Drying Induced Stresses

The evidence of a correlation between the drying induced stresses and the AE is illustrated on the cylindrical kaolin sample under convective drying. Although the AE method enables us to point out the period in which the stresses reach maximal values, we are not able yet to assess the magnitude of these stresses. 

The basic statement of this paper is that the magnitude of the drying induced stresses depends on the moisture distribution. The greater the non-uniformity in the distribution, the greater stresses arise in the dried body. 

Kowalski, S.J. and Rajewska, K. (2002) Drying induced stresses in elastic and viscoelastic saturated materials, Chemical Engineering Science 57, 3883-3892... 

Increased throughput by using air with lower humidity to enhance drying rate with little impact on drying-induced stresses. 

Our previous studies of stresses by convective drying show that the main reason for the drying-induced stresses is a nonuniform material shrinkage as a result of nonuniform distribution of moisture and/or temperature. 

The qualitative difference in distribution of temperature, moisture content, and the drying-induced stresses in materials under convective and microwave drying is illustrated on the examples of cylindrical kaolin samples, which are assumed here to be elastic or viscoelastic. 

Mihoubi D. and BeUagi A., Drying induced stresses during convective and combined microwave and convective drying of saturated porous media, Drying Technology, 2009,27(IS), 851-856. 

S. J. Perstrelski, T. Arakawa, and J. F. Carpenter, Separation of freezing and drying-induced denaturation of lyophilized proteins using stress-specific stabilization. II. Structural studies using infrared spectroscopy, Arch. Biochem. Biophys., 303, 465... 

The obtained results indicate that the enhanced emission of AE occurrences takes place at the moments when the drying induced tensional stresses reach their maximum. One can state that the plot of total energy released during drying may serve for assessment of the destruction of the material during drying because discontinuities in this plot correspond to cracks occurring in the material. 

Carpenter, J.F. Prestrelski, S. Arakawa, T. Separation of freezing- and drying-induced denaturation of lyophilized proteins by stress-specific stabilization I. Enzyme activity and calorimetric studies. Arch. Biochem. Biophys. 1993, 303, 456 64. 

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