Biomechanics concepts

Download Biomechanics concepts

Post on 07-May-2015



Health & Medicine

5 download

Embed Size (px)


<ul><li>1.BIOMECHANICSCONCEPTSBIOMECHANICS Study of Biological Systems by Means of Mechanical Principlesfather of MechanicsSir Isaac Newton</li></ul> <p>2. Biology PhysicsSkeletalMuscularNervousMechanicssystem system system Kinetics Kinematics22-Jun-12P.Ratan (MPT, Ortho &amp; Sports)2 3. HUMAN MOVEMENT ANALYSISBIOMECHANICSKINESIOLOGY KINETICSKINEMATICS FUNCTIONAL LinearAngularLinearAngular Position Position Velocity Velocity Force TorqueAcceleration Acceleration 22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 3 4. Basic types of Motion Linear Rectilinear Curvilinear Angular or rotational Combined or general22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 4 5. Human Analysis Internal: mechanical factorscreating and controllingmovement inside the body External: factors affectingmotion from outside the body22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 5 6. Kinematics Describes motion Time Position Displacement Velocity Acceleration Vectors Angular and linear quantities22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 6 7. Kinematics Formulas22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 7 8. Kinetics Explains causes of motion Axis Mass amount of matter (kg) Inertia: resistance to being moved Moment of Inertia (rotation) I = mr222-Jun-12 P.Ratan (MPT, Ortho &amp; Sports)8 9. Kinetics Force: push or pull that tends toproduce acceleration Important factor in injuries Vector22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 9 10. Kinetics Idealized force vector Force couple systemF FF M=Fdddd== FF22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 10 11. Kinetics: Force Force &amp; Injury factors Magnitude Location Direction Duration Frequency Variability Rate22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 11 12. Kinetics: Force System Linear Parallel Concurrent General Force Couple22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 12 13. Center of Mass (COm) orGravity (COG) It is an imaginary point where there is intersection of all 3 cardinal plane. Imaginary point where all the mass of the body or system is concentrated Point where the bodys mass is equally distributed22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 13 14. Pressure P = F/A Units (Pa = N m2) In the human body also called stress Important predisposing factor for injuries22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 14 15. Moments of Force(Torque) Effect of a force that tendsto cause rotation about anaxis M = F d (Nm) If F and d are Force through axis22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 15 16. Moments of Force(Torque) Force components Rotation Stabilizing or destabilizingcomponent22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 16 17. Moments of Force(Torque) Net Joint Moment Sum of the moments actingabout an axis Human: represent the muscular activity at a joint Concentric action Eccentric action Isometric22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 17 18. Moments of Force(Torque) Large moments tends to produce injuries on the musculo-skeletal system Structural deviation leads to different MAs22-Jun-12P.Ratan (MPT, Ortho &amp; Sports)18 19. NEWTONIANLAWS of Motion22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 19 20. 1st Law of Motion A body a rest or in auniform (linear or angular)motion will tend to remainat rest or in motion unlessacted by an external forceor torque Whiplash injuries22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 20 21. 2nd Law of Motion A force or torque acting on a body will produce an acceleration proportional to the force or torque F = m a or T= I F22-Jun-12P.Ratan (MPT, Ortho &amp; Sports)21 22. 3rd Law of Motion For every action there is anequal and opposite reaction(torque and/or force) Contact forces: GRF, otherplayers etc.GRF22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 22 23. Equilibrium Sum of forces and the sum ofmoments must equal zero F=0 M=0 Dynamic Equilibrium Must follow equations of motionsF=mxaT=Ix22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 23 24. Work &amp; Power Mechanical Work W= F d (Joules) W= F dcos ( ) Power: rate of work d P = W/ t (Watts)W W P = F v P = F (d/t)22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 24 25. Mechanical Energy Capacity or ability to do work Accounts for most severe injuries Classified into Kinetic (motion) Potential (position ordeformation)22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 25 26. Kinetic Energy Bodys motion Linear or Angular KE=.5mv2 KE =.5 I 222-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 26 27. Potential Energy Gravitational: potential to perform work due to the height of the body Ep= mgh Strain: energy stored due to deformation Es= .5kx222-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 27 28. Total Mechanical Energy Body segments: rigid (nodeformable), no strain energy in the system TME = Sum of KE, KE , PETME = (.5m v2)+(.5 I 2)+(m g h )22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 28 29. MomentumP Quantity of motion p=m v (linear) Conservation of Momentum Transfer of Momentum Injury may result when momentum transferred exceeds the tolerance of the tissue Impulse = Momentum22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 29 30. Angular Momentum Quantity of angular motion H=I (angular) Conservation of angular momentum Transfer of angular momentum22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 30 31. Collisions Large impact forces due to short impact time Elastic deformation Plastic deformation (permanent change) Elasticity: ability to return to original shape Elastoplastic collisions Some permanent deformation Transfer and loss of energy &amp; velocity Coefficient of restitution e=Rvpost/Rvpre22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 31 32. Friction Resistance between two bodiestrying to slide Imperfection of the surfaces Microscopic irregularities -asperities Static friction f&lt; sNf Kinetic f=kN N22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 32 33. Friction Rolling: Lower that static and kineticfriction (100-1000 times) Joint Friction - minimized Blood vessels - atherosclerosis22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 33 34. FLUID MECHANICS Branch of Mechanics Dealing with theProperties &amp; Behaviors of Gases &amp; Fluids 35. Fluid Flow Laminar Turbulent Effects of friction on arterial blood flow22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 35 36. Fluid Forces Buoyancy Drag Surface Pressure Wave Lift Magnus forces Viscosity Biological tissue must have a fluid component22-Jun-12P.Ratan (MPT, Ortho &amp; Sports) 36 37. Fluid Forces22-Jun-12 P.Ratan (MPT, Ortho &amp; Sports) 37 </p>