What is ANSYS?

ANSYS is general-purpose finite element analysis (FEA) software package.  Finite Element Analysis is a numerical method of deconstructing a complex system into very small pieces (of user-designated size) called elements. The software implements equations that govern the behaviour of these elements and solves them all, creating a comprehensive explanation of how the system acts as a whole. These results then can be presented in tabulated, or graphical forms.  This type of analysis is typically used for the design and optimization of a system far too complex to analyze by hand.  Systems that may fit into this category are too complex due to their geometry, scale, or governing equations.

ANSYS is the standard FEA teaching tool within the Mechanical Engineering Department at many colleges. ANSYS is also used in Civil and Electrical Engineering, as well as the Physics and Chemistry departments.¹

Why use it?

ANSYS provides a cost-effective way to explore the performance of products or processes in a virtual environment. This type of product development is termed virtual prototyping.

With virtual prototyping techniques, users can iterate various scenarios to optimize the product long before the manufacturing is started. This enables a reduction in the level of risk, and in the cost of ineffective designs. The multifaceted nature of ANSYS also provides a means to ensure that users are able to see the effect of a design on the whole behavior of the product, be it electromagnetic, thermal, mechanical etc.

ANSYS in the Professional World:

If you are interested in ANSYS and what it accomplishes in the professional world, here are two links that briefly discuss different aspects of the company.  (*note: Their headquarters is based 20 minutes outside of Pittsburgh.) For more information, just use www.google.com

1. http://www.shef.ac.uk/mecheng/staff/ay/cae/tutorials/ansys/ansys1.html

2. http://www.post-gazette.com/businessnews/20020406topstockbiz7P7.asp

Generic Steps to Solving any Problem in ANSYS:

Like solving any problem analytically, you need to define (1) your solution domain, (2) the physical model, (3) boundary conditions and (4) the physical properties. You then solve the problem and present the results. In numerical methods, the main difference is an extra step called mesh generation. This is the step that divides the complex model into small elements that become solvable in an otherwise too complex situation. Below describes the processes in terminology slightly more attune to the software.

Build Geometry

Construct a two or three dimensional representation of the object to be modeled and tested using the work plane coordinate system within ANSYS.

Define Material Properties

Now that the part exists, define a library of the necessary materials that compose the object (or project) being modeled.  This includes thermal and mechanical properties.

Generate Mesh

At this point ANSYS understands the makeup of the part.  Now define how the modeled system should be broken down into finite pieces. 

Apply Loads

Once the system is fully designed, the last task is to burden the system with constraints, such as physical loadings or boundary conditions.

Obtain Solution

This is actually a step, because ANSYS needs to understand within what state (steady state, transient… etc.) the problem must be solved.

Present the Results

After the solution has been obtained, there are many ways to present ANSYS’ results, choose from many options such as tables, graphs, and contour plots.

Specific Capabilities of ANSYS:

Structural

http://www.cs.unc.edu/~hirota/fem/

see a quicktime movie of the knee joint here:

http://www.cs.unc.edu/~hirota/fem/movies/op2tr.mov

Structural analysis is probably the most common application of the finite element method as it implies bridges and buildings, naval, aeronautical, and mechanical structures such as ship hulls, aircraft bodies, and machine housings, as well as mechanical components such as pistons, machine parts, and tools.

·         Static Analysis - Used to determine displacements, stresses, etc. under static loading conditions. ANSYS can compute both linear and nonlinear static analyses. Nonlinearities can include plasticity, stress stiffening, large deflection, large strain, hyper elasticity, contact surfaces, and creep.

·         Transient Dynamic Analysis - Used to determine the response of a structure to arbitrarily time-varying loads. All nonlinearities mentioned under Static Analysis above are allowed.

·         Buckling Analysis - Used to calculate the buckling loads and determine the buckling mode shape. Both linear (eigenvalue) buckling and nonlinear buckling analyses are possible.

In addition to the above analysis types, several special-purpose features are available such as Fracture mechanics, Composite material analysis, Fatigue, and both p-Method and Beam analyses.

Thermal

ANSYS is capable of both steady state and transient analysis of any solid with thermal boundary conditions.

Steady-state thermal analyses calculate the effects of steady thermal loads on a system or component. Users often perform a steady-state analysis before doing a transient thermal analysis, to help establish initial conditions. A steady-state analysis also can be the last step of a transient thermal analysis; performed after all transient effects have diminished. ANSYS can be used to determine temperatures, thermal gradients, heat flow rates, and heat fluxes in an object that are caused by thermal loads that do not vary over time. Such loads include the following:

·         Convection

·         Radiation

·         Heat flow rates

·         Heat fluxes (heat flow per unit area)

·         Heat generation rates (heat flow per unit volume)

·         Constant temperature boundaries

A steady-state thermal analysis may be either linear, with constant material properties; or nonlinear, with material properties that depend on temperature. The thermal properties of most material vary with temperature. This temperature dependency being appreciable, the analysis becomes nonlinear. Radiation boundary conditions also make the analysis nonlinear. Transient calculations are time dependent and ANSYS can both solve distributions as well as create video for time incremental displays of models.

Fluid Flow

The ANSYS/FLOTRAN CFD (Computational Fluid Dynamics) offers comprehensive tools for analyzing two-dimensional and three-dimensional fluid flow fields.  ANSYS is capable of modeling a vast range of analysis types such as: airfoils for pressure analysis of airplane wings (lift and drag), flow in supersonic nozzles, and complex, three-dimensional flow patterns in a pipe bend.  In addition, ANSYS/FLOTRAN could be used to perform tasks including:

·         Calculating the gas pressure and temperature distributions in an engine exhaust manifold

·         Studying the thermal stratification and breakup in piping systems

·         Using flow mixing studies to evaluate potential for thermal shock

·         Doing natural convection analyses to evaluate the thermal performance of chips in electronic enclosures

·         Conducting heat exchanger studies involving different fluids separated by solid regions

FLOTRAN analysis provides an accurate way to calculate the effects of fluid flows in complex solids without having to use the typical heat transfer analogy of heat flux as fluid flow.  Types of FLOTRAN analysis that ANSYS is able to perform include:

·         Laminar or Turbulent Flows

·         Thermal Fluid Analysis

·         Adiabatic Conditions

·         Free surface Flow

·         Compressible or incompressible Flows

·         Newtonian or Non-Newtonian Fluids

·         Multiple species transport

*NOTE: These types of analyses are not mutually exclusive. For example, a laminar analysis can be thermal or adiabatic. A turbulent analysis can be compressible or incompressible.

Magnetic

Magnetic analyses, available in the ANSYS/Multiphysics and ANSYS/Emag programs, calculate the magnetic field in devices such as:

Typical quantities of interest in a magnetic analysis are:

Magnetic fields may exist as a result of an electric current, a permanent magnet, or an applied external field.

Acoustics / Vibration

(Noise analysis and optimization of a Craftsman Table Saw Blade)

http://www.cdc.gov/niosh/noise/acnoisecontrl/index.html

ANSYS is capable of modeling and analyzing vibrating systems in order to that vibrate in order to analyze

Acoustics is the study of the generation, propagation, absorption, and reflection of pressure waves in a fluid medium. Applications for acoustics include the following:

·         Sonar - the acoustic counterpart of radar

·         Design of concert halls, where an even distribution of sound pressure is desired

·         Noise minimization in machine shops

·         Noise cancellation in automobiles

·         Underwater acoustics

·         Design of speakers, speaker housings, acoustic filters, mufflers, and many other similar devices.

·         Geophysical exploration

Within ANSYS, an acoustic analysis usually involves modeling a fluid medium and the surrounding structure. Characteristics in question include pressure distribution in the fluid at different frequencies, pressure gradient, particle velocity, the sound pressure level, as well as, scattering, diffraction, transmission, radiation, attenuation, and dispersion of acoustic waves. A coupled acoustic analysis takes the fluid-structure interaction into account. An uncoupled acoustic analysis models only the fluid and ignores any fluid-structure interaction.

The ANSYS program assumes that the fluid is compressible, but allows only relatively small pressure changes with respect to the mean pressure. Also, the fluid is assumed to be non-flowing and inviscid (that is, viscosity causes no dissipative effects). Uniform mean density and mean pressure are assumed, with the pressure solution being the deviation from the mean pressure, not the absolute pressure.

Coupled Fields

A coupled-field analysis is an analysis that takes into account the interaction (coupling) between two or more disciplines (fields) of engineering. A piezoelectric analysis, for example, handles the interaction between the structural and electric fields: it solves for the voltage distribution due to applied displacements, or vice versa. Other examples of coupled-field analysis are thermal-stress analysis, thermal-electric analysis, and fluid-structure analysis.

Some of the applications in which coupled-field analysis may be required are pressure vessels (thermal-stress analysis), fluid flow constrictions (fluid-structure analysis), induction heating (magnetic-thermal analysis), ultrasonic transducers (piezoelectric analysis), magnetic forming (magneto-structural analysis), and micro-electro mechanical systems (MEMS).