Objective:
1) To find the yield strength and ultimate tensile strength unknown steel bar using U.T.M.
2) To find the grade of the steel bar.
Apparatus:
Steel bar, U.T.M, Vernier caliper, Ruler.
U.T.M ;
It is a machine used to find tensile test or compressive test.
Loading unit ;
This part helps in clamping the specimens.
Main parts of control unit :
1) Table 2) Table cover 3) Upper and lower cross head.
4) Upper and lower jaws. 5) Upper and lower clamping handles etc.
Control unit :
This part helps in controlling the amount of load to be applied on the specimen , and also controls the motion of the jaws.
1) Automatic control
2) Manual control
3) Dial gauge.
Theory and background
Yield strength:
That particular stress after which the material start to deform in elastically . prior to the point the material will deform elastically and return to its original shape when applied stress is removed.
Ultimate tensile strength:
The maximum stress that a material can with stand without failed or rupture.
1) Till U.T point both peak value and load increase.
2) At U.T point peak value stop and load decrease.
Experimental procedure:
1) take a steel bar and mark two point on the steel bar at 8 inch apart = gauge length.
2) Measure the diameter by using the vernier caliper.
3) Clamp the bar between the jaws of the U.T.M machine.
4) Turn on the U.T.M and applied load on the specimens.
5) Load increase gradually, a point will come where the peak reading pauses and applied load decreasing that will be yield point.
6) If load is further increase a point will come where the specimen will break. This is a tensile load.
7) take the broken pieces of the specimen and again measure the distance between the two points on the specimen and determine the elongation.