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Created: 2024/05/22 04:54

Experiment No. 03

Experiment Name: Impact test of metal specimen

Objective

1. To study the impact testing machine.
2. To evaluate the energy absorbing characteristics of metal material at room temperature using Charpy, and Izod impact methods.

Significance

Fundamental knowledge on impact behavior of metal is crucial for material selection in order to ensure safety and reliability. Impact loadings are observed on materials such as when train passes over a bridge or a hammer drops. In such cases the resilience of those materials is a significant property. Impact tests are adequate to derive the resilience of materials.

Apparatus

1. Digital pendulum impact testing machine
2. Specimen: Charpy (simple beam), Izod (cantilever beam)

Data sheet

Calculation

For Izod method

• Notch depth: $2\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Length: $127\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Width: $10\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Height: $10\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Initial error: $1\text{[PARSE ERROR: Undefined("Command("space")")]}J$
• Energy absorbed: $118\text{[PARSE ERROR: Undefined("Command("space")")]}J$

Hence,

• Effective height: $(10-2)\text{[PARSE ERROR: Undefined("Command("space")")]}mm=8\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Effective volume: $127\times 10\times 8=10160\text{[PARSE ERROR: Undefined("Command("space")")]}m{m}^3$

$\mathrm{\therefore }$ Corrected energy absorbed,

$$(118-1)\text{[PARSE ERROR: Undefined("Command("space")")]}J=117\text{[PARSE ERROR: Undefined("Command("space")")]}J$$

$\mathrm{\therefore }$ Toughness,

$$\frac{Corrected\text{[PARSE ERROR: Undefined("Command("space")")]}energy\text{[PARSE ERROR: Undefined("Command("space")")]}absorbed}{Effective\text{[PARSE ERROR: Undefined("Command("space")")]}volume}=\frac{117\text{[PARSE ERROR: Undefined("Command("space")")]}J}{10160\times {10}^{-9}\text{[PARSE ERROR: Undefined("Command("space")")]}{m}^3}=11.52\times {10}^6\text{[PARSE ERROR: Undefined("Command("space")")]}J{m}^{-3}$$

For Charpy method

• Notch depth: $2\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Length: $55\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Width: $10\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Height: $10\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Initial error: $1.5\text{[PARSE ERROR: Undefined("Command("space")")]}J$
• Energy absorbed: $48\text{[PARSE ERROR: Undefined("Command("space")")]}J$

Hence,

• Effective height: $(10-2)\text{[PARSE ERROR: Undefined("Command("space")")]}mm=8\text{[PARSE ERROR: Undefined("Command("space")")]}mm$
• Effective volume: $55\times 10\times 8=4400\text{[PARSE ERROR: Undefined("Command("space")")]}m{m}^3$

$\mathrm{\therefore }$ Corrected energy absorbed,

$$(48-1.5)\text{[PARSE ERROR: Undefined("Command("space")")]}J=46.5\text{[PARSE ERROR: Undefined("Command("space")")]}J$$

$\mathrm{\therefore }$ Toughness,

$$\frac{Corrected\text{[PARSE ERROR: Undefined("Command("space")")]}energy\text{[PARSE ERROR: Undefined("Command("space")")]}absorbed}{Effective\text{[PARSE ERROR: Undefined("Command("space")")]}volume}=\frac{46.5\text{[PARSE ERROR: Undefined("Command("space")")]}J}{4400\times {10}^{-9}\text{[PARSE ERROR: Undefined("Command("space")")]}{m}^3}=10.57\times {10}^{\text{[PARSE ERROR: Undefined("Command("space")")]}}J{m}^{-3}$$

Result

The energy delivered to the metal specimen was found to be $117\text{[PARSE ERROR: Undefined("Command("space")")]}J$ for Izod method and $46.5\text{[PARSE ERROR: Undefined("Command("space")")]}J$ for Charpy method.

Discussion

In this experiment, we determined the energy absorption of metal specimen on sudden loading. The impact value of the metal specimen was found to be 117 J for Izod method and 46.5 J for Charpy method. Which means that the mild steel specimen absorbed 117 J and the Aluminum specimen absorbed 46.5 J energy before fracturing under the conditions of Izod method and Charpy method respectively.

We also gained some insights into the material's toughness which was found to be $11.53\text{[PARSE ERROR: Undefined("Command("space")")]}MJ{m}^{-}3$ and $10.57\text{[PARSE ERROR: Undefined("Command("space")")]}MJ{m}^{-}3$ for Izod and Charpy methods respectively.

Impact value of metal specimen is highly affected by temperature and sharpness of the notch. The experiment was conducted at room temperature, however, impact values may be lower at lower temperature. Hence, additional cares must be taken for selecting materials for design.

Assignments