A parametric model for rapid analysis of automotive joints

Abstract

In the early design stages of car bodies, many alternative designs need to be evaluated quickly. This requires checking whether these designs satisfy given performance targets and manufacturing and packaging constraints. Therefore, it would be very useful to have a tool that rapidly analyzes the performance of a design, checks if this design is manufacturable, and meets packaging and styling requirements.

This thesis presents a method for developing a tool, called translator, that translates physical design parameters defining a joint into performance (stiffness of the joint) and operational parameters (mass of the joint) using a parametric model and structural analysis software. A parametric model is a solid or surface model defined by a set of parameters that specify the dimensions and topology of the design. When the user changes the values of the parameters, the model changes automatically. Physical design parameters, such as the main dimensions of the joint (height and width of the members, plate thickness, etc.) and dimensions of adjacent components and also parameters that specify the type of construction of the joint are used to define the parametric model. These parameters are selected in a way that they make sense and can be controlled by designers. Once these parameters are specified, all dimensions of the joint fall into place due to packaging, manufacturing, and styling constraints.

The translator first derives a set of master parameters, which completely define the geometry of the joint from the physical design parameters using the packaging and manufacturing constraints. Examples of master parameters include the coordinates of the edges of the cross section of a member. Pro-Engineer, parametric modeling software, is used to construct a solid model of the joint using the transparent master parameters. A finite element model is then created using Pro-Engineer mesh generator, and this model is used to estimate the stiffness and mass of the joint using finite element analysis.

The method also calculates parameters associated with the constraints and checks if the values of these parameters are within limits dictated by the constraints. The translator is demonstrated on two joints of an actual car.