TENSILE TESTING-Lab 3
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Test specimens of
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6061-T6 aluminum
1018 cold rolled steel
PMMA (polymethymethacrylate) (cast acrylic)
Polycarbonate (PC)
ASTM E8/E8M testing standards
Tensile test machine
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INSTRON 5585H Series Floor Model Testing Systems
Universal Testing Equipments
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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:
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Mechanically with screw drives
Hydraulically with pressurized oil/piston
Screw-Driven Machines
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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
Hydraulic Piston
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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
Instron
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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
@1958 MTS Systems Corp used transistor technology
and closed-loop concepts for the first time
Instron types (screw driven)
Single column
Dual column
Floor column
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
Testing Machine & specimen
Dogbone specimen
load cell
grip
universal
joint
Load train
fillet
grip
Load frame
gage section
grip
specimen
grip
universal
joint
Load train
Clip-on extensomete
crosshead
LVDT
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Load Cell and Extensometer
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Both based on strain-gaged beam with mounted wheatstone 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
LVDT
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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