Explicit finite element analysis and experimental verification of a sliding lead rubber bearing

Based on the explicit finite element (FE) software ANSYS/LS-DYNA, the FE model for a sliding lead rubber bearing (SLRB) is developed. The design parameters of the laminated steel, including thickness, density, and Young’s modulus, are modified to greatly enlarge the time step size of the model. Three types of contact relations in ANSYS/LS-DYNA are employed to analyze all the contact relations existing in the bearing. Then numerical simulations of the compression tests and a series of correlation tests on compression-shear properties for the bearing are conducted, and the numerical results are further verified by experimental and theoretical ones. Results show that the developed FE model is capable of reproducing the vertical stiffness and the particular hysteresis behavior of the bearing. The shear stresses of the intermediate rubber layer obtained from the numerical simulation agree well with the theoretical results. Moreover, it is observed from the numerical simulation that the lead cylinder undergoes plastic deformation even if no additional lateral load is applied, and an extremely large plastic deformation when a shear displacement of 115 mm is applied. Furthermore, compared with the implicit analysis, the computational cost of the explicit analysis is much more acceptable. Therefore, it can be concluded that the proposed modeling method for the SLRB is accurate and practical.中文概要目 的随着隔震技术在工程结构中的逐步推广应用, 橡 胶隔震支座的试验与数值模拟都得到国内外工 程研究人员的重视。其中后者因支座大变形时计算较难收敛、铅芯与周边橡胶以及钢板的复杂接 触关系较难模拟、采用隐式积分算法时计算规模 较难控制等问题, 目前仍是这一方向的研究热 点。本文旨在探讨基于显式积分算法对一种新型 可滑移式铅芯橡胶支座进行准确可行的数值模 拟的方法。创新点1. 探究基于显式积分算法的隔震支座数值模拟方 法; 2. 采取多种方法有效地控制了数值模拟计算 规模,同时实现了较高的数值模拟精度; 3. 采用 程序中提供的3 种接触方式较好地模拟了支座中 存在的复杂接触关系。方法本文主要采用4 种方法减小数值模拟计算规模: 1. 激活程序内置的质量缩放功能; 2. 合理增大支 座中对支座竖向刚度与水平剪切性能影响较小 的非关键部件——叠层钢板的厚度; 3. 合理减小 叠层钢板的弹性模量; 4. 考虑到支座中所有材料 均未考虑材料的率变效应, 即加载速率对支座的 力学性能没有影响, 本文数值模拟中所用加载频 率为实际加载频率的10 倍。此外, 本文采用了 一般接触、绑定接触与单边接触模拟支座中不同 的接触关系。结论1. 显式积分的计算时间步长由2.4×10−7 s 增大到 3.5×10−6 s; 2. 与试验结果对比验证了本文提出的 基于显式积分算法对该新型可滑移式铅芯橡胶 支座进行数值模拟的方法的准确实用性; 3. 该支 座在纯压作用下, 部分铅芯发生塑性变形, 而在 最大剪切位移时, 铅芯发生了很大的塑性流动变 形; 4. 与采用隐式算法对该支座进行数值模拟研 究所用时间相比, 显式算法所用时间少很多。

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