The forced torsional vibration of a nanobeam by using the nonlocal strain gradient theory and incorporating the surface effects is investigated in the current work. The aim of this paper was to analyze the surface effect on the forced torsional vibration of a nanobeam. The simulated nanobeam is under the distributed external torque and moving external harmonic torque. The governing equations are derived by employing the Hamilton principle. The extracted partial differential equation is converted to ordinary differential equation by deploying the Assumed Modes method. The dynamic torsion of clamped–clamped end supports of nanobeam is determined by using the Convolution integral. The effect of nondimensional material length scale parameter, the nondimensional nonlocal parameter, the velocity parameter and the nondimensional moment, on the maximum nondimensional dynamic torsion of nanobeam are studied. Eventually, the effect of residual surface torsion and surface shear modulus on the maximum nondimensional dynamic torsion of nanobeam, which is obtained from the nonlocal strain gradient theory under the distributed torsional and moving harmonic dynamic moments, is studied.

在当前的工作中，利用非局部应变梯度理论并结合表面效应研究了纳米梁的受迫扭转振动。本文的目的是分析表面效应对纳米束的受迫扭转振动的影响。模拟的纳米束在分布外力矩和运动外谐波力矩下。控制方程是利用哈密顿原理推导出来的。通过部署假设模式方法将提取的偏微分方程转换为常微分方程。纳米梁的夹紧-夹紧端部支撑的动态扭转是通过使用卷积积分确定的。无量纲材料长度尺度参数、无量纲非局部参数、速度参数和无量纲力矩的影响，研究了纳米束的最大无量纲动态扭转。最后，研究了在分布扭转和运动谐波动矩下，根据非局部应变梯度理论得到的纳米梁最大无量纲动态扭转的残余表面扭转和表面剪切模量对纳米梁最大无量纲动态扭转的影响。