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General Information

Summary of LUSAS analysis features as at Version 15.1

Last updated: 14 December 2015

The following summarises the analysis features available in the range of LUSAS finite element software products and additional software product options for Version 15.0

Note: For detailed information relating to each LUSAS software product click here


General System Facilities

  • Online help
  • Comprehensive error diagnostics
  • User defined element and nodal output options
  • Full range of load types
  • General purpose load curve input
  • Generalised constraint equations
  • Resolution for multiple load cases
  • Flexible restart facility
  • Superelements (substructures)
  • Efficient automatic frontwidth optimisation
  • Efficient frontal equation solver for both large and small problems
  • Pre-conditioned conjugate gradient iterative solver for fast solutions of large problems

General Analysis Capabilities

  • Solve multiple analyses in one model
  • Solve selected analyses/loadcases
  • Cable tuning analysis for linear structures (selected products only)
  • Specify target values for linear structures
  • Direct method influence analysis
  • Reciprocal method influence analysis
  • Nonlinear analysis
  • Dynamic analysis
  • Thermal analysis
  • Heat of Hydration analysis
  • Coupled analysis

Verification

  • Rigorous internal Quality Assurance procedures
  • Comprehensive machine checked testing
  • HECB calibration and NAFEMS calibration tests

Implicit Stress Element Types

  • Plane frame/truss
  • Grillage
  • Space frame/truss
  • Curved thin and thick beams with constant/variable cross sections
  • Plane stress/plane strain
  • Plate flexure (thin and thick)
  • Ribbed plates
  • Axisymmetric solids with non axisymmetric loading
  • Axisymmetric membranes
  • Axisymmetric thin shell
  • Flat thin shells
  • Curved thin Semiloof shells
  • Flat/curved thin/thick co-rotational shells
  • 3D solids
  • Composite shell
  • Composite solids
  • Generalised joint/gaps including seismic isolators, viscous dampers, lead rubber bearings and friction pendulum
  • 2D plane stress/plane strain/ axisymmetric solid crack tip
  • Pore water pressure modelling (Plane strain only)

Explicit Stress Element Types

  • Plane stress/strain with hourglass stabilisation
  • Solid with hour glass stabilisation

Thermal (Field) Element Types

  • Bars
  • Plane
  • Axisymmetric solids
  • Axisymmetric membranes
  • 3D solids
  • Links

Solvers

  • Frontal (direct) solver
  • Iterative (PCG) solver
  • Fast multifrontal direct solver
  • Fast multifrontal block Lanczos eigensolver
  • Fast complex eigensolver
  • Fast Parallel Direct Solver
  • Fast Parallel Iterative Solver

Linear Materials

  • Isotropic, orthotropic, anisotropic and rigidity models
  • Isotropic and orthotropic thermal materials
  • Composite lay-ups for shell and solid material models
  • Temperature dependency for all linear material models
  • Piecewise linear joint material model
  • Piecewise linear (axial  force dependent) joint material model
  • Piecewise linear bar material model
  • Trilinear earth pressure joint material
  • Piecewise linear hysteretic and compound hysteretic joint models

Nonlinear Materials

  • Plasticity model with isotropic and kinematic hardening using von-Mises criteria, includes a backward Euler stress update algorithm with consistent tangents
  • Anisotropic plasticity model with isotropic hardening using Hill or Hoffman criteria, includes a backward Euler stress update algorithm with consistent tangent
  • Plasticity model with isotropic hardening using a modified von Mises criteria with different properties in tension and compression, includes a backward Euler stress update algorithm with consistent tangent
  • Concrete models with opening and closing cracks and strain softening based on fracture energy in 2D and 3D
  • Concrete creep and shrinkage model to CEB-FIP Model Code 1990, and EN1992-1-1:2004
  • Concrete creep to China code
  • Concrete heat of hydration modelling
  • Multi-surface cracking concrete with crushing material model
  • Viscous damped joints
  • Geotechnical model using Mohr Coulomb criteria including non-associative flow for soils and rocks
  • Modified Mohr-Coulomb material model with tensile/compressive cut-off.
  • Volumetric deformation model for soils and crushable foams
  • Two phase material
  • Geostatic control
  • Ogden and Mooney-Rivlin models for rubber materials with very large strains
  • Composite lay-ups for shell and solid nonlinear material models
  • Temperature dependency for all nonlinear material models
  • Creep model with time dependency and strain hardening
  • Viscoelasticity
  • User defined nonlinear material and creep interfaces
  • Damage model
  • Hashin material model for composite materials
  • Material model interface (MMI)

Eigen Analysis

  • Lanczos and Subspace EigenSolver
  • Frequency bracketing
  • Euler buckling analysis
  • Guyan reduction with automatic or user defined masters

Nonlinear Analysis

  • Incremental solutions with iterative correction
  • User defined combination of full or modified Newton Raphson iterations with line searches
  • Automatic arc length solution procedures with option for non-proportional loading
  • Automatic recovery upon convergence failure
  • Load or displacement control
  • Wide selection of convergence criteria
  • Large deformation, large rotation geometric nonlinearities
  • Large strains
  • Follower loads
  • Element birth and death facility
  • Centripetal stress stiffening
  • Temperature dependent material properties

Dynamic Analysis

  • Forced response analysis
  • Modal (viscous or structural) or Rayleigh damping
  • Response spectrum analysis with a choice of SRSS and CQC spectral combinations
  • Modal synthesis analysis using superelements
  • Implicit transient dynamic analysis using Hilber-Hughes-Taylor time integration scheme
  • Explicit transient dynamic analysis using central difference time integration scheme
  • Initial velocity/acceleration input
  • Implicit and explicit impact
  • Linear and nonlinear dynamic analysis
  • Automatic time step selection
  • Time dependent material properties
  • Time dependent loading
  • Interactive Model Dynamics option for multiple loading events and advanced loading options

Thermal Analysis

  • Steady state heat conduction/convection/radiation
  • Transient thermal analysis with a general two point recurrence scheme
  • Temperature dependent thermal properties
  • Temperature dependent nonlinear heat conduction/convection/radiation
  • Variable time step selection
  • Conduction/convection/gap radiation
  • Diffuse radiation using view factor with option to account for symmetry boundary conditions
  • Full and semi thermal-structural coupling

Boundary Conditions

  • Choice of restrained, prescribed or spring boundary conditions
  • Transformed freedom option for skew boundary conditions
  • Time dependent boundary conditions and loading
  • Nonlinear friction and gap models to represent deformation dependent boundary conditions and contact problems
  • Slideline/slidesurface contact algorithms for use with implicit/explicit plane stress/strain, Axisymmetric, shell and solid elements
  • Convection and nonlinear radiation boundary conditions
  • Tied slidelines to connect incompatible meshes
  • Contact cushioning
  • Automatic pre-contact algorithm
  • Curved surface contact

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Software Information


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Any modelling and analysis capabilities described on this page are dependent upon the LUSAS software product and version in use.