PTFE基复合材料中混合填料对摩擦学性能影响的数值模拟研究
发布时间：2018-11-04 17:00
【摘要】：聚合物基复合材料在与金属表面发生相对滑动的过程中,会在对偶件金属表面形成一层转移膜,转移膜的质量对于提高复合材料的摩擦学性能具有十分重要的意义。研究发现转移膜的形成是一个伴随着局部碎片脱落和再修复的动态过程,了解其动态变化过程对于研究转移膜的形成机理及其对摩擦学性能的影响至关重要,但由于一般的实验条件的限制,很难观察到转移膜的动态形成过程,这也在一定程度上制约了对聚合物材料摩擦学性能的研究。鉴于此,本文利用基于离散元法开发的二维颗粒流软件(PFC2D)建立了PTFE复合材料/45#钢摩擦副系统的摩擦磨损离散元计算模型,再现了PTFE与45#钢的动态摩擦过程。在此基础上,重点探究了复合材料中混合填料Cu、石墨的添加对PTFE复合材料磨损性能、转移性能、转移膜粘结强度、摩擦系数以及相关的力学性能(压缩性能、剪切性能)的影响。并运用统计学中的相关性分析研究了PTFE复合材料的磨损性能、摩擦系数分别与转移膜粘结强度、材料的压缩强度、剪切强度之间的相关性。基于以上研究,本文主要得出如下创新性结论:(1)在PTFE与45#钢滑动摩擦过程中,45#钢粗糙表面会对PTFE产生剪切挤压作用,使位于接触表面的PTFE被拖拽下来形成PTFE碎片,部分脱落的碎片粘附于对偶件表面从而形成转移膜。随着摩擦的进行,转移膜逐渐趋于稳定,稳定的转移膜能够有效地减小摩擦、降低磨损。且转移膜的形成并不是一成不变的静态过程,而是一个伴随着转移颗粒不断脱落与再修复的动态过程。(2)复合材料中的混合填料Cu、石墨对其摩擦学性能具有显著的影响,转移颗粒数随着混合填料中Cu质量分数的增加而增加,辅助填料石墨的加入能够在一定程度上增加转移颗粒数,混合填料对形成的转移膜粘结强度具有类似的影响;混合填料的加入能够有效地改善PTFE的磨损性能,磨损量随Cu含量的增加而减小,而石墨对其的增强效果对载荷具有一定的敏感性;复合材料的宏观摩擦系数随着混合填料中Cu含量的增加而增大,石墨的加入能够有效降低摩擦系数。(3)复合材料中的混合填料Cu、石墨对复合材料的压缩性能、剪切性能影响明显。两种性能均随着填料中Cu质量分数的增加而增强。辅助填料石墨的加入能在一定程度上提高复合材料的压缩性能,且这种增强效果随着混合填料中Cu含量的增加而递减。而石墨对复合材料剪切性能的影响较为复杂,其影响效果随着混合填料中Cu含量的增加先增强后减弱。(4)通过对复合材料的摩擦学性能与力学性能的相关性分析发现,材料的磨损性能与其转移膜粘结强度、材料的压缩强度之间的相关关系较强,而摩擦系数仅与材料的剪切强度之间存在较为显著的相关关系。
[Abstract]:In the process of relative sliding between polymer matrix composite and metal surface, a transfer film will be formed on the metal surface of the dual part. The quality of the transfer film is very important for improving the tribological properties of the composite. It is found that the formation of the transfer film is a dynamic process accompanied by local shedding and rerepair. It is very important to understand the dynamic process of the film formation mechanism and its influence on the tribological properties. However, due to the limitation of general experimental conditions, it is difficult to observe the dynamic forming process of the transfer film, which to some extent restricts the study of the tribological properties of polymer materials. In this paper, the discrete element model of friction and wear of PTFE composite / 4steel friction pair system is established by using two-dimensional particle flow software (PFC2D) based on discrete element method, and the dynamic friction process between PTFE and 4steel is reproduced. On this basis, the wear properties, bond strength, friction coefficient and related mechanical properties of PTFE composites with the addition of Cu, graphite were investigated. Shear properties). The correlation between the friction coefficient and the adhesive strength of the transfer film, the compressive strength and the shear strength of the PTFE composite was studied by statistical correlation analysis. Based on the above research, the main conclusions are as follows: (1) in the process of sliding friction between PTFE and 4steel, the rough surface of 4steel will shearing and extruding PTFE, and the PTFE located on the contact surface will be dragged down to form PTFE fragments. Partially shedding debris adheres to the surface of the dual part to form a transfer film. With the development of friction, the transfer film tends to be stable, and the stable transfer film can effectively reduce friction and wear. Moreover, the formation of the transfer film is not a static process, but a dynamic process accompanied by the continuous shedding and rerepair of the transfer particles. (2) the Cu, graphite, a mixed filler in the composite, has a significant effect on the tribological properties of the composite. The number of transfer particles increases with the increase of Cu mass fraction in the mixed filler, and the number of transferred particles can be increased to a certain extent by the addition of the auxiliary filler graphite, and the bonding strength of the transfer film formed by the mixed filler has a similar effect. The addition of mixed filler can improve the wear performance of PTFE effectively, and the wear rate decreases with the increase of Cu content, while graphite has a certain sensitivity to the load. The macroscopic friction coefficient of the composite increases with the increase of Cu content in the mixed filler, and the addition of graphite can effectively reduce the friction coefficient. (3) Compression properties of Cu, graphite, the mixed filler in the composite, increase with the increase of the content of Cu, in the composite. The shear properties are obviously affected. Both properties were enhanced with the increase of mass fraction of Cu in filler. The compressive properties of the composites can be improved to a certain extent by the addition of auxiliary filler graphite, and the reinforcement effect decreases with the increase of Cu content in the mixed filler. However, the influence of graphite on the shear properties of composites is more complex, and the effect of graphite on the shear properties of composites increases firstly and then weakens with the increase of Cu content. (4) the correlation analysis of tribological properties and mechanical properties of composites is made. There is a strong correlation between the wear performance of the material and the bond strength of the transfer film and the compressive strength of the material, while the friction coefficient only has a significant correlation with the shear strength of the material.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33
本文编号：2310541
[Abstract]:In the process of relative sliding between polymer matrix composite and metal surface, a transfer film will be formed on the metal surface of the dual part. The quality of the transfer film is very important for improving the tribological properties of the composite. It is found that the formation of the transfer film is a dynamic process accompanied by local shedding and rerepair. It is very important to understand the dynamic process of the film formation mechanism and its influence on the tribological properties. However, due to the limitation of general experimental conditions, it is difficult to observe the dynamic forming process of the transfer film, which to some extent restricts the study of the tribological properties of polymer materials. In this paper, the discrete element model of friction and wear of PTFE composite / 4steel friction pair system is established by using two-dimensional particle flow software (PFC2D) based on discrete element method, and the dynamic friction process between PTFE and 4steel is reproduced. On this basis, the wear properties, bond strength, friction coefficient and related mechanical properties of PTFE composites with the addition of Cu, graphite were investigated. Shear properties). The correlation between the friction coefficient and the adhesive strength of the transfer film, the compressive strength and the shear strength of the PTFE composite was studied by statistical correlation analysis. Based on the above research, the main conclusions are as follows: (1) in the process of sliding friction between PTFE and 4steel, the rough surface of 4steel will shearing and extruding PTFE, and the PTFE located on the contact surface will be dragged down to form PTFE fragments. Partially shedding debris adheres to the surface of the dual part to form a transfer film. With the development of friction, the transfer film tends to be stable, and the stable transfer film can effectively reduce friction and wear. Moreover, the formation of the transfer film is not a static process, but a dynamic process accompanied by the continuous shedding and rerepair of the transfer particles. (2) the Cu, graphite, a mixed filler in the composite, has a significant effect on the tribological properties of the composite. The number of transfer particles increases with the increase of Cu mass fraction in the mixed filler, and the number of transferred particles can be increased to a certain extent by the addition of the auxiliary filler graphite, and the bonding strength of the transfer film formed by the mixed filler has a similar effect. The addition of mixed filler can improve the wear performance of PTFE effectively, and the wear rate decreases with the increase of Cu content, while graphite has a certain sensitivity to the load. The macroscopic friction coefficient of the composite increases with the increase of Cu content in the mixed filler, and the addition of graphite can effectively reduce the friction coefficient. (3) Compression properties of Cu, graphite, the mixed filler in the composite, increase with the increase of the content of Cu, in the composite. The shear properties are obviously affected. Both properties were enhanced with the increase of mass fraction of Cu in filler. The compressive properties of the composites can be improved to a certain extent by the addition of auxiliary filler graphite, and the reinforcement effect decreases with the increase of Cu content in the mixed filler. However, the influence of graphite on the shear properties of composites is more complex, and the effect of graphite on the shear properties of composites increases firstly and then weakens with the increase of Cu content. (4) the correlation analysis of tribological properties and mechanical properties of composites is made. There is a strong correlation between the wear performance of the material and the bond strength of the transfer film and the compressive strength of the material, while the friction coefficient only has a significant correlation with the shear strength of the material.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33
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