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Quadrupedal Mechanics - Anatomy & Physiology (view source)
Revision as of 03:30, 25 April 2013
, 03:30, 25 April 2013→2 Elasticity: external forces and stored energy
::For this reason, and also because when the stress is removed some of the deformation remains, the block in this instance is imperfectly elastic. Such a residual deformation is not useful in animal mechanics.
::For this reason, and also because when the stress is removed some of the deformation remains, the block in this instance is imperfectly elastic. Such a residual deformation is not useful in animal mechanics.
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::
[[File:QMSection2.4.png|thumb|'''Fig. 2.4 Elastic resilience''']]
'''Elastic resilience'''
'''Elastic resilience'''
Passive musculoskeletal tissues should be as resilient as possible, to conserve energy.
Passive musculoskeletal tissues should be as resilient as possible, to conserve energy.
[[File:QMSection2.4.png|thumb|'''Fig. 2.3 Elastic resilience''']]
::Fig. 2.4 Elastic resilience
::The work done in deforming the material is Fd, the product of force and distance. This is the area under the curve made during the application of the force (blue). The work done by the elastic restoring force is the area under the curve made during the removal of the deforming force (red hatching). In this example, these two areas are not the same. The difference in area is the energy lost as heat. The resilience is the red hatched area as a percentage of the blue area.
[[File:QMSection2.5.png|thumb|'''Fig. 2.5 Hopping kangaroo''']]
::Fig. 2.5 A hopping kangaroo
::Compare the angle of the hock joint when the limb bears weight, and when not weight-bearing. The passive tissues supporting this joint store energy in A and release it in B. At hopping speeds of between 10 and 35 km/h, kangaroo locomotion is remarkably efficient. This is due to the almost 100% resilience of the elastic support of the hock joint.