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Support elements and analysis functions

Supporting Elements and Interpretation

LNG System falls under Plus in the LUSAS product feature level classification and includes the following features.

1. LNG System Feature Summary

classification
Summary of content
Element family
Advanced High-performance element library
: Bar, Beam, Plate, Plane stress/strain, Joint/spring/gaps, Shell, Solid, Axisymmetric solid/shell 80 types

Extended advanced high-performance element library
: Curved Bars/Beams/Shells/Solids, etc. 30 kinds of high-end elements
Analysis and design

Standard
: Linear Static, Linear Buckling, Natural Vibration, Interactive Modal Dynamic (IMD), Fatigue

Nonlinear
 : Geometric
Material nonlinearities (concrete cracking, creep and drying shrinkage, Mohr-Coulomb geometry, heat of hydration, etc.)
Boundary Nonlinear (Construction Step-by-Step Analysis)

Dynamic
 : Implicit/Explicit Dynamic

Thermal/Field
 Static thermal analysis, time-dependent thermal analysis, thermal-structural coupling analysis (with temperature-dependent material property changes)

IMDplus
 : Interactive Modal Dynamic Plus

RC Slab/Wall Design
 Design review for reinforced concrete structures according to reinforcement conditions and national specifications.

LNG
 Modeling, analysis and design review of LNG tanks as described on this website.

2. Analyze feature details

(1) 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
  • Generalized 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

(2) Verification

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

(3) 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 modeling (Plane strain only)

(4) Explicit Stress Element Types

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

(5) Thermal (Field) Element Types

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

(6) Solvers

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

(7) 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

(8) 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
  • Concrete heat of hydration modeling
  • 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
  • Volumetric deformation model for soils and crushable foams
  • 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
  • Phase changes
  • User defined nonlinear material and creep interfaces
  • Damage model
  • Hashin material model for composite materials
  • Material model interface (MMI)

(9) Eigen Analysis

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

(10) 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

(11) 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

(12) 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

(13) 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