Direct Shear of mild steel on Universal Testing Machine

Aim:- To determine experimentally, the ultimate shear strength in double shear of mild steel rod.

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Apparatus used:-  Universal testing machine, Shear attachments, Vernier callipers.

Theory :- 

In direct shear test, the shearing  stress is considered as uniformly distributed over the entire cross section. The shear force is applied by a suitable test rig, two different cases of shearing may arise,  i.e. , single shear and double shear. In single shear sharing occurs across a single surface and in  double shear shearing occurs across two surfaces.Knowledge of shear failure is important while designing any structures or machine components.Shear force causes the surface to go out of the alignment with each other and thus the material fails.

Procedure:-

 1. Insert the specimen in position and grip one end of the attachment in the

upper portion and one end in the lower portion.

2.  Switch on the main switch of universal testing machine machine

3.  The drag indicator in contact with the main indicator.

4.  Select the suitable range of loads and space the corresponding  weight  in the

pendulum and balance it if necessary with the help of small balancing

weights.

5.  Operate (push) buttons for driving the motor to drive the pump.

6.  Gradually move the head control level in left-hand direction till the specimen

shears.

7.  Down the load at which the specimen shears.

8.  Stop the machine and remove the specimen

Observation Table

Diammeter (mm)	Area of cross- Section (𝐴 πd4/32)m2	Failure load  P (kg)	Double shear Strength= (P*9.81)/2A(N/mm2)		Percentage Error
			Actual Value	Entered Value
5.91	27.42	1300	232.55	255	-9.65
5.95	27.79	1450	255.93	245	4.27
6	28.26	1500	260.35	220	15.50

Average Double shear Strength= 249.61 N/mm2

Results:- The shear test on mild steel specimen is found to be = 249.61 N/mm2