摘要
当双筒流变仪的外筒以较高频率振摆时，即使被测的是牛顿流体，连接于内筒的扭丝所测出的力矩仍有相位滞后（“水的弹性分量困惑”），其原因是流体和内筒都有惯性。本文采用作者以前提出的化为常微分方程两点边值问题的新算法，对于流体与内筒的惯性效应做了详细的讨论。文中指出，只要设法减小内筒转动惯量和提高扭丝刚度，或者增大对内筒的空气阻尼，就可以避免在工作频率范围内发生共振现象。这时，可以不考虑内筒振摆而假设内筒静止，只考虑流体自身的惯性而使问题简化。
When the outer cup of a co-axial rheometer oscillates at a relatively high frequency , the moment measured by the wire connected to the inner bob shows a phase lag, even if the fluid under measurement is Newtonian(“the paradox of the elastic component of the water”). It is believed that such a phase lag is attributed to the inertia due to the fluid as well as due to the inner bob. Without special modifica-tions , significant error may be incurred in the measurements of the viscoelasticity. The present paper is a new step of the authors, attempts to account for these iner-tial effects. Comprehensive theoretical analysis is made about the inertial effects both due to the fluid and due to the bob,by adopting the new scheme of reducing to a two-point boundary value problem of ordinary differential equations , proposed earlier by the present authors; It is indicated that the harmful resonance phenomena can be eliminated in the working range of oscillation frequency by decreasing therotational inertia moment of the bob and increasing the rigidity of the wire ,or by increasing the damping of the bob by the air. Under such circumstances the inertial effect due to the bob may be neglected (with the bob being considered stationary)and only the inertial effect due to the fluid needs considering,thus greatly simplify-ing the problem.
出处
《北京大学学报（自然科学版）》
CAS
CSCD
北大核心
1994年第5期524-533,共10页
Acta Scientiarum Naturalium Universitatis Pekinensis
基金
国家自然科学基金
关键词
惯性效应
流变仪
流体
内筒
measurements of the viscoelasticity
inertial effects
co-axial rheome-ter
resonance phenomena
inherent frequency
damping
