FEA and ANSYSChapter 2

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Chapter 2 - FEA and ANSYS

What is FEA?

• Finite Element Analysis is a way to simulate loading conditions on a design and determine the design’s response to those conditions.

• The design is modeled using discrete building blocks called elements.

– Each element has exact equations that describe how it responds to a certain load.

– The “sum” of the response of all elements in the model gives the total response of the design.

– The elements have a finite number of unknowns, hence the name finite elements.

Historical Note

• The finite element method of structural analysis was created by academic and industrial researchers during the 1950s and 1960s.

• The underlying theory is over 100 years old, and was the basis for pen-and-paper calculations in the evaluation of suspension bridges and steam boilers.

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Chapter 2 - FEA and ANSYS

...What is FEA?

• The finite element model, which has a finite number of unknowns, can only approximate the response of the physical system, which has infinite unknowns.– So the question arises: How good is the approximation?

Physical System F.E. Model

– Unfortunately, there is no easy answer to this question. It depends entirely on what you are simulating and the tools you use for the simulation. We will, however, attempt to give you guidelines throughout this training course.

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Chapter 2 - FEA and ANSYS

...What is FEA?

Why is FEA needed?

• To reduce the amount of prototype testing– Computer simulation allows multiple “what-if” scenarios to be tested

quickly and effectively.

• To simulate designs that are not suitable for prototype testing– Example: Surgical implants, such as an artificial knee

• The bottom line:– Cost savings– Time savings… reduce time to market!– Create more reliable, better-quality designs

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Chapter 2 - FEA and ANSYS

About ANSYS

• ANSYS is a complete FEA software package used by engineers worldwide in virtually all fields of engineering:– Structural– Thermal– Fluid, including CFD (Computational Fluid Dynamics)– Electrical / Electrostatics– Electromagnetics

• A partial list of industries in which ANSYS is used:– Aerospace– Automotive– Biomedical– Bridges & Buildings

– Electronics & Appliances– Heavy Equipment & Machinery– MEMS - Micro Electromechanical Systems– Sporting Goods

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Chapter 2 - FEA and ANSYS

…About ANSYS

• ANSYS/Multiphysics is the flagship ANSYS product which includes all capabilities in all engineering disciplines.

• There are three main component products derived from ANSYS/Multiphysics:– ANSYS/Mechanical - structural & thermal capabilities– ANSYS/Emag - electromagnetics– ANSYS/FLOTRAN - CFD capabilities

• Other product lines:– ANSYS/LS-DYNA - for highly nonlinear structural problems– DesignSpace - an easy-to-use design and analysis tool meant for quick

analysis within the CAD environment– ANSYS/ProFEA - for ANSYS analysis & design optimization within

Pro/ENGINEER

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ANSYS/ANSYS/StructuralStructural

ANSYS/ANSYS/ProfessionalProfessional

ANSYS/ANSYS/ProFEAProFEA

DesignSpaceDesignSpace

Chapter 2 - FEA and ANSYS

…About ANSYS

ANSYS/ANSYS/EDED

ANSYS/ANSYS/UniversityUniversity

ANSYS/ANSYS/PrepPostPrepPost

ANSYS/ ANSYS/ MultiphysicsMultiphysics

ANSYS/ ANSYS/ FLOTRANFLOTRAN

ANSYS/ANSYS/EmagEmag

ANSYS/ANSYS/LS-DYNALS-DYNA

ANSYS/ANSYS/MechanicalMechanical

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Compression of a Hyperelastic Seal

Chapter 2 - FEA and ANSYS …About ANSYS

• Structural analysis is used to determine deformations, strains, stresses, and reaction forces.

• Static analysis

–Used for static loading conditions.

–Nonlinear behavior such as large deflections, large strain, contact, plasticity, hyperelasticity, and creep can be simulated.

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Chapter 2 - FEA and ANSYS

…About ANSYS

• Dynamic analysis– Includes mass and damping effects.– Modal analysis calculates natural frequencies and mode shapes.– Harmonic analysis determines a structure’s response to sinusoidal

loads of known amplitude and frequency.– Transient Dynamic analysis determines a structure’s response to time-

varying loads and can include nonlinear behavior.

• Other structural capabilities– Spectrum analysis– Random vibrations– Eigenvalue buckling– Substructuring, submodeling

Mode Shape Animation

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Chapter 2 - FEA and ANSYS

…About ANSYS

• Explicit Dynamics with ANSYS/LS-DYNA– Intended for very large deformation simulations where inertia forces

are dominant.– Used to simulate impact, crushing, rapid forming, etc.

Impact Analysis of a Vehicle Crash Test

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Chapter 2 - FEA and ANSYS

…About ANSYS

• Thermal analysis is used to determine the temperature distribution in an object. Other quantities of interest include amount of heat lost or gained, thermal gradients, and thermal flux.

• All three primary heat transfer modes can be simulated: conduction, convection, radiation.

• Steady-State– Time-dependent effects are

ignored.

• Transient– To determine temperatures, etc.

as a function of time.– Allows phase change (melting or

freezing) to be simulated.

Transient Temperature of a Warming Clothes Iron

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Chapter 2 - FEA and ANSYS

…About ANSYS

• Electromagnetic analysis is used to calculate magnetic fields in electromagnetic devices.

• Static and low-frequency electromagnetics– To simulate devices operating with DC power sources, low-frequency

AC, or low-frequency transient signals.

– Example: solenoid actuators, motors, transformers

– Quantities of interest include magnetic flux density, field intensity, magnetic forces and torques, impedance, inductance, eddy currents, power loss, and flux leakage.

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Chapter 2 - FEA and ANSYS

…About ANSYS

• High-frequency electromagnetics– To simulate devices with propagating electromagnetic waves.– Example: microwave and RF passive components, waveguides,

coaxial connectors– Quantities of interest include S-parameters, Q-factor, Return loss,

dielectric and conducting losses, and electric and magnetic fields.

Electric field (EFSUM) in a coaxial cable

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Chapter 2 - FEA and ANSYS

…About ANSYS

• Electrostatics– To calculate the electric field from voltage or charge excitation.– Example: High voltage devices, micro-electromechanical systems

(MEMS), transmission lines– Typical quantities of interest are electric field strength and

capacitance.

• Current Conduction– To calculate current in a conductor from an applied voltage

• Circuit Coupling– To couple electric circuits with electromagnetic devices

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Chapter 2 - FEA and ANSYS …About ANSYS

• Types of electromagnetic analysis:– Static analysis calculates magnetic fields due to direct current (DC) or

permanent magnets.– Harmonic analysis calculates magnetic fields due to alternating

current (AC).– Transient analysis is used for time-varying magnetic fields.

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Chapter 2 - FEA and ANSYS

…About ANSYS

• Computational Fluid Dynamics (CFD)– To determine the flow distributions and temperatures in a fluid.– ANSYS/FLOTRAN can simulate laminar and turbulent flow,

compressible and incompressible flow, and multiple species.– Applications: aerospace, electronic packaging, automotive design– Typical quantities of interest are velocities, pressures, temperatures,

and film coefficients.

Velocity of Fluid in a Duct Pressure Distribution on a Football

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Chapter 2 - FEA and ANSYS

…About ANSYS

• Acoustics– To simulate the interaction between a fluid medium and the surrounding

solid.– Example: speakers, automobile interiors, sonars– Typical quantities of interest are pressure distribution, displacements,

and natural frequencies.

• Contained-Fluid Analysis– To simulate the effects of a contained, non-flowing fluid and calculate

hydrostatic pressures due to sloshing.– Example: oil tankers, other liquid containers

• Heat and Mass Transport– A one-dimensional element is used to calculate the heat generated by

mass transport between two points, such as in a pipe.

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Deflection of a bi-metal bar due to heating

Chapter 2 - FEA and ANSYS

…About ANSYS

• Coupled-Field Analysis considers the mutual interaction between two or more fields. The fact that each field depends upon another makes it impossible to solve each separately, therefore you need a program that can solve both physics problems by combining them.

• Examples:– Thermal-stress analysis– Piezoelectrics (electric & structural )– Acoustics (fluid & structural)– Thermal-electric analysis– Induction heating (magnetic and thermal)– Electrostatic-structural analysis

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Chapter 2 - FEA and ANSYS

About the Company

ANSYS, Inc.

• Developer of ANSYS family of products

• Headquartered in Canonsburg, PA - USA (south of Pittsburgh)

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Chapter 2 - FEA and ANSYS

…About the Company

ANSYS Support Distributors (ASDs)

• Sales and support network for ANSYS

• Over 75 offices worldwide

• Local expertise for ANSYS consulting and training

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Chapter 2 - FEA and ANSYS

…About the Company

ANSYS Support Coordinator (ASC)

• Contact for ANSYS at your company site

• Focal point for ANSYS correspondence; software updates, error notices, newsletter and other mailings, etc.

For more information about ANSYS and the company:

• www.ansys.com

• On-line documentation

• Training manuals from other ANSYS courses