Problem Solving Techniques

1. Problem Solving Techniques MST326 lecture 3 MATS326-3 problem.ppt

2. Outline of lecture • Brainstorming • Mind maps • Cause-and-Effect diagrams • Failures Mode and Effects Analysis • Fault Tree Analysis • Design of Experiments MATS326-3 problem.ppt

3. Brainstorming • proposed by Alex Osborn“for the sole purpose ofproducing checklists of ideas” • technique to identify causesand develop solutions to problems • “seeking the wisdom of ten people rather than the knowledge of one person” [Kaizen Institute] MATS326-3 problem.ppt

4. Brainstorming • no criticism is permitted • “only stupid question is one that is not asked” [Ho] • wild ideas are encouraged • often trigger good ideas from someone else • each person contributes one idea • further single ideas on second circuit • repeat until no further ideas • all contributions are recorded in view MATS326-3 problem.ppt

5. Brainstorming • Osborn proposed 75 fundamental questions • can be reduced to:  seek other uses?  adapt? • modify?  magnify? • minify?  substitute?  rearrange?  reverse?  combine? MATS326-3 problem.ppt

6. TRIZ • Teorija Reshenija Izobretatel'skih Zadach • loosely translates asTheory of Inventive Problem Solving (TIPS) • 40 Inventive Principles MATS326-3 problem.ppt

7. 40 inventive principles of TRIZ IP 01: Segmentation IP 02: Taking out IP 03: Local quality IP 04: Asymmetry     IP 05: Merging     IP 06: Universality IP 07: Nested doll IP 08: Anti-weight IP 09: Preliminary anti-action IP 10: Preliminary action IP 11: Prior cushioning IP 12: Equipotentiality IP 13: The other way round IP 14: Spheroidality or curvature    IP 15: Dynamics IP 16: Abundance IP 17: Another dimension IP 18: Mechanical vibration IP 19: Periodic action IP 20: Continuity of useful action    IP 21: Rushing through     IP 22: Blessing in disguise IP 23: Feedback IP 24: Intermediary IP 25: Self-service IP 26: Copying     IP 27: Cheap short-lived objects IP 28: Mechanics substitution IP 29: Pneumatics and hydraulics IP 30: Flexible shells and thin films    IP 31: Porous materials IP 32: Colour change IP 33: Homogeneity IP 34: Discarding and recovering    IP 35: Parameter change IP 36: Phase transition IP 37: Thermal expansion IP 38: Strong oxidants IP 39: Inert atmosphere IP 40: Composite materials MATS326-3 problem.ppt

8. Mind maps • attributed to Tony Buzan • classic book “Use Your Head” MATS326-3 problem.ppt

9. Mind maps Image from http://www.loanedgenius.com/scrabble_2_letter_words.gif MATS326-3 problem.ppt

10. Cause-and-Effect diagrams • Cause-and-Effect diagram • often referred to as a fishbone diagram • or an Ishikawa diagram • introduced by Kaoru Ishikawa • simple graphical method to record and classify a chain of causes and effects in order to resolve a quality problem MATS326-3 problem.ppt

11. Cause-and-Effect diagrams • Clarify the object effect • Pick causes • Determine the priority causes • Work out the counteractions for priority causes • implement appropriate solutions to eliminate or reduce the causes of problems MATS326-3 problem.ppt

12. Cause-and-Effect diagrams I • Clarify the object effect • a numerical measurement should be established against which subsequent improvement can be judged MATS326-3 problem.ppt

13. Cause-and-Effect diagrams II • Pick causes • create a team of people to brainstorm possible causes that may lead to the effect • study the actual effect in the problem environment • on a horizontal line draw diagonal branches for direct causes of the effect • using arrows onto the branches create sub-branches for appropriate secondary causes • confirm all elements of the diagram are correctly positioned • quantify the causes wherever possible MATS326-3 problem.ppt

14. Cause-and-Effect diagrams III • Determine the priority causes • analyse any existing data for the problem • if practical, create a Pareto diagram.  • otherwise, determine a ranking of the relative importance of each cause. MATS326-3 problem.ppt

15. Cause-and-Effect diagrams IV • Work out the counteractions for priority causes • put in place appropriate solutionsto eliminate or reduce the causes of problems MATS326-3 problem.ppt

16. Cause-and-Effect diagram: • Image from http://www.ifm.eng.cam.ac.uk/dstools/gif/ishika.gif MATS326-3 problem.ppt

17. Failures Mode and Effects Analysis • FMEA is • a useful tool for reliability analysis • systematic check of a product or process • function • failure causes • failure modes • failure consequences MATS326-3 problem.ppt

18. Failures Mode and Effects Analysis • Requires a thorough knowledge of • functions of the components • contribution of those components to function of the system • For every failure mode at a low level,failure consequences are analysed at • the local level • the system level MATS326-3 problem.ppt

19. Failures Mode and Effects Analysis • FMEA is usually qualitative but may also be quantitative • initiated during planning and definitionof a project to investigate qualitative reliability demands of the market • during design and development, for quantitative reliability activities MATS326-3 problem.ppt

20. Table From Evans and Lindsay Chapter 13 MATS326-3 problem.ppt

21. Failures Mode and Effects Analysis • design-FMEA for design reviews • definition and limiting of the system • choice of complexity level • check of component functions • check of system functions • identification of possible failure modes • identification of consequences of failures • possibility of failure detection and failure localisation • assessment of seriousness of failure • identification of failure causes • interdependence of failures • documentation MATS326-3 problem.ppt

22. Failures Mode and Effects Analysis • quantitative design-FMEA a.k.a. FMECAFailure Mode, Effects and Criticality Analysis • consider every component • quantify and rank different failure modes • F = probability of failure • A = seriousness (consequences of failure) • U = probability of detection • subjective judgements on a scale of 1-5 or 1-10 • Product (F*A*U) = Risk Priority Number (RPN) MATS326-3 problem.ppt

23. Failures Mode and Effects Analysis • Process-FMEA for • pre-production engineering • design of process control • process improvement • FMEA is efficient where component failure leads directly to system failure • for more complex failures, FMEA may be supplemented by Fault Tree Analysis (FTA) MATS326-3 problem.ppt

24. Some URLs for FMEA • http://www.fmeainfocentre.com/ • http://supplier.intel.com/ehs/fmea.PDF • http://www.cs.mdx.ac.uk/puma/wp18.pdf • http://www.sverdrup.com/safety/fmea.pdf • http://www.uscg.mil/hq/msc/fmea.doc • http://www.competitiveedge.net/pdfs/fmea.pdf • http://www.fmeca.com/ffmethod/methodol.htm • http://www-personal.engin.umich.edu/~wmkeyser/ioe539/fmea.pdf • http://www.engin.umich.edu/class/eng401/003/LCNotes/fmea.pdf MATS326-3 problem.ppt

25. Fault Tree Analysis • Logical chart of occurrences to illustrate cause and effects • developed by DF Haasl, HA Watson, BJ Fussell and WE Vesely • initially at Bell Telephone Laboratories then North American Space Industry MATS326-3 problem.ppt

26. Fault Tree Analysis • Common symbols used 1 • main event • basic event • incompletely analysed event • restriction MATS326-3 problem.ppt

27. + 1 & Fault Tree Analysis • Common symbols used 2 • or-gate • and-gate • transfer to or from another place MATS326-3 problem.ppt

28. Figure From Evans and Lindsay Chapter 13 MATS326-3 problem.ppt

29. Design of Experiments • originally conceived byRonald Aylmer Fisherat Rothampstead Experimental Station during the 1920s • analysing plant growing plotsunder different conditions, andneeded to eliminate systematic errors. Image from http://www.csse.monash.edu.au/~lloyd/tildeImages/People/Fisher.RA/ MATS326-3 problem.ppt

30. Experimental design • Randomisation • Replication - repetition so that variability can be estimated • Blocking - experimental units in groups (blocks) which are similar • Orthogonality - statistically normal. • Use of factorial experimentsinstead of one-factor-at-a-time MATS326-3 problem.ppt

31. Design of Experiments • full factorial experiment • where a number of factorsmay influence the output of a process, it is possible to study all combinationsof levels of each factor • if the number of factors considered increases, then number of experiments required increases more rapidly.  MATS326-3 problem.ppt

32. Design of Experiments • For two levels of n-variables,the number of experiments required is 2n • 4 experiments for two variables(low-low, low-high, high-low and high-high) • 16 experiments for four variables • 64 experiments for six variables. • If three levels (low - normal - high) or more are to be studied, then a full factorial experiment soon becomes impractical. MATS326-3 problem.ppt

33. Design of Experiments • results plotted to indicate the influence of each of the factors studied • when one factor affects the response,this is known as the main effect. • when >1 factor affects the response,this is termed an interaction. MATS326-3 problem.ppt

34. Design of Experiments Genichi Taguchi developed orthogonal arrays • fractional factorial matrix • permits a balanced comparisonof levels of any factor with a reduced number of experiments. • each factor can be evaluated independently of each of the other factors.  MATS326-3 problem.ppt

35. Orthogonal arrays L4: three two-level factors L9: four three level factors Arrays from http://www.york.ac.uk/depts/maths/tables/orthogonal.htm MATS326-3 problem.ppt

36. Common orthogonal arrays Table from Tony Bendell “Taguchi Methods”, 1989 MATS326-3 problem.ppt

37. Taguchi • Quality Loss FunctionL(x) = k ( x - t )2 • L = the loss to society of a unit of output at value x   • t = the ideal target value • k = constant • as non-conformance increases,losses increase even more rapidly MATS326-3 problem.ppt