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In this work, the application of the split sleeve cold expansion process on different aerospace aluminum alloys was investigated. The study was undertaken for a number of aluminum-lithium alloys in order to provide a recommendation for material / process optimization. The results showed that, in general, these materials can undergo this process without cracking in severe but realistic conditions. In addition, in order to apply the process for the most difficult cases, the performance of a new sleeve design was investigated on a 7085-T7651 aerospace aluminum alloy plate. Although the new design was not optimized, experimental evidence showed that it can significantly reduce cracking near a sleeve split.

This work describes a sheet forming process simulation, cup drawing and redrawing, using a new plane stress anisotropic yield function that describes the anisotropic behavior of aluminum alloy sheets well. The anisotropy of the function was introduced in the formulation using only linear transformations on the Cauchy stress tensor or deviator. The implementation of this constitutive equation in finite element codes was briefly explained. Simulation results were presented and compared with experimental data.

With consideration of the importance (for oil passing and blow-by) of the issue of three-dimensional deformation of piston rings in a cylinder due to either installation stress, or operational gas, friction, and thermal loads the subject of piston ring distortions still generates continuing interest. The current paper demonstrates application of a mathematical model developed in the former works of the authors for analysis of the distortions of arbitrary cross-section rings loaded by tangential force. Applications of the model to the several typical cross-sections are given for illustration. The work is a necessary step for the development of a comprehensive three-dimensional theory of piston ring installation and operational distortions.

The paper is a step in an ongoing work targeted at the development of an engineering methodology to estimate sealing properties of a piston ring, and for the development of ring design guidelines. This work is necessary because the sealing properties of a ring significantly affect oil passing and blow by in the reciprocating air compressors and engines. It is known that the sealing function of a piston ring depends on the ring's ability to elastically deform in its plane under its own tension by conforming to the deviations of the cylinder bore. At the same time, if it has an asymmetrical cross section, the ring fitted in the cylinder bore is subjected to the additional, three-dimensional, distortions called twist. This type of cross section is usually imparted to the ring to further improve its sealing functions by interlocking (because of twist) between the piston groove and the cylinder wall.