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The Direct Metal Laser Sintering (DMLS) process is widely used for biomedical applications and to fabricate Cellular Structures (CS). Titanium alloy (Ti64) CS were modelled as a honeycomb structure with variations in pore diameters (0.8 mm, 0.9 mm and 1.0 mm) and interpore distances (1.6 mm, 1.7 mm and 1.8 mm) in this research work. The maxillofaci...
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... Because material flow under any loading condition can be most effectively determined by von Mises stress. 41 For stress-shielding analysis, the femoral bone was divided into eight equal zones, each 15 mm long, from the starting point of the femoral head cut (in the vertical plane) to the distal end of the implanted hip stem. In addition, this femur bone was divided into two parts again from the intersection of the medial and lateral sides, and a total of 16 zones were obtained, 8 zones on the medial side and 8 zones on the lateral side. ...
... Similarly, von Mises stress was used in the evaluation of porous materials in many studies in the literature. 41,[53][54][55][56][57][58][59] Moreover, the von Mises stresses on the implanted hip stem are an important indication in assessing the transfer of load from the hip For this reason, it was considered that it would be more accurate to evaluate von Mises stress distribution graphs according to their scales. As seen in Figure 3(b) to (d), the stress was concentrated in the neck region and was mostly distributed along the shell of the medial side of the hip implant stem. ...
The term stress-shielding is frequently used to mention the reduction in mechanical stimulus in the surrounding bone due to the presence of a biomaterial inert implant whose mechanical properties are superior to bone. As the natural consequence of this, mineral loss occurs in the bone over time and creating subsequent weakness. One of the methods to reduce stress-shielding problem is to develop hip-stem implant designs that will transfer the load more to the bone. Therefore, in this study, multi-lattice designs were developed to reduce the stress-shielding effect in hip implant applications. For this, the proximal part of the hip implant stems has been divided into three parts. Simple cubic, body centered cubic, and face centered cubic lattice structures were created on the upper parts. Inner vertical and inner vertical + inner horizontal beams were added to the lattice structure of the upper part for middle and lower parts, respectively. Due to the multi-lattice designs, the maximum von Mises stress values on the hip implant stem were reduced from 289 to 189 MPa, as well as a weight reduction of up to 25.89%. Stress-shielding signals were obtained by determining the change in strain energy per unit bone mass caused by the presence of the femoral hip implant stem and its ratio to intact bone. In the case of using hip-stems having multi-lattice designs, there is a significant increase (max. 150.47%) in stress-shielding signals from different zones of the femur.
The commonly used titanium alloy dental implants currently apply solid structures. However, issues such as stress shielding and stress concentration may arise due to the significant difference in elastic modulus between the implant and host. In order to address these problems, this paper proposes five porous structures based on the Gibson-Ashby theoretical model. We utilized selective laser melting technology to shape a porous structure using Ti-6Al-4V material precisely. The mechanical properties of the porous structure were verified through simulation and compression experiments. The optimal porous structure, which best matched the human bone, was a circular ring structure with a pillar diameter of 0.6mm and a layer height of 2mm. The stress and strain of the porous implant on the surrounding cortical and cancellous bone under different biting conditions were studied to verify the effectiveness of the optimal circular ring porous structure in alleviating stress shielding in both standard and osteoporotic bone conditions. The results confirm that the circular ring porous structure meets implant requirements and provides a theoretical basis for clinical dental implantation.
Trabecular bone, a porous and spongy kind of bone tissue composed of a lattice of connecting rods and/or plates, is crucial for the transfer of weight in crucial joints including the spine, hip, and knee. It is impacted by a variety of metabolic bone illnesses, such as osteoporosis, which result in bone loss, reduced bone strength, and an elevated risk of bone fracture. To promote osseointegration due to the permeable porous, we suggest, in this study, a new approach to design a femoral permeable porous implant to achieve suitable stiffness, lightweight, and biocompatibility for the bone. Accordingly, data are collected from a digital bio-model to design a femoral implant for mimics segmental bone defect (SBD) with a biocompatible material Ti6Al4V (Ti64). To do this, three lattice structures (LSs) are compared and derived from implicit surface modeling called a triply periodic minimal surface (TPMS) to obtain the LS suitable to create it within the solid inner volume of the tibia implant. Thus, performed the finite element analysis (FEA) method for the enhanced Designs and compare them in terms of stress, deformation, and lightweight.
