Mechanical Behaviour of Soft Tissue
To speak of tensegrity, is necessary to speak of the trusses, initially.
Trusses are an interconnected set of bars in which the links are given at
the extremity of them. The links are considered kneecaps, so they do not
give moment to the other bars. With this setting, interesting properties
are observed. The bars, regardless of the external request, are only loaded
with forces of compression or traction. Therefore, there are not shear strength
or internal moments. They are also capable of handling hard requests than
if they were a single bar, ie, is necessary to have a bar too thick to support
the same that a truss that has a less weight supports. They are easier to
transport and assemble and may have specific bars replaced if there is any
incident without losing the structure as a whole.
A structure with tensegrity is a truss in which, for any loading, the compressive
elements suffer only compression and are represented by bars; the traction
elements suffer only traction and can be replaced by cables without loss
of stability and function of the structure. This is due to the geometry
of the structure that consists in maintaining the stability of the system.
It follows from this fact that not all trusses structures can be structures
with tensegrity, but all these structures can be replaced by trusses with
no problem.
Figure 1 - Structure with the principles of tensegrity
As some biomechanical problems, especially the structural problems
of large living beings, are not solved using traditional principles
of mechanics,
begin to think on tensegrity as a possible solution. For example, when
mounting an experience of request the head weight of a common human
being in the
column of a skeleton is proved that the column acting separately can
not resist these forces and the bones of the vertebrae are broken. But
day by
day our columns supporting loads far greater than the weight of our
head consuming little power. How is it possible? The theory of tensegrity
search
try solve problems in a cinematic nature, incorporating at the structural
system muscles, ligaments and tendons and with high load consuming
minimal power, ie, at the same way that our body works.
Figure 2 - Model of the column with tensegrity.
Through the use of this new theory, intended to model a vertebral column
that supports the actual external demands, be flexible, with movement
and that consumes little power. Additionally, in partnership with IST
Lisbon, aims to streamline the steps of a surgical correction of scoliosis
through finite element modeling using the parameters of the tensegrity.
TEAM: Ana Lydia Reis Castro e Silva, Estevam Barbosa
de las Casas, Sérgio Teixeira da Fonseca, David Gonçalves
de Oliveira and Lucas Ferreira Ricoy.
