Types of Assessment

LIMIT Nachweisarten

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The software LIMIT offers three different types of strength assessments:

  • - Static strength
  • - Fatigue strength
  • - Variable amplitude fatigue strength

These assessment types can be used for base material and welded structures, depending on the design code.

For base material, stresses supplied by the FE codes are mostly assessed directly. Load case superposition and load spectrum definition are possible in this mode.

In case of weld assessments, element stresses provided by the FE code are used to calculate shell section forces and, subsequently, local stresses in the throat sections from analytical relationships. Stress values can be transformed into nominal stresses or structural hot spot stresses. A weld assessment in LIMIT requires information about sheet thicknesses, weld geometry and weld path (via node sets). The preprocessor LIMIT-CAE contains several functions which facilitate the definition of weld geometries and notch cases.

Starting with version LIMIT 2012, the program offers a new assessment mode named *WELD_GLOBAL. In this mode, shell stresses are assessed directly, but the definition of direction-dependent weld notch cases is not possible. In this case, LIMIT varies the weld orientation (critical plane) and saves the relevant result.

Strength assessments on the basis of effective notch stresses are a sub-method of the local stress approach used for solid meshes and base material.
 

The following assessment modes are available:

  • Base material:                                    *BASE_MATERIAL
  • Overall fast weld assessment:           *WELD_GLOBAL
  • Detailed weld assessment:                 *WELD


The following table gives an overview of the available methods:

Assessment types

 

 

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