Izod Test Example And Specimen

Izod Impact Test: A Comprehensive Guide

Introduction

The Izod impact test is a standardized test method used to assess the toughness of materials, particularly plastics and composites. It measures the energy absorbed by a notched specimen when it is struck by a pendulum hammer. The test is named after the British engineer Edwin Izod, who developed it in 1903.

Test Procedure

The Izod impact test is conducted according to the following procedure:

1. Specimen Preparation: A rectangular specimen with a V-shaped notch is prepared from the material to be tested. The dimensions and shape of the specimen are specified in the relevant test standard.
2. Test Apparatus: The test apparatus consists of a pendulum hammer, a specimen holder, and a release mechanism. The hammer is suspended from a horizontal arm and is released to strike the specimen.
3. Test Execution: The specimen is clamped in the holder, and the hammer is released from a predetermined height. The hammer strikes the specimen at the base of the notch, causing it to break.
4. Energy Measurement: The energy absorbed by the specimen is calculated from the difference in height between the initial and final positions of the hammer.

Test Results

The Izod impact strength is expressed in joules per meter (J/m) and is calculated as follows:

Izod impact strength = Energy absorbed / Area of fractured surface

The area of the fractured surface is determined by measuring the length and width of the broken specimen.

Factors Affecting Izod Impact Strength

The Izod impact strength of a material is influenced by several factors, including:

• Material composition: The type and proportion of materials used in the specimen can significantly affect its impact strength.
• Specimen thickness: Thicker specimens generally exhibit higher impact strength than thinner specimens.
• Notch depth: The depth of the notch in the specimen affects the stress concentration and, consequently, the impact strength.
• Test temperature: The temperature at which the test is conducted can influence the impact strength of some materials.
• Specimen orientation: The orientation of the specimen relative to the direction of impact can affect the test results.

Applications of Izod Impact Test

The Izod impact test is widely used in various industries to evaluate the toughness of materials. Some of its applications include:

• Automotive: Assessing the impact resistance of plastic components used in vehicles.
• Aerospace: Testing the impact strength of composite materials used in aircraft structures.
• Construction: Evaluating the impact resistance of building materials, such as concrete and roofing tiles.
• Packaging: Determining the impact resistance of packaging materials to ensure product protection.
• Research and Development: Investigating the impact behavior of new materials and optimizing their properties.

Izod Test in South Africa

In South Africa, the Izod impact test is commonly used in the following industries:

• Automotive: The South African automotive industry has adopted the Izod impact test as a standard method for evaluating the impact resistance of plastic components used in vehicles.
• Plastics Manufacturing: Plastic manufacturers in South Africa use the Izod impact test to ensure the quality and durability of their products.
• Research Institutions: Universities and research institutions in South Africa utilize the Izod impact test to study the impact behavior of various materials and develop new materials with improved toughness.

Specimen Dimensions and Standards

The dimensions and shape of the Izod impact test specimen are specified in various international and national standards, including:

• ISO 180: International Organization for Standardization (ISO) standard for plastics.
• ASTM D256: American Society for Testing and Materials (ASTM) standard for plastics.
• BS EN ISO 180: British Standard (BS) and European Standard (EN) for plastics.

The most common specimen dimensions for the Izod impact test are:

• Length: 63.5 mm (2.5 in)
• Width: 12.7 mm (0.5 in)
• Thickness: 3.2 mm (0.125 in)
• Notch depth: 2.5 mm (0.1 in)

Conclusion

The Izod impact test is a valuable tool for assessing the toughness of materials. It provides a standardized method for comparing the impact resistance of different materials and evaluating their suitability for specific applications. The test is widely used in various industries, including automotive, aerospace, construction, and packaging. In South Africa, the Izod impact test is commonly employed to ensure the quality and durability of materials used in various products and industries.