Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 54 10 2022 12 22 Nonlocal Vibration of Nanobeam Embedded in Viscoelastic Pasternak Foundation with Longitudinal and Rotational Motions with Surface Effects Nonlocal Vibration of Nanobeam Embedded in Viscoelastic Pasternak Foundation with Longitudinal and Rotational Motions with Surface Effects 2215 2238 4934 10.22060/mej.2022.21234.7407 FA Omid Koochakianfard Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran Akbar Alibeigloo Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran Journal Article 2022 03 19 <span style="letter-spacing: .05pt;">This paper analyzes the size-dependent vibration of nanoscale beams with simultaneously longitudinal and rotational motions based on nonlocal theory for the optimum design of nanoscale surgical robots. Also, for the first time, a parametric study is performed to explain the surface effects, viscoelastic-Pasternak foundations characteristics, thermal loads, geometric properties, symmetric and asymmetric cross-sections, axial and follower loads on the dynamics and stability of the system. Adopting the Galerkin discretization approach, the reduced-order dynamic model of the system is acquired. Also, analytical and numerical methods are exploited. To ensure the accuracy of the proposed model and method, the present study results are compared and validated with those of published articles. Stability maps and Campbell diagrams are drawn for different working conditions. The results showed that increasing the surface elastic modulus and residual stress improves the vibration frequencies and dynamic instability threshold. It is also found that with increasing system thickness/length, the axial velocity of static instability decreases/increases. In addition, it is observed that the system performance improves with increasing the elastic and shear coefficients of the foundation. The results of the present study significantly help designers and engineers control the vibration of bi-gyroscopic nanoscale robots.</span> <span style="letter-spacing: .05pt;">This paper analyzes the size-dependent vibration of nanoscale beams with simultaneously longitudinal and rotational motions based on nonlocal theory for the optimum design of nanoscale surgical robots. Also, for the first time, a parametric study is performed to explain the surface effects, viscoelastic-Pasternak foundations characteristics, thermal loads, geometric properties, symmetric and asymmetric cross-sections, axial and follower loads on the dynamics and stability of the system. Adopting the Galerkin discretization approach, the reduced-order dynamic model of the system is acquired. Also, analytical and numerical methods are exploited. To ensure the accuracy of the proposed model and method, the present study results are compared and validated with those of published articles. Stability maps and Campbell diagrams are drawn for different working conditions. The results showed that increasing the surface elastic modulus and residual stress improves the vibration frequencies and dynamic instability threshold. It is also found that with increasing system thickness/length, the axial velocity of static instability decreases/increases. In addition, it is observed that the system performance improves with increasing the elastic and shear coefficients of the foundation. The results of the present study significantly help designers and engineers control the vibration of bi-gyroscopic nanoscale robots.</span> https://mej.aut.ac.ir/article_4934_4dc3ed26a29c9c3df3ec373524377a5b.pdf