Peak compression force

Control chart is a simple graph of peak compression force vs. time. Each point on the chart corresponds to the average of N tablets made, with N ranging from 1 to several revolutions. The horizontal lines would indicate the control limits. 

PEAK COMPRESSION FORCE QUANTITATIVE ANALYSIS Crushing Strength vs. Pmax... 

The explanted bone samples should be tested intact to estabhsh reference mechanical properties [78]. Loads should be appHed in a manner that minimizes focal loading of the specimen, so that accurate, representative material properties are measured. Preconditioning the specimens by cycHc loading, over several complete load-unload cycles, to a peak compressive force of approximately one average body weight (70 kg) is reasonable to do. This technique tends to smooth out variabdity in the data, and increases the likelihood of obtaining reproducible data. 

Further, some parameters can be directly read from the curves. The peak offset time of eccentric tableting machines is defined as the time difference between maximum displacement and maximum compression force [101,103]. 

When the average tablet hardness is plotted against the average compression peak force, we get the so-called compactibility profile that allows us to compare different formulations or different processing speeds. Referring to Fig. 8, which formulation is better Well, formulation No. 2 makes harder tablets for the same compression force, and this would mean less wear and tear on the production press is required to achieve desired hardness. On the other hand, if the hardness tolerance limits are exceptionally narrow, the steeper slope of formulation No. 2 may be a detriment. 

Otherwise, a similar upshift of 10-15 cm" was observed in the Raman spectra of poly(butadiene)-MWNT composites [67], The CH-ti interactions observed between nanotube and polymer are stronger than that of the n-n interactions observed between nanotube bundles, resulting in a restriction of the C-C bond vibrations and a corresponding upshift of the Raman signal. A 17 cm" upshift in G-band Raman signal of MWNTs embedded in melt-blended polyethylene-MWNT composites and the evolution of a shoulder to this peak were attributed to compressive forces exerted on the MWNTs by polyethylene chains following intercalation into MWNT bundles. So, the proposed compression-induced effect on MWNT Raman G-band position appears to be consistent with the results obtained for rrP3HT-MWNT composites. 

Another interesting feature is that although the strength falls, and the peak values of the compression relax for higher exchange times, the internal tension increases monotonically. This implies that the rate of penetration of ions is such that despite the relaxation, the summation of the compressive stress, across the cross-section increases, i.e., the compressive force increased. 

Modelling of the tme contact area between surfaces requires consideration of the defonnation that occurs at the peaks of asperities as they come into contact with mating surfaces. Purely elastic contact between two solids was first described by H Hertz [7], The Hertzian contact area (A ) between a sphere of radius r and a flat surface compressed under nonnal force N is given by... 

Microindentation hardness normally is measured by static penetration of the specimen with a standard indenter at a known force. After loading with a sharp indenter a residual surface impression is left on the flat test specimen. An adequate measure of the material hardness may be computed by dividing the peak contact load, P, by the projected area of impression1. The hardness, so defined, may be considered as an indicator of the irreversible deformation processes which characterize the material. The strain boundaries for plastic deformation, below the indenter are sensibly dependent, as we shall show below, on microstructural factors (crystal size and perfection, degree of crystallinity, etc). Indentation during a hardness test deforms only a small volumen element of the specimen (V 1011 nm3) (non destructive test). The rest acts as a constraint. Thus the contact stress between the indenter and the specimen is much greater than the compressive yield stress of the specimen (a factor of 3 higher). 

The distance between chemically bound atoms in many molecules is shorter than the sum of the radii of the same atoms when free, and the specific volume of the compound may be actually smaller than the total covolume of its gaseous products. If, as seems plausible, the drastic compression within the detonation front ruptures chemical bonds, many atoms suddenly expand, exerting forces like those by which solids resist compression. Such forces could result in a spike pressure much higher than the peak pressure of the non-reactive shock front, exert a brisant effect on the surroundings, and expedite the progress of the detonation wave. This view accords with observations of cases in which... 

The major use of the instrumented press in the operations or production area is for tablet weight monitoring and control. Early research in this field was able to show that the measured force of compression was proportional to the mass of material in the die cavity. This, of course, led to systems that could monitor the uniformity of the peak heights measure, send a signal to a servo motor on the press to adjust the weight control if necessary, and finally turn off the press or... 

The most common parameters derived from the TPA curve are shown in Table H2.3.1 (Friedman et al., 1963 Bourne, 1968). The peak force during the first compression cycle is defined as hardness. Fracturability (originally called brittleness) is defined as the force at the first significant break in the curve during the first compression cycle. The ratio of the positive force area during the second compression cycle to that during the first compression... 

Szczesniak, A.S., et al. 1970. Behavior of different foods in the standard shear compression cell of the shear press and the effect of sample weight on peak area and maximum force. J. Texture Studies 1 356-378. 

Only eccentric machine data allow us to calculate the R value (maximum upper punch force/maximum lower punch force), which is an indication of friction. They also allow us to calculate the time difference between the maximum upper punch force and the maximum lower punch force. Only dwell time and the minimum force during the dwell time can be calculated for rotary tableting machine data. The rise time of rotary machines is defined as the time during the compression phase, and peak offset time is defined as the time difference between maximum pressure and vertical alignment of the punches. Further the inflection points during the compression and decompression phases are mostly only calculated for rotary machine data. 

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