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2011-10-04 04:33:50

Mche467 test3 vocab
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  1. Shear Center
    The point on the cross section plane for which the plane of loading must mass through to avoid twisting of the member
  2. Principal plane
    • the plane through an element at a point in a stressed body which is free of shear stress.
    • HP&VP for element are principal planes
  3. Isotropic Material
    a material with the same properties in all directions throughout its volume
  4. Octahedral stress
    A stress which acts on planes which make equal angles with the principal axis. θ1=θ2=θ3
  5. Neutral Axis
    • The locus of points on a beam's cross section for which the normal stress is zero.
    • *NA passes through centroid for pure bending M
  6. System
  7. any isolated part or portion of a machine or structure
    • that we wish to study, may consist of
    • particle, several particles, a part of a rigid body, an entire rigid body, or
    • even several rigid bodies
  8. Section modulus
    • the ratio of the moment of inertia to the maximum
    • distance from the centroid to the outer fiber of the cross section
  9. Shear Strain
    the change in a right angle of a stress element subject to pure shear
  10. Elasticity
    material returns to tis original shape immediately upon removal of load, property of a material that enables it to regain its original configurations after having been deformed.
  11. Homogeneity
    material has the same properties throughtout its volume
  12. Limitations of deflection formula
    • 1. Bar is straight
    • 2. Bar is axially
    • and centrally loaded
    • 3. Bar has uniform
    • cross section
    • 4. No stress
    • concentrations
    • 5. Gradually applied
    • load
    • 6. No residual
    • stresses present
    • 7. Hooke’s law
    • applies
  13. Mohr's circle diagram
    a graphical solution to the combines stress problem
  14. Principal stress
    • a particular orientation in the stress element occurs
    • in space for which all shear stress components are zero.
  15. Normal Strain
    elongation per unit length
  16. Limitations for stress (F/A) and shear stress
    • 1. Bar is straight and made of homogeneous material
    • 2. Line of action of
    • force coincides with the centroid of the cross section
    • 3. St. Venant’s
    • principle applies
    • 4. No initial
    • stresses in material
    • 5. Load is gradually
    • applied, (static loading)
  17. Center of Gravity
    • the sum of the moments of the
    • areas about the axis through the C.G. must equal zero
  18. Pure bending
    • when the shear force is zero and there is no net axial
    • load
  19. Limitations of stress (My/I)
    • 1. Beam is subjected to pure bending
    • 2. Material is isotropic and homogeneous
    • 3. Material obeys Hooke’s law
    • 4. Beam is initially straight with a cross section that is constant throughout the beam length
    • 5. Beam has an axis of symmetry in the plane of bending
    • 6. Cross section of beam remains plane during bending
    • 7. No residual stresses or stress concentration
  20. Limitations of shear stress (VQ/It)
    • 1. Same as bending stress
    • 2. Shear stresses are uniformly distributed across the beam width
    • 3. Shearing stresses throughout the cross section is the same as the direction of the shear force
    • 4. Width of cross section where stress is being computed it small in comparison to the depth of
    • the beam
  21. True Strain
    logarithmic strain, the sum of incremental elongations divided by the current gauge length at load P
  22. Stress
    a state property at a specific point within a body, a function of load, geometry, temperature, and manufacturing processing
  23. Strength
    An inherent property of a part, a property built into the part b/c of the use of a particulat material and process.
  24. Specific modulus, specific stiffness
    E/p, ratio of young;s modulus to density