Biomedical Engineering Reference
In-Depth Information
Fig. 7.28
Loads and constrains of the first mechanical case of the calcaneus bone [
2
]
Fig. 7.29
Loads and constrains of the second mechanical case of the calcaneus bone [
2
]
movement (gait). The calcaneus bone is submitted to high tensile forces from the
Achilles tendon and the plantar fascia tendon. The talus bone distributes most of
the compressive forces to the navicular bone and the cuboide bone, constraining
the calcaneus bone movements. The pressures applied in the distinct natural
boundaries have the magnitude, distribution and orientation indicated in Fig.
7.29
.
The essential boundary condition ebc
1
constrains the movement on the direction
normal to the surface, the ebc
2
essential boundary condition constrains the
movement on the x direction and ebc
3
on the y direction.
In Fig.
7.30
the third mechanical case is presented. This case corresponds to the
standing position. During the standing position the Achilles tendon is always in
tension, providing a dynamic equilibrium for the body. In this mechanical case
there is a balance between the compressive forces and the tensile forces applied in
the calcaneus. In Fig.
7.30
are presented the pressures applied in the distinct
natural boundaries and the respective magnitudes, distributions and orientations.
The essential boundary conditions ebc
1
and ebc
3
constrain the movement on the
direction normal to the surface and the ebc
2
essential boundary condition con-
strains the movement on the y direction.
Firstly each one of the load cases is independently analysed. In all studied
examples it is imposed an initial uniform density distribution q
max
app
ΒΌ 2
:
1 g/cm
3
,
