Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2000-02-25
2003-01-21
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S212000
Reexamination Certificate
active
06510357
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to generating welded finite element models. More particularly, the present invention relates to a method and system for automatically projecting predefined weld data onto a finite element mesh and automatically welding the finite element mesh together based on the predefined weld data.
2. Discussion of the Related Art
In the automotive industry, full body vehicle computer simulation models are used to study crash, noise, and vibratory effects on the final design of automotive bodies. Two types of information necessary to generate these computer models are surface information and weld information. Surface information includes information about the shapes and contours of the body parts, while weld information includes information about how the body parts interrelate and connect. Computer tools are available to make use of surface information as well as welding information. For example, commercial finite element processors have been developed to provide helpful visual assistance to scientists and engineers in determining the structural characteristics of vehicles. It is common for these finite element processors to generate a “mesh” of the vehicle body, which is essentially a representation of the vehicle body in terms of fundamental elements. Thus, a given part is divided into a collection of geometrical shapes (triangles and rectangles), with each element defined by a plurality of nodes (or grids). A finite element mesh of a full vehicle body having three hundred parts, for example, will likely have thousands of nodes.
While portraying surface information or parts via computer-based finite element meshes is generally well known in the industry as well as the generation of electronic data representing predefined weld locations, considerable difficulty has remained regarding actually welding the parts together via computer. In fact, the welding process for finite element models has conventionally been a manual one. For example, a finite element processor such as Hypermesh allows the user to manually input predefined weld locations into a pre-existing finite element mesh. The predefined weld locations are typically contained in an electronic weld file, which is created by a commonly available macro such as ZMAWELD. To complete such a task manually has been found to take approximately fifteen hours for 357 welds under the conventional approach. It is therefore desirable to provide a method and system for automating the projection of predefined weld locations onto a given finite element mesh such that processing time is reduced.
Once the predefined weld locations have been projected onto the finite element mesh, the next task is to generate the actual welds. While the predefined weld locations typically identify a grid's XYZ coordinate for a given assembly of parts, generation of the actual weld entails determining the specific node on each part that will be included in the weld. Once again, conventional approaches have required manual selection of each and every node. Thus, it has been approximated that to weld a full vehicle body having 150,000 elements takes around eighty hours. It is therefore highly desirable to provide a method and system for automatically welding a finite element mesh together such that processing time is reduced.
A common occurrence in the creation of finite element models is the mismatch of parts, nodes, and welds. For example, the weld file will often include parts that are not found in the finite element mesh, and vice versa. Similarly, the nodes of a part to be welded may fall outside of a predefined weld tolerance with respect to a predefined weld location. It is therefore desirable to provide error information regarding parts, nodes, and welds to the user, so that inconsistencies can be corrected with minimal effort and processing time.
SUMMARY OF THE INVENTION
The present invention provides a computer-based method for generating a welded finite element model of a vehicle body. The method includes the steps of retrieving weld data for the vehicle body from a weld input source, and automatically projecting the weld data onto a finite element mesh with an executable control file. The finite element mesh represents surface data for the vehicle body, such that the automatic projection of the weld data creates a modified finite element mesh. The method further provides for automatically welding the modified finite element mesh, such that a welded finite element model is generated.
The present invention also provides an automated method for generating an assigned weld element for an assembly of parts in a computer model of a full vehicle body. The executable file determines on each part to be welded, the nearest node with respect to the predefined weld location, and generates a weld connecting the parts at these nodes.
The present invention further provides an automated computer modeling system for generating a welded finite element model of a vehicle body. The modeling system includes a projection module, and a welding module. The projection module projects weld data onto a finite element mesh representing surface data for the vehicle body such that a modified finite element mesh is generated. The welding module automatically generates assigned weld elements for the modified finite element mesh and welds the parts. The assigned weld elements and the modified finite element mesh define the welded finite element model of the vehicle body.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.
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Naik Ram
Rao Sudheendra Vasudeva
Shetty Subhas V
DaimlerChrysler Corporation
Picard Leo
Rapp Chad
Smith Ralph E.
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