数字梯度敏感法的改进与应用
发布时间：2018-08-15 14:36
【摘要】：透明的高分子材料有良好的透光、耐热、力学、化学等方面的性能,正逐步替代金属、塑料等传统材料,在建筑、汽车和航空航天等领域大放异彩。但透明材料在生产过程中必然存在细微的损伤和残余应力,并且在服役中面临断裂、疲劳等多种问题。光弹性法、云纹法、相干梯度敏感法等许多光测力学手段,都曾应用于透明材料的力学问题的研究。而最近两年提出的数字梯度敏感法,可以得到透明材料的面内正应力和梯度,凭借设备简单等优势在断裂力学等领域广为应用。本文在介绍数字梯度敏感法的基本原理的基础上,提出了数字梯度敏感法中的光-力学参数的最小二乘标定方法,通过引入线性误差项,提高了标定算法的准确性。分析结果显示本文提出的方法能有效地标定聚甲基丙烯酸甲酯的光-力学参数,可方便地用于各种透明材料的应力测量。随后通过标定好的光-力学参数,测量了聚甲基丙烯酸甲酯的Ⅰ型裂纹的应力强度因子。将多元函数回归问题简化为曲线拟合,简单估算得到应力强度因子,并与边界配置法的理论解进行对照,验证了其准确性。最后,创新性地将IPS屏幕引入数字梯度敏感法,提出背光式测试系统,不仅简化了实验装置,更提高了散斑图像质量与测试结果的准确性。通过凸透镜实验将新测试系统与传统测试系统进行对比,既验证了基于IPS屏幕的背光式测试系统的可行性与有效性,又体现出该系统在装置、操作、准确性等多方面的优势。
[Abstract]:Transparent polymer materials are gradually replacing traditional materials such as metals, plastics and so on because of their excellent performances in light transmission, heat resistance, mechanics, chemistry and so on. They are shining brilliantly in construction, automobile, aerospace and other fields. However, transparent materials are bound to have subtle damage and residual stress in the production process, and are faced with fracture, fatigue and so on in service. Photoelastic method, moire method, coherent gradient sensitive method and many other photomechanical methods have been applied to the study of mechanical problems of transparent materials. However, the digital gradient sensitive method proposed in the last two years can obtain in-plane normal stress and gradient of transparent materials. It is widely used in fracture mechanics and other fields by virtue of its simple equipment. On the basis of introducing the basic principle of digital gradient sensing method, a least square calibration method for optical-mechanical parameters in digital gradient sensing method is proposed. The accuracy of the calibration algorithm is improved by introducing a linear error term. The analysis results show that the proposed method can effectively calibrate the photomechanical properties of polymethyl methacrylate. The stress intensity factors of mode I crack in polymethyl methacrylate (PMMA) were measured by calibrated optical-mechanical parameters. The regression problem of multivariate function was simplified to curve fitting, and the stress intensity factors were estimated simply. The results were compared with the theoretical solution of boundary collocation method. Finally, the IPS screen is innovatively introduced into the digital gradient sensing method, and a backlight testing system is proposed, which not only simplifies the experimental device, but also improves the quality of speckle image and the accuracy of testing results. The feasibility and validity of the backlight test system also shows the advantages of the system in device, operation, accuracy and so on.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB324
本文编号：2184505
[Abstract]:Transparent polymer materials are gradually replacing traditional materials such as metals, plastics and so on because of their excellent performances in light transmission, heat resistance, mechanics, chemistry and so on. They are shining brilliantly in construction, automobile, aerospace and other fields. However, transparent materials are bound to have subtle damage and residual stress in the production process, and are faced with fracture, fatigue and so on in service. Photoelastic method, moire method, coherent gradient sensitive method and many other photomechanical methods have been applied to the study of mechanical problems of transparent materials. However, the digital gradient sensitive method proposed in the last two years can obtain in-plane normal stress and gradient of transparent materials. It is widely used in fracture mechanics and other fields by virtue of its simple equipment. On the basis of introducing the basic principle of digital gradient sensing method, a least square calibration method for optical-mechanical parameters in digital gradient sensing method is proposed. The accuracy of the calibration algorithm is improved by introducing a linear error term. The analysis results show that the proposed method can effectively calibrate the photomechanical properties of polymethyl methacrylate. The stress intensity factors of mode I crack in polymethyl methacrylate (PMMA) were measured by calibrated optical-mechanical parameters. The regression problem of multivariate function was simplified to curve fitting, and the stress intensity factors were estimated simply. The results were compared with the theoretical solution of boundary collocation method. Finally, the IPS screen is innovatively introduced into the digital gradient sensing method, and a backlight testing system is proposed, which not only simplifies the experimental device, but also improves the quality of speckle image and the accuracy of testing results. The feasibility and validity of the backlight test system also shows the advantages of the system in device, operation, accuracy and so on.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB324
【参考文献】
相关期刊论文 前2条
1 周春艳;姜月伟;徐兵;;国内聚甲基丙烯酸甲酯(PMMA)的生产及市场[J];塑料工业;2011年09期
2 李复生,魏东炜,崔金华,殷金柱,宋光复;聚碳酸酯光学性能应用及改进研究进展[J];塑料;2003年03期
，本文编号：2184505
本文链接：https://www.wllwen.com/kejilunwen/cailiaohuaxuelunwen/2184505.html
