biomechanical aspects of workplace design


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biomechanical aspects of workplace design

  1. 1. Biomechanical Aspects of Workplace Design Presented By- Pushkar Ghatole Roll no.56
  2. 3. Workplace : A closer look
  3. 4. Factors Contributing To Problems In Work Tasks <ul><li>Awkward postures </li></ul><ul><li>• Repetitive motions </li></ul><ul><li>• Forceful exertions </li></ul><ul><li>• Pressure points (e.g., local contact stress) </li></ul><ul><li>• Vibration </li></ul><ul><li>Miscellaneous </li></ul><ul><ul><li>Environmental Factors </li></ul></ul><ul><ul><li>The duration of tasks </li></ul></ul><ul><ul><li>The length and frequency of muscle relaxation breaks </li></ul></ul><ul><ul><li>Activities outside workplace </li></ul></ul><ul><ul><li>Personal Factors </li></ul></ul>WHY?
  4. 5. Awkward Postures <ul><li>Posture affects which muscle groups are active during physical activity </li></ul><ul><li>Awkward postures can make work tasks more physically demanding, by increasing the exertion </li></ul>Reaching Twisting Bending Working overhead Holding of fixed positions Pinch grips Visual Effort
  5. 6. Repetitive motions <ul><li>In repetitive work the same types of motions are performed over and over again using the same muscles, tendons, or joints </li></ul><ul><li>The amount of repetition can be affected by: </li></ul><ul><ul><li>The pace of work </li></ul></ul><ul><ul><li>The recovery time provided </li></ul></ul><ul><ul><li>The amount of variety in work tasks </li></ul></ul>
  6. 7. Forceful exertions <ul><li>Exerting large amounts of force can result in fatigue and physical damage to the body </li></ul><ul><li>The amount of force exerted depends on: </li></ul><ul><ul><li>Load shape, weight, dimensions, and bulkiness </li></ul></ul><ul><ul><li>• Grip type, position, and friction characteristics </li></ul></ul><ul><ul><li>• Amount of effort required to start and stop the load when moving it </li></ul></ul><ul><ul><li>• Length of time continuous force is applied by the muscles </li></ul></ul><ul><ul><li>• Number of times the load is handled per hour or work shift </li></ul></ul><ul><ul><li>• Amount of associated vibration </li></ul></ul><ul><ul><li>• Body posture used </li></ul></ul><ul><ul><li>• Resistance associated with moving the load </li></ul></ul><ul><ul><li>• Duration of the task over the work shift </li></ul></ul><ul><ul><li>• Environmental temperature </li></ul></ul><ul><ul><li>• Amount of rotational force (e.g., torque from tools or equipment </li></ul></ul>
  7. 8. Pressure points <ul><li>Sides of the fingers </li></ul><ul><li>• Palms </li></ul><ul><li>• Wrists </li></ul><ul><li>• Forearms </li></ul><ul><li>• Elbows </li></ul><ul><li>• Knees </li></ul>
  8. 9. Vibration <ul><li>Fatigue </li></ul><ul><li>Pain </li></ul><ul><li>Numbness </li></ul><ul><li>Tingling </li></ul><ul><li>Increased sensitivity to cold </li></ul><ul><li>Decreased sensitivity to touch in the fingers hands and arms. </li></ul>
  9. 10. Miscellaneous
  10. 11. Biomechanical Aspects of Workplace Design Prof. Don Chaffin The University of Michigan Center for Ergonomics <ul><li>Computerized biomechanical models of the human musculoskeletal system </li></ul><ul><li>This knowledge can help ergonomists: </li></ul><ul><li>Evaluate the extent to which existing jobs place physical demands on the workers. </li></ul><ul><li>2. Simulate alternative work methods and determine potential reduction in physical </li></ul><ul><li>demands. </li></ul><ul><li>3. Provide a basis for employee selection and placement procedures. </li></ul>
  11. 12. Background
  12. 13. Factors determining workplace layout <ul><li>Shoulder-dependent Overhead Reach limitations </li></ul><ul><li>Shoulder and arm Dependent Forward reach Limits </li></ul><ul><li>Neck/Head posture work limitations </li></ul><ul><li>Torso postural Considerations in workplace height limitations </li></ul>
  13. 14. Shoulder-dependent Overhead Reach limitations <ul><li>Hands should not have to reach frequently or be held for sustained periods above the shoulder </li></ul><ul><li>Shoulder flexed and held above 90 0 causes muscle fatigue even in no load </li></ul><ul><li>For tossing ,the receiving container should be placed low to minimize arm elevations , above 50 0 from vertical </li></ul>
  14. 15. Shoulder-dependent Overhead Reach limitations
  15. 16. Shoulder and arm Dependent Forward reach Limits Expected time to reach significant shoulder muscle fatigue for different FORWARD ARM REACH POSTURES (Chaffin, 1973). When reaching forward, a load of 56N held in hands will create a load moment at shoulder , for average female and 115 N for average male
  16. 17. Shoulder and arm Dependent Forward reach Limits
  17. 18. Shoulder and arm Dependent Forward reach Limits
  18. 19. Shoulder and arm Dependent Forward reach Limits Hand orientation + Arm Postures - Design of hand tools ,tote boxes handles, control on machines
  19. 20. Shoulder and arm Dependent Forward reach Limits
  20. 21. Shoulder and arm Dependent Forward reach Limits Forearm rotation strengths
  21. 22. Neck/Head posture work limitations <ul><li>The requirement of work postures with the neck flexed forward can occur because of a combination of: </li></ul><ul><li>The seat height being too high </li></ul><ul><li>The seat placement being too far back from the work area </li></ul><ul><li>A workbench or table being too low </li></ul><ul><li>The visual demands of the task requiring a specific eye location </li></ul><ul><li>( e.g. to look into a near-vertical microscope) </li></ul><ul><li>Maximum - 30 0 </li></ul>
  22. 23. Torso postural Considerations in workplace height limitations <ul><li>At 30 0 inclination of torso from the erect posture, the load moment is 50% of its maximum value achieved at 90 0 . </li></ul><ul><li>Prolonged forward stooped posture </li></ul><ul><li>Low height of the working table. </li></ul><ul><li>Back pain </li></ul><ul><li>Back muscle endurance times in various stooped postures decreased when posture required more than about 30% of isometric strength. </li></ul><ul><li>Most men and 80-90% women can maintain 20 0 stooped posture during a day. </li></ul>
  23. 24. The final design <ul><li>Work area 5cm below the elbow when standing or seated in an erect posture. </li></ul><ul><ul><li>Adequate clearance for necessary elbow and forearm motions </li></ul></ul><ul><ul><li>Requires little stooping or shoulder rotations </li></ul></ul><ul><li>Workbench height adjustable between 94 and 115 cm </li></ul><ul><li>Heavy objects to be kept at 75cm. – Concept is to provide the location of the load close to the body of operator. </li></ul>
  24. 25. The final design
  25. 26. The final design
  26. 27. There is no single ‘Correct’ Posture
  27. 28. Adjustable Chair
  28. 29. The Computer Problem
  29. 30. References <ul><li>Control and Display Design/Anthropometry Lecture Outline </li></ul><ul><li>Easy Ergonomics, A Practical Approach for Improving the Workplace developed by the Education and Training Unit, Cal/OSHA Consultation Service, California Department of Industrial Relations </li></ul><ul><li>How to identify, control, and reduce musculoskeletal disorders in your workplace! - Presented by the Public Education Section Department of Business and Consumer Business Oregon OSHA </li></ul><ul><li>Practical solutions for a safer workplace- Prepared by WISHA Services Division Washington State Department of Labor and Industries </li></ul>