织构化涂层表面的黏附接触力学行为研究

Adhesive Contact Mechanical Behaviors of the Textured Coating Surface

目的建立刚性微球与织构化涂层表面黏附接触数值分析模型,探究织构化涂层属性对微观接触副黏附力学性能的影响。方法基于Hamaker求和法以及Lennard–Jones势能定律,考虑织构高度对接触体间距离分布的影响以及涂层、织构材料属性对接触体间黏附力的影响,建立织构化涂层表面黏附接触力学模型并验证所提模型。基于所提模型,研究不同Tabor数下织构形貌、密度、高度以及涂层厚度对接触系统黏附力学性能的影响。结果在相同参数下,圆柱型织构黏附力最大,半椭球型织构次之,四棱锥型织构最小。织构密度从200μm^(‒2)增加到4000μm^(‒2)时,最大黏附力随着织构密度的增加而增加,圆柱型织构增加约5~6倍,四棱锥型织构增加约1.5倍。随着织构高度从1ε_(bs)增加至30εbs,最大黏附力减小,四棱锥型织构减小最多,约为原来的1%,圆柱形织构减小最少,约为原来的90%。涂层厚度能够影响黏附力的大小,但影响规律与织构化涂层的Tabor数及织构高度相关。随着涂层厚度从1ε_(bs)增加至16ε_(bs),大Tabor数时黏附力逐渐增加,小Tabor数时黏附力逐渐减小。Tabor数较大、织构高度较小时,黏附力–接近距离曲线会出现2次峰值。结论揭示了织构形貌、密度、高度及涂层厚度对接触系统黏附力学性能的影响,总结了黏附力与最大黏附力的变化规律,所得规律可为工程实践中的黏附微纳米结构设计与应用提供理论指导。

Dry adhesion is demonstrated as one of the best ways to realize attachment on space irregular objects and space cruise,as a result of its reliable adhesive ability when exposed to the vacuum and high or low-temperature atmosphere,and its unnecessity of chemical medium or electromagnetic filed.Traditional measures,including coating and texture technique,are utilized to realize higher adhesive force,however,interface high adhesion and mechanical reliability are difficult to realize at the same time.Hence,a new method named textured coating technique trying to process textures on the coating is proposed in this paper such that the interface comprehensive mechanical properties can meet the requirements.Furthermore,a new numerical adhesive contact model of textured coating surface was established to explore the influence of the textured coating on the adhesive mechanical properties of micro contact pairs.The results can be utilized to help instruct the design of the proposed textured coating technique.Based on the Hamaker summation method and Lennard-Jones potential law,the adhesion contact model of textured coating surface was constructed by considering the effects of textures height on the approach distribution between two contact bodies and the effects of coating and texture properties on the adhesive force.The model was validated with the numerical results from existing literature.Based on the proposed model,the effects of texture types,texture density,texture height,and coating thickness on the adhesive properties under two typical Tabor parameters are investigated.The influences of different materials represented by two kinds of Tabor parameters on the adhesive force are revealed.Three different kinds of textures,including ellipsoid-shaped texture,pyramid-shaped texture and cylinder-shaped texture are selected to explore the effects of texture types on adhesive behaviors.Results showed that cylinder-shaped texture corresponds to the biggest pull-off force,followed by ellipsoid-shaped texture and pyramid-shaped texture under the same conditions.When the texture density increases from 200μm^(‒2) to 4000μm^(‒2),the pull-off force of three kinds of textures increases gradually.Cylinder-shaped texture increases by about 5~6 times and pyramid-shaped texture increases by about 1.5 times of the original.With the increase of texture height from 1εbs to 30εbs,the pull-off forces of three kinds of texture decrease gradually.Pyramid-shaped texture decreases to 1%of the original with the largest decrease proportion and the cylinder-shaped decreases the least,about 90%of the original.The coating thickness has an influence on the adhesion force but the effects are related to the Tabor parameters and texture height.The pull-off force increases gradually at a large Tabor parameter but decreases gradually at a small Tabor parameter with the coating thickness increasing from 1ε_(bs) to 16ε_(bs).At larger Tabor parameter and bigger texture height,a secondary peak occurs in the adhesive force versus approach curves.All in all,the effects of texture types,density,height and coating thickness on the adhesive mechanical properties are revealed and the variation law of adhesive force and the pull-off force are summarized.The obtained results can provide theoretical guidance for the design and application of the adhesion mechanical structure of micro or nano texture surfaces in engineering practice.