Cyclic Load Testing of Steel Bars
By: Jacob Stone &
Francisco Felix.
Spring 2002 CE 334 Prof. Xiao
Discussion Topics
Testing Procedure
Types of Loads
What Happens to During Cyclic Loading
Comparison Between Monotonic & Cyclic
Loading
Problems with Tests
Discussion of results
Testing Procedure
Clean samples and
apply strain gauges
with super glue.
Testing Procedure Cont.
Attach strain gauges to
six foot long wires.
Test wires for
conductivity
Testing Procedure Cont.
Insert sample into
SATEC Machine
Connect wires to
terminals
Begin test
Testing Procedure Cont.
Material Behavior During Cyclic
Loading
Two Types of Cyclic Stress-Strain
relationships
1) Cyclic Hardening
2) Cyclic Softening
Cyclic Graphs
Cyclic Hardening -
Stresses increase with
increasing number
of cycles
Cyclic Softening -
Stresses decrease
with increasing
number of cycles
Typical Monotonic
Loading Curve
Cyclic Loading
Stress-Strain
100000
80000
60000
40000 Series1
20000
0
0 0.5 1
-20000
Comparison Between Monotonic
and Cyclic Loading Behavior
100000
80000
60000
40000 Series1
20000
0
0 0.5 1
-20000
Problems During Testing
1)Strain gauges snaps of
easily when attaching
them to the machine
2)SATEC machine is
unable to apply cyclic
loads, so they must be
done by hand
3)Strain readings in plastic
region not reliable because
gauges break in test
Conclusion
There needs to be a more accurate way to test
cyclic loading in the plastic region.
Cyclic loading is encountered in daily life
constantly and must be taken into account for
when designing things that will subjected to it.
Cyclic loading graphs are very similar to
Monotonic loading, showing that a material’s
behavior under load is more dependent on the
properties of the material then the loading type.