A universal testing machine is used to perform tensile, compressive, and shear strength tests on materials and structures. It consists of a loading unit, control panel, and control devices. The document outlines the components, working principle, and procedures for conducting compressive, tensile, and shear tests using a universal testing machine. Specimens are gripped firmly and loaded incrementally until the yield point is reached, then the maximum load is recorded to determine the material's strength. Proper specimen dimensions and a uniform loading rate without jerks are important to get accurate test results.

1. Maneeb Masood
M.Tech.Part-1(15152010)
IIT(BHU), Varanasi

2. Introduction
 A Universal Testing Machine is a machine that is used
to perform standard tensile and compressive tests on
materials, components and structures.
 It can be used to perform following tests:
Tensile Test
Compression Test
Shear Test

3. Components.....
 Loading Unit
Load Frame
Load Cell
Cross Head
 Control Panel
Hydraulic Power Unit
Load Measuring Unit
 Control Devices
Electric Control Devices
Hydraulic Control Devices
Load Indicating Devices

6. Control Panel
A Control Panel Comprises of:
 Power Pack (with drive motor & oil tank)
 Control Valves
 Pendulum Dynamometer
 Load Indicator System
 Autograph Recorder

7. Working Principle
 It is a load-controlled machine and works on the
principle of elongation/deformation of material
on the application of load.

8. TESTS
To assess various rock properties we can use different kind of
machines among them universal testing machine is one of
the most widely used and versatile machine which can
measure compressive/tensile/shear strength, directly or
indirectly using sample/specimen of rock mass.
 Compressive strength can be assessed directly but for the
tensile and shear strength we need to use different kind of
cages and calculations.
 Tension and Shear tests are conducted by indirect testing.
 In the Old UTMs, the lower cross head can be raised or
lowered rapidly by operating the screwed columns , thus
facilitating ease of fixing of test specimen.
 New UTMs have a fixed table and the adjustable cross head
moves up and down.

9. LOAD CELL
TENSION CROSSHEAD
TABLE
ADJUSTABLE CROSS HEAD
SCREW
COLUMN
Notched
column
Hydraulic cylinder
CONTROL
PANEL

11. OPERTAIONAL PROCEDURE
 Compressive strength:-
Specimen: The cross section of the specimen may be
circular, squire, rectangular or in special cases of any other
form. Specimens of circular sections are generally be made
to the dimensions.
Steps
1. Mark the gauge length as per specification and record it
accurately. The gauge length should be symmetrical with
the length of the bar.
2. Grip the specimen firmly in the jaw of the Universal
testing machine and adjust the machine to read zero.
3. Continue loading at increments each time and this
loading should be continued till yield point is reached.
4. Record the load at the yield point. That is uniaxial
compressive strength of the specimen.

13.  TENSILE STRENGTH:-
Specimen: The cross section of the specimen may be
circular, squire, rectangular or in special cases of any other
form. Speimen of circular sections are generally be made to
the dimensions
Steps
1. Mark the gauge length as per specification and record it
accurately. The gauge length should be symmetrical with
the length of the bar.
2. Grip the specimen firmly in the jaw of the Universal
testing machine in brazilian cage and adjust the machine
to read zero.
3. Continue loading at increments each time and this
loading should be continued till yield point is reached.

14. Brazilian cage

15.  Shear strength:-
Steps
1. Mark the gauge length as per specification and
record it accurately. The gauge length should be
symmetrical with the length of the bar.
2. Grip the specimen firmly in the jaw of the UTM in
suitable cage for single shear or double shear and
adjust the machine to read zero.
3. Continue loading at increments each time and this
loading should be continued till yield point is
reached.
4. Record the load at the yield point. That is shear
strength of the specimen.

16. Double shear cageSingle shear cage

17. PRECAUTIONS
1. Apply the load at a uniform rate and without any jerk.
2. Selection of proper dimension of specimen when
testing of different type of strength.