Iskanje po katalogu digitalne knjižnice

Opis: Metals with certain porosity are a new class of materials with extremely low density and a unique combination of excellent mechanical, thermal, electrical, and biocompatible properties. Absorption of impact and shock energy, dust and fluid filtration, construction materials, and most importantly, biocompatible implants are all potential applications for metallic foams. An orthopaedic implant made of metallic foam can provide an open-cell structure that allows for the ingrowth of new bone tissue and the transport of body fluids. Due to its strong biocompatibility and stable fixation between the implant and human bone, titanium foam has recently received much attention as an implant material. Finite element modelling is a suitable method to obtain an efficiently designed implant. Accurate finite element analyses depend on the precision before implementation as well as the functionality of the material properties employed. Since the mechanical performances of titanium foam and solid titanium are different, a constitutive model for porous metal is required. The model of Deshpande and Fleck in the finite element analysis software ABAQUS is used to describe the compressive and flexural deformation properties of titanium foam with 63.5% porosity. The finite element simulation results were compared with the practical mechanical properties obtained by compression testing of the foam. Finally, the material modelling was used to investigate the stress distributions on the dental implant system.
Ključne besede: finite element analysis, ABAQUS, titanium foam, sintering, dental implant, material modeling, mechanical properties, bending, compressing
Objavljeno v DKUM: 25.09.2024; Ogledov: 0; Prenosov: 3
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Opis: Strain rate hardening caused by the changed deformation mode is a fascinating phenomenon in cellular metamaterials where the material’s stiffness and energy absorption capabilities increase as the strain rate increases. This unique behaviour is attributed to a combination of micro-inertia effects, base material’s strain rate hardening and inertia effects. At high strain rates, the metamaterial’s inertia influences its deformation response, which changes to shock mode. This work briefly presents the geometry and fabrication of different metallic metamaterials. Then, it evaluates their mechanical response at different strain rates, ranging from quasi-static to intermediate dynamic and shock, determined by experimental and computational investigation. The three deformation modes can be separated into two critical loading velocities, unique for each metamaterial, which are also presented and compared in this work for various metamaterials. The investigations show that the deformation mode change in metallic metamaterials depends on their porosity. The critical velocities separating the deformation modes decrease with increasing porosity, i.e., decreased density of the metamaterial results in reduced critical loading velocities. The shock deformation mode in cellular metamaterials is thus attainable at much lower loading velocities than in homogeneous (nonporous) materials.
Ključne besede: metamaterials, cellular structures, high strain rate, experimental testing, computational modelling, compression loading, mechanical properties
Objavljeno v DKUM: 22.05.2024; Ogledov: 204; Prenosov: 17
Celotno besedilo (3,42 MB)
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Ključne besede: magnetic nanoparticles, 3D-printed scaffolds, iron oxide nanoparticles, mechanical properties, cellular responses
Objavljeno v DKUM: 20.05.2024; Ogledov: 195; Prenosov: 13
Celotno besedilo (2,03 MB)
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Opis: The production of personal protective equipment (PPE) has increased dramatically in recent years, not only because of the pandemic, but also because of stricter legislation in the field of Employee Protection. The increasing use of PPE, including disposable surgical masks (DSMs), is putting additional pressure on waste collectors. For this reason, it is necessary to find high-quality solutions for this type of waste. Mechanical recycling is still the most common type of recycling, but the recyclates are often classified as low-grade materials. For this reason, a detailed analysis of the recyclates is necessary. These data will help us to improve the properties and find the right end application that will increase the value of the materials. This work represents an extended analysis of the recyclates obtained from DSMs, manufactured from different polymers. Using surface and morphology tests, we have gained insights into the distribution of different polymers in polymer blends and their effects on mechanical and surface properties. It was found that the addition of ear loop material to the PP melt makes the material tougher. In the polymer blends obtained, PP and PA 6 form the surface (affects surface properties), while PU and PET are distributed mainly inside the injection-molded samples.
Ključne besede: mechanical recycling, disposable surgical mask, morphology, surface properties, mechanical properties, nonwoven materials, PPE
Objavljeno v DKUM: 09.04.2024; Ogledov: 232; Prenosov: 15
Celotno besedilo (8,08 MB)
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Opis: This study explores the potential of using basalt reinforced UHPC by incorporating simultaneously self-cleaning and self-luminescent features, paving the way for sustainable advancements in civil engineering. New green formulations of UHPC were developed by integrating supplementary cementitious materials and optimizing water to the binder ratio, followed by using basalt fibers to enhance strength and ductility. The fabricated samples with high particle-packing density exhibit sufficient workability and compressive strength up to 136 MPa, and, when incorporating basalt fibers, a notable reduction in brittleness. The inner microstructure of basalt fibers was observed to be smooth, homogeneously distributed, and well adhered to the UHPC matrix. To ensure the desired long-lasting visual appearance of decorative UHPC and reduce future maintenance costs, a time-effective strategy for creating a light-emitting biomimetic surface design was introduced. The samples exhibit high surface roughness, characterized by micro to nano-scale voids, displaying superhydrophobicity with contact angles reaching up to 155.45°. This is accompanied by roll-off angles decreasing to 7.1°, highlighting their self-cleaning features. The self-luminescence feature showcased intense initial light emission, offering a potential energy-efficient nighttime lighting solutio
Ključne besede: UHPC, basalt fibers, mechanical properties, morphology, superhydrophobic, self-luminescence
Objavljeno v DKUM: 29.01.2024; Ogledov: 368; Prenosov: 17
Celotno besedilo (14,47 MB)