# Simulation Quiz 3

### Sunglass Arm

An arm of a pair of flexible plastic sunglasses is analyzed to determine the amount of moment experienced at the hinge when the arm is pulled too far.  The geometry is shown below.  The surface where the arm is attached to the hinge of the frame will be fixed while a force is applied to the end of the frame in a direction normal to the surface. 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 20 mins but, the Maximum Available Time to complete the quiz is 45 mins.

#### Total Number of Questions - 15

Times up! Understanding the Physics of Structural Mechanics - 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 / 15

What is the maximum magnitude of deformation in the y-direction under the applied load?  Select the BEST option below.

2 / 15

What is the maximum equivalent stress experienced in the plastic arm?  Select the BEST option.

3 / 15

Consider the locations A through D in the figure below.  Where is the location of the maximum XZ shear stress component? 4 / 15

Assume that the hinge connecting the arm to the sunglass frame can withstand a total moment of up to 80 Nmm.  Select TWO statements that are correct, based on the analysis results.  (Hint: use Moment Reaction probe.)

5 / 15

Which component of stress contributes most to the equivalent stress?  Select the BEST option.

6 / 15

Let’s say that the maximum deformation of the arm is designated as deformation_current.  Consider a separate case where the force is doubled on the arm, and the maximum deformation of the arm is called deformation_twice.  (Do not run such an analysis.)  Assuming that the plastic material still responds in a linear elastic manner, which statement below is correct?

7 / 15

Review the Reaction Force probe and notice that the reaction force history (Force vs Time) is linear.  Select the option below that is correct.

8 / 15

Add a Maximum Shear Stress result object and review the result.  What is the value of the Maximum Shear Stress when half of the load is applied?  (Do not run such an analysis.)  Select the correct option.

9 / 15

Examine the Total Deformation result.  Based on the result history, how would the result compare if your ran with Large Deflection effects turned off?  (Do not run such an analysis.) Select the best option below.

10 / 15

Consider the intermediate result at “Time = 0.1 [s]”.  Select the correct statement below.

11 / 15

What is the maximum deformation of the sunglass arm under the applied load?  Select the BEST option.

12 / 15

Consider the same model with the same loads and boundary conditions, but the arm is made of a stiffer plastic (higher elastic modulus).  (Do not run such an analysis.)

Select two correct statements below.

13 / 15

Assume that this plastic will crack if the maximum principal stress exceeds 20 MPa.  Select the two correct statements.

14 / 15

Carefully review the model and Reaction Force probe results at the Fixed Support.  Why is the reaction force in the x-direction at “Base” not equal to 0.75 N (within a tolerance of 0.1%)?

15 / 15

Why are Large Deflection effects used in this simulation?  Select the BEST option.