Download - Biomechanics in Human Body
Biomechanics in Human Body
االنسان فيجسم االحيائية الميكانيكية
Mechanics
Statics deal with nonmoving parts (equilibrium).
Dynamics deal with moving systems
Kinematics Describes motion and includes consideration of time, displacement, velocity, acceleration and mass.
Kinetics Describes forces that
cause motion of a body
Mechanics-study of forces and motions for the body.
Basic Biomechanics
• Biomechanics-apply mechanics to the structure and function of the human body.
Is the scientific study of the mechanics of biological systems.
Engineering(Mechanics)
Anatomy Physiology
Biomechanics
Applications Biomechanics
- Improved the performance ( Human movement)- Preventing or treating injury- Design prosthesis & orthosis or artificial limb
Biomechanics• Biomechanics is be used to:
–To understand the biomechanical analysis (motion) (Gait cycle) (for normal and patient human).
–To understand function of vascular system in order to analysis the fluid biomechanics (blood flow).
–To analysis the biomechanics of : soft tissue (muscle) hart tissue (bones).
–To model these systems to aid in the design of prosthetic devices (e.g. artificial artery or artificial limb)
Principles associated to biomechanical analysis
• Density• Momentum• Velocity• Time• Acceleration• Deceleration• Mass• Inertia• Dimensions• Viscosity
• Balance and stability• Centre of gravity• Elasticity• Forces (action & reaction)• pressure• power• Bending moment• Torque moment
• Friction• Wear
Biomechanical principles associated with basic movement patterns
forcesacceleration and decelerationNewtons lawsfriction
StoppingRunning
forces (action/ reaction)motion (straight line)momentumfriction
General Motion
Most movements arecombination of both
• Newton’s First Law–Law of inertia
• Newton’s Second Law–Law of Acceleration
• Newton’s Third Law–Law of Action and
Reaction
Linear motion
Angular motion
JOINTREACTIO
NFORCES
LoadsThe external forces that act on the body impose loads that affect the internal structures of the body.
First class lever
There are 3 classes of levers.
Second class lever Third class lever
Humans moves through a system of levers
First Class Levers
Up and down movement of the head about the atlas joint.
First Class Levers
Using a crowbar to move a rock.
First Class Levers
Using a hammer to pull out a nail.
First Class Levers
A see-saw.
Second Class Levers
The movement of the foot when walking.(the calf muscle provides the effort and
the ball of the foot is the pivot)
Second Class Levers
Opening a bottle with a bottle opener
Second Class Levers
Pushing a wheel barrow.
Third Class Levers
Biceps curl.
Levers• The mechanical advantage of levers may be
determined using the following equations:Mechanical advantage =
ResistanceForceor
Mechanical advantage =Length of force arm
Length of resistance arm
Bitting Force
Dog bite = 1,410 N 2.5
Lion bite down with 5,533 N 10
Boxer can punch with 10,528 N 18
• Human female bite = 360 N• Human male bite = 564 N
Biomechanics of the denture
• Continuity Equation:• mass in = mass out outin uAuA
Assumptions- Laminar Flow- Newtenian fluid- Incompressible fluid- Single phase
Du
Re
Fluid biomechanics (blood flow).Vascular Biomechanics
Q = ((P1-P2)..R4)/(8.µ.L)
Atherosclerosis
Blood viscosity0.0035 kg/m.s
Blood density1060 kg/m3
Atherosclerosis
Velocity PathlinesSteinman, 2000
Wall Shear Stress ContoursAugst et al, 2007 Jamalian Ardakani, 2010
In healthy vessels, tw is low (~ 15-20 dynes/cm)
Velocity Pathlines
Model 1 (peak of systole) Model 1 (peak of diastole)
Bone Biomechanics (Hard tissue)
• Bone is anisotropic material (modulus is dependent upon the direction of
loading).• Bones are:
strongest in compression.weakest in shear.
• Ultimate Stress at Failure Cortical Bone Compression < 212 N/m2
Tension < 146 N/m2
Shear < 82 N/m2
Mechanical Properties of Bone
return to original shape after fracture
Ductile or BrittleDepends on age and rate at which it is loaded
- Younger bone is more ductile- Bone is more brittle at high speeds
Bending
Type of Loading
TorsionAxial LoadingCompressionTension
Fracture Mechanics
•Bending load:– Compression strength greater
than tensile strength– Fails in tension
Tension
Compression
Stress Freein the middle
Bending of a Long, Solid Bone:
Save weight & keep strength:
Tension
Compression
Bending of a Long, Hollow Bone: =M . y / I
I = .(R4-r4)/4
Biomechanics Bone fixation
External fixation
Internal fixation
Biomechanics of External Fixation
• Number of Pins– Two per segment– At least 3 pins
IM Nails (Rod)• Stiffness is high
proportional to the 4th power.
Biomechanics of Internal Fixation
Plate Fixation• Functions of the plate Compression Neutralization Buttress
Biomechanics of Internal Fixation
Bending moment = F x DF = Force
D
D = distance from force to implant
F = Force
D
The bending moment for the plate is greater due to the force being applied over a larger distance
IM Nail
Plate
Biomechanical principlessimilar to those of external fixators
Stress distribution
Osteoarthritis may result from wear and tear on the joint
The medial (inside) part of the knee is most commonly affected by osteoarthritis.
• Moving surfaces of the knee are metal against plastic
Treatment or Total Knee Replacement
UHMWPE
Structural Alignment
Hyperextension
Genu Valgum (knock kneed)
Genu Varum (Bowlegged)
Biomechanics of Flat Foot
Gait Cycle
Swing Phase
Stance Phase
Heel Strike Midstance Toe off
Biomechanics of motion of human body
To design artificial lower limb
Ground reaction force (by force plate “platform”)
1.3 W
Hip, knee, and ankle joint centers lie along a
common axis.
-Socket alignment-Static alignment-dynamic alignment
Biomechanics of motion of human body
(Interface pressure sensor between socket and skin)
Numerical Study of Prosthetic Socket
Numerical Study of Prosthetic Socket
Theoretical Part
-Stress- Max. Normal Stress- Max. Shear Stress- Von Mises stress
- Deformation- Linear- Angular
-Fatigue ratio-Strain energy-Failure index-Safety factor
Contours of Deformation Distribution
Contours of Equivalent Von Mises Stress Distribution
Thanks you for listening