土木工程结构损伤识别与诊断研究综述

首先阐述了结构损伤识别与诊断在土木工程结构中的重要性,介绍了国内外损伤识别与诊断方法现状,在此基础上,又介绍了用于土木工程结构的各种损伤识别与诊断方法,最后提出了土木工程结构损伤识别与诊断的发展方向。

工程机械结构损伤的再制造胶粘修复技术

利用再制造胶粘修复技术对工程机械中含有表面疲劳裂纹的损伤结构进行再制造修复。在明确研究背景和技术优势的基础上,建立损伤结构-胶粘剂-复合材料补片三者为一体的再制造修复模型,运用有限元分析方法,引入应力强度因子下降率R的概念,对再制造修复结构进行修复效果评价。分析表明,选用硼/环氧树脂作为补片材料能够得到最佳的修复效果,为工程机械再制造实践中的修复材料选择提供理论指导。

数据融合方法在结构损伤识别中应用

在我国很多大型的土木工程的结构健康监测中会应用到多传感器数据融合方式,以便于提高对结构损伤的辨识。本文主要基于融合技术提出相应的识别工程结构损伤的模型,设置相应的评估指标,并基于钢筋混凝土板试验探讨数据融合方式的科学性与有效性。结果证明使用数据融合方式能够得到较高的评价指数,也就是该方法对工程结构损伤的辨识效果较好。

损伤与断裂耦合效应的能量理论研究及应用

以Ⅰ型裂纹为主要研究对象,基于能量法和损伤能量释放率的概念,推导出一种用于描述裂纹尖端邻域内损伤场与断裂场的耦合效应参数:损伤型能量释放率.运用双G模型理论,应用ANSYS仿真分析三点弯曲梁的裂纹扩展过程,把得到的损伤型能量释放率结果与损伤断裂的参数进行对比分析.结合盖下拱坝工程有限元模型,将人工底缝前沿损伤型的能量释放率、平均损伤、能量释放率以及损伤能量释放率4者随水位变化的发展进行比较,说明该参数可以综合考虑损伤与断裂的耦合效应.此外,建立了该参数的应用模式.

Study on the cutting plane friction law of sandstone

The friction characteristics of rock damage plane have important impact on the stability of block structure formed after the stratum is broken. The mechanics properties of rock damage plane are described by parameters such as roughness coefficient, wall compress strength and basic friction angle. These three coefficients for fine grain sandstone and medium granular sandstone and grit sandstone are test. The friction stress is researched at the condition of different normal compressive stress acting on the tension damage plane. The friction law of tension damage plane of sandstone abided by is summed up. This law will provide scientific basis for block structure stability judging in basic roof stratum and roof pressure intensity calculating.

An Improved Damage Identification Method Based on Mode Information

This paper presents a new algorithm to predict locations and severities of damage in structures by changing modal parameters. An existing algorithm of damage detection is reviewed and the new algorithm is formulated to improve the accuracy of damage locating and severity estimation by eliminating the erratic assumptions and limits in the existing algorithm. The damage prediction accuracy is numerically assessed for each algorithm when applied to a two-dimensional frame structure for which pre-damage and post-damage modal parameters are available for only a few modes of vibration. The analysis results illustrate the improved accuracy of the new algorithm when compared to the existing algorithm.

基于实用完备模态空间的两阶段损伤识别方案

利用结构模态参数构造指标进行损伤识别的方法研究较早,但能够敏感识别损伤并具有较好抗噪性的方法还很少见。在改进损伤变量和单元刚度折减系数的基础上,结合实用完备模态空间理论,提出了一种两阶段损伤识别方案,即先利用改进的损伤变量进行损伤定位,然后利用较少的前几阶模态振型扩充得到实用完备模态空间,结合改进的单元刚度折减系数方法进行损伤定量。分别选取了连续梁、桁架和框架仿真算例对单元刚度折减系数和该方案的识别效果进行了对比分析。结果表明:该方案的识别效果在仅采用少数前几阶模态的情况下明显更优,能在一定噪音程度下同时达到损伤定位和定量的目的。