Research On Analysis-Oriented Parametric Model Of Bus Frame

Designing bus frame rapidly and accurately is very helpful to increase reliability and shorten the design cycle of bus products at the concept design stage. In the traditional body design method, geometry modeling, model modification, and finite element pre-processing require a vast amount of manual operation and great time. Besides, the design and analysis stages are decoupled as they are undertaken by different experts utilizing different softwares, and this goes against fast optimization of product.Aiming at fast analysis of bus body frame at the concept design stage, parameterized modeling module and automatic pre-processing module were developed based on UG NX platform. In the parameterized modeling module, the beams were classified into the following six types according to bus frame structure characteristic:X beam, Y beam, Z beam, Skew beam, Symmetric beam and Boundary beam, and the bus frame structure was decomposed combined with the concept of zoning. Then, according to the assembly relationships of bus frame, the following self-defined classes in different layers were separately generated:beam classes, regional frame classes and the whole frame class.17basic geometric inputs and64structure parameters were extracted while generating regional frame classes, and many beams were created while generating the whole frame class. Parameterized bus frame model was created rapidly after instantiation of the whole frame class, and it was charactered by intelligent connection and easy to modify. In the automatic pre-processing module, finite element model was created rapidly and automatically based on UG/Open API secondary development tool. The process included creating FEM file, meshing the beams, setting sectional property, assigning material properties and building welded connections.An example was made to detailedly explain the operation flow of the two modules, taking a bus body surface model as input. The result showed that parameterized modeling, rapid modification and automatic pre-processing at the concept design stage could be realized using the two modules, and the design efficiency was improved significantly. In the next stage, several simulation models can be made based on the finite element model to implement many types of performance simulations, thus determining basic structure of bus frame and affording the optimum plan and parameters for subsequent detailed design.