Abstract
In industrial applications where contact behavior of materials is characterized, fretting-associated fatigue plays a vital role as a failure agitator. While considering connection, it encounters friction. Biomaterials like polytetrafluoroethylene (PTFE) and ultra-high-molecular-weight polyethylene (UHMWPE) are renowned for their low coefficient of friction and are utilized in sophisticated functions like the hip joint cup and other biomedical implants. In addition to the axial stresses, some degree of dynamic bending stress is also developed occasionally in those fretting contacts. This research investigated the fracture behavior of a polymer PTFE under bending fretting fatigue. Finite element analysis justified the experimental results. A mathematical model is proposed by developing an empirical equation for fracture characterization in polymers like PTFE. It was found that the bending stiffness exists below the loading point ratio (LPR) 3.0, near the collar section of the specimen. Along with fretting, the bending load forces the specimen to crack in a brittle-ductile mode near the sharp-edged collar where the maximum strain rate, as well as stress, builds up. For a loading point ratio of above 3, a fracture takes place near the fretting pads in a tensile-brittle mode. Strain proportionality factor, k was found as a life optimization parameter under conditional loading. The microscopic analysis revealed that the fracture striation initiates perpendicularly to the fretting load. The fretting fatigue damage characteristic of PTFE may have a new era for the biomedical application of polymer-based composite materials.
Highlights
Fretting fatigue is a type of wear process that takes place in contact pairs, joints under static or dynamic cyclic stresses [1]
It is solid at room temperature and has one of the lowest coefficien2tsofo1f6 friction of any solid
Synthetic polymers are made by step-growth polymerization and chain polymerization methods. These materials show superior mechanical performance and that is why their applications are seen in transportation, medicine and construction [28,29,30,31,32]
Summary
Fretting fatigue is a type of wear process that takes place in contact pairs, joints under static or dynamic cyclic stresses [1]. Compared to other material, the composite showed a higher rate of infection and loosening The materials those will be used as hip implant must be highly non-toxic, and should not cause any inflammatory or allergic reactions in the human tissues or cells, high corrosion- and wear resistant, should have excellent thermal conductivity, high strength, high fracture toughness, hardness, biocompatibility, and high stiffness [33]. Iatnisdlosaydnetdhbeytica psouicnht loaasd F at polyethylene, polypthroe pfryeeleenned,apnodltywsotyfrreetntien,g ppaodlys vatinl ydilstcahnlcoerfirdome, tshyenotthheertiecndr.uTbhbeerre,stpohfethnioslend is formaldehyde resinc,onseiodperreednaes,anfiyxleodnsueptcp.orSt.ynthetic polymers are made by step-growth polymerization and chain polymerization methods These materials show superior mechanical performance and that is why their applications are seen in transportation, medicine and construction [28,29,30,31,32]. This aspect could be researched in greater scope in the future It is just an interpretation of fretting failure characterization of biomedical implants under variable loading point and stain ratios. It is a new idea, and may require more research in the laboratory
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