火灾混凝土红外热像检测实验研究

本文根据红外检测原理，采用红外热像技术对Ｃ３０混凝土的火灾损伤进行了实验研究。建立了火灾混凝土红外热像平均温升与其受灾温度及强度损失的回归方程。     

水泥砂浆火灾损伤的红外热像检测与评定

本文基于红外检测技术的原理和特点,采用红外热像技术对水泥砂浆试件火灾损伤的红外热像特征进行了实验研究,得出了水泥砂浆红外热像平均温升的变化曲线及其表与表受灾温度及强度损失的回归方程。     

基于承载力评估的混凝土结构火灾损伤的无损检测与评估方法

建立了基于承载力评估的混凝土结构火灾损伤的无损检测与综合评估方法,主要包括红外热像无损检测分析、电化学无损检测分析、构件截面温度场数值分析等方面。利用该方法,可由表及里、由现场实测结合理论计算,全面获取混凝土结构的火灾损伤信息,使评估指标和判据更科学合理,使评估结果更准确可靠。     

基于激光热激励红外热成像纤维增强聚合物复合材料加固混凝土结构界面损伤无损检测

红外热成像（IRT）检测技术常被用于纤维增强聚合物复合材料（FRP）加固混凝土板的剥离损伤无损检测。但传统热源激励IRT法受加热距离短、热灵敏度低、功耗大等因素影响较大。本文提出了基于光学激发线激光热源的IRT法对FRP加固混凝土的剥离检测方法,该方法通过控制线热束在FRP加固混凝土结构的表面形成移动扫描热激励,通过红外热像仪测量结构中的界面剥离引起的表面局部热分布异常。基于模拟和实验研究结果,证明该方法对FRP加固混凝土结构中界面剥离检测具有如下优势:利用激光扫描热成像技术检测FRP改造混凝土结构中剥离损伤的可行性;实现了FRP加固混凝土结构的远距离、高热灵敏度及低功耗的损伤检测。      

小型风力发电机叶片的红外无损检测研究

为获得风力发电机叶片现场红外无损检测的最佳光照条件,该文以赋有不同损伤类型及不同损伤程度的2 kW小型风力发电机叶片为研究对象,利用被动式红外热成像检测方式,在夏季光照充足的室外条件下对损伤叶片进行自然激励,采集红外热像图。研究结果表明光照强度对损伤检测有着极大的影响,并且得到风机叶片三种典型损伤的最佳检测光照条件,其中异物附着和面部损伤在午间光照强度达到1 000 W/m²及以上检测效果最佳,而裂纹损伤在晴朗的午后光照强度为900 W/m²左右检测效果佳,从而证明利用太阳辐射作为发射源的被动式红外热成像检测技术来检测风机叶片损伤的方法在一定光照强度范围之内是可行的。     

广州飒特电力红外技术有限公司

广州飒特电力红外技术有限公司是我国大规模进行红外热成像仪研发、生产和销售的民营企业，自上世纪九十年代初，飒特公司即率先进行国产红外热像仪的研制和生产，并将其产品投入电力、石油、冶金等超大型国有企业进行使用，勇敢地充当了中国工业检测型红外热像仪制造业的排头兵。     

红外热成像技术在零件无损检测中的发展和应用现状

红外热成像技术是一种通过外加激励获得零件表面温度场分布,并从热像图中提取零件损伤信息的无损检测技术,它具有快速、实时、非接触等优点,研究和应用前景广阔。综述了红外热成像无损检测技术的发展现状和应用实例,通过对比3种常用的红外热成像技术:脉冲红外热成像、超声红外热成像和锁相红外热成像,认为超声锁相红外热成像技术具有其他几种技术无法比拟的优势,并从检测工艺和信号处理等方面提出了改进此技术的具体措施。     

定量热像法预测焊接接头的S-N曲线和残余寿命

在恒定的平均应力作用下,考虑焊接接头的实际工况,利用红外热像技术建立了快速预测焊接接头疲劳参数和残余寿命的模型,实现了定量热像法对非均质焊接接头疲劳性能的评估.通过红外热像仪监测焊接接头表面局部热点的变化,定性分析了损伤演化状态.结果表明:定量热像法克服了传统疲劳实验方法的局限性,可快速、准确地确定非均质焊接接头的疲劳...     

碳纤维层合板低速冲击后的红外热波检测分析

采用红外热波无损检测技术对低速冲击后的碳纤维层合板进行检测和分析, 研究了损伤面积与冲击能量之间的关系。对比发现, 实验结果与文献结果一致; 实验结果说明红外热波不仅可以检测冲击损伤的大小, 还可以确定损伤在材料内部绕冲击点沿纤维方向呈旋转方式进行扩展的损伤模式。采用超声C扫描对相同复合材料层合板进行了检测, 详细对比了2种检测方法的优缺点, 发现对于碳纤维层合板的低速冲击损伤, 红外热波检测技术是一种快速、 有效、 可靠的无损检测技术和评估手段。      

红外热像仪的原理及其在电气设备检测中的应用

红外热像仪是利用现代高科技手段,对运行的电气设备进行无接触检测的一种仪器设备,详细介绍红外热像仪的工作原理、系统组成、分类、性能参数及其在电气设备检测中的应用.     

The drilling resistance test for the assessment of fire damaged concrete

In this paper, the evaluation of the drilling resistance is regarded as a method to ascertain the thermal damage undergone by concrete members after fire. Some preliminary tests on a good quality concrete were functional in defining the test procedure, the optimal bit diameter and the effect of the drilling thrust. A further study on uniformly damaged concrete cubes (ordinary and lightweight concretes – R_cm = 50 N/mm²) allowed to ascertain the sensitivity of the method. The reliability of this technique for the assessment of the damage depth within structural members exposed to fire has then been checked by testing some concrete panels exposed to marked temperature gradients. Finally, the viability of the method for in situ applications has been confirmed by testing the members of a precast RC structure which survived a real fire.     

基于非线性超声技术的热损伤混凝土微裂纹检测实验研究

混凝土结构在受热或者火灾作用后其内部极易形成微裂纹,这将严重影响混凝土的耐久性与强度等特性。基于非线性声场调制理论,提出边带峰计数法及损伤指标概念,以评估热损伤混凝土微裂纹的发展。通过高温制备热损伤混凝土,对热损伤混凝土微裂纹的检测结果表明,损伤指标会随微裂纹的发展而增大,与理论研究吻合。证明了非线性声场调制法的可行性,并引入非线性声场共振法进行对比实验,分析了调制法的优越性。并对不同水灰比、骨料比与升温速率的热损伤混凝土微裂纹的检测实验发现,损伤指标峰值会随混凝土水灰比或骨料比的增大而增大,缓慢升温方式对混凝土的损伤较快速升温方式大,并建立起了残余强度与损伤指标峰值之间的关系,为混凝土材料的热损伤评估奠定基础。     

Experimental Investigation of Strain Behaviour of Heated Cement Paste and Concrete

The material degradation of concrete subjected to fire events has a severe influence on the load‐carrying capacity of support structures. Spalling of concrete layers, exposing the reinforcement bars and degradation of the material properties (Young's modulus, compressive strength) may lead to significant damage of the reduced cross‐section and, therefore, cause failure of the structure. In order to understand the stress build‐up at the heated surface caused by thermal expansion due to fire loading, finally leading to damage and spalling of concrete, the strain behaviour of cement paste and concrete exposed to combined thermo‐mechanical loading is the focus of this work. Hereby, the evolution of thermal strains, Young's modulus and Poisson's ratio with increasing temperature are investigated experimentally. For this purpose, the specimens are loaded uniaxially while the temperature is increased up to 800 °C. The obtained results provide the proper basis for the development of realistic material models, allowing more sophisticated simulations of structures exposed to fire.     

Effect of fire exposure on cracking,spalling and residual strength of fly ash geopolymer concrete

Fly ash based geopolymer is an emerging alternative binder to cement for making concrete. The cracking, spalling and residual strength behaviours of geopolymer concrete were studied in order to understand its fire endurance, which is essential for its use as a building material. Fly ash based geopolymer and ordinary portland cement (OPC) concrete cylinder specimens were exposed to fires at different temperatures up to 1000 °C, with a heating rate of that given in the International Standards Organization (ISO) 834 standard. Compressive strength of the concretes varied in the range of 39–58 MPa. After the fire exposures, the geopolymer concrete specimens were found to suffer less damage in terms of cracking than the OPC concrete specimens. The OPC concrete cylinders suffered severe spalling for 800 and 1000 °C exposures, while there was no spalling in the geopolymer concrete specimens. The geopolymer concrete specimens generally retained higher strength than the OPC concrete specimens. The Scanning Electron Microscope (SEM) images of geopolymer concrete showed continued densification of the microstructure with the increase of fire temperature. The strength loss in the geopolymer concrete specimens was mainly because of the difference between the thermal expansions of geopolymer matrix and the aggregates.     

温压药剂爆炸火球温度测量研究

温压药剂热毁伤效应评估中火球温度至关重要。为了精确测量火球温度,应用红外热成像技术测试并分析了温压药剂爆炸时火球的温度随时间的变化规律。结果表明,相对于算术平均值等方法获得的温度值,基于等效热辐射强度的温度平均值(T_AVE)更适用于温压药剂爆炸火球热辐射的计算。 在等效热辐射强度的温度平均值基础上,提出了爆炸火球表面单位面积平均热辐射量的概念。在忽略热对流及热传导的前提下,该火球表征参量可作为温压药剂热毁伤效应评估的基准。     

单向面内约束混凝土双向板火灾试验及承载力分析

为研究混凝土板在面内约束作用下的火灾行为,对1块面内约束混凝土双向板进行了恒载-升温条件下的火灾试验,获得了试验板沿板厚的温度场分布、钢筋温度、板挠度和平面外变形以及板角约束力等规律。基于EC2和ASCE两本构模型,采用五种理论对四块不同面内约束作用下试验板的极限承载力进行对比分析。结果表明：单向面内约束作用时,试验板板顶出现沿约束力方向的平行裂缝;与挠度相比,板在垂直约束力方向的平面内膨胀变形较大且不可忽略;面内约束作用和破坏准则对火灾下混凝土双向板极限承载力有重要影响。     

超高分子量聚乙烯人工髋臼材料压缩性能的红外辐射研究

采用先进的试验设备和方法对超高分子量聚乙烯(UHMW PE)人工髋臼材料在不同的加载速度下进行压缩力学性能试验的同时,对其压缩变形过程进行了热红外辐射温度的监测。对超高分子量聚乙烯人工髋臼材料试验过程中的应力与应变、平均红外辐射温度与应变、平均红外辐射温度与机械功之间的关系进行了分析。试验结果为超高分子量聚乙烯人工髋臼材料在特殊的人体环境中的应用提供了参考。     

Behaviour of fiber reinforced concrete columns in fire

This paper presents the results of a research program on the behaviour of fiber reinforced concrete columns in fire. Several fire resistance tests on fiber concrete columns with restrained thermal elongation were carried out. The percentage of steel reinforcing bars on the testing columns varied in function of the percentage of steel fibers being always the total amount of steel (steel fibers + steel reinforcement) similar. The aim of this research was to study the possibility of replacing the longitudinal reinforcement bars on the concrete columns by steel fibers. Furthermore, polypropylene fibers were also used on the concrete in order to enhance the fire behaviour of the columns and avoid the concrete spalling. Polypropylene fibers under fire action will create a network of micro-channels for the escape of the water vapour.