Modeling Fracture Formation, Behavior and Mechanics of Polymeric Materials: A Biomedical Implant Perspective

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.

Comprehensive Review on Biomaterials and Their Inherent Behaviors for Hip Repair Applications

“…208 Several investigations have determined that PTFE is nontoxic to the host body, has a low coefficient of friction, is hydrophobic, and has remarkable heat stability. 209 However, in recent years, PTFE has not been the preferred material for hip surgeries because of its high wear rate (estimated at 0.5 mm per month) and vast masses of amorphous foreign material emission that generate significant tissue reactions in human cells. 210 Additionally, the continuous increment of particle production decreases compressive strength and stiffness and induces rapid wear during sliding.…”

“…Charnley adapted the PTFE acetabular cup and stainless-steel femoral head in the early 1960s . Several investigations have determined that PTFE is nontoxic to the host body, has a low coefficient of friction, is hydrophobic, and has remarkable heat stability . However, in recent years, PTFE has not been the preferred material for hip surgeries because of its high wear rate (estimated at 0.5 mm per month) and vast masses of amorphous foreign material emission that generate significant tissue reactions in human cells .…”

Properties of Ultra-High Molecular Weight Polyethylene Produced by Cyclic Impact Compaction and Reinforced with Graphene Nanoplatelets and Single-Walled Carbon Nanotubes

“…The ultra-high molecular weight polyethylene (UHMWPE) has a number of remarkable properties that make it suitable for a wide range of applications in industry and medicine. It is a proper material for manufacturing various parts of machines, mechanisms and devices, shoulder and hip implants and for defective bone replacement along with polytetrafluoroethylene (PTFE) [1][2][3][4][5][6]. UHMWPE is highly resistant to impact, so it is also used for protection against penetration by metallic projectiles, especially when it is reinforced with various additives and inserts [7][8][9][10].…”

Molybdenum disulfide nanosheet/polyimide composites with improved tribological performances, surface properties, antibacterial effects and osteogenesis for facilitating osseointegration

“…1,2 Among them, polymeric composites possess some potential advantages for application as orthopaedic implants due to the limitation of single materials in chemical, physical and biological properties. 3,4 Particularly, varying the elastic properties of polymeric composites exhibits mechanical compatibility with the host bone while maintaining high strength as well as durability. 5 Therefore, polymeric composites are regarded as a promising candidate for bone repair due to their advantages over most metals and ceramics; furthermore, this led to interest in the use of polymeric composites for artificial joint applications, such as hips, knees, shoulders and ankles.…”