Metal fusion bonding – Process – With measuring – testing – indicating – inspecting – or...
Reexamination Certificate
2000-08-29
2002-06-04
Shaw, Clifford C. (Department: 1725)
Metal fusion bonding
Process
With measuring, testing, indicating, inspecting, or...
C148S503000, C219S130010
Reexamination Certificate
active
06398102
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a method for providing a solution for thermal modeling of a welding process and, more particularly, to a method for providing an analytical solution for determining a temperature history on a material that is subjected to a welding process.
BACKGROUND ART
The process of welding materials has some amount of detrimental effect on the materials being welded. For example, materials being welded are subjected to residual stresses and distortions due to the extreme heat caused by the weld process.
In the past, attempts have been made to analyze and determine the effects of heat on materials from the welding process. One method in particular, the finite element method (FEM), uses finite element analysis to model the weld process, and has been widely used to analyze the thermal effects of welding. However, FEM can be extremely cumbersome to implement and very costly.
Rosenthal, in
Mathematical Theory of Heat Distribution During Welding and Cutting,
Welding Journal, Vol. 21(5), pp. 220s-234s, discloses an analytical solution for the thermal history of a welding process which works by the superposition of point heat source solutions. The method proposed by Rosenthal did not require the extremely cumbersome finite element analysis techniques previously used, and therefore provided a much more rapid analytical solution procedure. However, the method of Rosenthal's does not account for such features as weld joint geometry and multi-pass welding. Furthermore, it may be desired to use both types of thermal models for some applications. For example, an analytical based model may be used for providing rapid, global solutions, and the FEM may be used to provide accurate temperature models for local areas of concern.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention a method for providing an analytical solution for a thermal history of a welding process having multiple weld passes is disclosed. The method includes the steps of inputting a plurality of files and parameters, preprocessing information from the plurality of files and parameters to determine a set of conditions associated with the welding process, determining a region of influence of at least one heat source used in the welding process as a function of the set of conditions, determining a plurality of point heat source solutions within the region of influence, determining a temperature solution for each weld pass as a function of a superposition of the plurality of point heat source solutions, and determining the thermal history of the welding process as a function of the temperature solutions.
REFERENCES:
patent: 4475963 (1984-10-01), Takahashi et al.
patent: 0512972 (1992-05-01), None
A Heat-Flow Solution With Convective Boundaries, Dr. Cao, Dr. Brust, Dr. Dong, Battelle Memorial Institute.
“Finite element analysis of GMA (MIG) welded joints”, Barberis et al., vol. 10, 1996.
“Surface Temperature Distribution of GTA Weld Pools on Thin-Plate 304 Stainless Steel”, Zacharia et al. 11/1995.
“Finite element analysis of GMA (MIG) welded joints”, Barberis et al., vol. 10, 1996.
“Surface Temperature Distribution of GTA Weld Pools on Thin-Plate 304 Stainless Steel”, Zacharia et al. Nov. 1995.
Brust Frederick W.
Cao Zhenning
Dong Yi
Nanjundan Ashok
Zhang Jinmiao
Caterpillar Inc.
Lundquist Steve D.
Shaw Clifford C.
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