The Elastic Analysis Of The Fuel Injector Of Engine With Boundary Face Method

As one of the important parts of automobile engine, the fuel injector is verycomplicate and precise. Under the high pressure of fuel, stress concentrations alwaysoccure at the small features in the structure. If the stress value is up to the ultimatestrength of materials, it may lead to crack. Therefore, it is important to do elasticanalysis of the injection and know its stress distribution for the structure design andimprovement.The Boundary Face Method (BFM) is one of the numerical mehod based on theboundary integral integration. In this method, both boundary integration and variableapproximation are performed in the parametric space of boundary face. The geometricdata at Gaussian integration points, such as the Jacobians, the coordinates and the outnormals are calculated directly from the surface expression and thus avoid geometricerrors that inevitably introduced by the traditional interpolation approximationthrough elements, such as the Finite Element Method (FEM) and the BoundaryELment Method (BEM). It is beneficial to realize the integration of CAD and CAE.This paper employs the original stress analysis aoftware, which is developed basedon the BFM, to analyse the elastic problem of the key parts of injector. In the analysis,the local small features in the structure, such as fillets, oil holes, are preserved exactlyas their real shape and size. Inorder to verify the accuracy of the method in this paper,we compared the results of BFM with that of FEM. Results demonstrated that thestress field in the concentration area obtained by the BFM is much better than that byFEM with much fewer grids and BFM has very good stability for stress analyses.Moreover, because of absence of geometric error, the stress field is also smoother,which are closer to the real physical phenomena.