同结构活塞在FPE与CE两种工作模式下应力变形差异

To study the stress and deformation characteristic of piston for free piston engine, a finite element method was used to analyze the differences of the piston stress and deformation between free piston engine(FPE)and crank engine(CE). Results show that: the stress level of FPE's piston is lower than that of CE and the difference is mainly caused by mechanical load. As a result is of lower combustion pressure load and larger inertial load, the max stress of FPE's piston is less, which is nearly 72% of CE's piston. Under the thermo-mechanical coupling load, the difference of piston deformation between FPE and CE is small at the top and large at the skirt. The characteristics of the thermal load and the mechanical load of FPE piston result in smaller skirt deformation compared with CE piston, and the max FPE's piston skirt radial deformation is nearly 56% of CE's piston.