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Số người truy cập: 109,885,917

 Nondestructive characterization of elastic modulus under different tensile stresses through laser ultrasound combined inversion technique
Tác giả hoặc Nhóm tác giả: Nguyen Le Van, N. Jeyaprakash, and Che-Hua Yang
Nơi đăng: International Journal of Modern Physics B; Số: Vo.38, No. 4;Từ->đến trang: 2450059(1-19);Năm: 2023
Lĩnh vực: Kỹ thuật; Loại: Bài báo khoa học; Thể loại: Quốc tế
TÓM TẮT

ABSTRACT
Stainless steel (SS) is widely used in many fields including aeronautics, automobiles, marine andmechanical industries due to its outstanding feature such as good corrosion resistance andhardness. However, changes in material properties under stress, particularly changes in Young'smodulus, result in the formation of cracks, a reduction in load-bearing capacity, and fatiguedamage. So, the structural integrity needs to be evaluated based on a precise measurement ofmechanical properties. In this study, Stainless Steel 304 (SS-304) is used as the base materialand various tensile stresses are applied ranging from 0MPa to 100MPa with increment of10MPa in each step. Nondestructive Laser Ultrasound Technique (LUT) has been used tocharacterize the elastic modulus under various tensile stresses. An inverse program was developedbased on the Particle Swarm Optimization (PSO) algorithms to determine materialproperties. Nonlinear Gauss fitting method was proposed and established the fitting equationand nonlinear curve for Young's modulus and residual stress. The outcome of this researchshows that when tensile stress is applied, the mechanical properties decrease by shifting thedispersion curve and also it is evident that the dispersion curves move toward the high-frequency-thickness while increasing the tensile stress. When the tensile stress was increased from0MPa to 100 MPa, the value of Young's modulus decreased from 201.7GPa to 193.5 GPa.Especially, the predominant changes were observed during 30–100 MPa. This observation displays the bonding strength and binding energy between the atomics. Further, the proposednonlinear Gauss fitting substantiated the experimental values and confirmed that the thicknessaccuracy is close to the inversion values, with an average difference of 4.32%. This researchsuggests a potential nondestructive method to determine the residual stress of a material bycalculating the changes in the elastic modulus.
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