 10 show that the powder bulk density increased as the pressure increased but remained constant after the pressure reached a critical value of 207 MPa for spray-dried coffee and 276 MPa for freeze-dried coffee at different water activities. The final compressed densities were not significantly different. When the pressure is higher than the critical value, there are no void spaces between the agglomerates or primary particles even the primary particles are crushed, leaving no open or closed pores within. Bear in mind, it is assumed that the compression mechanisms are the same as those in the confined uniaxial compression tests. 

Both compression mechanisms in fine and agglomerated powders are influenced by particle size and size distribution, particle shape, and surface properties. Potato starch and powdered milk have demonstrated that powders will crackle during compression, that is, change in volume... 

A further study was conducted to study the effect of compression temperature on the consolidation mechanism of the polymorphs of chlorpropamide [51]. The effect of environmental temperature on the compression mechanism of the A and C forms of chlorpropamide was investigated with an eccentric type tableting machine with two load cells and a noncontact displacement transducer. The temperature of the sample powders was controlled at 0 and 45°C, and these were compressed at almost 230 MPa. The tableting dynamics were evaluated by Cooper and modified Heckel analyses. The results suggest that particle... 

The principle radial compression has successfully solved the problems of packed-bed uniformity and of bed stability. However, radial compression has its Umitations in the strength of the partied If excessive radial compression is applied, and particles start to fracture, the homogeneity of the bed is lost. This sets an upper limit to the hydraulic compression that can be applied to soft or fragile particles. Since the column backpressure cannot exceed the compression pressure, this limits the applicability of hydraulic compression. Mechanical compression does not suffer from this problem, but it is more difficult to achieve a uniform compression, and therefore a good implementation of... 

HEAT OF COMPRESSION - Mechanical energy of pressure changed into energy of heat. 

The human spinal cord is mechanically strong enough to withstand torsion and compression mechanical stresses. 

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