ME 478 Introduction to Finite Element Analysis

Instructor: Dr. Alexander Veress Email: averess@u.washington.edu

Office Hours: Tues. 10:00 – 11:20 a.m. MEB 309

TA: Michael Au Yeung Email: michael.auyeung@gmail.com

Office Hours: Tue. and Wed. 1:30-3:00 p.m. MEB 236

Finite Element Analysis ME 478A

University of Washington, Seattle Fall Quarter 2013 Lecture: MEB 242 Time: M, T, Th 11:30-12:20 am Lab: MEB 231 Time: F 11:30-12:20 Website: http://faculty.washington.edu/averess/html/me_478_lecture_notes_.html

GoPost: https://catalyst.uw.edu/gopost/board/averess/37886/

Lecture/Lab Topic Book Readings Assign Due

Thurs Sept. 25 Introduction to Finite Elements Chapter 1

Lab 26 ANSYS tutorial

Mon Sept. 29 Direct Assembly Springs pp 23-35

Tues 30 Direct Assembly Springs pp 23-35 HW 1

Thurs Oct. 2 Direct Assembly Bars pp 36-51

Lab 3 pp 36-51

Mon Oct. 6 Minimum Potential Energy pp 36-51 HW 2

Tues 7 Minimum Potential Energy example HW 1

Thurs 9 Minimum Potential Energy example

Lab 10 pp 55-62

Mon Oct. 13 2D Truss Formulation Local Global Coordates pp 63-82

Tues 14 2D Truss pp 63-82 HW 3

Thurs 16 3D Truss/Special Topic pp 83-84 HW 2

Lab 17 pp 95-118

Mon Oct. 20 Bending pp 95-118

Tues 21 Torsion pp 124-128 HW 4

Thurs 23 Torsion and Special Topic pp 124-128 HW 3

Lab 24 Isoparametric Formulation pp 177-187

Mon Oct. 27 Isoparametric Formulation pp 188-206

Tues 28 Isoparametric Formulation HW 5 HW 4

Thurs 30 Midterm Exam

Lab 31

Mon Nov. 3 2D Plane Stress/strain pp 332-347

Tues 4 2D Plane Stress/strain pp 363-364 HW 6

Thurs 6 2D Plane Stress/strain Example HW 5

Lab 7

Mon Nov. 10 3D Stress Analysis pp 368-379

Tues 11 Veteran's Day HW 7

Thurs 13 3D Stress Analysis and Special Topic pp 368-379 HW 6

Lab 14

Mon Nov. 17 Heat Transfer pp 226-239 HW 8

Tues 18 Heat Transfer pp 240-263 HW 7

Thurs 20 Heat Transfer and Special Topic pp 263-274

Lab 21

Mon Nov. 24 Vibration pp 391-393

Tues 25 Vibration pp 393-407 HW 8

Thurs 27 Thanksgiving

Fri 28 Thanksgiving

Mon Dec. 1 Vibration and Special Topic pp 408-412

Tues 2 Electrostatics

Thurs 4

Lab/Review 5

Expectations Homework Policy: All assignments must be handed in before class starts. If you used MATLAB or other software to complete your homework, print out the code and results and circle your answer. Late homework will be accepted if and only if arrangements are made by the evening before it is due. Lab Policy: There will be lab sessions for this course where you will run guided tutorials with the TAs. Must show TA your work to receive credit. Project Report Policy: This course has projects that require you to run commercial FEA software and write a memo report on the results Collaboration Policy: You may discuss projects and homework with your fellow students, and even collaborate on the solution, but you must list on the report or homework the name of the person(s) that collaborated with you on the effort. You may not copy someone else’s reports, data, or figures. There is a zero-tolerance for cheating or plagiarism.

Grading: 1) Homework 20% 2) Labs 15% 3) Projects 30% 4) Midterm Exam 15% 5) Final Exam 20% Exams: Tests will be closed book and closed notes.

Project Grading for Project Reports

Introduction: 15

Very brief background and purpose for the model.

Methods: 25

Indicate the elements used, the boundary conditions/loads assigned, and how the model was meshed (number of nodes, node seeding if any, etc.).

Results (and Appendices):

Analysis of the modeling data is complete, clear, and correct. 20

Results in figures, graphs, and tables are accurate and important features are described in the text. Captions for each figure describe results of figure. 10

Format of graphs and tables is professional looking. Appropriate units are indicated. Captions to describe the contents of the graph or table. Reference to graphs, tables, and appendices are made in the report. 10

Discussion: 20

Take a critical view of results. Are the results expected? Compare with simplified analytical solutions.

Conclusion:

100

Typical Class

• FEM theory

• Example problems

• Practical considerations

http://www.me.washington.edu/remotedesktop

Remote Desktop

Remote Desktop Start Page

Storing your work

• Remote desktop files will be deleted every couple of days.

• Obtain U drive storage http://www.washington.edu/itconnect/wares/online-storage/u-drive-central-file-storage-for-users/

Storing your work on U drive http://www.washington.edu/itconnect/wares/online-storage/u-drive-central-file-storage-for-users/

When that doesn’t work, open WinSCP from the start page.

When that doesn’t work, open WinSCP from the start page.

When that doesn’t work, open WinSCP from the start page.

Finite Element Analysis

• Allows for the stress/strain/heat transfer analysis of complex geometries for which there is no analytical solution.

• Allows for defining complex materials such as composites.

Finite Element Analysis

• Grew out of aerospace industry

• Post-WW II jets, missiles, space flight

• Need for light weight structures

• Required accurate stress analysis

• Paralleled growth of computers

Examples #1

Modeling complex geometries

Examples #2

Modeling complex contact problems

Examples #3

Modeling composite materials

Biological Examples Head of the femur

Bones of the forearm.

Biological Examples Left Ventricle modeling the heart cycle

Biological Examples

Modeling considerations of modeling of Left Ventricle over the heart cycle.

Biological Examples

Modeling considerations of modeling of Left Ventricle over the heart cycle. What is the material? What are the boundary conditions? What can you ignore?

Biological Examples

Modeling considerations of modeling of Left Ventricle over the heart cycle. What is the material? Orthotropic often modeled as isotropic. What are the boundary conditions? LV pressure What can you ignore? Intrathoracic pressure

A B

FEM Based Image Registration

• A pair of 3-D MRI image data sets representing two deformation states with a known deformation map

were needed.

Template Image end-systole

Target Image end-diastole

(X) Deformation map

Biological Examples Image registration of cardiac cycle

Biological Examples Hypertension induced hypertrophy

Components of an FEM Model • Descritization of model body

by dividing it into a system of many smaller bodies or elements interconnected at points common to two or more elements (nodes ).

• Nodes – locations for solution of discretization problem in FEM.

• Element – connectivity of the nodes make up the element.

Typical FEM Analysis

• Creation of the mesh from geometric definition.

– CAD/CAM output

• Meshing iges, dxf, stl surface definitions

• Biological Applications

– Segmentation of medical images.

• High resolution images, typically CT and MRI.

Typical FEM Analysis • Pre-processing – mesh creation, material and

loading definitions. – Ansys has pre-processing built in. – Abaqus has pre-processing built in. – Preview (FEBio.org) – TrueGrid (www.truegrid.com) – LSPrePost (lstc.com) – AutoFEM (www.autofemsoft.com) Requires AutoCAD

Analysis

• Import mesh into finite element analysis package.

• ANSYS – start analysis.

• Abacus– start analysis.

• Command line – “FEBio.exe –i mesh.feb”

“lsdyna.exe –i mesh.k”

“NIKE3d.exe i=mesh.n”