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12

  1. 1. Wood Strength
  2. 2. Wood Strength <ul><li>1.) Wood is Anisotropic, it's properties vary with direction </li></ul><ul><li>a.) Compressive Strength // to grain is highest. </li></ul><ul><li>b.) Tensile Strength // to grain is slightly lower. </li></ul><ul><li>c.) Compressive Strength perpendicular to grain is lowest. </li></ul>
  3. 3. Wood Strength <ul><li>2.) Temperature increases decrease wood strength and toughness. </li></ul><ul><li>3.) MC increase also hurt wood strength and toughness </li></ul>
  4. 4. Wood Strength <ul><li>4.) S trength varies a lot with Species & Grade </li></ul><ul><li>a.) Lower grades of lumber have more imperfections (knots, shakes, etc.) which hurt the strength. </li></ul><ul><li>b.) Wood strength values for visually grade lumber are drastically reduced to allow for imperfections. </li></ul><ul><li>Illustration: The Compressive Strength of Eastern White Pine used for design ( Table 4D) varies from 450 psi to 1050 psi. Our lab results were 5000 psi. </li></ul>
  5. 5. Wood Strength
  6. 6. Wood Strength <ul><li>5.) Strength-to Weight is good </li></ul><ul><li>E.W.P. = 1050 psi = 2100 psi </li></ul><ul><li> 0.5 </li></ul><ul><li>Steel = 24000 psi = 3000 psi </li></ul><ul><li> 7.9 </li></ul>
  7. 7. Balsa Wood <ul><li>Hypothesis: </li></ul><ul><li>The balsa wood at Hobby Shop A is better than the balsa wood at Hobby Shop B </li></ul>
  8. 8. Balsa Wood <ul><li>What properties will the MET 211 students working on their balsa truss project be concerned with in deciding which shop to purchase from? </li></ul>
  9. 9. Balsa Wood <ul><li>Tests Required: </li></ul><ul><li>1.) </li></ul><ul><li>2.) </li></ul><ul><li>3.) </li></ul><ul><li>4.) </li></ul>
  10. 10. Balsa Wood <ul><li>Samples Required: </li></ul><ul><li>1.) </li></ul><ul><li>2.) </li></ul><ul><li>3.) </li></ul><ul><li>4.) </li></ul>
  11. 11. Balsa Wood <ul><li>Test Procedures Required: </li></ul><ul><li>1.) </li></ul><ul><li>2.) </li></ul><ul><li>3.) </li></ul><ul><li>4.) </li></ul>
  12. 12. Balsa Wood <ul><li>Equipment Required: </li></ul><ul><li>1.) </li></ul><ul><li>2.) </li></ul><ul><li>3.) </li></ul><ul><li>4.) </li></ul>

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