基于ABAQUS与数字图像处理技术的轻骨料混凝土细观力学研究

发布时间：2018-03-21 00:05

本文选题：天然轻骨料混凝土　切入点：三点弯曲试验　出处：《内蒙古农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：内蒙古地区天然浮石储量丰富,天然轻骨料混凝土在工程上的应用越来越广泛。目前对轻骨料混凝土大都是耐久性、抗冻性等宏观层次的研究,忽略了混凝土材料内部复杂的细观结构,难以揭示材料变形和破坏的物理破坏机理,基于这一点,本文研究轻骨料混凝土的抗折性能,结合数字图像处理技术和数值模拟对轻骨料混凝土的细观力学性能进行研究。本研究选取粉煤灰和偏高岭土作为掺合料,采用已设计好的配合比和制备工艺制作尺寸为350mm × 300mm × 75mm的试块,制备三种不同的轻骨料混凝土,分别为粉煤灰轻骨料混凝土、偏高岭土轻骨料混凝土、普通轻骨料混凝土。用以上三组试件,养护28d后,用岩石切割机切割成350mm × 75mm × 75mm的小梁试件,共9块,并用数码相机拍摄切割面,用于之后的数字图像处理。然后进行小梁的三点弯曲试验,研究其抗折性能以及其应力应变。将采集小梁试件的切割面的图像进行数字图像处理,包括图像增强、锐化、图像分割、图像二值化(图中只含有轻骨料和水泥砂浆)、图像矢量化等,使其成为能导入ABAQUS有限元软件的DXF格式图形。采用ABAQUS有限元软件对基于数字图像处理技术的轻骨料混凝土弯曲试验进行有限元模拟,研究其应力应变分布情况,将其与室内试验的数据进行对比,验证数值模拟的可靠性与准确性。并在此基础上分别对骨料和水泥砂浆的应力应变情况进行分析,研究其破坏机理。最后整理分析试验数据并对室内试验和数值模拟的对比分析得出以下主要结论：三种轻骨料混凝土的抗折能力相差不大,加载时,其内部水泥砂浆的承担的应力要比浮石的应力要大。数字图像处理技术结合ABAQUS有限元软件技术可以准确地模拟轻骨料混凝土的力学性能,可以减少室内试验的工作量,可以更好地对轻骨料混凝土的破坏机理在细观层次进行研究。
[Abstract]:There are abundant natural pumice in Inner Mongolia, and the application of natural lightweight aggregate concrete in engineering is more and more extensive. At present, most of the researches on lightweight aggregate concrete are at the macro level, such as durability, frost resistance, etc. It is difficult to reveal the physical failure mechanism of material deformation and failure by neglecting the complex mesoscopic structure of concrete material. Based on this point, the flexural properties of lightweight aggregate concrete are studied in this paper. Combined with digital image processing technology and numerical simulation, the meso-mechanical properties of lightweight aggregate concrete were studied. Fly ash and metakaolin were selected as admixtures in this study. Three different kinds of lightweight aggregate concrete, fly ash lightweight aggregate concrete and metakaolin lightweight aggregate concrete, were prepared by using the designed mix ratio and the preparation process of the test block with the size of 350 mm 脳 300 mm 脳 75 mm. Ordinary lightweight aggregate concrete. After 28 days of maintenance with the above three groups of specimens, the trabeculae were cut into 350mm 脳 75mm 脳 75mm trabeculae by rock cutting machine, 9 pieces of trabeculae were cut with digital camera. Then the three-point bending test of trabecular beam is carried out to study its flexural performance and stress and strain. The image of the cut surface of trabecular specimen is processed by digital image processing, including image enhancement and sharpening. Image segmentation, image binarization (image containing only lightweight aggregate and cement mortar, image vectorization, etc.). ABAQUS finite element software is used to simulate the bending test of lightweight aggregate concrete based on digital image processing technology, and the distribution of stress and strain is studied. The reliability and accuracy of the numerical simulation are verified by comparing it with the data of laboratory test. On this basis, the stress-strain situation of aggregate and cement mortar is analyzed respectively. The failure mechanism of the concrete is studied. Finally, the test data are analyzed and compared with the numerical simulation. The main conclusions are as follows: the flexural strength of the three lightweight aggregate concrete is not different from that of the other three kinds of lightweight aggregate concrete, when the concrete is loaded, The internal stress of cement mortar is greater than that of pumice. Digital image processing technology combined with ABAQUS finite element software technology can accurately simulate the mechanical properties of lightweight aggregate concrete and reduce the workload of laboratory test. The failure mechanism of lightweight aggregate concrete can be studied at meso level.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528.2

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