Post‐yielding fracture mechanics of 3D printed polymer‐based orthopedic cortical screws

Abstract

The internal fixation of a fractured bone is generally achieved with bone screws during most orthopedic surgeries. Biodegradable screws have not received as much attention as they deserve. Biodegradable screws reduce the stress‐shielding effect, screw failure, complex, painful revision surgery for screw extraction. The vital focus of the present research is to fabricate cortical bone screws using polylactic acid (PLA) by fused deposition modeling technology. The PLA cortical screws were manufactured with different infill patterns (triangular, honeycomb, grid, and concentric), keeping other parameters constant using three‐dimensional printing. The mechanical behavior and fracture mechanism of different patterned cortical screws were observed based on compression testing and tensile testing of screws. Scanning electron microscopy (SEM) observed the surface topographical features, fracture behavior, and microstructure characterization of different patterned polymeric cortical screws were observed using SEM. Based on the SEM micrographs, mechanical characterization of compression and tensile testing shows the stress, fractures and fatigue cracks propagation at the bone screw interfaces by fractures copy. Moreover, it was observed that the fracture mechanism of ductile to brittle fracture was observed with variation in the infill pattern of the bone screw. The outcomes revealed that the cortical screw with honeycomb infill pattern has the highest compressive and tensile strength than other infill patterns. Honeycomb structured cortical screws have approximately 17% higher compressive strength and 30% higher tensile strength than the triangular patterned cortical screw due to higher bonding surface area at the intercalated layers.

Influence of process parameters on mechanical strength, build time, and material consumption of 3D printed polylactic acid parts

“…Literature survey indicated that any variation in the FDM process parameters causes significant variation in the mechanical characteristics of the printed part. [ 16,17 ] Corral et al [ 18 ] also highlighted that very few studies have been available to investigate the surface part quality and tensile strength by varying nozzle diameter and print speed. Thus, most of the studies reported in literature focused on evaluation of mechanical performance of the prepared samples.…”

Development of artificial intelligence‐based neural network prediction model for responses of additive manufactured polylactic acid parts

“…During recent years, exploration of the FDM technique makes additive manufacturing process cost effective as it reduces the cost of making mold for small batch production, therefore, FDM has become choice for the small batch production. [10] Review of previous literature studies on mechanical properties [2,[11][12][13][14] and surface quality of FDM parts pointed that nozzle diameter, build orientation, infill density, raster pattern, layer height and print speed are significant parameters which decide the tensile strength, build time, material consumption and surface quality of FDM fabricated parts. [6,[15][16][17][18][19][20][21][22] These critical process parameters require further exploration to study the impact of these parameters on tensile strength, surface quality, material consumption, and build time.…”

“…The AM helps in resolving a number of issues of various fields like aerospace, biomedical, architecture, engineering, automotive, sports, and manufacturing. [2,3] A variety of materials like polymers, ceramic, metal, tissues, and cells, [4] can be shaped to desired product through rapid prototyping process. [5] Various additive manufacturing techniques like fused deposition modeling (FDM), selective laser sintering (SLS), stereolithography (STL), and laminated object manufacturing (LOM) have been introduced for the conversion of raw material into desired 3D products through AM.…”

Polymer composites: Additive manufacturing of composites

“…The papers published in this special issue of Polymer Composites give the polymer composites engineer insight into challenges that exist in the field of additive manufacturing (AM) of composites, the presentation of new materials and material systems, improvements on the resulting properties of 3D printed parts using existing manufacturing methods, new and novel applications of 3D printed polymer composite parts, and how problems that arise from these innovations are being addressed by the research community. [ 1–29 ]…”

“…Bio‐ and sustainability inspired research was a major theme, including the use of nature‐derived materials, green or environmentally friendly materials, sustainable applications, and medical applications. [ 1,10,14,19,20,25,27,29 ] The authors in [ 14,16,19 ] use biomaterials to enhance the properties of PLA material systems, Gupta [ 29 ] focuses on the fracture behavior of AM composite orthopedic cortical screws, and Wang [ 27 ] studies the fatigue behavior of a new natural rubber based composite system.…”