ME 450: Computer-Aided Engineering

1. ME 450: Computer-Aided Engineering Applications of the Finite Element Method K. Nema & H. Akay Spring 2004

2. Engineering Analysis and Design • Engineers need to analyze various components/designs for a variety of loading, material, manufacturing conditions • Come up with a best design without extensive experiments and prototype building • FEA is a computational (numerical) modeling method

3. Types of Computer-Based Simulations • Solution of Algebraic equations • – Set of algebraic equations • – Geometric equations • – Kinematics, synthesis • Solution of Ordinary Differential Equations • – One dimensional • – Control systems • – 1D field problems • Solution of Partial Differential Equations • – Multi-dimensional • – Mechanics, heat transfer, fluid flow, electro-magnetics,acoustics, etc.

4. Why FEA is Needed? • Reduces the amount of prototype testing • Computer simulation allows multiple “what-if” scenarios to betested quickly and effectively • Models designs that are not suitable for prototype testing • Example: Surgical implants, such as an artificial knee • The bottom line • Cost savings • Time savings… reduces time to market! • Create more reliable, better-quality designs

5. What is FEA? • Finite Element Analysis is a way to simulate various conditions (loading, material, etc.) on a design and determine the Design’s response • Finite Element Method (FEM) divides a design model into smaller“elements” and solves the resulting system of equations • FEA is used in many industries to conduct modal, structural, harmonic, thermal and other analysis

6. Historical Note • The finite element method ofstructural analysis was created byacademic and industrial researchersduring the 1950s and 1960s • The underlying theory is over 100years old, and was the basis forpen-and-paper calculations in theevaluation of suspension bridgesand steam boilers

7. Three Phases of the Finite Element Method • Preprocessing • Solution • Postprocessing

8. Preprocessing Phase • Discretizing the solution domain into finite elements • Assuming a solution that approximates the behavior of an element • Developing equations for an element • Assembling the elements to present the entire problem

9. Solution Phase • Solving a system of algebraic equations simultaneously to obtain nodal values of primary variables, e.g., displacements

10. Postprocessing Phase • Obtaining information on elemental values of secondary variables, e.g., strains, stresses and forces

11. About ANSYS • ANSYS is a complete FEA software package used byengineers worldwide in virtually all fields of engineering: • Structural • Thermal • Fluid, including CFD (Computational Fluid Dynamics) • Electrical / Electrostatics • Electromagnetics • Coupled field analysis: • Fluid-Structure interactions • Acoustics and vibration • Thermal-stress analysis (heat transfer and stress analysis) • Piezoelectrics (electric & structural )

12. FEA Definitions • Node • Degree of Freedom (DOF) • Element • Boundary Conditions

13. Steps of FEA with ANSYS • Preprocessing • Specify element types to be used • Specify options for element behavior • Specify real constants • Specify material model • Specify material properties • Create geometry (primitives, hierarchical – points, lines, areas,volumes, direct generation) • Specify meshing options • Mesh model • Apply boundary conditions • Solve problem • Postprocessing (reviewing results)

14. Structural Analysis: Statics • Structural analysis is used to determine deformations, strains, stresses, and reaction forces • Static analysis • Used for static loading conditions • Linear behavior under small deflections and strains • Nonlinear behavior under large deflections and strains, plasticity, hyperelasticity, and creep can be simulated

15. Structural Analysis: Dynamics • Dynamic analysis– Includes mass and damping effects • Modal analysis calculates natural frequencies and mode shapes • Harmonic analysis determines a structure’s response tosinusoidal loads of known amplitude and frequency. • Transient dynamic analysis determines a structure’s responseto time-varying loads and can include nonlinear behavior • Other structural capabilities • Spectrum analysis, random vibrations • Substructuring, submodeling

16. Various Applications • Stress analysis of structures • Static and dynamic • Linear nonlinear • Buckling • Heat transfer analysis • Fluid dynamics • Biomechanics • Solid-fluid interactions • Materials processing

17. Stress Analysis of Geer Tooth

18. IUPUI Electric Race Car Components Structural Analysis

19. 2,950 lbf 0.35 sq in 8,450 psi Trailer Hitch • Design Constraints

20. Trailer Hitch (con’t) • ANSYS Modeling • Proposed Trailer Design

21. Car Crash Simulations -- Ford Taurus --

22. Car Crash Simulations

23. Electronic Package Reliability

24. Thermal Fatigue of a Surface Mount AssemblyLow-cycle thermal fatigue of solder joints connecting electronic chips to the printed circuit board due to solder creep is of concern.

25. Different types of interconnection methods in electronic packages lead chip carrier solder copper pad PWB Schematic of a LDCC type (gull-wing)

26. Different types of interconnection methods in electronic packages chip carrier solder copper pad PWB Schematic of a LLCC type

27. Typical 2D LLCC and LDCC cases used for curve fitting Y X Finite element mesh for 20-pin LLCC

28. Typical 2D LLCC and LDCC cases used for curve fitting Y X Finite element mesh for 28-pin LDCC-TSOP (gull-wing)

29. Biomedical Application -- Hip Implant-- Interaction of a hip implant with the femur -- Computed stresses

30. Mesh for Flow Around an Oscillating Missile

31. Mach Number Contours Around an Oscillating Missile (Unsteady Flow)

32. Biomedical Application -- Prosthetic Cardiac Valve Simulations

33. Patient Specific Three-Dimensional Finite Element Models of Defibrillation • Ventricular fibrillation characterized by unsynchronized contraction of heart - deadly if not reversed • Defibrillate by delivering an electrical shock to reset heart • Implantable cardioverter defibrillator (ICD) for patients who are at high risk Rib Cage Lungs Heart

34. HVAC/Climate control in a passenger car, showing transient ice melting on the windscreen

35. Aerodynamics of Jeff Gordon’s NASCAR Race Car

36. Aerodynamic Simulations with ANSYS FLOTRAN Velocity by 100 m/s Velocity by 30 m/s

37. Static Pressures with ANSYS at 100 m/s

38. Parallel Computing • A computational mesh is generated for the domain • The mesh is partitioned into blocks • The blocks are distributed to processors on the network and solved concurrently • Processors communicate data through interfaces between blocks using a message passing library, such as MPI and PVM

39. Aerodynamics, Aeroelasticity, and Structural Integrity of an Aircraft Using Computer Simulations

40. Unsteady Aerodynamics Deformed mesh at maximum and minimum angle of attack positions (16-block partition)

41. Unsteady Aerodynamics Mach Contours

45. Metacomputing with I-Light at CFDL Metacomputing is an efficient approach to utilize the resources of geographically distant computers that are connected by a network. CFDL uses I-light, a high speed optical fiber network connecting IU, IUPUI, and PU and to Internet2, for that purpose. I-Light has presently increased the access speed to 30 times than before (1 Gb/s) and is expandable to 100 Gb/s in the future. CFDL, IUPUI, Indianapolis 5 CPU PIII/Linux 14 CPU PII/W2K 6 CPU RS6K/AIX NASA/Glenn, Cleveland, OH 128 CPU PIII/Linux I-light IU Bloomington 500 CPU IBM SP2/AIX 32 CPU PIII/Linux Univ of Lyon, Lyon, France 10 CPU PIII/Linux

46. Aeroelastic Coupling Algorithm • Obtains solution of: • Aerodynamic pressures using a CFD (Computational Fluid Dynamics) code • Deformation of structures using a CSD (Computational Solid Dynamics) code • Movements of the flow mesh using an elastic spring network • Uses separate computational meshes for flow and structure (CFD and CSD meshes) • The CFD and CSD meshes are loosely coupled using a code coupling approach across multiple processors • CFD mesh is subdivided into multiple blocks for parallel and metacomputing on distributed systems

47. Test Case • Transient solid-fluid interactions of an aircraft wing is solved using two codes: • CFD code: USER3DP • CSD code: MODAL • The CFD domain is solved via partitioned flow meshes for parallel computing • The codes and their meshes are coupled via MpCCI • Transient solutions of 500,000 flow and 2,000 structural equations are obtained in a coupled fashion • Objectives: • To demonstrate the feasibility of I-light for metacomputing • To test the speed of I-light

48. Aeroelastic Flutter – A Solid-Fluid Interaction Problem

49. Results of Test Case with I-Light Parallel Speedup:

50. Surface Pressures Escape System Analysis Mach Contours