數(shù)字梯度敏感法的改進與應(yīng)用
發(fā)布時間：2018-08-15 14:36
【摘要】：透明的高分子材料有良好的透光、耐熱、力學、化學等方面的性能,正逐步替代金屬、塑料等傳統(tǒng)材料,在建筑、汽車和航空航天等領(lǐng)域大放異彩。但透明材料在生產(chǎn)過程中必然存在細微的損傷和殘余應(yīng)力,并且在服役中面臨斷裂、疲勞等多種問題。光彈性法、云紋法、相干梯度敏感法等許多光測力學手段,都曾應(yīng)用于透明材料的力學問題的研究。而最近兩年提出的數(shù)字梯度敏感法,可以得到透明材料的面內(nèi)正應(yīng)力和梯度,憑借設(shè)備簡單等優(yōu)勢在斷裂力學等領(lǐng)域廣為應(yīng)用。本文在介紹數(shù)字梯度敏感法的基本原理的基礎(chǔ)上,提出了數(shù)字梯度敏感法中的光-力學參數(shù)的最小二乘標定方法,通過引入線性誤差項,提高了標定算法的準確性。分析結(jié)果顯示本文提出的方法能有效地標定聚甲基丙烯酸甲酯的光-力學參數(shù),可方便地用于各種透明材料的應(yīng)力測量。隨后通過標定好的光-力學參數(shù),測量了聚甲基丙烯酸甲酯的Ⅰ型裂紋的應(yīng)力強度因子。將多元函數(shù)回歸問題簡化為曲線擬合,簡單估算得到應(yīng)力強度因子,并與邊界配置法的理論解進行對照,驗證了其準確性。最后,創(chuàng)新性地將IPS屏幕引入數(shù)字梯度敏感法,提出背光式測試系統(tǒng),不僅簡化了實驗裝置,更提高了散斑圖像質(zhì)量與測試結(jié)果的準確性。通過凸透鏡實驗將新測試系統(tǒng)與傳統(tǒng)測試系統(tǒng)進行對比,既驗證了基于IPS屏幕的背光式測試系統(tǒng)的可行性與有效性,又體現(xiàn)出該系統(tǒng)在裝置、操作、準確性等多方面的優(yōu)勢。
[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.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB324
本文編號：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.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB324
【參考文獻】
相關(guān)期刊論文 前2條
1 周春艷;姜月偉;徐兵;;國內(nèi)聚甲基丙烯酸甲酯(PMMA)的生產(chǎn)及市場[J];塑料工業(yè);2011年09期
2 李復(fù)生,魏東煒,崔金華,殷金柱,宋光復(fù);聚碳酸酯光學性能應(yīng)用及改進研究進展[J];塑料;2003年03期
，本文編號：2184505
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