大量弹丸随机分布的薄壁件喷丸强化形变仿真

Simulation for Shot Peening Strengthening Deformation of Thin-Walled Parts With Multiple Random Shots

利用有限元与离散元(FEM–DEM)耦合方法对薄壁件喷丸强化过程中的形变特征进行了仿真,建立以Almen试片为对象的大量弹丸随机分布喷丸强化模型,并采用喷丸试验进行验证。模型中平直薄壁试片经随机弹丸喷丸强化后呈弧状向上翘曲,形变特征与实际Almen试片喷丸形变一致,当喷丸气压由0.07 MPa增加至0.11 MPa时,模拟弧高由0.340 mm增加到0.521 mm,弧高值模拟准确率可达95%;随机喷丸强化在Almen试片表面引入的残余应力场沿深度方向呈“S”形倒钩状分布,随着喷丸气压的增大,模拟得到的表面残余压应力由–400 MPa左右增大到–700 MPa左右,与试验测试结果最大误差为11.31%;Almen试片表面粗糙度Ra随喷丸气压增加而增加,模拟粗糙度值由0.476μm增加到0.630μm,模拟最大误差为6.78%。经过对比验证,构建的模型仿真结果与喷丸试验吻合度较高。FEM–DEM耦合随机喷丸模型能够较好地模拟薄壁件形变、残余应力场和表面粗糙度的变化规律。

The deformation characteristics of thin-walled parts during shot peening are simulated by the coupled finite and discrete element methods(FEM–DEM). A shot peening strengthening model with multiple random shots based on Almen strip is established and verified by shot peening test. The flat, straight and thin-walled specimen in the model warps upward in arc shape after random shot peening. The deformation characteristics are consistent with the actual shot peening deformation of Almen strip. When the shot peening pressure increases from 0.07 MPa to 0.11 MPa, the simulated arc height increases from 0.340 mm to 0.521 mm, and the simulation accuracy of arc height can reach 95%;The residual stress field introduced by random shot peening on the surface of Almen strip shows an S-shaped barb distribution along the depth direction. With the increase of shot peening pressure, the simulated surface residual compressive stress increases from about –400 MPa to about –700 MPa, and the maximum error comparing with the test results is 11.31%;The surface roughness Ra of Almen strip rises with the increase of shot peening pressure, and the simulated roughness value increases from 0.476 μm to 0.630 μm, and the maximum error of simulation is 6.78%. Through comparison and verification, the simulation results of the model are in good agreement with the shot peening test results. FEM–DEM coupled random shot peening model can better simulate the variation law of deformation, residual stress field and roughness of thin-walled parts.