【摘要】 将轴向运动梁试验平台上处于滑槽以后的梁简化为轴向运动的悬臂梁,先给出其平衡微分方程,再利用模态叠加法得出轴向运动梁横向振动的离散微分方程。通过测试梁在不同长度下的第1阶固有频率,调整理论计算模型中悬臂的长度以修正悬臂梁的边界条件。试验表明,梁的长度修正量与梁的悬臂长度无相关性。使用对数衰减率法识别多个长度下梁的第1阶衰减系数表明,衰减系数随梁悬臂长度的增加而下降,并通过数值拟合建立了衰减系数与梁长度的关系。修正后梁计算模型的横向振动响应计算结果与测试结果吻合较好,验证了模型修正的有效性。更多还原

【Abstract】 A beam which slides through a prismatic joint is considered as an axially moving cantilever beam.The transverse vibration equation is given and the discretized equation of motion of the beam with time-dependent coefficients is derived by the mode superposition method.The fixed boundary condition is modified by the adjustment of the cantilever length of the theoretical beam model with the measured results of its first order natural frequencies under various cantilever lengths.It is found that the correction lengths to the model beam have no explicit relationship with the cantilever lengths.The first order decay coefficients are identified by logarithmic decrement method and the decay coefficients of the beam decrease with the increase of the cantilever length.The calculated responses by the modified model agree well with the experimental results,which verify the effectiveness of the proposed model modification method.更多还原