Download BE105_9_slug_mucus

Figure 1
F
shear stress, t
= force/area
shear strain, g
= angular
deflection
g
A
Small angle approximations:
sin g ~ g
tan g ~ g
thus, strain = y/x
shear modulus:
viscosity:
Figure 2
Figure 3
Figure 4
r
d
slope, m
angular velocity = wr
thickness, d = mr
shear strain = wr/mr = w/m
Rube Goldberg (1883-1970)
Figure 5
Low strain, low strain rate
Hookian
behavior
Figure 6
High strain, high strain rate
Hysteresis
Figure 7
Gt/Go = 1
purely elastic material
lack of linearity implies
multiple time constants
Figure 7
At low strain/strain rate
slime dominated by
elastic Modulus, G’
Figure 9
Key figure: slime undergoes solid to liquid transition at critical stress
healing
healing
Figures 10, 11
Yield stress and
flow stress
increase with
strain rate…
slope =
viscosity
…but ratio
remains constant.
Figure 12
after long healing
after short healing
Figure 14
time course
of healing process
liquifying
here
solidiifying
here