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4.1 Question 1: Analysis of Four-Bar Linkage (12 Marks Total)

This document describes a kinematic analysis problem involving a four-bar linkage. It provides the link lengths and asks the student to: 1) Conduct position and velocity analysis using an analytical method to find positions and velocities when q2=60 degrees. 2) Set up a multibody dynamics model in ANSYS to analyze the linkage over one revolution of q2. Graphs of joint positions, velocities and point B velocity are requested. 3) Explain details of the ANSYS model such as degrees of freedom, joints used, and show results match the analytical method when q2=60 degrees. The ANSYS file is also to be submitted.

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Sh Younus Qreshi
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567 views2 pages

4.1 Question 1: Analysis of Four-Bar Linkage (12 Marks Total)

This document describes a kinematic analysis problem involving a four-bar linkage. It provides the link lengths and asks the student to: 1) Conduct position and velocity analysis using an analytical method to find positions and velocities when q2=60 degrees. 2) Set up a multibody dynamics model in ANSYS to analyze the linkage over one revolution of q2. Graphs of joint positions, velocities and point B velocity are requested. 3) Explain details of the ANSYS model such as degrees of freedom, joints used, and show results match the analytical method when q2=60 degrees. The ANSYS file is also to be submitted.

Uploaded by

Sh Younus Qreshi
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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v.

4.1 Question 1: Analysis of four-bar linkage (12 marks total)


Consider the four-bar linkage shown in Figure 1 below. The lengths of the links are: L1 = d = 100mm;
L2 = a (see details below, based on your student number); L3 = b = 90mm; L4 = c = 65mm.

Note: figure is not to scale.


Refer to the dimensions of the
links provided in the text.

Figure 1: Schematic of the general configuration of the four-bar link for Question 1.

For Question 1, the value of the length a (in mm) is:


𝑏 = 30 + 2𝛼
where α is the last digit of your student number, as detailed in Section 3 above.

Part A: Position analysis for q2 = 60° and ω2 = 6 rad/s (4 marks)


Using the analytical vector loop method (from SEM327 dynamics of machines), conduct position analysis to
find all possible values of q3 and q4 – i.e. for both the open and crossed configurations (circuits).
Conduct velocity analysis to calculate ω3 and ω4 and velocity at Point B.
Show all of your working and draw the solution to the problem – i.e. the possible positions of the links (open
and crossed circuits) when q2 = 60° and the velocity vector at Point B.

Part B: Kinematic analysis for one revolution of the joint at O2 (8 marks)


Set up the MBD model of the four-bar linkage shown in Figure 1 in ANSYS, for the open configuration only.
You can choose to use a separate CAD package to create the geometry for the links, or create these parts in
ANSYS.
Conduct a kinematic analysis for one revolution of the joint at O2 – i.e. actuate q2 from 0 to 360°. Assume
that ω2 is 6 rad/s. Provide the following results:
• Graph of q3 and q4 for one revolution (i.e. vs. q2).
• Graph of ω3 and ω4 for one revolution.
• Graph of velocity components at Point B for one revolution.

(see next page)


v.1

Explain the following details of your MBD model:


• Analysis of degrees of freedom of the system (Gruebler calculations)
• Explanation of each of the joints in ANSYS
• Show that model is not over-constrained
• Show that the hand calculations in Part A match the ANSYS model output when q2 = 60°. This
should include the values of q3 and q4 and the velocity vector at Point B. You may consider referring
to the graphs above and showing an image of the model, showing the position of the links.
• Explanation of other key components and settings of your MBD model.
• Please also submit your ANSYS model file.

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