The stone chip resistance performance of automotive coatings has attracted increasing attention in academic and industrial communities.Even though traditional gravelometer tests can be used to evaluate stone chip resi...The stone chip resistance performance of automotive coatings has attracted increasing attention in academic and industrial communities.Even though traditional gravelometer tests can be used to evaluate stone chip resistance of automotive coatings,such experiment-based methods suffer from poor repeatability and high cost.The main purpose of this work is to develop a CFD-DEM-wear coupling method to accurately and efficiently simulate stone chipbehaviorof automotive coatings inagravelometer test.Toachieve this end,an approach coupling an unresolved computational fluid dynamics(CFD)method and a discrete element method(DEM)are employed to account for interactions between fluids and large particles.In order to accurately describe large particles,a rigid connection particle method is proposed.In doing so,each actual non-spherical particle can be approximately described by rigidly connecting a group of non-overlapping spheres,and particle-fluid interactions are simulated based on each component sphere.An erosion wear model is used to calculate the impact damage of coatings based on particlecoating interactions.Single spherical particle tests are performed to demonstrate the feasibility of the proposed rigid connection particle method under various air pressure conditions.Then,the developed CFD-DEM-wear model is applied to reproduce the stone chip behavior of two standard tests,i.e.,DIN 55996-1 and SAE-J400-2002 tests.Numerical results are found to be in good agreement with experimental data,which demonstrates the capacity of our developed method in stone chip resistance evaluation.Finally,parametric studies are conducted to numerically investigate the influences of initial velocity and test panel orientation on impact damage of automotive coatings.展开更多
This research explores Microwave Plasma Chemical Vapor Deposition (MPCVD) for depositing diamond films on steel alloys (316L, 4140, and 1018) with a vanadium carbide interlayer to enhance adhesion and compatibility. T...This research explores Microwave Plasma Chemical Vapor Deposition (MPCVD) for depositing diamond films on steel alloys (316L, 4140, and 1018) with a vanadium carbide interlayer to enhance adhesion and compatibility. The study reveals that a soft vanadium carbide interlayer and the FCC lattice match lead to a Ta-C film. The results of the graphite inhibition and diamond deposition varied with the steel alloy underlayer composition. In the 316L steel alloy, we successfully formed a thick, compressive strain-induced, sp3-bonded tetrahedral amorphous carbon layer without graphite. The findings have wide-ranging applications in environments demanding high durability and thermal conductivity.展开更多
基金supported by the National Key R&D Program of China(No.2017YFE0117300)the Science and Technology Planning Project of Guangzhou(No.201804020065)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.311021013).
文摘The stone chip resistance performance of automotive coatings has attracted increasing attention in academic and industrial communities.Even though traditional gravelometer tests can be used to evaluate stone chip resistance of automotive coatings,such experiment-based methods suffer from poor repeatability and high cost.The main purpose of this work is to develop a CFD-DEM-wear coupling method to accurately and efficiently simulate stone chipbehaviorof automotive coatings inagravelometer test.Toachieve this end,an approach coupling an unresolved computational fluid dynamics(CFD)method and a discrete element method(DEM)are employed to account for interactions between fluids and large particles.In order to accurately describe large particles,a rigid connection particle method is proposed.In doing so,each actual non-spherical particle can be approximately described by rigidly connecting a group of non-overlapping spheres,and particle-fluid interactions are simulated based on each component sphere.An erosion wear model is used to calculate the impact damage of coatings based on particlecoating interactions.Single spherical particle tests are performed to demonstrate the feasibility of the proposed rigid connection particle method under various air pressure conditions.Then,the developed CFD-DEM-wear model is applied to reproduce the stone chip behavior of two standard tests,i.e.,DIN 55996-1 and SAE-J400-2002 tests.Numerical results are found to be in good agreement with experimental data,which demonstrates the capacity of our developed method in stone chip resistance evaluation.Finally,parametric studies are conducted to numerically investigate the influences of initial velocity and test panel orientation on impact damage of automotive coatings.
文摘This research explores Microwave Plasma Chemical Vapor Deposition (MPCVD) for depositing diamond films on steel alloys (316L, 4140, and 1018) with a vanadium carbide interlayer to enhance adhesion and compatibility. The study reveals that a soft vanadium carbide interlayer and the FCC lattice match lead to a Ta-C film. The results of the graphite inhibition and diamond deposition varied with the steel alloy underlayer composition. In the 316L steel alloy, we successfully formed a thick, compressive strain-induced, sp3-bonded tetrahedral amorphous carbon layer without graphite. The findings have wide-ranging applications in environments demanding high durability and thermal conductivity.
