Case Study of Additively Manufactured Mountain Bike Stem.

This article is focused on a case study of the topology optimisation of a bike stem manufactured by selective laser melting (SLM) additive technology. Topology optimisation was used as a design tool to model a part with less material used for transferring specific loads than the conventional method. For topology optimisation, Siemens NX 12 software was used with loads defined from the ISO 4210-5 standard. Post-processing of the topology-optimised shape was performed in Altair Inspire software. For this case study, the aluminium alloy AlSi10Mg was selected. For qualitative evaluation, the mechanical properties of the chosen alloy were measured on the tensile specimens. The design of the new bike stem was evaluated by Ansys FEA software with static loadings defined by ISO 4210-5. The functionality of the additively manufactured bike stem was confirmed by actual experiments defined by ISO 4210-5. The resulting new design of the bike stem passed both static tests and is 7.9% lighter than that of the reference.

Development of an additively-manufactured functionally-graded expandable implant via the application of the adaptive response surface method: feasibility study on intramedullary humerus nail.

The paper introduces the concept of the rational design of a deployable humeral intramedullary nail plug based on a honeycomb structure used for the surgical treatment of humeral shaft fractures. The concept serves for to restore the axial alignment of bone fragments and to maintain stability via bone-nail friction and locking screws. The design nail plug was gained by optimisation process the Latin Hypercube Sampling Design algorithm and Multi-Objective Genetic Algorithm. It was shown that we can use statistical shape function combined by 3 D printing for designing of a new rationally designed implants.

Alumina Manufactured by Fused Filament Fabrication: A Comprehensive Study of Mechanical Properties and Porosity.

This article deals with a comprehensive study of the processing and mechanical properties of the ceramic material Al2O3 on Fused Filament Fabrication technology (FFF). It describes the basic input analyses of the material, such as TGA, FTIR, and MVR. These analyses enabled the design and testing of process parameters for the 3D printing of parts. The article also presents the post-processes, including the technological parameters required to finalize parts made from this material, i.e., chemical debinding in acetone at elevated temperatures + thermal debinding and sintering. The microhardness was measured on the processed samples, depending on the density of the inner filling. The resulting hardness had an almost linear relationship between the percentage of filler (20-40-60-80-100%) and the resulting microhardness (1382-2428 HV10). Flexural strength was also measured on the test specimens with different degrees of internal filling (80-90-100%). However, inner filling do not affect the flexural strength (316.12-327.84-331.61 MPa). The relative density of the final parts was measured on a ZEISS METROTOM 1500 CT machine and reached 99.54%.

Influence of Selective Laser Melting Technology Process Parameters on Porosity and Hardness of AISI H13 Tool Steel: Statistical Approach.

The correct setting of laser beam parameters and scanning strategy for Selective Laser Melting (SLM) technology is a demanding process. Usually, numerous experimental procedures must be taken before the final strategy can be applied. The presented work deals with SLM technology and the impact of its technological parameters on the porosity and hardness of AISI H13 tool steel. In this study, we attempted to map the dependency of porosity and hardness of the tested tool steel on a broad spectrum of scanning speed-laser power combinations. Cubic samples were fabricated under parameters defined by full factorial DOE, and metallurgic specimens were prepared for measurement of the two studied quantities. The gathered data were finally analyzed, and phenomenological models were proposed. Analysis of the data revealed a minimal energy density of 100.3 J/mm3 was needed to obtain a dense structure with a satisfactory hardness level. Apart from this, the model may be used for approximation of non-tested combinations of input parameters.

Mechanical Properties of Polypropylene: Additive Manufacturing by Multi Jet Fusion Technology.

Multi jet fusion (MJF) technology has proven its significance in recent years as this technology has continually increased its market share. Recently, polypropylene (PP) was introduced by Hewlett-Packard for the given technology. To our knowledge, little is known about the mechanical properties of polypropylene processed by MJF technology. During this study, standardised specimens were printed under all of the major orientations of the machine's build space. Each of these orientations were represented by five samples. The specimens then underwent tensile, bending and Charpy impact tests to analyse their mechanical properties. The structural analysis was conducted to determine whether PP powder may be reused within the MJF process. The mechanical tests showed that the orientation of the samples significantly influences their mechanical response and must be carefully chosen to obtain the optimal mechanical properties of PP samples. We further showed that PP powder may be reused as the MJF process does not significantly alter its thermal and structural properties.

How does the surface treatment change the cytocompatibility of implants made by selective laser melting?

INTRODUCTION: The study investigates the potential for producing medical components via Selective Laser Melting technology (SLM). The material tested consisted of the biocompatible titanium alloy Ti6Al4V. The research involved the testing of laboratory specimens produced using SLM technology both in vitro and for surface roughness. The aim of the research was to clarify whether SLM technology affects the cytocompatibility of implants and, thus, whether SLM implants provide suitable candidates for medical use following zero or minimum post-fabrication treatment. Areas covered: The specimens were tested with an osteoblast cell line and, subsequently, two post-treatment processes were compared: non-treated (as-fabricated) and glass-blasted. Interactions with MG-63 cells were evaluated by means of metabolic MTT assay and microscope techniques (scanning electron microscopy, fluorescence microscopy). Surface roughness was observed on both the non-treated and glass-blasted SLM specimens. Expert Commentary: The research concluded that the glass-blasting of SLM Ti6Al4V significantly reduces surface roughness. The arithmetic mean roughness Ra was calculated at 3.4 µm for the glass-blasted and 13.3 µm for the non-treated surfaces. However, the results of in vitro testing revealed that the non-treated surface was better suited to cell growth.