Near Term Timetable. Homework 7: two FEM problems, posted yesterday, due Th October 22.

Transcription

1 Near Term Timetable Homework 7: two FEM problems, posted yesterday, due Th October 22. RQ#5 on FEM on Tuesday Oct 20. Read Chapters (omit 16). Only basic questions. Recitation next week on Friday Oct 23 will cover beams by DF and FEM (two problems) Midterm exam Friday Oct 29, announced in HW 7.

2 Returned Today Midterm Exam 2 and HW 5 have been graded, may be picked up from table Solutions for both are posted on the Web

3 ANSYS Demos for Computer Portion of Lab 2 To be held on Friday October 15, at Visions Lab (ECAE 1B73) - No recitations that day. To get access with your Buff Card and get an account, register at the OIT site specified on the ANSYS tutorial. Attendance recommended but not required Demo is a hands-on, self-learning (individual) tutorial. Once in, sit at any empty computer and try logging in Using your Identikey and PW. T.A.s available to help. Access to VL is 24/7, except if classes are being held

4 Demo Times Because of limited seating (physically 25 workstations) the demo will be divided into four roughly-one-hour subsections Sec 011: 1 PM and 2 PM Sec 012: 3 PM and 4 PM Student distribution on next slide

5 Section 011 (1-3 PM) Splitting A-L M-Z 1 PM 2 PM Section 012 (3-5 PM) Splitting A-L M-Z 3 PM 4 PM

6 No Grouping Necessary Note: members of a group need not attend the same demo subsection, since the tutorial is individual

7 A Short Pictorial Introduction to FEM

8 Before 1950, standard structural elements such as beams, ribs and spars, were sufficient for modeling low aspect ratio aircraft structures (e.g. Lockheed Constellation, pictured on left)

9 The modern FEM was developed starting about 1952 as a modeling tool to simulate delta wing military aircraft on digital computers Digital computers began to be commercially sold by Only aerospace companies and some government agencies could afford them (a vacuum-tube monster weighting several tons and with the power of an iphone cost the equivalent of $100M today)

10 Most of the pre-1960 work was done at a few places

11 A key 1956 paper described the DSM as used today

12 The method was well on its way by but it had a marketing problem: no brand name

13 Name was coined by Ray Clough in 1960

14 Ray Clough s early career I b. 1921, Seattle served in Air Force during WWII Ph.D. Aero & Astro MIT, 1950 joined Civil Engrg faculty at UC Berkeley, 1951 avid mountaineer & skier (holds many climbing records)

15 Ray Clough s early career II spent summers at Boeing at Jon Turner s group so he could go mountain climbing on weekends modern FEM started by 1956 JAS paper by Turner, Clough, Martin & Topp back at Berkeley, became interesting in Civil applications, especially earthquake engineering formed FEM research group in 1958

16 First Civil structure analyzed by FEM (1962)

17 Ray with Kurt Gerstle (his 1st student) on left pic

18 Ray Clough s late career gave up FEM research in 1972 for earthquake engineering head of NSF Earthquake Engineering Center at Richmond, CA, retired from Berkeley 1987 honored with National Medal of Science, 1994

19 An Unimpeachable Gentleman

20 Explosive Success... By 1970, FEM (DSM) had taken over computational mechanics and was expanding beyond structures Some samples follow

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23 F-16 Structural Model

24 F-16 Exterior Surface Zoom 95% of elements are HPSHEL3 18 DOF shells

25 F-16 Interior Structure Zoom Some solid elements (bricks & tets) used for wing fingers

26 Liquid Natural Gas (LNG) Ship - Global FEM Model

27 Stepwise Construction of Global Model

28 Hot Spots Detailed Local Models

29 Wave Motion and Hull Pressures

30 The Troll Platform 470 m high including superstructure m3 of concrete tons of steel reinforcement Design life of 50 years Largest man-made object ever moved Supplies 10 percent of Europe s gas consumption

31 The Heidrun Platform Floating TLP Platform Made of reinforced concrete 16 vertical anchoring lines (tethers) of pre-tensioning Transverse stiffness supplied by secondary geometric effects

32 Last But Not Least...

33 16-bay Truss for Lab #2: FEM Model (Mathematica)

34 Idealization Process

35 FEM-DSM Breakdown

36 FEM-DSM Assembly & Solution

37 The Example Truss

38 The Truss Example

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