156A Week 10

Goal of demo:

In this class, students might still be struggling with free body diagrams so the goal of this demo is to help students visualize forces and moments. The rod will be different length on either side and students can calculate how much mass needs to be on either side to keep the system in equilibrium. Professor can have students solve for m1 and m2 and then test to see if they got it correct (increasing student engagement and making the lecture more interactive).

Learning objective from Professor Qi’s syllabus:

1.1 Students will demonstrate an understanding of force balance in case of equilibrium

(Newton’s first law of motion), the principle of action and reaction (Newton’s third law),

and the principle of transmissibility of force for rigid bodies.

Additional Notes:

-Vertical beam could be multi-functional and reconfigured into a beam to demonstrate bending moment in future designs

3D moment about a point

• 3D moment about an axis

OPTION 1: Develop a “find the moment about the axis due to force” problem for Lindsey’s structure

OPTION 2: Hinge Based Model

- Can serve as both an assignment for finding moments about an axis due to force and as a demonstration tool to show reactions/moments for a hinge.

- Additional tools needed (all tools could probably be used in the kit for

other purposes/demonstrations):

- Spring Scale to measure Force of Rubber Band

- Protractor to measure theta

- Ruler to measure various system vectors/lengths

Reaction/Moment at Various Supports

List your specific risk reduction objectives.

• Is this an effective learning tool?

  • Engages different learning styles

• Does the kit explain or demonstrate static/solid mechanic topics?

  • Yes

• Goal is to help student’s form an intuition so that they understand what is going on physically

  • These demos are an an efficient way to convey information

• 2D Moment About a Point

• 3D Moment About a Point

• 3D Moment About an Axis

• Reaction/Moment at Various Supports

Indicate if there are any engineering resources that you would like to help you with these objectives.

• MAE 131A & MAE 30A Textbook and Solutions Manuals

Feedback from last meeting with instructor

• Original risk reduction idea might be too complicated for the limited amount of time we have before the risk reduction presentation

• Should address more basic concepts

Feedback from meeting with sponsor

• Ideal topics for risk reduction are 2D moments, 3D moments (about a point & about an axis), and reaction forces

• Be clear about the goal for each demo

• Different types of beams would be good for future design (e.g: materials, cross sections)

What have been done in the past week

• Conducted research

• Reassessed original risk reduction idea and brainstormed alternative ideas

• Finalized risk reduction prototype designs

What is the next step of your project

• Each team member is responsible for building a physical mockup of her topic and using it for the Individual Component Analysis

• • 2D moment -- Sam

  • 3D moment about an axis -- Allie

  • 3D moment about a point -- Lindsey

  • Reaction forces -- Trish

• Working on risk reduction presentation

List your current concern according to the importance:

• Individual component analysis -- technical phone call necessary?

• Which moment about an axis (Allie’s part) option should be pursued? RESOLVED

INSTRUCTOR NOTES

Sami

-Showing loading that’s not just perpendicular to base would be helpful for students

-Maybe the pegboard moment demonstration in EBU 2 would be better?

Lindsey

-Find a material that is deformable to show deformation in direction perpendicular to base plate

Allie

-Find a material that is deformable to show deformation in more directions

Trish

-Start with the journal bearings

-how does that change with 1 bearing supporting a shaft vs 2

Overall Advice:

-Accurately use your model.

-When you present the model, what kind of explanation are you trying to do?

-Wants a user manual for each demonstration

Meeting with Sponsor: 12/11/2020

3D Moment about an Axis

Progress: Currently sourcing materials and tools, will build over the weekend

Survey Topics Frequently Chosen:

MAE 30A:

Trusses: 12

Reaction forces/moments at different types of supports, connections, and constraints: 9

Pulley Systems: 7

Loading, Shear, and Bending Moment In a Beam: 9

Moments in a 3D structure/frame: 9

MAE 131A:

Statically Indeterminate Structures: 14

Torsion: 12

Elasticity and Deformation: 12

Loading, Shear, and Bending Moment In a Beam: 9