Heat Transfer In Structures

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Simulation Quiz 3

Heat Transfer In Structures Simulation Quiz 3

Cooling of a Cardiovascular Stent

A cardiovascular stent is a medical device to open a plaque-blocked vessel. A commonly-used material for stents is Nitinol, a Nickel and Titanium alloy. During the manufacturing process, a stent is annealed and quenched into a specific shape. The annealing process is a heat treatment that keeps the stent under high temperature for a certain time, and the quenching process submerges the stent into a quenchant to cool it at a certain rate. The cooling rate of a stent should be controlled, as too slow of cooling rate is inefficient for the manufacturing process, and too fast of cooling rate can increase the brittleness of the stent, which can cause heat-induced stress and even cracking. In this simulation, we model the quenching process of an annealed stent and study how different quenchants affect the cooling process. For this, we will use a Transient Thermal Analysis to understand the time-dependent response of the stent.

Follow instructions to set up the simulation and get results BEFORE starting the quiz. Download the instructions and necessary simulation files from here.

Note: The Expected Completion Time for this quiz is 15 mins but, the Maximum Available Time to complete the quiz is 30 mins.

Total Available Time - 30 mins.

Total Number of Questions - 10

Times up!

Heat Transfer for Structures - Simulation quiz 3

Complete the simulation and have all the results ready BEFORE starting the quiz.

Once you have finished the exam, click on the 'Mark Complete' button to save your progress and move to the next section.

1 / 10

For both analyses, if the number of elements across the stent thickness is reduced to 1, how does it affect the cooling down time? (Hint: Set “Sweep Num Divs: 1” under Mesh > Sweep Method > Definition)

2 / 10

For both analyses, what is the ending time for these simulations?

3 / 10

For both analyses, what is the final temperature of the stent at end of the simulation? Select the best answer.

4 / 10

For both analyses, the stent starts cooling down from what temperature?

5 / 10

Compare the results of System A (“Water Cooling”) with System B (“Forced Air Cooling”). How much faster does it take for the stent to cool below 21 °C in water as compared to forced air? Choose the best option. (Hint: Use Temperature result objects)

6 / 10

For System B (“Forced Air Cooling”), at a time of 0.5 seconds, what is the maximum temperature for the stent? Choose the nearest option. (Hint: Use Temperature result object)

7 / 10

For System A (“Water Cooling”), at time of 0.25 seconds, what is the temperature on the stent? Choose the nearest option. (Hint: Use Temperature result object)

8 / 10

For these simulations, why is Transient Thermal analysis used instead of Steady-State Thermal analysis? Select the best option.

9 / 10

For System A (“Water Cooling”), how much time does it take for the stent to cool to 100 °C? Choose the closest option. (Hint: Use Temperature result object)

10 / 10

For System B (“Forced Air Cooling”), at what time does the stent reach a maximum temperature of 25 °C? Choose the closest option. (Hint: Use Temperature result object)

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