TENSILE TESTING-Lab 3

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TENSILE TESTING-Lab 3

• Test specimens of
• 6061-T6 aluminum
• 1018 cold rolled steel
• PMMA (polymethymethacrylate) (cast acrylic)
• Polycarbonate (PC)
• ASTM E8/E8M testing standards
• Tensile test machine
• INSTRON 5585H Series Floor Model Testing Systems

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Universal Testing Equipments

• Universal testing machines first became widely
  used from 1900 to 1920.
• Used to apply forces to specimens
• Vary from simple devices to complex systems that
  are controlled by computer
• Tensile Testing loads are applied
• Mechanically with screw drives
• Hydraulically with pressurized oil/piston

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Screw-Driven Machines

• Mechanical screw driven machine
• Rotation of large threaded screws moves the
  crosshead that applies a force to the specimen
• Before load cells, force was measured by weighing
  the system (see Dowling Figure 4.3)
• High accuracy
• High cost

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Hydraulic Piston

• Preferred because of their higher load
  capacities, lower cost and accuracy (with the
  introduction of digital control loops)
• Applied by using the pressure oil pumped into
  hydraulic piston
• Before load cell force was measured by The
  pressure of the oil in the system.
• Oil in the cylinder is controlled by means of
  coarse and fine load and unload valves

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Instron

• Established in 1946, Boston, MA
• Owners Harold Hindman George Burr Both MIT
  graduates
• Decided to fulfill the need for machines used for
  testing new materials used in parachutes.
• Designed first material testing machine based on
  strain gauge load cells and servo control
• _at_1958 MTS Systems Corp used transistor technology
  and closed-loop concepts for the first time

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Instron types (screw driven)
Single column
Dual column
Floor column
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Instron 5585H Series Floor Model Testing
for tension, compression, bending and component
testing 250kN (56,250 lbf) capacity 0.001-500
mm/min (0.00004 20 in/min) speed range 1256 mm
x 575 mm (49.4 in x 22.6 in) test area Bluehill
2 Software compatibility
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Testing Machine specimen
Dogbone specimen
Clip-on extensometer
LVDT
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Load Cell and Extensometer

• Both based on strain-gaged beam with mounted
  wheat-stone bridge
• Load signals actually strain readings calibrated
  to appropriate loading levels
• UW ME Instron is capable of 250kN
• Clip-on axial and transverse extensometers
• Both send analog electronic signals to Instron
  control tower
• Bluehill (software) is used to retrieve the data

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LVDT

• linear variable differential transformer
• a type of electrical transformer used for
  measuring linear displacement
• RVDT is the rotary variable differential
  transformer to measure angular displacement