The Interior Defect Detection And Fatigue Life Prediction Of Tire Manufacturing Based On Laser Speckle

This paper is titled “The interior defect detection and fatigue life prediction of tire manufacturing based on laser speckle” which is of great academic value and practical significance to improve the tire performance,to reduce the traffic accident rate caused by tire quality defects,and to improve the advanced manufacturing level and manufacturing inspection technology level of tires.Based on thoroughly reviewing the research achievements at home and abroad,and putting forward research ideas the framework,and comb related concepts,the main part of the paper focuses on the problems of the tire laser shearography detection system structure,the speckle wrapped phase image processing,defect depth measurement,constitutive relation selection method of rubber material and fatigue life prediction under multiaxial fatigue characteristics.The main points of this paper are as follows:⑴ The mechanism and key technologies of the tire laser shearography detection are studied which lays a foundation for further research on the information processing of internal defects based on laser speckle patterns.(a)The paper analyzes the characteristics of laser shearography and its requirements for testing environment,and then the laser speckle detection system for tire internal defection is rationally distributed.(b)Through analyzing the characteristics of laser shearing speckle pattern interference fringes containing tire internal defects,the method of adaptive multidirectional frequency domain filter for noise removal in wrapped phase patterns is studied,which can automatically set the filter cut-off frequency,filter the noise effectively,and preserve the detailed information of the image.(c)In order to realize the recognition of the internal defect size,phase integral and integral graph two value processing are applied to the phase diagram with the features of tire internal defects according to the phase relation between the stripe phase and the displacement of the defect surface during loading deformation.(d)Based on the system main program designed by Visual C++,the functions such as the image region capture,the noise filtering for interferometric phase image,phase-unwrapping,the reconstructed 3D model of defect deformation,the measurement of the out of plane displacement of the defect surface are realized.⑵ The paper is devoted to carrying on exploratory research on the depth measurement mechanism of internal defect based on laser speckle shearing interference to provide basis for mechanical properties of the defects in the loading process combined with the tire structure and defect configuration.(a)The formulas for calculating internal defect depth under different conditions are derived through modeling different types of common internal defects in non-destructive testing.(b)Taking Lab VIEW as the developing environment,a software for calculating the depth of tire internal defects is developed to realize the calculation of defect depth and database management combined with tyre internal defect size and surface displacement.(c)The preset defect sample is tested by means of laser shearing speckle interference detection platform for tires.The law of affecting the defect identification rate and the measurement accuracy of defect depth is discussed by controlling the loading amount 0q.The experimental results show that the method can effectively measure the depth of internal defects,and the relative error is less than 10%.Meanwhile,the loading amount 0q has obvious influence on the measurement accuracy under the premise of the defect size is greater than the resolution of the detection system.If 0q is small,the measured valuedepthT ? is slightly smaller than the actual defect depth depthT;when 0q is too large,the measured valuedepthT ? will be slightly larger than the actual defect depth depthT.⑶ Tire fatigue life prediction technology based on multiaxial fatigue characteristics of rubber is studied combined with the location of defects,which can overcome the one sidedness of traditional tire safety performance evaluation method which is merely based on defect size information.(a)The selection method of constitutive relation in rubber fatigue analysis is discussed,in view of the complexity of tire structure,the difference of mechanical properties of rubber materials in various parts of tire and the variety of stress field in tire.(b)The CED criterion was used to study the relationship between strain energy density W and crack energy density Wc under different loading conditions when the principal stretch ratio1? and ? are changed.On this basis,the fatigue characteristics of rubber under multiaxial loading are analyzed.(c)The finite element software is adopted to calculate and analyze the life prediction technology of tire based on multiaxial fatigue characteristics by using the global local model technology.The influence of crack depthdepthT and crack direction angle ? on fatigue crack growth is analyzed after setting up the fatigue damage area in different parts of the tire.⑷ The defect depth measurement and crack propagation test based on laser shear speckle detection are carried out to verify the effectiveness of the method.(a)The law of affecting the defect identification rate and the measurement accuracy of defect depth is discussed by detecting internal defect specimens with different depths and sizes.The test results showed that the depth measurement method is effective and the relative error is less than 10%.(b)The crack propagation life of formulated rubber specimens is calculated respectively by using the SED criterion and the CED criterion in this paper.The results showed that the fatigue life prediction results based on the SED criterion is greatly affected by the crack direction angle?.The minimum relative prediction error based on the SED is close to 50% when(7)(8)0 0? ?0,45.In contrast,the minimum relative prediction error based on the CED standard is only 12.25%.It shows that the fatigue life calculation method based on CED standard is closer to the actual crack growth.