PSI - Issue 14

Sukamal Adhikary et al. / Procedia Structural Integrity 14 (2019) 127–133 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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mass of 120 gm. Complete set of practical results are compiled as Table 2. Variation of charge mass and applied load both are reflected in the Table. During analysis of the results, it was deliberated that an equation needs to be developed which would ascertain the length of pellet with variation of charge mass and applied load at constant dwell time of 15 seconds. The equation can be represented as: L = 9.035 + 0.39 *W – 5.53*ln F (1) In the equation, L is the length of pellet in mm, W is the charge mass in gm and F is the applied load in tons. The actual density obtained through practical calculation vis a vis the calculated values of density are tabulated in Table 2.

Table 2. Comparison of calculated density and practically calculated density Charge Mass (gm) Applied Load (F tons) Calculated Density (gm/cc)

Practically Calculated Density(gm/cc)

Deviation

% Deviation

40 60 80

06 06 06 06 06 06 06 01 02 03 04 05 06 07 08 09

1.636 1.605 1.589 1.580 1.574 1.570 1.567 1.254 1.363 1.436 1.492 1.539 1.580 1.616 1.649 1.679

1.489 1.532 1.551 1.579 1.587 1.565 1.556 1.242 1.338 1.423 1.475 1.525 1.579 1.620 1.663 1.649

0.147 0.073 0.038 0.001 -0.013 0.005 0.011 0.012 0.025 0.013 0.017 0.014 0.001 -0.004 -0.014

9.87 4.76 2.45 0.06 -0.81 0.32 0.71 0.97 1.87 0.91 1.15 0.92 0.06 -0.25 -0.84 1.82

100 120 140 160 100 100 100 100 100 100 100 100 100

0.03

The effect of variation of charge mass on density of pellets formed is less significant compared to variation in applied load (Table 2). The density variation for variation of charge mass from 40 gm to 160 gm compacted at constant applied load of 6 tons for a fixed duration of 15 sec is only 4.5% (1.489-1.556 gm/cc). As mass of pellet is increased, length of compaction increases. The effect of pressing by plunger from the top on loose powder is felt at a certain distance only. It is natural to have reduction in density with increase in charge mass powder beyond an optimum charge mass. It is reflected well in practically calculated density. It increases till a particular height of compacted piece and then the density reduces. However, calculated density failed to depict this trend. In this case, the trend shows a continuously decreasing graph. On the other hand, the variation of density with applied load is significantly large at 33.9% (1.242-1.663 gm/cc). The density progressively increased with increase in loading owing to reduction in inter-particle spaces. The deformation/fracture of particles with higher loading resulted in more effective compaction. The maximum compaction for 50 mm diameter pellets and 100 gm of charge mass is attained at 8 tons of load. With further increase in loading, there is no further increase in density and the sight decrease in density may be accepted as an aberration. However, in the case of variation of loading, the calculated value of density and the practically calculated value of density are in close proximity. It may also be observed from Table 2 that the variation of density comparatively reduces between the 100 120 gm of charge mass and also 6-8 tons of applied load. 4. Conclusion

The salient observations of this study may be listed as follows: