Thermal And Mechanical Properties Of Kagome Lattice Sandwich Structure With K418

The Kagome lattice sandwich structure is a lightweight structure with low relative density,high specific strength,high specific modulus and high buffering action.Manufacturing the K418 alloy rudder of kagome lattice sandwich structure by investment casting can simplify the process,reduce the quality,improve the mechanical properties and high temperature performance of the rudder.Thus,it has high prospects and research value.However,it is necessary to fully study the performance of the lattice structure if we would like to design the wing rudder through the lattice structure.In this way,the rudder can meet the performance requirements by optimizing the rudder design.Therefore,this paper discusses the thermal and mechanical properties of K418 alloy Kagome lattice sandwich structure.The compression and shear properties of Kagome lattice unit cells under different kinds of loads were analyzed.When there is a displacement load on the upper panel,the expressions of compression strength,compression modulus,shear strength,shear modulus by structure size are given.These expressions are verified by finite element simulation software.It is concluded that under this load,the core rod bears most,and the mechanical properties are only related to the structure size and not to the core position.However,when there is a uniform pressure load on the upper panel,the core position has an influence on the compression strength and shear strength due to the additional moment.When the core is in the center,the unit cell has the best mechanical properties.Combined with the follow analysis,the mechanical properties of four different multi-cell plate with different lattice distributions are simulated by finite element software.When there is a displacement load on the upper panel,the lattice distribution has no obvious effect on the compression and shear performance of the multi-cell plate.Relatively,when there is a uniform pressure load,compression and shear performance are affected by the lattice distribute.When the lattice is evenly distributed,the multi-cell plate has the best mechanical properties.In addition,when the periphery of the plate is a free boundary,the mises stress of the cores near the periphery is relatively large,and these cores should be closer to the boundary when distributed.Through the above conclusions,the lattice distribution of the lattice rudder is designed.According to the design,the lattice rudder was prepared by investment casting.The thermal conductivity between the upper and lower panels of the unit cell is studied,and the temperature field of the unit cell is obtained by finite element software when heat transfer occurred.During the heat conduction process,the Kagome core can be simplified into a cubic core.In the heat conduction,as the temperature of the panel increases,the proportion of heat radiation in heat conduction becomes larger and larger.When considering aerodynamic heating,the upper and lower areas heat up quickly,and temperature rise lags in the middle.The temperature difference of the structure increases first and then decreases with time.The temperature gradient mainly appears in the core.The rudder has similar heat transfer characteristics as the unit cell.In addition,due to the larger height of the outer core of the rudder,the temperature rise in the middle of the outer core is most lagging.According to the temperature field distribution of,the thermal stress field of the unsteady heat transfer process of the unit cell and the rudder is obtained through thermalmechanical coupling simulation.The thermal stress mainly comes from the uneven distribution of the temperature field.The thermal stress increases first and then decreases over time.In the lattice part of the rudder,the maximum thermal stress gradually shifts from the inner core to the outer core.