The combined piston can be used in an aero piston heavy fuel engine because of its light weight, so as to reduce the reciprocating inertia force and improve the engine power-weight ratio. However, the pin bore of the combined piston is prone to deform leading to the failure of the piston. Based on the structure of the piston, the stress of the piston under thermomechanical coupling is analyzed, the temperature field of the piston is determined by experiments, and the deformation rule of the piston pin bore under the thermomechanical coupling is summarized. A design scheme is proposed to change the position of the thread connection between the piston crown and the piston head. Under the same conditions, the deformation of the piston pin bore of the original scheme and the new scheme is analyzed. The results show that together with the changing of the connection thread between the piston crown and the piston head, the deformation of the piston pin bore decreases by 60 μm and the deformation of the piston pin bore is controlled. The test results show that the deformation of the pin bore is within the acceptable range, which proves the effectiveness of the improved scheme.

A device Riser Support is designed for Chinese S-Lay vessel 'HYSY-201'. The device is used to install risers as well as subsidiary structures, such as pipeline end termination (PLET), pipeline end manifold (PLEM), in-line sled (ILS) and so on for submarine pipelines. The paper mainly elaborates the finite element analysis and dynamic experiment of the deep-water Riser Support based on a truncated hybrid model. To test the mechanical property and verify the reliability of the Riser Support, some dynamic tests with the scale 1:10 are done to simulate the installation process of risers in the South China Sea. A truncation method is used to solve the problem that 3000 m riser model is still too long though it is reduced to one-tenth of the original size. Six degrees of freedom platform (SDFP) is used to simulate the movement of 'HYSY-201' vessel while a boundary control system (BCS) is also used to control and simulate the motion state of cut-off point of the riser model. SDFP and BCS together make the model test more accurate and reliable. Testing results show that stress values based on 24 kinds of typical working conditions and calculated values are accordant in the range of allowable inaccuracy, but the small error is considered reasonable because of the difference between virtual model and scaled reality model. Then, truncated hybrid method is verified to be very useful in simplifying models during the research of large-size thin tube, rod-shaped or linear model experiment, and especially the 3000 m truncated dynamic hybrid riser model experiment is a good example.

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