Biomechanics Flashcards
What is an elastic body?
A material that returns to its orginal shape after deformation
What is a plastic body?
A material that does not return to its orginal state after deformation
Examples of elastic body materials
rubber band, spring
Examples of inelastic materials
clay,steel, human bone
How can material elasticity be defined?
material elasticity can be defined in terms of stress-strain property
Stress
the force on a material divided by the area
F/A= σ
Strain
the definition of how much a material has been stretched or compressed (/\L) when compared to its original length
ε = /\L / L
Youngs modulus
is a property of a material
E = stress / strain
Elastic limit
materials yield or become irreversibly altered if they are deformed beyond a critical yield strain
Yield stress
this irreversible change that occurs at a specific stress
further strain of the material then the amount it can is
plastic deformation
failure stress (max stress)
maximum stress that material can endure without failing
If there is a higher young’s modulus is the material stiffer or more flexible?
a stiffer material
area under the curve of a stress vs strain curve
energy storage
Will a complaint material or brittle material store more energy at a given stress?
a compliant material
The lower the youngs modulus equals a ______ energy storage
higher
Elastic strain energy equations
Uo = 1/2σε = 1/2 E ε^2
Orthopedic prosthetics
- functionally sufficient
-design unique to each individual
-comfortable,aesthtically pleasing
-convient
-simple in attachment
What is more important when it comes to orthopedic prosthetics, looks or fucntion?
Function is more important
Neural prosthetics
devices implanted in the body that stimulate the function of an organ or organ system that has since failed due to disease or injury
Internally powered neural prosthetics
electrical signals sent via electrodes from an external source
Externally powered neural prosthetics
functional electrical stimulation to restore “sensory or motor function”
Stimulations should exceed a threshold to cause tentanization (smooth motion contraction of muscle)
Myoelectrical prothesis
Using your existing muscles in your residal limb to control its functions
How does myoelectrical prothesis work?
One or more sensors are placed into the prosethic socket to recover electrival signals when you engage specific muscles in your residal limb
Functions of neural prothestics
hearing, seeling, feeling abilities, pain relief and restoring damaged brain cells
Types of sensory implants
visual, spinal cord stimulator, auditory
cochlear implant
has 2 components 1 is worn behind the ear- it is the sound processor, contains microphones, digital signal processor + coil that transmits signals
other compont is the actual implant has a coil to retrieve signals, electronics, electrodes placed into the cochlea to stimulate the nerves to hear