Mechanical Engineering Fourth Year Impact Toughness Chapter 3

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Questions and Answers

What is the primary difference between the Charpy and Izod impact test techniques?

  • The type of pendulum used
  • The manner of specimen support (correct)
  • The temperature of the impact test
  • The material of the specimen

What is the formula to calculate the impact strength ($\sigma_{impact}$)?

  • $\sigma_{impact} = mh/hÌ€$
  • $\sigma_{impact} = E/Ah$
  • $\sigma_{impact} = E/mh$
  • $\sigma_{impact} = E/A$ (correct)

What does the ductile-to-brittle transition temperature (DBTT) indicate?

  • The temperature at which a material experiences maximum brittleness
  • The temperature at which a material behaves in a brittle manner in an impact test (correct)
  • The temperature at which a material experiences maximum ductility
  • The temperature at which a material behaves in a ductile manner in an impact test

What is the impact energy related to in the ductile-to-brittle transition?

<p>Mode of fracture (C)</p> Signup and view all the answers

What does the appearance of a dull and fibrous surface indicate in the context of fracture surfaces?

<p>Ductile fracture (A)</p> Signup and view all the answers

What factor has an important influence on the impact test result?

<p>Temperature of the specimen (D)</p> Signup and view all the answers

What is the measure of impact energy in the Charpy V-notch (CVN) technique?

<p>$m(h-h̀)$ (B)</p> Signup and view all the answers

How does the impact energy change with decreasing temperature during the ductile-to-brittle transition?

<p>It decreases suddenly over a narrow temperature range (C)</p> Signup and view all the answers

What is used to determine whether a material experiences a ductile-to-brittle transition?

<p>Temperature dependence of measured impact energy absorption (C)</p> Signup and view all the answers

What is the primary purpose of using the Charpy V-notch (CVN) technique in impact testing?

<p>To evaluate energy absorption (A)</p> Signup and view all the answers

What does the impact test involve?

<p>Striking a standard specimen with a pendulum and measuring the energy absorbed in breaking the specimen (D)</p> Signup and view all the answers

What does the impact energy value indicate?

<p>The toughness of the material under test (C)</p> Signup and view all the answers

What shape is the specimen used in Charpy and Izod tests?

<p>Bar of square cross-section (A)</p> Signup and view all the answers

What type of notch is machined into the specimen for Charpy and Izod tests?

<p>V-notch with 45° angle and 2-mm depth (C)</p> Signup and view all the answers

Under what conditions can impact test conditions be chosen to represent those most severe relative to the potential for fracture?

<p>Deformation at a relatively low temperature, high strain rate, and triaxial stress state (B)</p> Signup and view all the answers

What are the two standardized tests used to measure impact energy or impact toughness?

<p>Charpy and Izod (B)</p> Signup and view all the answers

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