摘要
地震栓波器是用来栓测竖向地震波的仪器.本文根据它的实际结构,提出了一个较精确的力学模型——双层三悬丝模型.把悬丝作为曲杆,用动力稳定性理论进行分析,揭示了地震仪栓波器由于竖向地震波以外的因素而产生输出的所谓假频现象产生的原因:位于悬丝所在水平面内的激励在一定条件下将导致悬丝在面外动力失稳而产生强烈振动,从而引起虚假输出.计算结果说明了影响假频的诸因素,为激励速度峰值、激励相对于栓波器的方向和曲杆面内振动的固有频率等的作用,并与实验值作了比较.
A geophone is a device for detecting vertical seismic waves. Based on its structure, in the present present paper a geophone is modelled by a suspension system consisting of a coil suspended from the hull through six springs. The springs are actually curved beams with one end rigidly attached to the hull and the other end to the coil. A dynamic-stability analysis of the curved beams reveals the cause of the spurious frequency of the geophone: The horizontal excitation upon a curved beam in the horizontal plane under certain conditions may result in an out-of-plane dynamic buckling with drastic vibration, which causes spurious signal output. Numerical results show the effects of the factors, such as the exciting velocity, the direction of the excitation relative to the geophone and the eigen frequencies of in-plane vibration of the curved beams, on the spurious frequency. Numerical results are compa(?)ed with experimental data.
出处
《应用力学学报》
CAS
CSCD
北大核心
1989年第2期1-9,125,共9页
Chinese Journal of Applied Mechanics
关键词
地震仪
栓波器
假频
动力稳定性
dynamic stability
geophone
curved beam
vibration
spurious
frequency
