结合部法向黏弹性性质及有限元模型

Normal Viscoelastic Properties and Finite Element Model of Joint

通过试验研究了铸铁结合部在法向阶跃激励下的变形响应规律,发现阶跃响应曲线存在明显的瞬时弹性部分和持续时间较长的、渐变的黏性部分,并且在不同激振幅值和预紧力作用下,黏性部分大约是总变形的1/3,并且保持不变,这些现象无法用结合部建模中经常采用的Kelvin-Voigt模型反映,为此提出了一种新的结合部法向特性的建模方法。首先介绍了研究采用的试验原理和试验装置,分析了结合部在阶跃激励下的变形响应特点,研究了Kelvin-Voigt模型和黏弹性分析中常用的三元件模型在结合部建模中存在的问题,在此基础上将三元件模型加以改造,提出一种适合结合部建模的四元件模型。最后将该模型的阶跃响应与试验结果进行了比较,结果表明提出的模型能更准确地反映结合部法向的黏弹性性质。

By means of experiments, the laws of deformation response of joint of cast irons are studied under normal step exciting force. It was discovered that the curve of step response consisted of two parts of instantaneous elastic part and long-lasting viscous part. Also, under action of different amplitude of exciting force and pretightening force, viscous part was about a third of total deformation and the proportion remained unchanged. The phenomena could not be expressed by Kelvin-Voigt model, which often is used in model- ing joint. Therefore, a new modeling method of normal characteristics of joint was presented. The experiment principle and experiment setup were introduced in study first, and then characteristics of deformation response of joint were analyzed under step exciting force. Problems existed in Kelvin-Voight model and three-element model, which often is used in viscoelasticity analysis, were studied in mod- eling joint. On that basis, three-element model was modified, and then a four element model was presented for modeling joint. Finally, step responses of the new model are compared with experimental results, which indicates that the proposed model can more accurately reflect normal viscoelastic properties of joint.