| LYU Yuan,YI Cong,ZHOU Liucheng,WANG Lingfeng,PAN Xixiang,WANG Yifan,WANG Yan,CHEN Junji.Inverse Analysis of Constitutive Equation of IP Anti-corrosion Coatings Based on Nanoindentation[J],54(11):203-210 |
| Inverse Analysis of Constitutive Equation of IP Anti-corrosion Coatings Based on Nanoindentation |
| Received:December 05, 2024 Revised:March 26, 2025 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2025.11.017 |
| KeyWord:IP anti-corrosion coatings nanoindentation dimensional analysis constitutive equation finite element simulation |
| Author | Institution |
| LYU Yuan |
School of Mechanical Engineering, Xi'an University of Science and Technology, Xi'an , China |
| YI Cong |
School of Mechanical Engineering, Xi'an University of Science and Technology, Xi'an , China |
| ZHOU Liucheng |
National Key Lab of Aerospace Power System and Plasma Technology, Air Force Engineering University, Xi'an , China |
| WANG Lingfeng |
National Key Lab of Aerospace Power System and Plasma Technology, Air Force Engineering University, Xi'an , China |
| PAN Xixiang |
School of Mechanical Engineering, Xi'an University of Science and Technology, Xi'an , China |
| WANG Yifan |
School of Mechanical Engineering, Xi'an University of Science and Technology, Xi'an , China |
| WANG Yan |
School of Mechanical Engineering, Xi'an University of Science and Technology, Xi'an , China |
| CHEN Junji |
School of Mechanical Engineering, Xi'an University of Science and Technology, Xi'an , China |
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| Abstract: |
| IP coatings provide excellent corrosion resistance for blades working in marine corrosive environments for long periods of time, but they may fall off due to fatigue life when facing complex loads to which the stress-strain response relationship of the coating is highly relevant. However, there are relatively few studies related to the elasticity and plasticity of coatings. The work aims to study the constitutive equation of coatings, so as to make repair in time before they fall off. The coating dimensions are so small and thin that it is not feasible to obtain a constitutive equation by making the test pieces required for conventional tensile experiments. In order to obtain the constitutive equation of the coating, the plastic properties of the coating were investigated by the method of nanoindentation inversion analysis. Nanoindentation experiments were conducted on the coating surface by the continuous stiffness method to obtain the hardness and elastic modulus and output the load-displacement curves. With the theorem of the magnitude analysis method, the dimensionless functions between each constitutive parameter was established to determine the constitutive equation of the coating, and finally, the constitutive equation was substituted into the finite element model to simulate the nanoindentation experiments, and the load-displacement curves of simulation and experiments were compared to verify the accuracy of the constitutive equation. The hardness of the coating was 5.49 GPa, and the modulus of elasticity was 69.31 GPa. In the finite element simulation of this study, 15 coating representative materials were simulated and analyzed for six cases with representative strains of 0.01, 0.033, 0.036, 0.044, 0.06 and 0.09. It was found that the dimensionless functions established by scholars in the past studies on a large number of different materials had large errors with the present studies, not well suited to the coating. The reconstructed dimensionless equation was more simplified than the previous one, and the new function was calculated to be 0.034, compared with 0.033 and 0.044 for Dao and Lee's equations, respectively, which improved the accuracy of the computation of the representative strain. It was also found that the value of the representative strain had a significant impact on the inversion results. If the strain was smaller, the curve shifted downward with the increase of hardening index in the loading stage, and shifted leftward with the increase of hardening index in the unloading stage. When the representative strain was larger, the load-displacement curve behaved the opposite way. When the hardening index was solved, the relevant 3D surface model was established, and it was proposed to merge and simplify the corresponding surface model. When the nanoindentation simulation was completely unloaded, the residual indentation depths were almost the same, which indicated that the model still met the accuracy of the results. Through comparison of the load-displacement curves obtained from experiment and finite element simulation, they were more consistent. The following conclusion is that the IP anti-corrosion coating has high surface hardness and good surface deformation resistance. When the representative strain is smaller, the load-displacement curve changes because the hardening index becomes larger, the plastic work in the loading stage increases, and the total work also increases. The opposite trend when the strain is larger is because the calculated yield strength decreases greatly and the plastic work increases due to the backward shift of the representative stress point. The inversion analysis method for coatings is still equally applicable and the obtained constitutive equation of the coating is highly accurate and the method is reliable. |
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