The material removal rate and required work- piece surface quality of thin-walled structure milling are greatly limited due to its severe vibration, which is directly associated with the dynamic characteristics of the...The material removal rate and required work- piece surface quality of thin-walled structure milling are greatly limited due to its severe vibration, which is directly associated with the dynamic characteristics of the system. Therefore, the suppression of vibration is an unavoidable problem during milling. A novel partial surface damping method is proposed to modify the mode of the thin walled cantilever plate and to suppress vibration during milling. Based on classical plate theory, the design criterion is analyzed and configuration of the partial surface damper is introduced, in which viscoelastic plate and constraining plate are attached to the surface of the plate to increase the system＇s natural frequency and loss factor. In order to obtain the energy expression of the cutting system, the Ritz method is used to describe the unknown displacements. Then, with Lagrange＇s equation, the natural frequency and loss factor are calculated. In addition, the plate is divided into a finite number of square elements, and the regulation of treated position is studied based on theoretic and experimental analysis. The milling tests are conducted to verify its damping performance and the experimentalresults show that with treatment of partial surface damper, the deformation of the hare plate is reduced from 0.27 mm to 0.1 mm, while the vibration amplitude of the bare plate is reduced from 0.08 mm to 0.01 mm. The proposed research provides the instruction to design partial surface damper.展开更多
Inspired by the shape of some plant leaves,we find that the thin-walled U-shaped strips exhibit different compliances under bending with opposite orientations.The asymmetric bending compliance is attributed to the buc...Inspired by the shape of some plant leaves,we find that the thin-walled U-shaped strips exhibit different compliances under bending with opposite orientations.The asymmetric bending compliance is attributed to the buckling of sidewalls of strips caused by the bending-induced compression.Integrating the Euler-Bernoulli beam theory with the Kirchhoff-Love thin plate theory,a theoretical model is derived for the in-depth understanding of the sidewall buckling.For pure bending,the critical moment applied to the strip for the sidewall buckling is found to be insensitive to the height,width and length of strip,which is the result of the compromise between the opposite geometric effects on the buckling behavior of sidewalls and the characteristics of cross sections.Then the critical moment can be approximated as a linear function of flexural rigidity DEt^(3)/12(1-ν^(2)),where t is the wall thickness of strip,E is Young’s modulus,and v is Poisson’s ratio.These predictions by our model agree well with the results obtained by finite element analysis.We also investigate the buckling behavior of sidewalls for bending under transverse loads,considering the loading conditions of concentrated force and distributed force.Our study unveils the mechanism behind the asymmetric bending compliance of thin-walled U-shaped strips.These results would offer convenient guidance for the promising engineering applications related to this structure,such as the design of soft robots with enhanced locomotion performance.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51575319)Young Scholars Program of Shandong University(Grant No.2015WLJH31)+1 种基金Major National Science and Technology Project of China(Grant No.2014ZX04012-014)Tai Shan Scholar Foundation,China(Grant No.TS20130922)
文摘The material removal rate and required work- piece surface quality of thin-walled structure milling are greatly limited due to its severe vibration, which is directly associated with the dynamic characteristics of the system. Therefore, the suppression of vibration is an unavoidable problem during milling. A novel partial surface damping method is proposed to modify the mode of the thin walled cantilever plate and to suppress vibration during milling. Based on classical plate theory, the design criterion is analyzed and configuration of the partial surface damper is introduced, in which viscoelastic plate and constraining plate are attached to the surface of the plate to increase the system＇s natural frequency and loss factor. In order to obtain the energy expression of the cutting system, the Ritz method is used to describe the unknown displacements. Then, with Lagrange＇s equation, the natural frequency and loss factor are calculated. In addition, the plate is divided into a finite number of square elements, and the regulation of treated position is studied based on theoretic and experimental analysis. The milling tests are conducted to verify its damping performance and the experimentalresults show that with treatment of partial surface damper, the deformation of the hare plate is reduced from 0.27 mm to 0.1 mm, while the vibration amplitude of the bare plate is reduced from 0.08 mm to 0.01 mm. The proposed research provides the instruction to design partial surface damper.
基金supported by the National Natural Science Foundation of China(Grant No.11972226).
文摘Inspired by the shape of some plant leaves,we find that the thin-walled U-shaped strips exhibit different compliances under bending with opposite orientations.The asymmetric bending compliance is attributed to the buckling of sidewalls of strips caused by the bending-induced compression.Integrating the Euler-Bernoulli beam theory with the Kirchhoff-Love thin plate theory,a theoretical model is derived for the in-depth understanding of the sidewall buckling.For pure bending,the critical moment applied to the strip for the sidewall buckling is found to be insensitive to the height,width and length of strip,which is the result of the compromise between the opposite geometric effects on the buckling behavior of sidewalls and the characteristics of cross sections.Then the critical moment can be approximated as a linear function of flexural rigidity DEt^(3)/12(1-ν^(2)),where t is the wall thickness of strip,E is Young’s modulus,and v is Poisson’s ratio.These predictions by our model agree well with the results obtained by finite element analysis.We also investigate the buckling behavior of sidewalls for bending under transverse loads,considering the loading conditions of concentrated force and distributed force.Our study unveils the mechanism behind the asymmetric bending compliance of thin-walled U-shaped strips.These results would offer convenient guidance for the promising engineering applications related to this structure,such as the design of soft robots with enhanced locomotion performance.
