Resources

  • PSD Calculation Efficiency [PDF]

    Sheldon Imaoka (ANSYS, Inc.)

    "A very common use of PSD analyses is to look at the response of a system under a single base excitation, such as the case with many aerospace and civil applications. The default PSD settings are very general in nature and may consequently be inefficient for such a situation. This memo hopes to outline some ways in which the user may obtain more efficient PSD solutions for the specific instance of single base excitation with relatively flat spectrum (although some techniques may be extrapolated for other cases)."…An older doc I recently reanimated and updated…

  • PSD Postprocessing [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "PSD, or random vibration, analyses present some interesting challenges in postprocessing due to the nature of the assumptions related to the analysis. This memo hopes to address some of these items, including evaluation of derived stresses and calculation of response power spectral density."
    …An older doc I recently reanimated and updated…

  • PSD Postprocessing of Relative Displacement [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "PSD users may wish to determine the relative 1-sigma results between two points. This memo covers three methods to perform this operation, in hopes that it will give users more familiarity with PSD postprocessing in ANSYS."

  • PZT Actuated Micromirror For Nano-Tracking Of Laser Beam For High-Density Optical Data Storage [PDF]

    Youngjoo Yee, Hyo-Jin Nam, See-Hyung Lee, Jong Uk Bu, Young-Sam Jeon, and Seong-Moon Cho

    A piezo-actuated micromirror. Used ANSYS for stress and modal analysis of mirror. (MEMS)

  • Parameter Studies For Enhanced Integrity Of Reciprocating Compressor Foundation Blocks

    Jayant S. Mandke, Anthony J. Smalley

    "The model development and analyses of reinforced concrete block used the ANSYS finite element program."

  • Parametric Studies in ANSYS [PDF]

    Sean Harvey (CSI)

    Automated parametric studies in ANSYS (generating and using parametric input files).

  • Patient Specific Spine Models - Development Of A Laboratory Intervertebral Disc For Validation Of The Models

    A. Mohsen, D. J. Siddall, P. Gillespie, S. Julian and M. J. Fagan

    "This research project is aimed at evaluating the feasibility of the modelling technique through the development of an artificial validation spine. The validation spine will be tested under controlled laboratory conditions and the results used to verify those found from analysis of the computer model. The intervertebral disc is the most critical component in the spine. Thus, the initial aim of this research was to develop a representative artificial disc. Concurrent development of a finite element model of the disc permits development theories to be analysed and laboratory results to be verified."

  • Physics first, using ANSYS to define the design: Real-life examples from the automotive supplier company Mannesmann VDO

    Zlatko Penzar

    "In many non-standard engineering development applications it strongly pays off to invest an effort into understanding the physics of the problem prior to undertaking complex numerical simulations. The better the knowledge of the leading physical effects in a complex system, the simpler and more cost-efficient the analytical model can be. Moreover, the understanding of the most important physical driving effects often enables one to build a simplified, closed-form mathematical effective model. Such models usually give insight into the interplay of various parameters governing the physical behavior of the complex system. In this way, a fast pre-optimization of the desired features is often possible. Subsequently, the rich arsenal of ANSYS multiphysics capabilities can be used to refine the judgements and obtain the desired quantitative solutions."

  • Plastic Deformation and Loss of Joint Force by Creep in High Current Joints

    Josef Kindersberger, Helmut Löbl, Stephan Schoft

    "The mechanical stress distribution in aluminum busbar joints is calculated using the Finite Element Method. Based on the physical fundamentals of creep in aluminum the reduction of the joint force by creep depending on the temperature of the joints as well as on the initial joint force and on the washer is simulated." (Creep)

  • Plasticity Hardening Rules [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "ANSYS has a wide range of constitutive models and element technology available to the user. In this memo, the basics of isotropic and kinematic hardening for plasticity will be discussed, specifically related to proportional/non-proportional, monotonic/cyclic loading, and finite strain applications."

  • Plotting Entities and Graphs in Multiple Windows [PDF]

    David Haberman (CSI)

    ANSYS 5.4 through 5.6 allow users to plot multiple entities (keypoints, lines, areas, volumes, nodes, and elements) in a given window. Prior to ANSYS 5.4, a user was required to plot entities on top of one another, like transparencies. Furthermore, multi-plotting also allows a user to generate graphs. The following memo discusses how the ANSYS multi-plotting feature works.

  • Post Refinement Element Shape Improvement for Quadrilaterial Meshes [PDF]

    Matthew L. Staten and Scott A. Canann

    "This paper presents techniques for improving the quality of quadrilateral meshes after Schneiders' refinement. Improvement techniques use topology and node valence optimization rather than shape metrics. Hence, improvement is computationally inexpensive."

  • Postprocessing Harmonic Results [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "In harmonic analyses, due to the fact that results may not be in phase, postprocessing quantities of interest can pose a challenge. Users may need to review non-sinusoidal results, such as equivalent stresses, at different locations, so accounting for phase information may be required.
    This memo hopes to cover some of the more important points regarding postprocessing structural harmonic analysis results in both the General and Time-History Postprocessors."

  • Predicting Human Thermal Comfort in a Transient Nonuniform Thermal Environment

    J.P. Rugh, R.B. Farrington, D. Bharathan, A. Vlahinos, R. Burke, C. Huizenga, and H. Zhang

    "The National Renewable Energy Laboratory (NREL) has developed a suite of thermal comfort tools to assist in the development of smaller and more efficient climate control systems in automobiles. These tools, which include a 126-segment sweating manikin, a finite element physiological model of the human body, and a psychological model based on human subject testing, are designed to predict human thermal comfort in transient nonuniform thermal environments such as automobiles. The manikin measures the heat loss from the human body in the vehicle environment and sends the heat flux from each segment to the physiological model. The physiological model predicts the body’s response to the environment, determines 126 segment skin temperatures, sweat rates, and breathing rate, and transmits the data to the manikin. The psychological model uses temperature data from the physiological model to predict the local and global thermal comfort as a function of local skin and core temperatures and their rates of change. Results of initial integration testing show the thermal response of a manikin segment to transient environmental conditions."

    [ANSYS Thermal, version unknown]

  • Pressure Load Macro [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "In ANSYS, pressure loading via the SFx family of commands allows users to apply a force per unit area in a direction normal to the surface. Structural surface effect elements SURF153 and SURF154 extend pressure loading capabilities by allowing users to specify normal, tangential, or arbitrary distributed loading. In fact, for an arbitrary ‘distributed loading vector,’ the full or projected area may be used, with or without the tangential component of load. This type of loading can be useful in mimicking a bearing load (include tangential component) or wind loading (no tangential component), to name a couple of examples.
    "Because of the fact that the vector-type of pressure loading can be based on full or projected area, with or without the tangential component, trying to determine an appropriate value for the loading can be cumbersome. The author has written a simple macro which can be used as an example in utilizing surface effects more effectively by allowing the user to specify the total force instead of pressure – the macro calculates the appropriate pressure value to be applied on the surface effect elements."
    (Week 27, week of 07/04/04.)

  • Pressure Mapping Example

    Bob Weathers (Trane)

    An example which demonstrates mapping between dissimilar meshes and element types.

    At the bottom of the macro is an example of how to apply the mapped results from the first model onto the second using a TABLe. The TABLe uses the second model's node numbers (sorted and stored in ascending order) to index into the TABLe. This results in a very efficient way to map boundary conditions that's fast and uses minimum memory.

  • Preventing Rigid-Body Motion in Contact Problems [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "In contact problems run in a static manner, controlling rigid-body motion may sometimes be an issue under the following circumstances: (a) force-controlled systems or (b) multiple bodies with some parts unconstrained."

    "This memo hopes to address some ways of controlling rigid-body motion in contact problems through the use of options available with the surface-to-surface contact elements."

  • Principles of Simulating Contact Between Parts using ANSYS

    David H. Johnson

    "The ANSYS finite element analysis (FEA) program offers a variety of elements designed to treat cases of changing mechanical contact between the parts of an assembly or between different faces of a single part. These elements range from simple, limited idealizations to complex and sophisticated, general purpose algorithms. FEA analysts are frequently faced with modeling situations where changing contact cannot be assumed negligible and ignored. Finding the best choices for contact elements, element options, solver, and solution options can drastically improve the model’s performance and reduce the analyst’s frustration with a contact simulation model."

  • Probabilistic Design System (PDS): A Realistic Approach of Finite Element Modelling for Capacitive Micro-machined Ultrasonic Transducers (cMUTS)

    Vamshi Kommareddy, Manoj Kumar, Ying Fan, James Barshinger

    "This paper represents a realistic approach for modeling a cMUT device. CMUTs have become very popular over the last decade because of the comparable bandwidth, sensitivity and dynamic range with its piezoelectric counterparts. The ease of fabrication is an added advantage. Modeling of CMUT is a coupled physics problem, which involves solving Electrostatics-Structural-Fluid interactions simultaneous. Finite Element models of the CMUT are constructed using the commercial code ANSYS (10.0). In the standard approach of modeling, from existing literature assumes deterministic values for design parameters, however fabrication of the device introduces some amount of variation in the design parameters. In this paper, the PDS FEM approach is discussed to account for the variability in fabrication. The results from the PDS approach on the performance characteristics like resonance frequency; collapse voltage and electromechanical coupling coefficient will be discussed."
    [ANSYS PDS, version 10.0]

  • QR Damped Modal Analysis [PDF]

    Sheldon Imaoka (CSI)

    Presentation on different damped eigenvalue extraction methods in ANSYS, focusing on the newer QR Damped method.
    Input files in zip format

  • QR Damped and Unsymmetric Stiffness [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "There have been significant enhancements to the QR Damped eigenvalue extraction method in the past several releases of ANSYS. At 8.0, the capability of including unsymmetric damping [C] matrix was introduced, along with support of damping defined via the DMPRAT and MDAMP commands.
    ANSYS 8.1, the material-based constant damping ratio MP,DMPR allowed users to specify constant damping ratios per material ID in mode-superposition harmonic analyses, when used with the QRDAMP eigensolver. With the release of 9.0, QRDAMP also supports unsymmetric stiffness [K] matrix, output of complex eigenvectors, and the use of the PSOLVE command. This memo hopes to cover the use of QR Damped eigenvalue extraction method in friction problems, where an unsymmetric stiffness [K] matrix may be present. An example of this type of problem is brake squeal analyses, where the combination of ANSYS 17x contact elements and the QRDAMP eigensolver provide an easy-to-use, efficient means of determining unstable modes."

  • Quality Based Design and Design for Reliability of MEMS Using Probabilistic Methods [PDF]

    Stefan Reh, Paul Lethbridge, Dale Ostergaard

    Presented at MSM 2000. (MEMS)

  • Quality Based Design from Probabilistic Methods [PDF]

    Stefan Reh, Paul Lethbridge, Dale Ostergaard

    (from ANSYS Solutions magazine, volume 2, #2) (MEMS)

  • Radiation article in ANSYS Solutions Magazine [PDF]

    Dave Looman (ANSYS, Inc.)

    Overview of ANSYS's radiation capabilities, including a discussion on the radiosity solution method.

  • Radiosity Solver [PDF]

    Sheldon Imaoka (ANSYS, Inc.)

    Information on radiation capabilities of ANSYS, focusing on the radiosity solution method.
    Accompanying input files 1, 2, 3 and 4

  • Random Vibration Analysis of a Circuit Board [PDF]

    Sean Harvey (CSI)

    Example of random vibration analysis of a circuit board in ANSYS.
    Input files in zip format

  • Reduced Order Modeling of Fluid Structural Interactions in MEMS Based on Modal Projection Techniques

    Jan Mehner, Wolfram Doetzel, Bernd Schauwecker, Dale Ostergaard

    This paper provides useful background information on the modal projection technique available in ANSYS with FLUID136 elements (RMFLVEC, DMPRAT, and ABEXTRACT macros). Although the ROM140 element has not been officially released (it is undocumented), this paper introduces that element as well.

  • Review of Anisotropy, Yield Criteria, Failure Criteria [PDF]

    Sheldon Imaoka (ANSYS, Inc.)

    "This memo hopes to serve as a review of the basics of anisotropy, yield criteria, failure criteria, and the ANSYS procedure related to these topics."
    (Week 15, week of 01/21/02.)

  • STI0904_USERFC.zip

    Sheldon Imaoka (ANSYS, Inc.)

    "The FC command provides users with the ability to predict first-ply failure using maximum strain, maximum stress, or Tsai-wu failure criteria. In ANSYS 12.0.1, users can also take advantage of the userfc subroutine to define up to nine different criteria.
    This memo reviews the userfc subroutine, and a sample implementation of the Hashin criterion is included."

  • Semiconductor Package Simulations: Assembly, Test, and Reliability [PDF]

    Steven Groothuis

    This is a presentation which demonstrates various types of analyses ANSYS can perform which are applicable to the semiconductor industry.

  • Shape Memory Alloy

    Sheldon Imaoka (ANSYS, Inc.)

    Short PDF describing differences between the superelastic and shape memory effect options for Shape Memory Alloy (SMA) material model. Simple input file can be downloaded here.

  • Simple APDL Implementation of a 3D FEM Simulator for Mutual Capacitances of Arbitrarily Shaped Objects Like Interconnects [PDF]

    Andreas Hieke

    Alternative download link here or here
    See other publication by A. Hieke. I can't recall if this or the above article is referenced in ANSYS 5.6 Theory Manual. A variant article "Tiny Devices, Big Problems: Computation of Capacitance in Microelectric Structures" was published in the ANSYS Solutions magazine Vol 2 No 3.

  • Simulation of Bellcore Testing of Electronics Cabinets for the Telecommunications Industry [PDF]

    Chris Andersen

    Various Bellcore tests performed with ANSYS.

  • Simulation of Brake Block Induced Corrugation on Railway Wheels

    Ulf Sellgren

    "Railway wheels that are equipped with cast-iron brake blocks generate significantly more rolling noise than wheels with other types of braking devices or block materials. The roughness of the treads on cast-iron block-braked wheels has typically a peak at a wavelength around 6 cm. The complex interaction between quasi-static and dynamic mechanical behavior and thermal, chemical, and metallurgical effects in the block-wheel contact combined with the rolling and sliding situation in the wheel-rail contact has made it difficult to get an understanding of the causes from field measurements. Coupled transient thermal and quasi-static mechanical FE simulations with ANSYS show that thermoelastic instability (TEI) may be a major cause for the roughness initiation."

  • Simulation of the Retroglossal Fluid-Structure Interaction During Obstructive Sleep Apnea

    Franz Chouly, Annemie Van Hirtum, Pierre-Yves Lagr´ee, Jean-Roch Paoli, Xavier Pelorson, and Yohan P

    "A method for computing the interaction between the airflow and the soft tissue during an Obstructive Apnea is presented. It is based on simplifications of the full continuum formulation (Navier- Stokes and finite elasticity) to ensure computation time compatible with clinical applications. Linear elasticity combined with a precomputation method allows fast prediction of the tissue deformation, while an asymptotic formulation of the full Navier-Stokes equations (Reduced Navier- Stokes/Prandtl equations) has been chosen for the flow. The accuracy of the method has already been assessed experimentally. Then, simulations of the complete collapsus at the retroglossal level in the upper airway have been carried out, on geometries extracted from pre-operative radiographies of two apneic patients. Post-operative geometries have been also used to check qualitatively if the predictions from the simulations are in agreement with the effects of the surgery."
    [ANSYS Structural, version unspecified]

  • Sine sweep simulation [PDF]

    David Haberman (CSI

    Discussion on harmonic sweeps, either via the direct displacement method or the large mass method.
    Direct displacement method example input file and Large mass method example input file

  • Smartsizing: Automatic Boundary Sizing for 2D and 3D meshes [PDF]

    Alexandre L. Cunha, Sunil Saigal, Scott A. Canann

    "We present in this paper a simple technique, called smart sizing, which automatically computes high quality initial element sizing on curves for triangular, quadrilateral and tetrahedral elements."

  • Space-Time Finite Element Approximation and Numerical Solution of Hereditary Linear Viscoelasticity Problems

    J. Orlik, A. Ostrovska

    "In this paper we suggest a fast numerical approach to treat problems of the hereditary linear viscoelasticity, which results in the system of elliptic partial differential equations in space variables , who’s coefficients are Volterra integral operators of the second kind in time. We propose to approximate the relaxation kernels by the product of purely time- and space-dependent terms, which is achieved by their piecewisepolynomial space-interpolation. A priori error estimate was obtained and it was shown, that such approximation does not decrease the convergence order, when an interpolation polynomial is chosen of the same order as the shape functions for the spatial finite element approximation, while the computational effort is significantly reduced."
    [ANSYS Nonlinear, version unknown]

  • Sparse Solver Improvements [PDF]

    Sheldon Imaoka (ANSYS, Inc.)

    "There have been various sparse solver improvements in each release of ANSYS. This memo hopes to cover some general information on the solvers available in ANSYS as well as performance improvements between ANSYS 5.6 and 6.0 related to linear static analyses."

  • Spatially-Varying Pressure Loading in Workbench Simulation [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "Workbench Simulation 11.0 allows users not only to apply constant pressure loads or force vectors per unit area but also to utilize hydrostatic pressure loads and line pressure loads (force per unit length), and these can be defined as a function of time. Moreover, fluid pressures can be mapped from a steady-state or transient ANSYS CFX solution.
    Despite these options, there may be situations where a user may want to import a predefined, spatially-varying pressure field from an external text file. This can be accomplished through the use of a “Commands” object and APDL tables, which this memo will introduce."
    (Week 38, week of 07/01/07.)