预应力下的结构模态计算

Modal Calculation under Prestressed Structures

摘要: 本文采用达朗伯原理建立动力学平衡方程，研究了梁类结构预应力下的模态计算方法，证明通过调节预应力，可有效改善结构的动态性能。本文通过有限元法计算比较正负预应力下桁架结构的变形和模态，提出预应力桁架可作为高速数控机床的横梁结构。在横梁内部施加预应力可大幅提高横梁的弯曲刚性。通过对桁架关键构件内应力的控制，可以使桁架内应力做到可调。根据加工参数的变化，优化调节桁架某些杆件的内应力大小及方向，使设备在加工过程中具有一定改变动态性能的能力，从而达到减小振动提高加工精度的目的。

Abstract: Using D’Alembert’s principle to establish the dynamic equations to study the mode calculating method of class structure under prestressed, evidenced by adjusting the prestressing, can effec-tively improve the dynamic performance of the structure. Deformations and modal comparatively positive and negative prestressed truss structure by the finite element method is proposed as a beam structure of prestressed truss speed CNC machine tools. The bending rigidity of the internal beam can be improved significantly by prestressing the beam. Through the truss key component stress control, it can make the truss internal stress to be adjustable. According to changes of processing parameters, the size and the direction of the internal stress of certain truss rods are optimized and adjusted so that the device has the certain ability to change the dynamic performance to achieve the purposes of reducing vibration and improving machining accuracy.