DVVA II 4000
Appendix B
400-42803-01 (Rev B) - July 2017
B-5
a, b, and c =
material characteristic constants derived from a nonlinear fit of the equation.
The pore fraction (1-D) is equal to the void ratio
, which is the ratio of the volume of the
voids V
v
to the volume of the solid sample V
S
. Also called the porosity.
The Heckel* equation is the solution to a first order reaction,
where the rate con-
stant,
k
, is equal to
. The standard Heckel equation results from setting the exponent
b
to unity.
Wu
The Wu equation is given by:
where
e
= void ratio
e
0
= void ratio at P=0
P
= applied pressure
a, b = constants
References
The Kawakita, Heckel, and Cooper-Eaton equations are discussed in the following:
1. Kmio Kawakita and Yuhbun Tsutsumi, “A Comparison of Equations for Powder
Compression,”
Bulletin of the Chemical Society of Japan
, 39, 1364-1368 (1966).
2. Patel and Patel, “Overview of Phenomenological Equations for Powder Compaction Study,”
International Journal of Pharmaceutical Research
, 1(1), 2-15 (2009).
3. Tansel Comoglu, “An Overview of Compaction Equations,”
Ankara Ecz. Fak. Derg. J. Fac,
Pharm, Ankara
, 36(2), 123-133 (2007).
The Bauer and Wu equations are discussed in:
4. D. Kolymbas,
Constitutive Modelling of Granular Materials
, Springer (1999).
V
V
V
S
------
dD
dP
-------
k
1
D
–
=
a b P
b
1
–
1
e
---
1
e
0
-----
aP
b
+
=
V
v
/V
S
Summary of Contents for DVVA II 4000
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