硕士毕业论文-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.pdf

华东理工大学 博士学位论文 第 I 页

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

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。

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

C 到 100

C 温度变化区间。确定了温

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 1-100 m 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 1 m、精度为 0.1 m 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。

第 II 页 华东理工大学 博士学位论文

(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

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

Unsteady fracture is the main reason for the components failure such as stress

concentration and crack propagation. Stress-Strain measurement and crack propagation

monitoring have been the major problem in engineering for the large scale structure

equipment. Quantum Dots (QDs), fluorescence nano-semiconductor materials, have extensive

application in biological probe, solar cells and light emitting diodes due to their unique

quantum effect property. Recently, luminescent nanocrystal stress-strain gauge has been

developed by utilizing QDs luminescence characteristics under different pressure.

Based on core/shell structured photo-luminescence (PL) QDs, QDs-Epoxy Resin

composite materials was prepared by mixing with epoxy resin. Through coating on the

QDs- epoxy resin blank sample under tensile experiment and the Ansys calculation between

metal and coating. Finally, the residual strain distribution was detected using a flat with a

preset hole in the middle.

The main research content and conclusions in this dissertation were as follows:

(1) Preparation and tensile property of QDs- epoxy resin composite material

A bisphenol-A type epoxy resin (6002) and modified amine curing agent (593) are

selected as carrier due to the epoxy reduced the influence of QDs PL properties and kept good

coating performance at the same time. Through adding different concentration of QDs in the

same volume of epoxy resin solution, the spectral intensity changed in the linear range on the

basis of 1:4. Based on standard addition amount, QDs- epoxy resin composite material wad

o

(2) Metal crack propagation of type I monitoring by photoluminescence enhancement of

QDs- epoxy resin composite material.

A visualization method to monitor type I metal crack propagation was presented in this

paper. Through the enhanced PL intensity of QDs mixed into an epoxy resin film, this crack

detection method provides a visualization signal in a real-time and non-contact fashion. The

method realized rapid response of PL signal, crack detection of micron grade width. Also it

could descript crack growth state accurately. The article confirmed the prerequisite for PL

signal through a high frequency fatigue testing for a coating with metal compact tensile

specimen. At the same time, the obvious PL signals and dynamic visual process of tracking

controlled the adding proportion. Meanwhile, it also avoided the slight delamination in the

interface and crack deflection and made sure that synchronous growing with metal crack. At

last, the mechanism analysis for this behavior is based upon different models of cracks which

have been briefly proposed based on the experimental results.

The stretch of the standard flat tensile test specimen results in a slight strain on a

QDs-epoxy resin composite coating extended along with the standard flat tensile. The

intensity of coating has been demonstrated a sensitive optical response kept a linear variation.

The accumulation effect of PL intensity in several cycles was caused by many factors

including structure changing of QDs-epoxy resin, stress relaxation and strain rebound. The

magnitude of PL intensity increase was consistent with the residual strain increase of

response

目录

摘 要 ...................................................................................................................... I

Abstract................................................................................................................ III

目录 ...................................................................................................................... V

第一章 绪论 ....................................................................................................... 1

1.1 研究背景及意义 ................................................................................................................. 1

1.2 疲劳断裂基本概念 .............................................................................. 错误!未定义书签。

1.2.1 疲劳的定义及其特点 ....................................................................... 错误!未定义书签。

1.2.2 疲劳的分类 ....................................................................................... 错误!未定义书签。

1.4 应力应变检测方法 .............................................................................. 错误!未定义书签。

1.4.1 应变片电测法 ................................................................................... 错误!未定义书签。

1.4.2 光纤 Bragg 光栅检测法 .................................................................. 错误!未定义书签。

1.4.3 光弹性法 ........................................................................................... 错误!未定义书签。

1.5 应力发光分析裂纹在线观察及应力分布分析 .................................. 错误!未定义书签。

1.5.1 应力发光的定义 ............................................................................... 错误!未定义书签。

1.5.2 应力发光的陶瓷裂纹检测 ............................................................... 错误!未定义书签。

1.5.3 应力发光的应力应变检测 ............................................................... 错误!未定义书签。

1.5.4 应力发光的冲击响应检测 ............................................................... 错误!未定义书签。

1.5.5 应力发光的扭矩检测 ....................................................................... 错误!未定义书签。