FORM DEFECT INFLUENCE ON THE SHRINKAGE FIT CHARACTERISTICS

Today, manufacturing products must meet more and more severe specifica tions. The different parts composing the product often necessitate hig h dimensional precision, which increases the difficulties for a large series production. Then it it necessary to optimize dimensioning of th e different components in an economic context. In the case of small di mensional fits, there is an influence of the micro-geometry (form of d efect, roughness) and time of the process on the geometrical character istics of the assembly. At the time of conception, it is necessary to obtain a good specification that relates the product functionalities w ith The best cost. The objective study of this is to simulate a shrink age fit process and provide the fit characteristics according to the m icrogeometrical defects. Only the form of the defects are taken into a ccount. In the first part, a method a solution of a three dimensional contact involving two cylindrical bodies is presented. The contact is closely conformed (non-Hertzian). The stress field and the strain fiel d, in both bodies, are calculated with the hypothesis that the interfa ce pressure is a sum of different concentrated loads superposing and d epending locally on the defects after rendering the contact area discr ete. The different basis loads are formulated by Fourier series and mo dified Bessel functions. Several cases are simulated for different typ es of defects that can show the influence of the microgeometry on the cylindrical characteristics Rt. Finally, an experiment is presented wh ich shows a good correspondence with theory and predicts the extract s trength. (C) Elsevier, Paris.