CAEFEM Analysis Types


Linear Static Analysis: Calculates displacements and stresses due to constant loads. Unlimited problem size and extremely fast solution speeds.
 
Natural Frequency and Mode shapes: Calculates natural frequencies and associated mode shapes. useful to find resonance and also to find transient response. Automatic calculation of rigid body modes, Sturm sequence check and stress stiffening.
 
Linear Buckling: Estimates critical loads at which model becomes unstable. Supports stress stiffening.
 
Frequency Response: Calculates steady state (harmonic) response due to external sinusoidal loads. Both magnitude and phase of external loads can be functions of frequency. Accepts Rayleigh, Overall structural and Modal  dampings. Damping factor, structural damping or quality factor can be specified as functions of frequency.
 
Response Spectrum analysis finds the response of a structure due to external loading such as earthquakes, wind loads etc.,
 
Transient Dynamic: Calculates transient response due to dynamic loads. Supports both Direct Time Integration and Mode Superposition methods. Accepts Rayleigh, Modal and Viscous dampings.
 
Heat Transfer: Supports both linear and nonlinear  steady state and transient heat transfer analyses. Radiation, Phase change, temperature dependent properties are some types of nonlinearities.
 
Nonlinear Structural: Supports Large deflections, Nonlinear materials and Contact (including surface to surface contact) conditions. Regular and Modified Newton Raphson, Updated and Total Lagrangian, Large rotations, Line search option and Automatic time stepping.  Corotational formulation of Beam element allows extremely large rotations. An initially straight cantilever beam was deformed into a complete circle in just four time steps.
 
Thermal Stress Analysis: Automatic transfer of temperature results from a heat transfer analysis to structural analysis. Hence no special command is required to consider temperature effects in a structural analysis.

Linear Static

Performing a linear static analysis is as easy as choosing Analysis option from LUMINO. It automatically transfers the finite element data from LUMINO to CAEFEM. Once the analysis is done, results are automatically transfer back to LUMINO for post processing. Of course, you will have complete control in selecting additional options for both the analysis and also for post processing data.

Some of the major features of Linear Static Analysis are:

  • Virtually unlimited problem size.
  • Supports both Direct and Iterative Solvers.
    • Problems of the order of 3,000,000 DOF have been solved in about 8 minutes on a Pentium PC.
  • Supports both Isotropic and Orthotropic Material properties
  • Hundreds of load and constraint set combinations can be analyzed in a single run.
    • User can select any combination of constraint and load cases to be included in the analysis by selecting the items from the Windows list boxes.
  • Automatically calculates thermal stresses from a prior heat transfer results.
  • Supports all types of loads including nodal, elemental pressure, varying beam loads, centrifugal and gravity loads etc.,

  • Natural Frequency

Calculates natural frequencies and associated mode shapes.  Some of the major features are:

  • Frequency extraction techniques
    • Jacobi Iterations
    • Lanczos algorithm
    • Subspace Iterations
    • Inverse Iterations
  • Automatic calculation of rigid body modes.
  • User specified frequency shift.
  • Calculation of Normal modes.
  • Sturm sequence check.
  • Stress stiffening.
  • Lumped, Special Lumped and Consistent mass matrices.
  • Ability to store only user specified mode shapes in the database.
  • Mode participation factors

 

  • Buckling

Calculates linear buckling load.  Some of the major features are:

  • Eigen value extraction techniques
    • Jacobi Iterations
    • Subspace Iterations
    • Inverse Iterations
  • Automatic calculation of rigid body modes.
  • Multiple buckling modes.
  • User specified eigen value shift.
  • Sturm sequence check.
  • Stress stiffening.
  • Ability to store only user specified mode shapes in the database.

  • Frequency Response

Calculates steady state response due to external harmonic loads.

  • Solution Method: Mode Superposition method
  • Loads and Boundary conditions: Frequency dependent magnitude and phase.
  • Supports all types of loads including nodal, pressure and line loads on beams.
  • Response at user selectable frequencies
  • A variety of damping options including Rayleigh, structural and frequency dependent modal dampings.
  • Automatic calculation of normal modes required for this analysis.

  • Response Spectrum

Calculates the maximum response due to external loads like earthquakes, wind loads etc.,

  • Displacement, velocity, acceleration, force and rocking spectrums.
  • Base excitation.
  • A variety of damping options including Rayleigh, structural and frequency dependent modal dampings.
  • Automatic calculation of normal modes required for this analysis.
  • Mode combination methods like CQC, Double sum, Grouping, SRSS and NRL.

  • Transient Dynamic

Following is a list of major features

  • Types of analyses.
    • Linear analysis
    • Nonlinear  analysis.
  • Newmark Beta Method
  • Solution Techniques
    • Direct Time Integration.
      • Supports both linear and nonlinear analyses.
      • Viscous and Rayleigh Dampings
    • Mode Superposition method (applicable only for a linear analysis)
      • Automatic calculation of required mode shapes.
      • Rayleigh Damping.
      • Modal damping based on Mode number.
      • Modal damping based on Modal frequency.
      • Overall Structural damping
  • Mass Matrices
    • Lumped Mass matrix.
    • Special lumped mass matrix
    • Consistent mass matrix.
  • Restart of analysis from the last successful time step.
  • Groups can be used to control the database size by specifying the list of time steps to be saved.

  • Heat Transfer

  • Types of Analyses
    • Linear heat transfer
    • Nonlinear heat transfer
  • State of Analyses
    • Steady state heat transfer.
    • Transient heat transfer
  • Solution strategies
    • Full and Modified Newton Raphson techniques
    • Euler Backward Implicit scheme for transient heat transfer
    • Line search option for faster convergence
    • Convergence checks on temperature and heat flow.
  • Elements
    • Supports all available elements except those elements specialized for structural analyses. example: Stiffness matrix, Mass matrix, Gap etc., These specialized structural elements will be simply ignored by heat transfer analysis.
    • No need to change the element types to perform  heat transfer analyses.
  • Analysis automatically switches to nonlinear analysis depending on the nonlinearities.
  • Time and temperature dependent properties, loads and boundary conditions.
  • Nodal loads
    • Heat flow
    • Heat generation
    • Nodal temperatures
  • Element loads
    • Convection
    • Radiation
    • Heat generation
    • Heat flux
  • Phase change effects
    • Considers latent heat effects during a phase change in a transient heat transfer.
    • Enthalpy formulation which is not very sensitive to the phase change interval.
  • Initial conditions
    • Prior steady state solution
    • From a user specified load set
  • Types of heat capacity matrices
    • Lumped capacity
    • Special lumped capacity
    • Consistent capacity
  • Automatic transfer of results to structural analyses for thermal stress calculation
  • Nonlinear Structural
  • Large deflection and rotation formulations
    • Total Lagrangian formulation
    • Updated Lagrangian formulation
    • Corotational formulation
      • An initially straight cantilever beam was deformed into a complete circle in just four time steps.
  • Large strains
  • Nonlinear Materials
    • Yield Functions
      • von Mises Yield condition
      • Drucker Prager Yield condition
      • Mohr Coulomb yield condition
  • Hardening Types
    • Isotropic hardening
    • Kinematic hardening
  • Mooney-Rivlin Hyperelastic rubber material
  • User defined stress-strain curve in plastic region
  • Temperature dependent properties.
  • Contact conditions
    • Surface to surface contact
    • Gap elements
    • Automatically estimates the necessary gap stiffnesses.
  • Supports Preconditioned Conjugate Gradient iterative and Sparse solvers.
  • Loads and constraints in any user specified coordinate system. Considers constraints in local coordinate system by the method of transformations.
  • Deformation dependent pressure loads (follower forces)
  • Solution Strategies
    • Full and Modified Newton Raphson techniques.
    • Line search option for faster convergence
    • Displacement, force and energy convergence criteria.
  • Restart of analysis from the previous successful solution.

Elements


CAEFEM supports a comprehensive library of elements including both linear and higher order elements. Here is a list of elements and some of the major features supported by CAEFEM.
All of the following elements can be used for either structural or heat transfer analyses unless otherwise specified.


Element Name

Major Features

Rod

Two node element. Usually accepts only translational degrees of freedom and hence CAEFEM automatically ignores rotational degrees of freedom. But it considers rotational degree of freedom about its axis, if user specifies nonzero torsional constant.

Cable

Same as Rod element except an initial tension can be specified. CAEFEM automatically treats Rod element as a Cable element if nonzero initial tension is specified.

Bar

Same as a uniform beam element.

Beam

Two node element.
Shear deformation effects.
End releases (both translational and rotational).
Nodal offsets.
User can specify the stress recovery locations.
Tapered beams.
Unsymmetrical beams.
Distributed line loads either in global coordinate system or in elemental coordinate system.
Large rotations using Co rotational formulation.

Tube (Pipe)

Same as a beam element with an annular cross section.

Gap

Two node element. (considers friction)
Automatically estimates the proper gap stiffnesses for efficient solution.
CAEFEM automatically switches to nonlinear analysis if Gap elements exist in the current model.
Applicable only for a structural analysis.

Contact

Surface to surface contact.

Spring and Damper

Supports both axial and torsional stiffnesses and dampers. Applicable only for a structural analysis.

DOF Spring

User can specify the stiffness values between any two degrees of freedom.   Degrees of freedom can be specified in the output coordinate system. Applicable only for a structural analysis.

Rigid

Any number of nodes can be connected by a rigid element. Applicable only for a structural analysis.

Membrane

Same as a Plane stress element except that it can be located in a three dimensional space.

Plane Stress

Supports 3 to 8 nodes. Should be defined in XY plane.

Plane Strain

Supports 3 to 8 nodes.  Should be defined in XY plane.

Axisymmetric Ring

Supports 3 to 8 nodes. Should be defined  in XY plane. (Y axis being the axis of revolution)

Shell

Supports 3 to 8 nodes.
Supports both Thick and Thin element formulations. Automatically considers shear deformation effects.

Laminated Shell

Supports 3 to 8 nodes.
Maximum number of layers = 90
Non-symmetric Laminates
Various failure criteria (Hill, Hoffman, Maximum Strain, Tsai-Wu, and Bond failure)

Solid Brick

Supports 4 to 20 nodes. Degenerated element can be formed by repeating the nodes.

Solid Tetrahedron

Supports 4 to 10 nodes.

Solid Wedge

Supports 6 to 15 nodes.

Stiffness Matrix

User can specify all 36 coefficients of a stiffness matrix. Applicable only for a structural analysis.

Mass Matrix

User can specify all 36 coefficient of a mass matrix. Applicable only for a structural analysis.

Nodal Mass

User can specify all six components of mass values at a node. Applicable only for structural analysis.
Considers nodal offsets.


Solution Techniques

CAEFEM supports the following types of methods for solution of equations. Depending on the requirement, user can easily select the solution method.

  • Direct method (Skyline)
    • Robust method.  Good for all types of analyses.
    • Very efficient for multi load case analyses.
  • Direct Method (Sparse Solver from CA&SI)
    • Robust method based on LU Decomposition
    • Requires only a fraction of disk space and CPU time as compared to the Skyline solver. Hence very equency and nonlinear analyses can be performed using a PC with limited resources.
  • Iterative Method
  • Preconditioned Conjugate Gradient method (PCGLSS from CA&SI)
    • User can select the convergence tolerance.
    • Out of core solution scheme is also available.
  • Supports all elements.
  • Good for solution of very large sparse matrices.
  • Solution speeds up to Sixty times the speeds of direct methods have been observed.
  • Requires a fraction of disk space as compared to the direct methods.
  • Supports all analyses.

Loads & BC’s


CAEFEM supports the following loads and boundary conditions. All structural loads and boundary conditions can be time dependent and can be specified in any user defined coordinate system. All thermal loads can be functions of both time and temperature.

  • Boundary conditions
    • Prescribed displacements in any user defined coordinate system.
    • Single point constraints
    • Multipoint constraints
    • Constraint equations
  • Loads
    • Body Loads
      • Gravity / Inertia loads
      • Centrifugal  loads
  • Nodal Loads
    • Forces and Moments
  • Displacements
  • Temperatures
  • Heat flux
  • Heat generation
  • Velocities
  • Accelerations
    • Element Loads
      • Pressure loads
      • Deformation dependent pressure loads (follower forces)
      • Distributed line loads on Beams and Rods
        • Either in global coordinate system or in elemental coordinate system.
        • Accepts linear variation of distributed loads.
      • Heat generation
      • Heat flux
      • Convection
      • Radiation

Other Features


Restart

Restart of an analysis (available for both structural and heat transfer analyses). CAEFEM recognizes it as a restart of an analysis if user attempts to run the same analysis. Hence no special command is required to continue the analysis from a previous successful time step. 

Aborting an analysis

CAEFEM allows you to abort the analysis before its completion. It helps you to stop the current analysis for a possible input correction. 

Groups

CAEFEM now reads all groups information from Lumino. Groups information can be used to control the ASCII file printout, to store different sets of data in CAEFEM database and also to control the results neutral file information. Groups can also be defined / modified in CAEFEM. Choose-Create-Groups to create a new group of entities. Choose Edit-Groups to edit an existing group of entities.
Example: Suppose you are performing a transient dynamic analysis of 10000 node problem for 1000 time steps. Suppose you are only interested in  results at time steps 100 and 1000 at nodes 5 and 400. Using Groups, you can store results only at time steps 100 and 1000 and hence saving a substantial amount of disk space. Similarly you can transfer results to Luminofor nodes 5 and 400 only. It, not only, reduces the amount of disk space but also the transfer time. 

Print Options

Displacements, Velocities, Accelerations, Stresses, Strains and Reaction forces. Both nodal and integration point stresses/strains are available. Beam end moments, Plate stress resultants and internal forces at element nodes. Temperature and heat flow rates. Stiffness and mass matrices (both global and elemental matrices)
All of the above quantities can be controlled with the help of associated groups. 

Batch Option

Supports a powerful batch option. It automatically runs all the specified analyses and prepares post processing files. 

DLL Interface

Supports Dynamic Link Library interface. It allows the customization of CAEFEM.


Quality Assurance


Supported by over 1000 internal verification and NAFEMS bench mark problems. This set includes problems with known analytical solutions, problems from the finite element analysis literature, large problems etc., A large set of output values are automatically compared with the reference solution to maintain the high quality of the software.