Torsion Testing

1
Torsion Testing

• Become familiar with Tinius Olsen Torsion Tester
  (10,000 in-lb capacity)
• ASTM E-143 Test Method
• Draw Shear Stress-Strain Curve
• Determine Material Properties in Torsion
• Ductile or Brittle Failure ?
• Compare results from Tensile, Poissons Torsion
  Test
• 2024-T351 Al-Cu Alloy Specimen

2
Torsion Data Sheet
3
Computing the Slip Angle
4
Manually Recorded Data
?slip ?H-(LH/LT)?T
?T(?R-?R0)-(?L-?L0)
?cor ?H - ?slip
?R0
?L0
5
Shear Strain and Stress
?Radians(?cor)D/2/LH
?16T/?/D3
6
Integrating Computer Data
?slip constant
?cor?H - ?slip
7
Selecting Computer Data
Head Angle 30.00 deg When Protractors taken OFF
Max Torque 1931 in-lb
8
Entire Stress Strain Curve
9
Elastic Curve
10
Proportional Limit
G?
11
Proportional Limit
Plot columns H, I, J
12
Key Ideas - Torsion

• Shear strain formula is valid in both elastic
  plastic region
• Torque formula is valid in linear elastic region
  ONLY
• Thus, shear stress formula is valid until
  proportional limit
• After proportional limit, shear stress formula
  overestimates stress.

13
Torsion Results
14
Comparing Tensile vs. Torsion Results
15
Comparing Lab 1, 2, 3Experimental Results
16
Failure Surface Torsion Test
17
Lab 3 Report due NEXT WEEK

• Cover Page Abstract
• Data Sheet
• Spreadsheet
• Plot 1 Entire Shear Stress-Strain Curve
• Plot 2 Shear Modulus
• Plot 3 Proportional Limit
• Material Property Tables (two tables) Fracture
  Surface
• Comments and Conclusions