Resources

  • Structural Beam Elements Overview [PDF]

    Sheldon Imaoka (CSI)

    An overview of beam elements available in ANSYS, including the new BEAM188/189 elements and differences between thin and thick beams.

  • Structural Shell Elements Overview [PDF]

    Sheldon Imaoka (CSI)

    Overview of structural shell elements in ANSYS, including differences between thin and thick shells, drilling DOF, etc.

  • Structural Surface Effect Elements Intro [PDF]

    Sheldon Imaoka (ANSYS, Inc.)

    Introduction to structural surface effect elements (SURF153/154).
    BOLTLOAD input file

  • Structural and Thermal Analysis of a MEMS Angular Gyroscope

    Chris C. Painter and Andrei M. Shkel

    "This paper describes the structural and thermal modeling of a Micro Electro Mechanical System (MEMS) z-axis angular gyroscope. The gyroscope consists of a oscillating proof mass supported by a suspension made up of six concentric interconnected rings rigidly attached to an anchored frame. The device is capable of measuring angular displacement through precession of the proof mass line of oscillation in the presence of rotation induced Coriolis force. Using a strain energy method,a closed form solution for the effective stiffness of the suspension system is developed, which is confirmed using finite element modeling. A comparative study of the suspension with a commonly used serpentine spring suspension demonstrates that the studied device is robust to thermal fluctuations and residual stresses. A parametric analysis is used to identify an appropriate micromachining technology suitable for the fabrication of the angular gyroscope."

  • Structural surface Effect Elements, General Overview

    Sheldon Imaoka (ANSYS, Inc.)

    An overview presentation and example workshop on structural surface effect elements. This is an old presentation I did at ANSYS 5.6.1, so if you use later versions of ANSYS, some of the menus and dialog boxes may have changed.

  • Subject Specific Finite Element Modelling of the Levator Ani

    Su-Lin Lee1, Ara Darzi, Guang-Zhong Yang

    "Understanding of the dynamic behaviour of the levator ani is important to the assessment of pelvic floor dysfunction. Whilst shape modelling allows the depiction of 3D morphological variation of the levator ani between different patient groups, it is insufficient to determine the underlying behaviour of how the muscle deforms during contraction and strain. The purpose of this study is to perform a subject specific finite element analysis of the levator ani with open access magnetic resonance imaging. The method is based on a Mooney-Rivlin hyperelastic model and permits dynamic study of subjects under natural physiological loadings. The value of the proposed modelling framework is demonstrated with dynamic 3D data from nulliparous, female subjects"[ANSYS Nonlinear, version unspecified]

  • Super Elastic Alloy Eyeglass Frame Design Using the ANSYS Workbench Environment

    Peter R. Barrett and Patrick Cunningham (CAEAI)

    "Up front analysis at the concept stages of developing a device most often result in reduced time to market and a better more efficient product development cycle. Design Modeler (1) / DesignXplorer (2) and ANSYS Structural’s super-elastic material model (3) are used in this demonstration of a design process for an eyeglass frame. This example provides an illustration of using the parametric functionality of the ANSYS Workbench environment for a highly nonlinear application. The Workbench environment can be used to perform design iterations in conjunction with material laws only available in the standard ANSYS environment. A shape memory superelastic material law was formally included in ANSYS 8.0. The material law captures the super-elastic behavior of Nitinol (4) along with its unique hysteretic response under cyclic loading. In the demonstration, the eyeglass frame is subjected to crushing and cyclic loading events. Geometric design variables are varied in an attempt to increase the frame stiffness yet keep the peak strain levels in the frame below 10% strain, which is a typical elastic limit for Nitinol. The cyclic behavior of the material is also monitored under the design load to evaluate the potential of fatigue failure. The procedure demonstrates the ease in interfacing the suite of Workbench products with geometric, material and contact nonlinear analysis problems."

  • Surface Effect Elements, General Overview

    Sheldon Imaoka (ANSYS, Inc.)

    An overview presentation and example workshop on generating surface effect elements. This is an old presentation I did at ANSYS 5.6.1, so if you use later versions of ANSYS, some of the menus and dialog boxes may have changed.

  • Tabular Boundary Conditions and Function Editor at 6.0 [PDF]

    Sheldon Imaoka (ANSYS, Inc.)

    "This tips and tricks is an introductory memo on the use of tabular and function boundary conditions. The use of the Function Editor is also discussed."

  • Techniques for Successfully Using ANSYS Contact Elements

    Rich Bothmann

    Presentation from the Midwest ANSYS User Group
    [ANSYS Nonlinear, version 9.0]

  • Text and compression utilities [PDF]

    Sheldon Imaoka (CSI)

    Memo on text editors which support syntax highlighting, useful in editing input files and/or macros. Also discusses compression utilities to reduce filesize of database and results files. (Also see "bzip2"compression utility, not discussed in memo)

  • The Building Blocks of Simulation: A New Family of Elements for Stress Analysis

    (ANSYS, Inc.)

    Presentation on 18x family of elements (part of the "Advanced Analysis with ANSYS"seminar during the 2002 User's Conference).

  • The Comparison of Biomechanical Breast Models: Initial Results

    C. Tanner, J.A. Schnabel, A. Castellano Smith, L.I. Sonoda, D.L.G. Hill, D.J. Hawkes, A. Degenhard

    "We present initial results from evaluating the accuracy with which biomechanical breast models based on finite element methods can predict the displacements of tissue within the breast. We investigate the influence of different tissue elasticity values, Poisson’s ratios, boundary conditions, finite element solvers and mesh resolutions on one data set. MR images were acquired before and after compressing a volunteer’s breast gently. These images were aligned using a 3D non-rigid registration algorithm. The boundary conditions (surface displacements) were derived from the result of the non-rigid registration or by assuming no patient motion at the posterior or medial side. Three linear and two non-linear elastic material models were tested."

  • The Control Of The Thermal Environment Of Perimeter Spaces In Buildings To Prevent Cold Drafts

    Yuji Hukushima, Yasuo Utsumi, Hiroshi Kobayashi, Yoshimi Ishikawa, Mitsuo Suzuki, And Tatsuya Yamash

    "This paper is focused on the evaluation of simulation system using the experiment result and the configuration of pericounter which is the part of counter unit setting at bottom of window side with heat panel to avoid the influence of cold draft, utilizing simulation system. The simulation shows similar flow pattern to full scale experiment and consequent simulations indicate that cold draft does not flow into interior zone when the heat generation rate exceeds heat loss from the window in most cases. When the heat generation portion is 75% of heat loss from the window, some cases which have certain configuration of pericounter successfully avoids the influence of draft without fan."

  • The Thermo-Mechanical Stress Issues in a Thermally Enhanced QFP

    Jack G. Hwang, T. J. Huang, and J. J. Lee

    "A finite element model with multiple load steps for different processes is used to predict the stresses in die in a thermally enhanced QFP (HQFP)."

  • Thermal Finite Elements Analysis of the BaBar Silicon Vertex Tracker

    D. Barni, D. Giugni, F. Lanni, F. Palombo

    "In this note we present nite elements calculations of the thermal behavior of the BaBar silicon vertex tracker. Layers 1-2, 3 and 5 have been studied. Results show the adequacy of the cooling system in keeping the front-end chips into their optimal working condition. Thermo-mechanical results of layers 1-2 are also presented."

  • Thermal Modeling of the Infrared Reflow Process for Solder Ball Connect (SBC)

    H.V. Mahaney

    "A thermal model of the infrared reflow process has been developed for an FR-4 card populated with an array of Solder Ball Connect (SBC) modules. The analysis of the three-dimensional, transient, finite element model accounts for radiative exchange within the infrared oven and for the heat conduction (nonisotropic) within the modules and card. Transient temperature profiles of selected points and three-dimensional temperature distributions at selected times are presented to describe the primary heat-transport mechanisms. Numerical predictions and empirical data indicate that the SBC modules are relatively isothermal throughout the infrared reflow process. Therefore, every solder ball within the array exhibits a nearly identical thermal profile. This result is fortunate, since the inner solder ball connections cannot be visually inspected. The influence of module spacing and the ability to improve the reflow process by use of a high-emissivity cap coating are demonstrated."

  • Thermal Stress Analysis of Numi Baffle

    Bob Wands

    (Thermal-stress analysis)

  • Thermal Surface Effect Elements Intro [PDF]

    Sheldon Imaoka (CSI)

    Introduction to thermal surface effect elements (SURF151/152).

  • Thermal contact overview [PDF]

    Yongyi Zhu (ANSYS, Inc.)

    Presentation on the thermal contact capabilities of the surface-to-surface contact elements, beta at 5.6.
    Input file for pressure-dependent thermal conductance

  • Thermal surface Effect Elements, General Overview

    Sheldon Imaoka (ANSYS, Inc.)

    An overview presentation and example workshop on thermal surface effect elements. This is an old presentation I did at ANSYS 5.6.1, so if you use later versions of ANSYS, some of the menus and dialog boxes may have changed.

  • Thermomechanical Fatigue Failure of Interfaces in Lead-Free Solders

    M¨uge Erinc (Eindhoven University of Technology)

    "The European Union Waste Electrical and Electronic Equipment Directive (WEEE) and Restriction of Hazardous Substances Directive (RoHS) banned lead from electronic systems from July 1, 2006 onwards, which has led to much interest in leadfree solders in the past years. Among several lead-free solder alternatives, SnAgCu is a widely accepted replacement due to its better creep-fatigue resistance and microstructural stability. SnAgCu has been extensively studied in the past decade, however, there are still issues to be resolved concerning solder reliability, the underlying mechanisms of thermo-mechanical fatigue failure, fatigue life predictions and the overall effect of decreasing component size, driven by the ongoing miniaturization trend. This thesis aims to scientifically contribute to this subject by a coupled experimental-numerical approach."

  • Time-Dependent Material Modeling for Finite Element Analyses of Flip Chips

    Frank Feustel, Steffen Wiese, Ekkehard Meusel

    "Finite element analyses (FEA) have established as effective method for reliability assessment of flip chip assemblies. The simulation results are significantly dependent on the selected material models. Regarding flip chip assemblies, this statement mainly applies to the tin lead solder of the flip chip joints and the encapsulant – the so-called underfill.
    Comprehensive material data of eutectic solder were determined on real flip chip joints by TU Dresden. Based on these data three modeling approaches were evaluated (target platform was the FEA code ANSYS): viscoplasticity (Anand's model), power law creep (with 2 terms) + plasticity, and sinh law creep + plasticity (as user defined model in ANSYS)."

  • Tooling up for Micro Electro Mechanical Systems [PDF]

    Dale Ostergaard

    (from ANSYS Solutions magazine, volume 2, #1) (MEMS)

  • Topology Optimization in ANSYS

    Brian King (IMPACT Engineering Solutions, Inc.)

    Presentation from Midwest ANSYS User Group on Topological Optimization capability in ANSYS and Workbench Simulation.

  • Towards Automated Determination of USERMAT for the Nonlinear Constitutive Behavior of Composites

    J. Michopoulos, P. Mast, R. Badaliance, L. Gause, T. Chwastyk, R. Foerch

    "Recent advances in finite element techniques and design optimization integration technologies along with the parallel hardware and software evolution have directed the CMS group to turn its attention to utilizing "of the shelf"technology of achieving the same goals. Thus, the "Z-mat"and "Z-Optim"packages from Northwest Numerics, Inc., have been utilized to extract the non-linear constitutive response from the available experimental data in an integrated and automated manner and in conjunction with the ANSYS/Mechanical infrastructure. The automation lies on the fact that the process automatically generates the code of a "USERMAT"subroutine that it can be subsequently used with any geometry and loading specification definable within the limits of ANSYS' non-linear element library. The geometry of the single notched specimen of NRL's In Plane has been used for developing and verifying the process."

  • Transient Behavior of a Polymer Fill Material with Time Dependent Viscoelastic Properties

    John Thompson, Steven Groothuis, Hong Tang, Paul Koeneman

    "In an effort to simplify the implementation of viscoelastic material models into ANSYS, an ANSYS User-Programmable Feature (UsrFictive) has been modified to allow a more practical definition of viscoelastic material parameters. Standard ANSYS input of material data may be based upon temperature. Currently, ANSYS material data may not be a function of any other parameter. Many polymers used in industry are initially liquid and must be “cured” in a manufacturing process. This fact means that the properties will change over time. This application demonstrates one method of implementing a curing process simulation for a viscoelastic polymer."
    [ANSYS Nonlinear, version 6.?]

  • Transient Thermal Analysis of Spot Welding Electrodes

    K. S. Yeung, P. H. Thornton

    "The accurate thermal simulation of a spot welding electrode cap could permit critical design parameters to be identified for improved electrode life. In this study, a parametric model has been developed to predict the transient thermal behavior of a typical spot welding electrode cap. The model employs the technique of conjugate heat transfer analysis to avoid the problem of estimating a value for the heat transfer coefficient that arises with conventional heat transfer analysis."

  • Transmission of Mechanical Stresses within the Cytoskeleton of Adherent Cells: a Theoretical Analysis Based on a Multi-Component Cell Model

    Philippe Tracqui and Jacques Ohayon

    "We investigate here the spatial distributions of intracellular stresses when adherent cells are probed by magnetic twisting cytometry. The influence of the cell nucleus stiffness on the simulated nonlinear torque-bead rotation response is analyzed by considering a finite element multi-component cell model in which the cell and its nucleus are considered as different hyperelastic materials. We additionally take into account the mechanical properties of the basal cell cortex, which can be affected by the interaction of the basal cell membrane with the extracellular substrate. In agreement with data obtained on epithelial cells, the simulated behaviour of the cell model relates the hyperelastic response observed at the entire cell scale to the distribution of stresses and strains within the nucleus and the cytoskeleton, up to cell adhesion areas. These results, which indicate how mechanical forces are transmitted at distant points through the cytoskeleton, are compared to recent data imaging the highly localized distribution of intracellular stresses."[ANSYS Nonlinear, version 6.0]

  • Underfill Constraint Effects during Thermo-Mechanical Cycling of Flip Chip Solder Joints

    I. Dutta, A. Gopinath, and C. Marshall

    "The presence of an 'underfill' encapsulant between a micro-electronic device and the underlying substrate is known to substantially improve the thermal fatigue life of flip-chip solder joints, primarily due to load-transfer from the solder to the encapsulant. In this study, a new single joint-shear (SJS) test, which allows the measurement of the strain response of an individual solder ball during thermo-mechanical cycling (TMC), has been utilized to investigate the impact of the constraint imposed by the underfill on a solder-joint. Finite element modeling has been utilized to demonstrate that the SJS sample geometry captures most of the deformation characteristics of a flip-chip joint, and to provide insight into the experimental observations."

  • Understanding Accuracy and Discretization Error in an FEA Model

    Jon Pointer

    "The often-ignored topic of mesh discretization error is examined to identify a simple set of rules that the average user can enlist to determine solution accuracy. The sources of discretization error are explained, tools to quantify it are introduced and an example is given. The purpose is to bring an understanding of these issues and usable tools to the common user who is not proficient in the mathematical basis of FEA."

    [ANSYS 7.1, 2004 Conference]

  • Understanding Lagrange Multipliers [PDF]

    Sheldon Imaoka (ANSYS, Inc.)

    "Lagrange multipliers are a general term used in different areas of ANSYS, specifically contact and element formulation. This memo hopes to provide the user with a simplified introduction to the most important concepts in using elements with Lagrange multipliers, in hopes that some of the element options and solver selection can be better understood.
    Currently, at ANSYS 6.0, the node-to-node gap element CONTA178 and the Mixed U-P formulation of the 18x elements (i.e., KEYOPT(6)>0) utilize Lagrange multipliers, so the discussion will focus on these elements."

  • Understanding the Response Surface Method in DesignXplorer [PDF]

    Sheldon Imaoka (ANSYS, Inc.)

    "ANSYS DesignXplorer enables the user to perform optimization studies based on multiple objectives, to account for uncertainties in product design and use, and to determine how best to improve product reliability. These tasks are accomplished through the use of response surfaces, and this memo hopes to cover some of the basics of DesignXplorer operation."

  • Undocumented Hyperelastic Material Models at 5.7-6.1 [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "From 5.7, the 18x series of elements support a variety of hyperelastic constitutive models, namely general polynomial, Mooney-Rivlin, Neo-Hookean, Arruda-Boyce, and Ogden. Four other models have been included in 5.7 onwards, although these are undocumented options for TB,HYPER. These four models consist of the Yeoh and Gent models for incompressible behavior and the Hyperfoam and Blatz-Ko options for compressible rubbers. This memo hopes to provide a summary of these material models and of the required input."

  • Use Of Finite Element Analysis To Simulate The Hyperelastic Behaviour Of Cardiovascular Tissue [PDF]

    S. Daly, P.J. Prendergast, F. Dolan, T.C. Lee

    Examination of Mooney-Rivlin.

  • User Implemented Nitinol Material Model in ANSYS

    Peter R. Barrett and Daniel Fridline

    "Nitinol is an acronym for NIckel TItanium Naval Ordinance Laboratory since the alloy was originally developed at the Naval Lab. It is used to describe a family of materials, which contain a nearly equal mixture of nickel and titanium. Nitinol alloys are attractive to the medical device industry because they are biocompatible and when processed correctly, are at their optimum superelastic behavior at body temperature.
    "Nitinol exhibits a different stress-strain curve for loading and unloading that cannot be modeled with existing material models in ANSYS. This paper describes the implementation of a unique user material model in ANSYS that simulates the nitinol superelastic behavior. Example analyses are provided demonstrating the application of this material model for medical implant devices called stents."[ANSYS Nonlinear, version unspecified]
    Note that TB,SMA allows users to access built-in shape memory alloy constitutive model in ANSYS.

  • User-Defined Creep Laws with USERCREEP [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "ANSYS provides 13 creep equations for use with implicit creep – these range from the simple Norton law to the hyperbolic sine form to the Blackburn model to a rational polynomial expression, to name a few – that can be used to model a range of creep behavior for metals. The TBFT command provides curve-fitting functionality for the user wishing to evaluate creep material parameters from test data. Also, the user can model anisotropic creep as well as combine implicit creep with rate-independent plasticity to model a wide range of complex material response.
    Despite this wealth of features, however, one may wish to incorporate one’s own creep law into ANSYS. For example, a company may have their own creep equation with material parameters already defined and validated through testing. The built-in creep laws in ANSYS assume creep used in design rather than failure analysis, so the available creep laws are meant to model primary and secondary creep – consequently, another need to incorporate a user-defined creep law would arise when a user wants to include tertiary creep and/or to evaluate creep damage.
    This memo will hope to address some aspects of writing one’s own user-defined creep law with the USERCREEP.F subroutine to address this issue."
    Example using Anand's model.

  • User-Defined Hyperelasticity with USERHYPER [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "User-Programmable Features (UPFs) are an extremely useful feature for analysts that need additional advanced functionality, especially in the area of constitutive modeling.
    TB,HYPER allows users to include many incompressible and compressible hyperelastic material behavior – Ogden, Arruda-Boyce, Gent, Yeoh, Blatz-Ko are but some of the available models. However, for those wishing to use a customized strain energy function, the USERHYPER.F subroutine is available."

  • User-Defined Output with USEROUT.F [ZIP]

    Sheldon Imaoka (ANSYS, Inc.)

    "There are various situations where a user may wish to define specific type of output to postprocess — this can range from simple evaluation of safety factors to more involved damage calculations. While APDL, the ANSYS command language, allows users to manipulate results in any manner one sees fit, user-programmable features (UPFs) also provide a means for users to calculate specific output results efficiently at the solution level."
    Example of calculating fatigue and Cap (Extended Drucker-Prager) output.

  • Using Abbreviations to Customize the Toolbar [PDF]

    Sheldon Imaoka (ANSYS, Inc.)

    "The ANSYS Toolbar provides a useful means of accessing commonly-used functions, especially for users who use the GUI rather than typing in commands."

    "This memo hopes to provide a brief introduction to the ANSYS Toolbar and, more importantly, how to assign macros or specific dialog boxes to the Toolbar buttons, including Fnc_ UIDL granules or ~eui Tcl/Tk dialog boxes."