CAD Apps for Core Courses in AE and ME Curricula

1. CAD Apps for Core Courses in AE and ME Curricula L. M. Silverberg, Director of Undergraduate Programs Mechanical & Aerospace Engineering J. Eischen, Chair of ME Course & Curriculum Committee Mechanical & Aerospace Engineering L. Battestilli, Instructor of Introduction to MATLAB Teaching Assistant Professor, Computer Science Students: Will Morrow, CS, MS Candidate – Coding Sean Maguire, ME, MS Candidate – Design & Assessment Konner White, ME, MS Candidate – Design & Assessment Point of Contact: L. M. Silverberg at lmsilver@ncsu.edu (919)515 5665 The Eiffel Challenge 1/14

2. CAD Apps: The Need for Design and Exploration in Early Engineering AE and ME Curricula • The need to increase design and exploration ranks high in student exit surveys. • This need originates from the central role of design and exploration in education and the difficulties that educators face in providing design and exploration experiences. • Whereas analysis tends to be about finding one correct solution, design and exploration tend to be about iterating parameters until a satisfactory solution is found. 2/14

3. CAD Apps: Course-Specific General-Purpose Tools are Developed for Design and Exploration • The offering of design problems in a classroom setting is greatly enhanced by using tools that allow the student to rapidly find solutions to complex problems. • Computer tools available to students today are largely general-purpose; not customized to specific courses. • This grant responds to the need for course-specific general-purpose tools for design and exploration for the early engineering years. 3/14

4. CAD Apps: Core Courses in AE and ME Curricula 4/14

5. CAD Apps: The Student Team MATLAB GUI Software Development GUI Design & Assessment MATLABBackend Code Will Morrow, Comp. Sci MS Candidate Sean Maguire, ME, MS Candidate Konner White, BS in ME, AE • Weekly Meetings Students & Faculty • Testing with Undergraduate/Graduate Volunteers 5/14

6. j i k u = D – L j D CAD Apps: Backend Code Dqk-- Dqk0 • Students use backend code specifically developed for the apps (truss, frame, mechanism, heat conduction, vibration). • Elements are one-dimensional. • Internally, nodes are unconstrained; constraints are modelled as highly stiff. • The process is dynamic. • 7 state variables for each node: 2 positions, 1 angle, 1 temperature, 2 velocities, 1 angular velocity • The static apps use default dynamic properties. L y i x Dqk0 Dqk B Qk(x) Y Pk (X) Vk(X) Mk(X) X PkA VkA MkA A QkA 6/14

7. CAD Apps: The Front End • GUIDE for overall front-end design • Utilities downloaded from community (e.g. plot_arrow.m ) or developed in-house (e.g. meshcolor.m, yieldLabelText.m) Main Window Editor Window Main Window runs simulations and displays or exports results. Invokes the Editor Window. Editor Window creates, edits, opens, and saves designs 7/14

8. CAD Apps: The Truss App • Installation • Tutorial • The Eiffel Challenge • Results & Winning • Design 8/14

9. CAD Apps: Installation • Double click on the file CADApp_Truss.mlappinstall • MATLAB Installed (2012b or higher) • URL: http://www.mae.ncsu.edu/academics/mae-course-websites.php At the bottom of the webpage click: Matlab App 9/14

10. CAD Apps: Tutorial Note: yE=16.32 mm (nonlinear) 10/14

11. CAD Apps: Tutorial – Additional Features • Return to Editor • Move a Node • Using the Mouse • Using Nodal Properties Table • Change the Length of a Member • Using the Mouse • Node Deletion • Using the Mouse Middle Button • Importing and Exporting Schematic Files • Using the Import from File Button and • the Export to File Button 11/14

12. CAD Apps: The Eiffel Tower Challenge (Wikipedia) • Eiffel said in 1887 (Le Temps (Paris), February 14): • “Now to what phenomenon did I give primary concern in designing the Tower? It was wind resistance. Well then! I hold that the curvature of the monument's four outer edges, which is as mathematical calculation dictated it should be … will give a great impression of strength and beauty, for it will reveal to the eyes of the observer the boldness of the design as a whole.” • As proof of the tower's effectiveness in wind resistance, it sways only 6–7 cm (2–3 in) in the wind. • ____________ • Named after the engineer Gustave Eiffel, whose company designed and built the tower. • Erected in 1889 as the entrance arch to the 1889 World’s Fair • The tallest building in Paris; most-visited paid monument in the world; 6.98 million people ascended it in 2011. The tower received its 250 millionth visitor in 2010. • 324 meters (1,063 ft) tall, about the same height as an 81-story building. • Has 3 levels for visitors, with restaurants on the 1st and 2nd. From ground level to the 1st level is over 300 steps, same from the 1st to the 2nd. There are stairs to the 3rd level but these are usually closed to the public and it is generally only accessible by lift. 12/14

13. The Eiffel Tower Challenge Top platform 2nd platform 1st platform Challenge: Find the widths of the 1st and 2nd platforms subject to the constraint that the total width L1+L2= 339ft in order to minimize the lateral deflection at the top platform Hint: Begin the iterative design process with the baseline configuration in file JWEEiffel.schm. 13/14

14. CAD Apps: The Eiffel Tower Solution (Top Secret) Minimum deflection is 0.207 ft = 2.5 in at the top when L1 ≈ 200 ftand L2 ≈139 ft. Actual Eiffel tower dimensionsare L1 = 216 ftand L2 = 123 ft. Given the simplicity of our 2D truss model, the insight than can be achieved is remarkable 14/14