Overview

Hyfeast's command-line finite element analysis program, hfAnalyzer, reads a text input file to perform analysis. The input file is composed of command blocks that start with reserved keywords beginning with *, such as *Node, *Element. Below is an example input file for a simple frame analysis.

# Portal Frame Example

*Node
 1, 0., 0.
 2, 0.,10.
 3,10.,10.
 4,10., 0.

*Element, Type=B2D2H, ELSet=ALL
 1, 1, 2 
 2, 2, 3
 3, 3, 4

*Material, Type=IsoElasticity, Name=beam
 210E9, 0.3, 0, 7700   # E, nu, alpha, density

*Section, Type=Beam, Name=BeamSection, Mass=Lumped
*Cell, TYPE=Rectangle, MAT=beam
 0.4, 0.1 

*Distribution, TYPE=Section
 ALL, BeamSection

*Constraint, Type=Support, Name=BC
 1, X|Y|RZ
 4, X|Y|RZ

*Load, Type=Concentric, Name=LC2
 2,X,100E3

*NSet, Type=SELECT, Name=23
 2, 3

*NSet, Type=SELECT, Name=14
 1, 4

#---------- Static analysis for odal concentric load
*Step, Type=Static, Name=Case1
*Activate, Type=Element
 ALL
*Activate, Type=Constraint
 BC
*Activate, Type=Load
 LC2
*Output, Frequency=1
 D,FN,BSF
*Print, File=Case1.prn
 D@23, FN@14

#---------- Frequency extraction analysis
*Step, Type=Frequency, Name=Case2
 10
*Activate, Type=Element
 ALL 
*Activate, Type=Constraint
 BC 
*Output
 D             # if frequency step, D means mode shape.
*Print, File=Case2.prn

This lists the general rules used in the input text file.

  • If non-Ascii characters such as Korean are present, the file must be encoded in UTF-8.
  • The input file is a text file and is parsed line by line in sequence.
  • Blank lines are ignored, and explanations (comments) can be written using the # character.
  • The backslash \ character can be used to concatenate with the next line.
  • Reserved keywords are case-insensitive, but user-defined strings (e.g., element set names) are case-sensitive.

  • Each line follows a free format such as n1, n2, n3 or n1, ..., ID=id1, .... In this case, tokens used for parsing are separated by equal sign (=) and comma (,) characters. The program operates internally as follows:

    • Find the equal sign (=) and recognize the keyword on the left
    • Parse each item in free format by splitting them into tokens using comma as delimiters
    • If enclosed in double quotes, treat it as a single token

  • For parts that are input as floating-point or integer values, simple arithmetic expressions can be used. For example, 1+2*(10+2) is valid. If spaces are present inside the expression, it will be split into tokens and thus spaces must not be included. If spaces are present and should be treated as a single token, the expression must be enclosed in double quotes (e.g., "1 + 2*(10+2)").

  • Arithmetic expressions may include predefined functions and constants such as in 20*sin(30*deg).

    • Functions of the form f(x): sin, cos, tan, acos, atan, cosh, sinh, tanh, abs, exp, log, log10, sqrt, step, sgn
    • Functions of the form f(x,y): pow, max, min
    • Constant: pi, e, deg

  • If a string input contains spaces, it must be enclosed in double quotes. For example: *Material, TYPE=IsoElasticity, Name="the material"

  • When a file name is provided as a string input, both relative and absolute paths are recognized. If the path contains spaces, it must be enclosed in double quotes. A relative path is resolved relative to the directory where the input file exists. For example:
*Include, File=model1.inp
*Include, File=templates/model1.inp
*Include, File="templates folder/model 1.inp" ← if spaces exist, use double quotes
*Include, File="./templates/frame model.inp" ← . means current directory
*Include, File="../frame model.inp" ← .. means parent directory
*Include, File="D:/DevProg/HFC4.0/EXAMPLE/frame model.inp" ← absolute path

Commands starting with an asterisk * can be broadly categorized into modeling commands, analysis commands, and miscellaneous commands. The following is a summary of the commands.

Node Commands
  • *Node: Define a node.
  • *NSet: Define a nset.
  • *NGen: Generate nodes with a line pattern and assign them to a nset.
  • *NFill: Generate nodes with a filling pattern and assign them to a nset.
  • *NCopy: Copy a nset.
Element Commands
  • *Element: Define an element.
  • *ELSet: Define an elset.
  • *ELGen: Generate elements and assign them to an elset.
  • *ELCopy: Copy an elset.
  • *Section: Define a section.
Load and Constraint Commands
  • *Load: Define a load.
  • *Constraint: Define a constraint.
Property Commands
  • *Material: Define a material.
  • *Function: Define a function.
  • *Surface : Define surface
  • *Construction : Define auxilieary geometric entities – spline and construciton line.
  • *CoordinateSystem: Define a coordinate system.
Analysis Commands
  • *Step: Define an analysis step.
  • *Activate: Activate elements, constraints, and loads.
  • *Inactivate: Inactivate elements, constraints, and loads.
  • *Convergency: Assign convergence criteria.
  • *SolutionAlgorithm: Assign the solution algorithm for equilibrium iteration.
  • *TimeIntegration: Assign a time integration scheme for a dynamic step.
  • *RayleighDamping: Assign Rayleigh damping for a dynamic step.
  • *Modal: Set dynamic analysis with modal analysis and assign modal damping ratios.
  • *Field: Set the element's field state.
  • *Output: Assign requests for field output for the output file (ODB file).
  • *Print: Assign requests for printing fields to a specified text file.
  • *Check: Assign requests for field checks.
Analysis Result Management Commands
  • *PostStep: Generate a new step from the results of another step.
  • *History: Assign requests for history output.
  • *PostHistory: Extract history output from existing steps.
  • *HDB: Load HDB file(.hdb)
Modeling Convenience Commands
  • *Include: Include an external file.
  • *DefaultParameter: Assign a default parameter expression.
  • *Distribution: Assign nodal and element properties.
  • *Model: Generate a template model.
Other Commands
  • *Environment: Setup environment
  • *Stop: Set up stop conditions.
  • *TestMaterial: Test the material model for a given strain history.