EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame Technical Communication: Written documents Introduction to Engineering Systems Lecture 9 (9/25/2009) Prof. Andrés Tovar

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame Announcements Look at the NOTE listed on the lower left hand corner of the design constraints which states that if there is "no bracing allowed" on a given floor you can still add 2 vertical members on the interior plane. SAP is now on computers in cluster and Cushing 303. Instructions for use of SAP in cluster is posted on CONCOURSE. Bring a camera to Learning Center next week if you want a picture of your group or design for the report. Review Learning Center 6 prior to testing day. In F.O.S. k SAP refers to the stiffness in SAP of unbraced five-story tower. 2Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame From last class Optimum refers to the best. An optimization problems has: –Objective function –Design variables (design space) –Constraints (feasible space) Optimization methods include: –Graphic –Analytic –Numeric –Heuristic Factor of safety (F.O.S.) –How to determine –How to use Probability of failure associated to F.O.S. (cdf) Results from topology optimization 3Technical communication up to 20 binary design variables per face

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame FAQ on probability 4 Probability in normal distribution Source: Wikipedia.com m=0;s=1;d=0.01; x=-3*s:d:3*s; f=pdf('norm',x,m,s); plot(x,f) y=[m-3*s,m-2*s,m-s,m,m+s,m+2*s,m+3*s]; p=cdf('norm',y,m,s) p = Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame FAQ on probability 5 What is the probability of failure? For N = 1 (one sigma design) P(  ≤  -  ) = ≈ 0.1% + 2.1% % Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame Where we are in the tower design process 6 Gather Data Develop Model Verify Model MODEL DEVELOPMENT Investigate Designs using Model Optimize Design Predict Behavior DESIGN STAGE Construct Design Experimentally Verify Behavior CONSTRUCTION & VERIFICATION Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame In-class exercise About the report “An Analysis of Colliding Pendulums” Read the paper and circle/write comments on any problems (5 min) In groups of 4 work assemble a list of all the problems they find (5 min) Each group identifies the most relevant issue with the paper –Is there enough information in the report so that another person who has not seen the experiment might be able to repeat it? –Are the calculations clear? Is enough information provided that another person could rework them? Are the variables in equations, including the use of subscripts or superscripts, well-selected and their meaning clearly defined. –Are tables and graphs clear and unambiguous? –Are there spelling or grammatical errors, or poor word choice? –Is there appropriate use of references? –Are the conclusions drawn from the results reasonable? 7Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame In-class exercise About the report “An Analysis of Colliding Pendulums” – Section 3 Lacking explanation Lack of clarity Charts have no labels Poor use of references Blames others Unclear procedures Unrealistic results Poor grammar and spelling Poor explanation of formulas The experiment cannot be recreated 8Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame In-class exercise About the report “An Analysis of Colliding Pendulums” – Section 4 Not enough information Graph doesn’t have title nor units Blames others Graph’s lines are the same No citations Procedure is out of order Figure’s captions not defined Not explicit equation No units on table Variables are undefined Misspellings and grammatical errors Wrong conclusion Significant figures don’t match in table 9Technical communication Too informal No info in abstract

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame About equations 10 C Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame About equations 11 B Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame About equations 12 A Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame About equations Use punctuation. Equations are part of the sentence. Do not use mathematical symbols unless they serve a purpose. Avoid starting a sentence with a mathematical expression. Use equations that are easy to read, e.g., exp instead of e. An equation is displayed when it needs to be numbered, when it be hard to read in-line, or when it merits special attention. Reference earlier (not future) equations. Do not use a letter as a dummy variable if it already serves other purpose, e.g., e, i. Be aware of universally accepted symbols, e.g., ∞, , e, i. 13Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame Table 14 TrialPullback Distance, X (m) Flight Distance, D (m) Table 1: Results of 6 trial launches of a softball from the slingshot number and caption above column headings with units Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame Plot 15 title line for theoretical result or best-fit points for experimental data label axes with units Figure 1: Experimental data and best-fit, least squares line for slingshot flight distance vs. pullback figure number and caption below Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame Report Expectations Read LC 6 Document! Read Sample Good Report on Concourse Body of Report - Limited to 10 pages –Abstract –Introduction –Procedure –Results/Discussion –Conclusion MAKE SURE TO INCLUDE REFERENCES!!! 16Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame Rubric for Tower Builder Project 17 CriterionMaximum grade Limit state satisfied55 Constraints satisfied20 (all or nothing) Efficiency rank15 F.O.S. > 110 Total100 Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame What to Bring to Testing Day PRINTOUT OF SAP MODEL CONSTRUCTED TOWER DATA FOR UNBRACED TOWER –SAP Stiffness (k SAP ) –Mean Stiffness from Experimental Database (  k ) Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame What to Bring to Testing Day DATA FOR BRACED TOWER –Target Deflection Limit State (  max ) –Factor of Safety –Predicted displacement (  SAP ) –Bracing Ratio: B = L Total /3000 mm –Stiffness Ratio (SAP): S = k braced /k unbraced –Predicted Efficiency Ratio: E = S/B Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame Testing Day No Instructions given on Test Day READ LC 6 Document!! Testing procedure identical to that used in Learning Center 1, repeating for three trials Correct for initial displacement Calculate average displacements Plot forces vs. displacement in MATLAB and fit line Correct for spring stiffness Other Calculations Stiffness, Bracing, and Efficiency Technical communication

EG 10111/10112 Introduction to Engineering Copyright © 2009 University of Notre Dame What if My Tower Fails? Teams showing honest effort still receive majority of points Force-displacement plot will be analyzed for non- linear behavior –Indicates connection failure 21Technical communication