The Charpy impact test is another widely used method to determine the impact toughness of materials.

It measures the energy absorbed by a notched specimen when struck by a pendulum hammer.

This test is commonly used to study brittle and ductile fracture behavior of materials.

Definition

Charpy Impact Test

A test used to determine the impact toughness of materials by measuring the energy absorbed when a horizontally supported notched specimen is fractured by a pendulum hammer.

Core Concept Explanation

In the Charpy test:

A notched specimen is prepared.
The specimen is placed horizontally between two supports.
A pendulum hammer is raised to a fixed height.
The hammer strikes the specimen at the opposite side of the notch.
The specimen breaks due to the impact.
The energy absorbed during fracture is measured.

Test Arrangement

Main parts of the Charpy testing machine:

Pendulum hammer
Specimen supports
Notched specimen
Energy scale or dial

Specimen Details

Parameter	Description
Shape	Rectangular bar
Position	Horizontal
Support type	Simply supported
Notch type	V-notch or U-notch

The notch acts as a stress concentration point.

Characteristics of Charpy Test

Specimen is supported horizontally
Hammer strikes opposite to the notch
Measures impact energy absorbed
Widely used for metals and alloys

Applications in Engineering

Charpy test is used in:

Steel industry
Structural engineering
Shipbuilding
Pressure vessel manufacturing
Pipeline materials testing

It helps determine brittle fracture behavior at different temperatures.

Important Comparison: Izod vs Charpy Test

Feature	Izod Test	Charpy Test
Specimen position	Vertical	Horizontal
Support condition	Cantilever	Simply supported
Notch direction	Faces hammer	Opposite hammer
Application	Plastics and metals	Mainly metals

Exam-Focused Points

Important for competitive exams:

Charpy specimen is horizontal.
Specimen is simply supported.
Hammer strikes opposite to the notch.
Measures impact toughness.

Common Exam Traps

Confusion

Students mix up specimen positions.

Correct rule for exams:

Izod → Vertical
Charpy → Horizontal

Example Competitive Exam Questions

Question: In the Charpy impact test, how is the specimen supported?
Answer: Horizontally between two supports (simply supported).

Question: What property is determined by the Charpy impact test?
Answer: Impact toughness.

Question: Which impact test uses a horizontally supported specimen?
Answer: Charpy impact test.

Quick Revision Summary

Charpy test measures impact toughness.
Specimen is horizontal and simply supported.
Hammer strikes opposite side of notch.
Used widely for metals and structural materials.

Unit 11.2: Charpy Impact Test