Presentation is loading. Please wait.

Presentation is loading. Please wait.

الميكانيكية الاحيائية في جسم الانسان

Similar presentations

Presentation on theme: "الميكانيكية الاحيائية في جسم الانسان"— Presentation transcript:

1 الميكانيكية الاحيائية في جسم الانسان
Biomechanics in Human Body الميكانيكية الاحيائية في جسم الانسان

2 Mechanics Mechanics-study of forces and motions for the body. 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

3 Basic Biomechanics Biomechanics-apply mechanics to the structure and function of the human body. Is the scientific study of the mechanics of biological systems.

4 Applications Biomechanics
Engineering (Mechanics) Anatomy Physiology Applications Biomechanics Improved the performance ( Human movement) Preventing or treating injury Design prosthesis & orthosis or artificial limb

5 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)

6 Principles associated to biomechanical analysis
Balance and stability Centre of gravity Elasticity Forces (action & reaction) pressure power Bending moment Torque moment Friction Wear Density Momentum Velocity Time Acceleration Deceleration Mass Inertia Dimensions Viscosity There are far too may to cover in 4- 5 weeks so go back to the context of striking and still there are a lot.

7 Biomechanical principles associated with basic movement patterns
Running Stopping forces (action/ reaction) motion (straight line) momentum friction forces acceleration and deceleration Newtons laws friction

8 General Motion Most movements are combination of both Linear motion
Angular motion Newton’s First Law Law of inertia Newton’s Second Law Law of Acceleration Newton’s Third Law Law of Action and Reaction


10 Loads The external forces that act on the body impose loads that affect the internal structures of the body.

11 Humans moves through a system of levers There are 3 classes of levers.
First class lever Second class lever Third class lever

12 Up and down movement of the head about the atlas joint.
First Class Levers Up and down movement of the head about the atlas joint.

13 First Class Levers Using a crowbar to move a rock.

14 First Class Levers Using a hammer to pull out a nail.

15 First Class Levers A see-saw.

16 The movement of the foot when walking.
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)

17 Second Class Levers Opening a bottle with a bottle opener

18 Second Class Levers Pushing a wheel barrow.

19 Third Class Levers Biceps curl.

20 Levers The mechanical advantage of levers may be determined using the following equations: Mechanical advantage = Resistance Force or Length of force arm Length of resistance arm

21 Biomechanics of the denture
Bitting Force Human female bite = 360 N Human male bite = 564 N Boxer can punch with 10,528 N 18 Lion bite down with 5,533 N 10 Dog bite = 1,410 N 2.5

22 Fluid biomechanics (blood flow). Vascular Biomechanics
Continuity Equation: mass in = mass out Q = ((P1-P2)..R4)/(8.µ.L) Assumptions - Laminar Flow - Newtenian fluid - Incompressible fluid - Single phase

23 Atherosclerosis Blood density 1060 kg/m3 Blood viscosity kg/m.s

24 Atherosclerosis

25 Velocity Pathlines Steinman, 2000

26 Wall Shear Stress Contours
Augst et al, 2007 Jamalian Ardakani, 2010 In healthy vessels, tw is low (~ dynes/cm)

27 Velocity Pathlines Model 1 (peak of systole)
Model 1 (peak of diastole)

28 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 < N/m2

29 Mechanical Properties of Bone
Ductile or Brittle Depends on age and rate at which it is loaded - Younger bone is more ductile - Bone is more brittle at high speeds Following a fracture, ductile material will not conform to original shape after fracture. Brittle will return to original shape after fracture. return to original shape after fracture

30 Type of Loading Fracture Mechanics Bending Torsion Bending load:
Compression strength greater than tensile strength Fails in tension Axial Loading Compression Tension

31 Bending of a Long, Solid Bone:
Tension Compression Stress Free in the middle Bending of a Long, Hollow Bone:  =M . y / I Tension Compression I = .(R4-r4)/4 Save weight & keep strength:

32 Biomechanics Bone fixation
External fixation Internal fixation

33 Biomechanics of External Fixation
Number of Pins Two per segment At least 3 pins


35 Biomechanics of Internal Fixation
IM Nails (Rod) Stiffness is high proportional to the 4th power.

36 Biomechanics of Internal Fixation
Plate Fixation Functions of the plate Compression Neutralization Buttress


38 Bending moment = F x D F = Force F = Force IM Nail Plate D D D = distance from force to implant The bending moment for the plate is greater due to the force being applied over a larger distance

39 Biomechanical principles similar to those of external fixators
Stress distribution

40 Osteoarthritis may result from wear and tear on the joint
The medial (inside) part of the knee is most commonly affected by osteoarthritis. 

41 Treatment or Total Knee Replacement
Moving surfaces of the knee are metal against plastic UHMWPE

42 Structural Alignment Genu Varum (Bowlegged) Genu Valgum (knock kneed)

43 Biomechanics of Flat Foot

44 Biomechanics of motion of human body To design artificial lower limb
Gait Cycle Swing Phase Stance Phase Heel Strike Midstance Toe off To design artificial lower limb

45 Ground reaction force (by force plate “platform”)
1.3 W

46 Biomechanics of motion of human body
-Socket alignment -Static alignment -dynamic alignment Hip, knee, and ankle joint centers lie along a common axis.

47 Numerical Study of Prosthetic Socket
(Interface pressure sensor between socket and skin)

48 Numerical Study of Prosthetic Socket

49 Theoretical Part -Stress - Max. Normal Stress - Max. Shear Stress
- Von Mises stress Deformation - Linear - Angular -Fatigue ratio -Strain energy -Failure index -Safety factor

50 Contours of Deformation Distribution
Contours of Equivalent Von Mises Stress Distribution

51 Thanks you for listening

Download ppt "الميكانيكية الاحيائية في جسم الانسان"

Similar presentations

Ads by Google