Battelle Memorial Institute

Caterpillar Inc.

Pingsha Dong

Jinmiao Zhang

Jeong Kyun Hong

Yi Dong

Ashok Nanjundan

Frederick W Brust

Zhigang Wei

Jeong K Hong

A method is provided for performing fatigue evaluation of a fatigue prone location of a tangible structure by converting multi-axial loading data of the fatigue prone location of the tangible structure to a set of equivalent constant amplitude loading data for the tangible structure. According to the method, a multi-axial load locus representing the tangible structure is generated. Time-dependent interior turning points R and any corresponding projected turning point R* art identified along the loading path from the point of origin P to the point of termination Q. Half cycles in the loading path are counted by referring to the interior and projected turning points R, R* along the loading path and to the point of origin P and the point of termination Q on the load locus. A stress range &#x394;&#x3c3;, loading path length L, and virtual path length for each of the counted half cycles are determined. Additional stress ranges &#x394;&#x3c3;, loading path lengths L, and virtual path lengths are determined recursively for half cycles counted in additional loading paths on the load locus. A system is also provided for performing fatigue evaluation. Methods are also provided for counting and displaying the number of load cycles represented in multi-axial loading data of a fatigue prone location of the tangible structure. Additional embodiments are disclosed and claimed.

Path-dependent cycle counting and multi-axial fatigue evaluation of engineering structures

Structural stress in a fatigue-prone region of a structure is determined and analyzed by using: i) the nodal forces and displacement values in the fatigue-prone region, or ii) equilibrium equivalent simple stress states consistent with elementary structural mechanics in the fatigue-prone region. Of course, it is contemplated that combinations, equivalents, or variations of the recited bases may alternatively be employed.

Structural stress analysis

Structural stress in a fatigue-prone region of a structure is determined by using the nodal forces and displacement values in the fatigue-prone region, or equilibrium-equivalent simple stress states consistent with elementary structural mechanics in the fatigue-prone region. The determination is substantially independent of mesh size and is particularly well-suited for applications where S-N curves are used in weld fatigue design and evaluation, where S represents nominal stress or stress range and N represents the number of cycles to failure.

This need is met by the present invention wherein structural stress in a fatigue-prone region of a structure is determined by using the nodal forces and displacement values in the fatigue-prone region, or equilibrium-equivalent simple stress states consistent with elementary structural mechanics in the fatigue-prone region. The determination is substantially independent of mesh size and is particularly well-suited for applications where S-N curves are used in weld fatigue design and evaluation, where S represents nominal stress or stress range and N represents the number of cycles to failure. The present invention is directed to structural stress analysis through various combinations of modeling, calculation, and direct measurement schemes.

A method for determining a model for a welding simulation, and the associated model. The method includes the steps of determining a history annihilation model of a material being welded, determining a strain hardening model of the material being welded, determining a three-dimensional virtual elements detection model of the material being welded, and incorporating the above models into a constitutive model for the welding simulation.

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Dublin, OH, United States of America

Pingsha Dong