Dr.Mohammed Abdulrazzaq

An impact test is a dynamic test conducted on a selected specimen which is usually notched. The specimen is struck and broken by a single blow in a specially designed machine. This demo illustrates the experiment setup, procedure and the energy absorbed in an impact test. Voice Over: An impact test is a dynamic test conducted on a selected specimen which is usually notched. The specimen is struck and broken by a single blow in a specially designed machine. This demo illustrates the experiment setup, procedure and the energy absorbed in an impact test. Click the start button to start the demo.

Impact Tests Toughness of metals is the ability to withstand impact.

Izod test Strikes at 167 Joules. Test specimen is held vertically. Notch faces striker.

Charpy impact test Strikes form higher position with 300 Joules. Test specimen is held horizontally. Notch faces away from striker.

Impact Test Aim: To measure the toughness, or energy absorption capacity of the materials. Notch Voice Over: The purpose of the impact test is to measure the toughness, or energy absorption capacity of the materials. The experiment setup consists of: Test-specimen of a specified dimensions with a notch of specific dimensions cut into it. The Charpy impact test uses a different support condition for the specimen than the Izod impact test. Which we will discuss in the next section. Pendulum machine A test device - which can vary. Visual Guidelines: In sync with the first narration fade in the text. In sync with the first two bullet narrations fade in the two images one by one. Test-specimen Pendulum Machine

Test Specimen – Support Conditions Charpy Test Setup Notch Point of Impact Specimen 44m Voice Over: In the Charpy test, the specimen dimensions are: Specimen Length = 55m Square cross section = 10mm Central u notch of = 5mm deep The specimen is supported as a simple beam with a span of 40mm. The specimen is supported that the notch is on the vertical face away from the point of impact. The figure shows the dimensions of the Charpy test specimen and the positions of the striking edge of the pendulum and the specimen in the anvil. Visual Guidelines: Initially animate the specimen dimensions in sync with the narration. Then show the Charpy Test equipment then slide it to the left and show the blown up of the specimen as shown. In sync with the narration show the respective labels & parts in the blown up flashing. Simple beam support Specimen

Test Specimen – Support Conditions Izod Test Setup Voice Over: In the Izod test, the specimen dimensions are: Specimen Length = 75m Square cross section = 10mm Central u notch of = 2mm deep The specimen is held on one end and is free on the other end. This way it forms a cantilever beam. The figure shows the dimensions of the Izod test specimen, the specimen in the anvil and the positions of the striking edge of the pendulum. In this case the notch is just at the edge of the supporting vise and facing into the direction of impact. As with the Charpy, this position places the notch at the location of the maximum tension. Visual Guidelines: Initially animate the specimen dimensions in sync with the narration. Then show the Izod Test equipment then slide it to the left and show the blown up of the specimen as shown. In sync with the narration show the respective labels & parts in the blown up flashing. Notch Cantilever beam support

Equations Initial Energy (Ei) = mga = Wa Impact Velocity = v = (2ga)‏ Energy after rupture (Er) = mbg = Wb Energy absorbed by the specimen (Eab) = Ei – Er = mga - mgb 1/2 Voice Over: In a typical Pendulum Machine, the mass of the hammer (m) is raised to a height (a). Before the mass (m) is released, the initial energy of the pendulum is its potential energy given by: mga After being released, the potential energy will decrease and the kinetic energy will increase. At the time of impact, the kinetic energy of the pendulum is equal to its potential energy. Therefore, the impact velocity is given by: After the rupture the energy is given by: mbg The energy absorbed by the specimen is then given by: mga - mgb The pendulum machine is equipped with an Energy meter that indicates the these energy levels. Visual Guidelines: Show the pendulum hitting the specimen & trace the path as given in the image below & label the image. In sync with the narration then fade in the equations.

Charpy Experiment Simulation Load the Specimen. Release the Pendulum. Hammer Voice Over: Here is an experiment setup for Charpy Test. First drag the specimen to load it on the simple beam support and click the hammer to start the experiment. Visual Guidelines: Allow the user to drag the specimen to the simple beam support. When the user drags it to the support align it to the center of the support. Please refer to the link: http://www.steeluniversity.org/content/html/eng/charpy-test.asp Then when the user clicks the hammer show the pendulum hitting with the conditions as shown on the next slide. Specimen Simple beam support Drag the specimen to the support and click hammer.

Charpy Experiment Simulation Load the Specimen. Release the Pendulum. Indicate P.E = 300J Energy Absorbed = 120J 150 Voice Over: Observe the amount of energy absorbed in breaking the metal indicated by the energy meter. Voice Over after the animation: You can check your understanding on this topic by taking a small quiz. Click the Quiz button. Visual Guidelines: When clicked on the Start button, show the pendulum hitting the specimen & the specimen breaking into two pieces. Show the breakage of the specimen in a blown up. Also show the energy meter indicating the energy as shown in the link. When the pendulum moves to the other end lock the pendulum. Do not allow the pendulum to swing. Click the Quiz button.

Resources Reference Links: http://en.wikipedia.org/wiki/Charpy_impact_test http://en.wikipedia.org/wiki/Izod_impact_strength_test http://www.matweb.com/reference/izod-impact.aspx http://www.steeluniversity.org/content/html/eng/default.asp?catid=151&pageid=2081271949

Results of the Charpy Impact test and the Izod impact test cannot be compared can be compared if the specimens have the same dimensions should be used in tandem to estimate the toughness of the material can be compared if the pendulum / hammer has the same weight Feedback when option 1 is selected: That’s correct. Irrespective of the specimen and pendulum characteristics, the results of the Charpy Impact Test and Izod Impact Test cannot be compared. Feedback when any other option is selected: Incorrect. Irrespective of the specimen and pendulum characteristics, the results of the Charpy Impact Test and Izod Impact Test

Results of an impact test can be used directly in design equations for components can be used in design equations for components only after empirical correlation has been obtained can be used in design equations after adjusting for temperature difference only cannot be used for design calculations Feedback when option 2 is selected: That’s correct. Results of an impact test can be used in design equations for components only after empirical correlation has been obtained. Feedback when any other option is selected: Incorrect.

Impact tests are independent of specimen size are independent of notch size are dependent on specimen size are dependent on notch size Feedback when options 3 & 4 are selected: That’s correct. Impact tests are dependent on specimen size and notch size. Feedback when options 3 or 4 is/are selected: Partially correct. Feedback when any other option is selected: Incorrect.

The temperature of the specimen does not affect the results of the test is directly proportional to the measured toughness is inversely proportional to the measured toughness affects the measured toughness differently for different materials Feedback when option 4 is selected: That’s correct. The temperature of the specimen affects the measured toughness differently for different materials. Feedback when any other option is selected: Incorrect.

Results of the impact test can be used directly to estimate yield strength cannot be used directly to estimate yield strength can be used to estimate yield strength based on empirical correlations can be used to estimate yield strength based on fundamental relationships Feedback when option 3 is selected: That’s correct. Results of the impact test can be used to estimate yield strength based on empirical correlations. Feedback when any other option is selected: Incorrect.