基于量子点荧光响应的金属裂纹检测及应力应变监测研究
发布时间：2018-07-23 17:46
【摘要】：构件失效通常是导致设备无法正常运转的主要原因,主要表现为应力分布不均与裂纹扩展,针对于大型设备的应力应变检测以及裂纹扩展监测一直是工程领域面临的重大问题。量子点作为一种纳米半导体材料,具有独特的荧光性能,广泛的应用在生物探针、太阳能电池以及发光二极管等方面。近年来,由于量子点纳米晶在受力条件下展现出荧光性能改变的特性,利用量子点的荧光性能制备的荧光纳米晶应力应变计得到了关注。本文基于核壳结构的荧光量子点,混合环氧树脂制备了量子点环氧树脂复合材料。以此为研究对象,在金属紧凑拉伸基底上覆膜,可动态监测金属裂纹扩展情况。考察量子点添加量浓度和裂纹区域荧光强度、裂纹宽度与裂尖、膜裂纹与金属裂纹同步性等变化的影响,分析了可视化荧光信号出现的机理。研究了拉伸下金属应力应变与膜荧光强度变化的响应,通过分析拉伸条件下金属应力和膜应力的大小、量子点树脂空白样在循环拉伸下应力应变/应力松弛/量子点浓度变化等因素的影响,提出了应力应变荧光强度响应机理,利用中间带圆孔的板材试样考察了残余应变分布。论文主要获得了以下研究结果：(1)量子点环氧树脂复合材料制备工艺优化及拉伸荧光响应通过对不同种类环氧树脂与量子点的混合测试研究,确定了6002型环氧树脂与593固化剂的混合搭配可最大程度降低环氧树脂对量子点荧光性能的影响,同时保持较好的混合成模性能。在同等体积下的环氧树脂中添加不同浓度的量子点溶液,发现以1：4为标准量子点添加量时,实验样品可以较好地在线性变化区间。基于量子点环氧树脂复合材料的拉伸性能及荧光响应,确定了量子点环氧树脂材料属于非线性粘弹性材料,在拉伸后会产生较大的残余应变,同时获得了随应变增大会,荧光强度整体呈现下降,但在小应变区,荧光强度会有不同程度上升的荧光响应变化趋势。通过温度稳定性的考察,获得了量子点环氧树脂材料的温度适用范围在30℃到100℃温度变化区间。确定了温度上升到150℃时,环氧树脂的老化现象使得量子点的荧光现象消失。(2)金属I型裂纹扩展的检测开发了量子点环氧树脂膜检测金属I型裂纹扩展的方法,实现了荧光信号的快速响应,可精确描述微米级宽度的裂纹生长状态。对涂覆量子点环氧树脂膜的金属紧凑拉伸试样的疲劳拉伸,确定了荧光信号出现的先决条件,并动态可视化地追踪了裂纹扩展过程,同时,确定了拉伸后裂纹区域的荧光强度要高于未出现裂纹区域的荧光强度。通过对比膜裂纹与金属裂纹的宽度及位置、裂尖形态的考察,获得了宽度为1-100μm的裂纹检测的适用范围及薄膜裂纹形成的过程,实现了灵敏度为1μm、精度为0.1μm的裂纹尖端检测,并提出控制薄膜厚度可更好的描述裂尖的形态。(3)膜裂纹与金属裂纹同步性考察及荧光响应机理研究通过对量子点环氧树脂膜的各添加剂比例的控制,确定了环氧树脂/氯仿/固化剂的体积比为3：1：1-4：1：1区间为最佳的配比,其固化后的产物维氏硬度相对较高。同时选用体积比为3：1：1做为反应配比,通过改变固化温度从50到80℃的变化,考察氯仿的挥发程度及固化产物的维氏硬度变化,避免了膜裂纹与金属裂纹偏移、裂尖位置相差较大以及树脂膜在拉伸过程中裂纹处薄膜剥离的发生,提高了树脂膜裂纹与金属裂纹的同步性,确保了裂纹的同步生长。最后,对量子点环氧树脂膜荧光响应机理进行了分析,研究认为在膜裂纹断裂处出现的收缩使得裂纹两侧的量子点相对浓度增加,同时由于膜裂纹的开裂,使得更多的量子点暴露于紫外激发光源下,导致了荧光信号的产生。(4)量子点环氧树脂膜监测金属应力应变建立了量子点环氧树脂复合材料检测金属应力应变的方法,新型的应力应变-荧光传感器可以较好的描述金属在线弹性区间内拉伸条件下的应变变化。通过对涂覆量子点环氧树脂的金属试样变应力循环拉伸,验证了膜结构的变化导致了荧光强度变化的结论。对量子点环氧树脂空白样的拉伸应力应变曲线、应力松弛、应力回弹变化的考察进一步验证了多次循环下荧光强度的累积来自于量子点环氧树脂循环拉伸后应变累积,同时其荧光变化幅度与量子点树脂每次循环的应变增量的呈对应关系。对比了拉伸前后量子点的分布浓度和应变变化,提出了荧光强度的上升和下降主要来源于拉伸前后单位范围内的量子点浓度的变化以及聚集的量子点间的距离增大导致更多量子点受到激发。对中间带圆孔的薄板试样拉伸测试,获得荧光强度的变化与薄板试样的应力分布及应变变化的对应关系。
[Abstract]:The failure of the component is usually the main cause of the failure of the equipment to operate normally. It is mainly manifested in the uneven distribution of stress and crack propagation. The stress and strain detection and crack propagation monitoring for large equipment have been a major problem in the field of engineering. As a nanomo semiconductor material, the quantum dots have a unique fluorescence performance. The ubiquitous applications are in biological probes, solar cells and light emitting diodes. In recent years, the fluorescence nanocrystalline stress-strain gage prepared by the fluorescence properties of quantum dots has been paid attention to because of the characteristics of the change in the fluorescence properties of the quantum dots nanocrystals under the force conditions. A quantum dot epoxy resin composite was prepared by epoxy resin. As a study object, film covered on a metal compact tensile substrate can dynamically monitor the expansion of metal cracks. The effects of quantum dots addition concentration, crack region fluorescence intensity, crack width and crack tip, membrane crack and metal crack synchronism are investigated. The mechanism of the appearance of the fluorescence signal was observed. The response of the stress strain and the change of the film fluorescence intensity under tension was studied. The stress strain and the stress relaxation of the quantum dot resin were influenced by the factors such as stress strain / stress relaxation / quantum dot concentration change under cyclic stretching. The distribution of residual strain was investigated by the plate specimen with round holes in the middle. The main results were as follows: (1) the optimization of the preparation technology of the quantum dots epoxy resin composite and the tensile fluorescence response of the epoxy resin and the quantum dots were determined by the mixing of different kinds of epoxy resin and quantum dots. The 6002 epoxy resin was determined. The mixing with 593 curing agent can minimize the effect of epoxy resin on the fluorescence properties of quantum dots, while maintaining a better mixing model performance. Adding different concentration of quantum dots solution at the same volume of epoxy resin under the same volume, it is found that the experimental sample can be well linearly changed when 1:4 is added as the standard quantum dot. Based on the tensile properties and fluorescence response of the quantum dots epoxy resin composite, it is determined that the quantum dots epoxy resin material belongs to the nonlinear viscoelastic material, which will produce large residual strain after stretching. At the same time, the fluorescence intensity as a whole decreases as the strain increases, but the fluorescence intensity will have different distances in the small strain zone. Through the investigation of temperature stability, the temperature range of the temperature applicable range of quantum dots epoxy resin materials was obtained at 30 degrees C to 100 C. The aging phenomenon of epoxy resin was determined to disappear the fluorescence image of the quantum dots at 150 C. (2) detection and development of the crack growth of the metal I type. The method of detecting the crack growth of the metal I type by the quantum dot epoxy resin film is used to realize the rapid response of the fluorescence signal, which can accurately describe the crack growth state of the micron width. The precondition of the appearance of the fluorescence signal is determined by the fatigue stretching of the compact tensile specimen of the metal coated with the quantum dots epoxy resin film, and the dynamic visual tracing is made. The crack propagation process is traced, and the fluorescence intensity of the crack region is determined to be higher than that of the uncracked region. By comparing the width and position of the crack to the metal crack and the shape of the crack tip, the suitable range of crack detection and the formation process of the crack in the crack are obtained by the investigation of the width and position of the crack and the crack tip. The sensitivity is 1 mu m and the precision of the crack tip is 0.1 M, and the control film thickness can better describe the shape of the crack tip. (3) the investigation of the synchronism of the crack and the metal crack and the mechanism of the fluorescence response are studied. The volume ratio of the epoxy resin / chloroform / curing agent is determined by the control of the ratio of each additive to the epoxy resin film of the quantum dots. The 1:1-4:1:1 interval is the best ratio, and the hardness of the cured product Vivtorinox is relatively high. At the same time, the ratio of the volume ratio is 3:1:1 as the reaction ratio. By changing the curing temperature from 50 to 80 C, the volatilization degree of chloroform and the change of the hardness of the cured product of the cured product are investigated, and the film crack and the metal crack offset and the crack tip are avoided. There is a large difference in position and the occurrence of film stripping at the crack of the resin film during the tensile process, which improves the synchronism of the crack of the resin film and the metal crack, and ensures the synchronous growth of the crack. Finally, the fluorescence response mechanism of the quantum dots epoxy resin film is analyzed. The study holds that the shrinkage of the crack at the crack of the membrane causes the two sides of the crack. The relative concentration of the quantum dots increases and the crack of the membrane cracks causes more quantum dots to be exposed to the ultraviolet light source, which leads to the production of the fluorescence signal. (4) the quantum dots epoxy resin membrane is used to monitor the metal stress and strain of the quantum dot epoxy resin composite to detect the stress and strain of the metal, and the new stress and strain. The fluorescence sensor can describe the strain change under the tensile condition of the metal on line. Through the cyclic stretching of the strain of the metal specimen coated with the quantum dots epoxy resin, the conclusion that the change of the membrane structure leads to the change of the fluorescence intensity is verified. The tensile stress strain curve and the stress on the blank sample of the quantum dots epoxy tree fat are stressed. The investigation of relaxation and stress rebound changes further verifies that the accumulation of fluorescence intensity in multiple cycles is derived from the strain accumulation after the cyclic tensile of quantum dots, and the amplitude of the fluorescence is corresponding to the strain increment in each cycle of the quantum dots, and the distribution of the quantum dots and the strain changes before and after the extension are compared. It is proposed that the rise and decrease of fluorescence intensity is mainly due to the change in the concentration of quantum dots within the unit range before and after stretching and the increase of the distance between the quantum dots, which leads to the excitation of more quantum dots. The tensile test of thin plate specimen with a round hole in the middle is used to obtain the change of the fluorescence intensity and the stress distribution and strain variation of the thin plate specimen. The corresponding relationship.
【学位授予单位】：华东理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG115
[Abstract]:The failure of the component is usually the main cause of the failure of the equipment to operate normally. It is mainly manifested in the uneven distribution of stress and crack propagation. The stress and strain detection and crack propagation monitoring for large equipment have been a major problem in the field of engineering. As a nanomo semiconductor material, the quantum dots have a unique fluorescence performance. The ubiquitous applications are in biological probes, solar cells and light emitting diodes. In recent years, the fluorescence nanocrystalline stress-strain gage prepared by the fluorescence properties of quantum dots has been paid attention to because of the characteristics of the change in the fluorescence properties of the quantum dots nanocrystals under the force conditions. A quantum dot epoxy resin composite was prepared by epoxy resin. As a study object, film covered on a metal compact tensile substrate can dynamically monitor the expansion of metal cracks. The effects of quantum dots addition concentration, crack region fluorescence intensity, crack width and crack tip, membrane crack and metal crack synchronism are investigated. The mechanism of the appearance of the fluorescence signal was observed. The response of the stress strain and the change of the film fluorescence intensity under tension was studied. The stress strain and the stress relaxation of the quantum dot resin were influenced by the factors such as stress strain / stress relaxation / quantum dot concentration change under cyclic stretching. The distribution of residual strain was investigated by the plate specimen with round holes in the middle. The main results were as follows: (1) the optimization of the preparation technology of the quantum dots epoxy resin composite and the tensile fluorescence response of the epoxy resin and the quantum dots were determined by the mixing of different kinds of epoxy resin and quantum dots. The 6002 epoxy resin was determined. The mixing with 593 curing agent can minimize the effect of epoxy resin on the fluorescence properties of quantum dots, while maintaining a better mixing model performance. Adding different concentration of quantum dots solution at the same volume of epoxy resin under the same volume, it is found that the experimental sample can be well linearly changed when 1:4 is added as the standard quantum dot. Based on the tensile properties and fluorescence response of the quantum dots epoxy resin composite, it is determined that the quantum dots epoxy resin material belongs to the nonlinear viscoelastic material, which will produce large residual strain after stretching. At the same time, the fluorescence intensity as a whole decreases as the strain increases, but the fluorescence intensity will have different distances in the small strain zone. Through the investigation of temperature stability, the temperature range of the temperature applicable range of quantum dots epoxy resin materials was obtained at 30 degrees C to 100 C. The aging phenomenon of epoxy resin was determined to disappear the fluorescence image of the quantum dots at 150 C. (2) detection and development of the crack growth of the metal I type. The method of detecting the crack growth of the metal I type by the quantum dot epoxy resin film is used to realize the rapid response of the fluorescence signal, which can accurately describe the crack growth state of the micron width. The precondition of the appearance of the fluorescence signal is determined by the fatigue stretching of the compact tensile specimen of the metal coated with the quantum dots epoxy resin film, and the dynamic visual tracing is made. The crack propagation process is traced, and the fluorescence intensity of the crack region is determined to be higher than that of the uncracked region. By comparing the width and position of the crack to the metal crack and the shape of the crack tip, the suitable range of crack detection and the formation process of the crack in the crack are obtained by the investigation of the width and position of the crack and the crack tip. The sensitivity is 1 mu m and the precision of the crack tip is 0.1 M, and the control film thickness can better describe the shape of the crack tip. (3) the investigation of the synchronism of the crack and the metal crack and the mechanism of the fluorescence response are studied. The volume ratio of the epoxy resin / chloroform / curing agent is determined by the control of the ratio of each additive to the epoxy resin film of the quantum dots. The 1:1-4:1:1 interval is the best ratio, and the hardness of the cured product Vivtorinox is relatively high. At the same time, the ratio of the volume ratio is 3:1:1 as the reaction ratio. By changing the curing temperature from 50 to 80 C, the volatilization degree of chloroform and the change of the hardness of the cured product of the cured product are investigated, and the film crack and the metal crack offset and the crack tip are avoided. There is a large difference in position and the occurrence of film stripping at the crack of the resin film during the tensile process, which improves the synchronism of the crack of the resin film and the metal crack, and ensures the synchronous growth of the crack. Finally, the fluorescence response mechanism of the quantum dots epoxy resin film is analyzed. The study holds that the shrinkage of the crack at the crack of the membrane causes the two sides of the crack. The relative concentration of the quantum dots increases and the crack of the membrane cracks causes more quantum dots to be exposed to the ultraviolet light source, which leads to the production of the fluorescence signal. (4) the quantum dots epoxy resin membrane is used to monitor the metal stress and strain of the quantum dot epoxy resin composite to detect the stress and strain of the metal, and the new stress and strain. The fluorescence sensor can describe the strain change under the tensile condition of the metal on line. Through the cyclic stretching of the strain of the metal specimen coated with the quantum dots epoxy resin, the conclusion that the change of the membrane structure leads to the change of the fluorescence intensity is verified. The tensile stress strain curve and the stress on the blank sample of the quantum dots epoxy tree fat are stressed. The investigation of relaxation and stress rebound changes further verifies that the accumulation of fluorescence intensity in multiple cycles is derived from the strain accumulation after the cyclic tensile of quantum dots, and the amplitude of the fluorescence is corresponding to the strain increment in each cycle of the quantum dots, and the distribution of the quantum dots and the strain changes before and after the extension are compared. It is proposed that the rise and decrease of fluorescence intensity is mainly due to the change in the concentration of quantum dots within the unit range before and after stretching and the increase of the distance between the quantum dots, which leads to the excitation of more quantum dots. The tensile test of thin plate specimen with a round hole in the middle is used to obtain the change of the fluorescence intensity and the stress distribution and strain variation of the thin plate specimen. The corresponding relationship.
【学位授予单位】：华东理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG115
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