Izod Impact Test – Specimen Dimensions
Introduction
An impact test is the Izod Impact Test, which assesses the ability of a specific material to withstand impacts. This determination is beneficial in determining the ability of plastics and composite materials to endure the various effects without breaking. The test is governed by ASTM D256 and ISO 180 standards and consists of swinging a pendulum at a notched sample to assess its notch sensitivity and the amount of energy required to break the sample. This test contributes to material performance evaluation, which is especially important in material selection for applications exposed to dynamic loading.
What is the Izod Impact Test?
The energy required to break a notched specimen is measured using a swinging pendulum to assess the impact resistance of the given object. This technique is commonly applied to measure the toughness and strength of various materials, particularly plastics.
Procedure
One of the variants of the Impact Test is the Izod Test. A notched specimen is placed in the fixture and held vertically without the notch on the bottom of the specimen. The pendulum is released from a particular height and hits the specimen at the notch to simulate a single, high-intensity impact. The energy used by a specimen to rupture is registered as a loss of kinetic energy by a pendulum after it strikes the specimen. This figure, which is usually referred to as the impact strength, demonstrates the level of toughness of the material and its ability to resist rapid fracture.
ASTM and ISO Standards
The Izod Impact Test is defined by ASTM D256 and ISO 180 standards. A sample measuring 64 x 12.7 x 3.2 mm in ASTM is acceptable with a notch depth of 10.2 mm. In contrast, the ISO test employs a Type 1A specimen excluding end tabs of 80 x 10 x 4 mm size with a notch of 8 mm depth. Results obtained using ASTM are expressed in J/m or ft-lb/in. Still, in the case of ISO, kJ/m squared is used, each of which is different in its sample dimensions and testing environments because the standards are meant for various geographical regions and materials.
Specimen Dimensions for ASTM and ISO
| Standard | Specimen Size | Notch Depth | Thickness | Units | Average Specimens |
| ASTM | 64 x 12.7 x 3.2 mm | 10.2 mm | 3.2 – 6.4 mm | J/m or ft-lb/in | 5 |
| ISO | 80 x 10 x 4 mm | 8 mm | 4 mm | kJ/m² | 10 |
Application of the Test
The Izod Impact Test is widely used in the automotive, aerospace, and manufacturing sectors to investigate the suitability of a particular material for parts likely to experience Impact loads. The test improves safety and performance efficiency and thus plays a vital role in selecting and controlling material quality.
Conclusion
The Izod Impact Test is an efficient way of performing performance testing on the toughness and impact strength of the material and incorporating notch sensitivity. Differences in standards under ASTM and ISO provide leeway for testing in case of varying industrial requirements, where results assist the manufacturers in evaluating the impact of the materials produced. This test is essential in making it easier to choose the suitable material for products that are likely to experience sudden changes in stress.
FAQs
What does the Izod Impact Test measure? It quantifies a material's impact resistance by measuring the energy required to break a specimen with a notch cut into it.
Why are specimens notched in the Izod test? This allows for a more accurate definition of the area over which the crack may spread and thus helps to obtain more precise toughness values.
What are the critical differences between ASTM D256 and ISO 180? ASTM D256 employs a 64 x 12.7 x 3.2 mm specimen with a 10.2 mm softness to the notch depth, whereas ISO 180 uses 80 x 10 x 4 mm with an 8 mm notch depth. The units for impact strength and the dimensions of test samples also differ.
How is impact strength calculated in ASTM and ISO tests? In ASTM, it is found by dividing the impact energy by the thickness of the specimen; in ISO, it is divided by the area of the notch.
What industries benefit most from the Izod Impact Test? The automobile, aircraft, and production industries use it to verify that materials are safe and durable for a specific application.
