Acoustic emission during powder compaction is observed to monitor the compaction process by the AE parameters. Discontinuous type AE produced during powder compaction is due to the successive periodic shear-yields that occurred in the compressed powder bed.
The AE cumulative count was proportional to the fractional volume compaction of the powder bed, and the AE cumulative count-compression strain relationship depends on the compressibility of the powder bed as in the compression stress-strain relationship.
The AE count rate relates to the behavior of particles undergoing compaction, and becomes lower as movement of particles is easier under low stress. These AE parameters are affected by the initial porosity of the bed, the powder property and the loading rate in powder compaction. The high frequency components in the frequency spectrum of the AE wave increase gradually as confined stress in the bed increases, and the frequency components also relate closely to the powder property and compression condition of the powder bed.
View full abstract