TENSILE TEST

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TENSILE TEST

• EXPERIMENT 3
• Instructor M.Yaqub

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TENSILE TEST

• The purpose of TENSILE TEST is to check the
  strength of any metal.
• Before understanding the test, following
  definition are required to know.
• Engineering Stress
• Ratio of the applied force to the initial area.

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• Where F is the applied force in newton or in
  pound.
• is the cross section area of the test piece in
  m2 or in inch2.
• The unit for the Engineering Stress is
• pascals(N/m2) or PSI (lb/ inch2)

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• Engineering Strain
• Ratio of the change in length (elongation) to the
  original length.
• Where
• Change in length because of the force applied.
• Where is the original length.

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TENSILE TEST SPECIMEN
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GRAPH FROM TENSILE TEST
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• Zone I
• Relation between stress and stain is linear and
  the curve is a straight line.
• Where E is proportionality constant and called
  YOUNGS MODULUS.
• Deformation is Elastic in this zone, means No
  permanent deformation.

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• Zone II
• Deformation is permanent. Stress and Strain are
  not linear. This zone starts from end of the
  first zone and ends at the highest point of the
  curve which is called NECKING POINT. This point
  corresponds to the maximum force applied during
  the test.
• The deformation in this zone is called PLASTIC
  DEFORMATION.

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• Zone III
• After necking point, the area of the specimen
  decreases and hence load carrying capacity of the
  sample also decreases. Load decreases in the zone
  and after some time sample fail (fracture) from
  necking point.

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• Yield Strength (sy) Stress corresponds to the
  Elastic Limit (up to where, the curve is linear,
  called yield point).
• If two limits, Lower will be yield point.

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Yield Strength at 0.2 (offset yield strength
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ULTIMATE TENSILE STRENGTH (su)

• Also called Tensile Strength (TS), or Engineering
  Tensile Strength (suts).
• Stress at highest point of the curve or at
  necking point.

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ENGINEERING FRACTURE STRENGTH (sF)

• Stress at the last point of the curve. This point
  is the fracture point.

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DUCTILITY

• Ability of a material to deform plastically
  without fracture. Measure in two terms.
• Percentage Elongation (EL)
• Percentage Reduction in Area (RA)

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RESILIENCE MODULUS OF RESILIENCE (UR)

• The ability of a material to absorb energy when
  deformed elastically and to return it when
  unloaded is called resilience. Modulus of
  Resilience is the energy per unit volume stored
  in the specimen while deform elastically. It is
  area under the curve up to elastic region and can
  be obtain from

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TOUGHNESS MODULUS OF TOUGHNESS (UT)

• Ability of the material to absorb energy in
  elastic region. This is the energy stored in the
  specimen during the test and can be expressed in
  energy per unit volume.
• It is the area under the hole curve and can be
  approximated by
• For ductile material
• For brittle material

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TRUE STRESS (st)

• Ratio of the instantaneous load and instantaneous
  (actual) Area.
• Area conserved during the test up to necking
  point.