scholarly journals Simulated and Experimental Investigation of Mechanical Properties for Improving Isotropic Fracture Strength of 3D-Printed Capsules

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4677
Author(s):  
Taeuk Lim ◽  
Hao Cheng ◽  
Wonil Song ◽  
Jasung Lee ◽  
Sunghoon Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Strength ◽  
High Speed ◽  
Applied Load ◽  
Low Cost ◽  
Powder Layer ◽  
Strength Analysis ◽  
Self Healing ◽  
Compression Tests ◽  
3D Printed

Three-dimensional (3D) printer-based self-healing capsules, embedded in cement composites, were proposed to heal cracks, as they allow for various structural designs of capsules, repeatable fabrication, and strength analysis. Out of many 3D printing methods, such as fusion deposition modeling (FDM), powder layer fusion, and PolyJet printing, FDM was used to design, analyze, and produce new self-healing capsules, which are widely used due to their high-speed, low-cost, and precise manufacturing. However, the PLA extruded in the FDM had low adhesion energy between stacked layers, which caused a degradation of the performance of the self-healing capsule, because it had different strengths depending on the angle between the stacked layers and the applied load within the concrete structure. Therefore, in this paper, specimens were produced, in accordance with ASTM specifications, using the FDM PLA method, and mechanical properties were obtained through tensile, shear, and compression tests. Additionally, the isotropic fracture characteristics of the four types of capsules were analyzed through finite element method analysis. Subsequently, the 3D-printed capsules were produced, and the fracture strength was analyzed in the x, y and z directions of the applied load through a compression test. As a result, the newly proposed capsule design was verified to have an isotropic fracture strength value of 1400% in all directions compared to conventional spherical thin film capsules

scholarly journals Additively Manufactured Parts Made of a Polymer Material Used for the Experimental Verification of a Component of a High-Speed Machine with an Optimised Geometry—Preliminary Research

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 137
Author(s):  
Artur Andrearczyk ◽  
Bartlomiej Konieczny ◽  
Jerzy Sokołowski
Keyword(s):  
Polymer Material ◽  
High Speed ◽  
Numerical Models ◽  
Flow Analysis ◽  
Experimental Tests ◽  
Strength Analysis ◽  
Compressor Wheel ◽  
Operational Characteristics ◽  
3D Printed ◽  
Novel Method

This paper describes a novel method for the experimental validation of numerically optimised turbomachinery components. In the field of additive manufacturing, numerical models still need to be improved, especially with the experimental data. The paper presents the operational characteristics of a compressor wheel, measured during experimental research. The validation process included conducting a computational flow analysis and experimental tests of two compressor wheels: The aluminium wheel and the 3D printed wheel (made of a polymer material). The chosen manufacturing technology and the results obtained made it possible to determine the speed range in which the operation of the tested machine is stable. In addition, dynamic destructive tests were performed on the polymer disc and their results were compared with the results of the strength analysis. The tests were carried out at high rotational speeds (up to 120,000 rpm). The results of the research described above have proven the utility of this technology in the research and development of high-speed turbomachines operating at speeds up to 90,000 rpm. The research results obtained show that the technology used is suitable for multi-variant optimization of the tested machine part. This work has also contributed to the further development of numerical models.

scholarly journals GEOMETRY AND MECHANICAL PROPERTIES OF A 3D-PRINTED TITANIUM MICROSTRUCTURE

2018 ◽  
Vol 15 ◽  
pp. 104-108
Author(s):  
Luboš Řehounek ◽  
Petra Hájková ◽  
Petr Vakrčka ◽  
Aleš Jíra
Keyword(s):  
Mechanical Properties ◽  
3D Printing ◽  
Uniaxial Compression ◽  
Elastic Moduli ◽  
Weight Ratio ◽  
Porous Structures ◽  
Compression Tests ◽  
Local Material ◽  
3D Printed ◽  
Titanium Microstructure

Construction applications sometimes require use of a material other than construction steel or concrete – mainly in cases, where strength to weight ratio needs to be considered. A suitable solution to this problem are structures manufactured using the 3D printing process, as they have a very good strength to weight ratio (i.e.: Ti-6Al-4V – σ<sub>ult</sub> = 900 MPa and ρ = 4500 kg/m<sup>3</sup>). Trabecular structures are porous structures with local material characteristics identical to their commonly manufactured counterparts, but due to their geometry, they have different global mechanical properties and are suited for special applications. We designed and manufactured six variants of these structures and subjected them to uniaxial compression tests, nanoindentation tests and subsequently evaluated their differences and elastic moduli. The values of global moduli E are in the range of 2.55 GPa – 3.55 GPa for all specimens.

scholarly journals Development of synthetic simulators for endoscope-assisted repair of metopic and sagittal craniosynostosis

2018 ◽  
Vol 22 (2) ◽  
pp. 128-136 ◽  
Author(s):  
Kyle W. Eastwood ◽  
Vivek P. Bodani ◽  
Faizal A. Haji ◽  
Thomas Looi ◽  
Hani E. Naguib ◽  
...  
Keyword(s):  
High Speed ◽  
Low Cost ◽  
Subcutaneous Fat ◽  
Real Life ◽  
Minimal Amount ◽  
Sagittal Craniosynostosis ◽  
Actual Patient ◽  
Surface Anatomy ◽  
Teaching Content ◽  
3D Printed

OBJECTIVEEndoscope-assisted repair of craniosynostosis is a safe and efficacious alternative to open techniques. However, this procedure is challenging to learn, and there is significant variation in both its execution and outcomes. Surgical simulators may allow trainees to learn and practice this procedure prior to operating on an actual patient. The purpose of this study was to develop a realistic, relatively inexpensive simulator for endoscope-assisted repair of metopic and sagittal craniosynostosis and to evaluate the models’ fidelity and teaching content.METHODSTwo separate, 3D-printed, plastic powder–based replica skulls exhibiting metopic (age 1 month) and sagittal (age 2 months) craniosynostosis were developed. These models were made into consumable skull “cartridges” that insert into a reusable base resembling an infant’s head. Each cartridge consists of a multilayer scalp (skin, subcutaneous fat, galea, and periosteum); cranial bones with accurate landmarks; and the dura mater. Data related to model construction, use, and cost were collected. Eleven novice surgeons (residents), 9 experienced surgeons (fellows), and 5 expert surgeons (attendings) performed a simulated metopic and sagittal craniosynostosis repair using a neuroendoscope, high-speed drill, rongeurs, lighted retractors, and suction/irrigation. All participants completed a 13-item questionnaire (using 5-point Likert scales) to rate the realism and utility of the models for teaching endoscope-assisted strip suturectomy.RESULTSThe simulators are compact, robust, and relatively inexpensive. They can be rapidly reset for repeated use and contain a minimal amount of consumable material while providing a realistic simulation experience. More than 80% of participants agreed or strongly agreed that the models’ anatomical features, including surface anatomy, subgaleal and subperiosteal tissue planes, anterior fontanelle, and epidural spaces, were realistic and contained appropriate detail. More than 90% of participants indicated that handling the endoscope and the instruments was realistic, and also that the steps required to perform the procedure were representative of the steps required in real life.CONCLUSIONSBoth the metopic and sagittal craniosynostosis simulators were developed using low-cost methods and were successfully designed to be reusable. The simulators were found to realistically represent the surgical procedure and can be used to develop the technical skills required for performing an endoscope-assisted craniosynostosis repair.

scholarly journals Additive Manufacturing of Bone Scaffolds Using PolyJet and Stereolithography Techniques

2021 ◽  
Vol 11 (16) ◽  
pp. 7336
Author(s):  
Shummaila Rasheed ◽  
Waqas Akbar Lughmani ◽  
Muhannad Ahmed Obeidi ◽  
Dermot Brabazon ◽  
Inam Ul Ahad
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Dimensional Accuracy ◽  
Human Bone ◽  
Compression Tests ◽  
3D Scaffold ◽  
Bone Scaffolds ◽  
3D Printed ◽  
Printing Direction ◽  
Printing Techniques

In this study, the printing capability of two different additive manufacturing (3D printing) techniques, namely PolyJet and micro-stereolithography (µSLA), are investigated regarding the fabrication of bone scaffolds. The 3D-printed scaffold structures are used as supports in replacing and repairing fractured bone tissue. Printed bone scaffolds with complex structures produced using additive manufacturing technology can mimic the mechanical properties of natural human bone, providing lightweight structures with modifiable porosity levels. In this study, 3D scaffold structures are designed with different combinations of architectural parameters. The dimensional accuracy, permeability, and mechanical properties of complex 3D-printed scaffold structures are analyzed to compare the advantages and drawbacks associated with the two techniques. The fluid flow rates through the 3D-printed scaffold structures are measured and Darcy’s law is applied to calculate the experimentally measured permeability. The Kozeny–Carman equation is applied for theoretical calculation of permeability. Compression tests were performed on the printed samples to observe the effects of the printing techniques on the mechanical properties of the 3D-printed scaffold structures. The effect of the printing direction on the mechanical properties of the 3D-printed scaffold structures is also analyzed. The scaffold structures printed with the µSLA printer demonstrate higher permeability and mechanical properties as compared to those printed using the PolyJet technique. It is demonstrated that both the µSLA and PolyJet printing techniques can be used to print 3D scaffold structures with controlled porosity levels, providing permeability in a similar range to human bone.

scholarly journals The Effects of Combined Infill Patterns on Mechanical Properties in FDM Process

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2792
Author(s):  
Mohammadreza Lalegani Dezaki ◽  
Mohd Khairol Anuar Mohd Ariffin
Keyword(s):  
Mechanical Properties ◽  
Computer Aided Design ◽  
Fused Deposition Modeling ◽  
Strength Analysis ◽  
Element Analysis ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
3D Printed ◽  
Complex Features ◽  
Aided Design

Fused deposition modeling (FDM) is commonly used to print different products with highly complex features. Process parameters for FDM are divided into controllable or uncontrollable parameters. The most critical ones are built orientation, layer thickness, infill pattern, infill density, and nozzle diameter. This study investigates the effects of combined infill patterns in 3D printed products. Five patterns (solid, honeycomb, wiggle, grid, and rectilinear) were combined in samples to analyze their effects on mechanical properties for tensile strength analysis. Polylactic acid (PLA) samples were printed in different build orientations through two directions: flat and on-edge. The limitation was that the software and machine could not combine the infill patterns. Thus, the patterns were designed and assembled in computer aided design (CAD) software. Finite element analysis (FEA) was used to determine the patterns’ features and results showed honeycomb and grid have the highest strength while their weights were lighter compared to solid. Moreover, 0° samples in both flat and on-edge direction had the strongest layer adhesion and the best quality. In contrast, perpendicular samples like 60° and 75° showed poor adhesion and were the weakest specimens in both flat and on-edge, respectively. In brief, by increasing the build orientation, the strength decreases in this study.

scholarly journals Graphite Modified Polylactide (PLA) for 3D Printed (FDM/FFF) Sliding Elements

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1250 ◽  
Author(s):  
Robert E. Przekop ◽  
Maciej Kujawa ◽  
Wojciech Pawlak ◽  
Marta Dobrosielska ◽  
Bogna Sztorch ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Stress ◽  
Low Cost ◽  
Chemical Properties ◽  
Spare Parts ◽  
The Other ◽  
Graphite Content ◽  
Before And After ◽  
3D Printed ◽  
And Chemical Properties

With the development of 3D printing technology, there is a need to produce printable materials with improved properties, e.g., sliding properties. In this paper, the authors present the possibilities of producing composites based on biodegradable PLA with the addition of graphite. The team created composites with the following graphite weight contents: 1%, 2.5%, 5%, 7.5%, and 10%. Neat material was also subjected to testing. Tribological, mechanical, and chemical properties of the mentioned materials were examined. Measurements were also made after keeping the samples in ageing and climatic ovens. Furthermore, SEM observations of samples before and after friction tests were carried out. It was demonstrated that increasing graphite content caused a significant decrease in wear (PLA + 10% graphite had a wear rate three times lower than for a neat material). The addition of graphite did not adversely affect most of the other properties, but it ought to be noted that mechanical properties changed significantly. After conditioning in a climatic oven PLA + 10% graphite has (in comparison with neat material) 11% lower fracture stress, 47% lower impact strength, and 21% higher Young’s modulus. It can be certainly stated that the addition of graphite to PLA is a step towards obtaining a material that is low-cost and suitable for printing sliding spare parts.

MAC Protocol of WiMAX Mesh Network

2010 ◽  
pp. 292-312
Author(s):  
Ming-Tuo Zhou ◽  
Peng-Yong Kong
Keyword(s):  
High Speed ◽  
Recent Progress ◽  
Mac Protocol ◽  
Low Cost ◽  
Mesh Network ◽  
Frame Structure ◽  
Self Healing ◽  
Medium Access ◽  
Allocation Algorithms ◽  
Wimax Mesh Network

WiMAX based on IEEE std 802.16 is believed one of the important technologies of 4G. It aims to provide high-speed access over distance of several to tens kilometers. In IEEE std 802.16-2004, WiMAX defines an optional mesh mode, with which multi-hop, multi-route, self-organizing and self-healing communications can be achieved in metropolitan-level areas. This chapter presents medium access control (MAC) protocol of WiMAX mesh mode, on frame structure, network configuration, network entry, and scheduling algorithms. It also summaries the most recent progress on data slots resource scheduling and allocation algorithms. Finally, an application example of using WiMAX mesh network for high-speed and low-cost maritime communications is also presented in this chapter.

Study on the AZ31B Magnesium Alloy in the Application on High-Speed Trains

2012 ◽  
Vol 535-537 ◽  
pp. 875-879 ◽  
Author(s):  
Jia Zhen Liu ◽  
Yan Hui Zhao ◽  
Lei Song ◽  
Zhong Xia Xiang
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Magnesium Alloy ◽  
High Speed ◽  
Equivalent Stress ◽  
Strength Analysis ◽  
Az31b Magnesium Alloy ◽  
High Speed Trains ◽  
6063 Aluminum Alloy ◽  
The Impact

6063 aluminum alloys are used as the luggage rack’s material on high-speed trains recently. The study on the AZ31B magnesium alloy is aimed to demonstrate the feasibility of the magnesium alloy’s application as the material of the luggage rack on high-speed trains. First, the mechanical properties of the AZ31B magnesium was obtained after a series of experimental tests on basic mechanical properties of the AZ31B magnesium alloy. The results show that the strength of the magnesium alloy is 1.25 times of the 6063 aluminum alloy and the impact toughness of the AZ31B magnesium alloy is twice as much as the 6063 aluminum alloy. Second, the stress distribution and the maximum value of the equivalent stress in given loading conditions was obtained by finite element strength analysis on the structure of the aluminum alloy luggage rack on high-speed trains. And the FE analysis results indicate that if the AZ31B magnesium alloy is used as the material of the luggage rack instead of the 6063 aluminum alloy, it will have a weight loss of the luggage rack for approximately 33%. In addition, the application of AZ31B magnesium alloy has more advantages in energy-saving, environmental protection and safety control.

scholarly journals Mechanical Properties of PolyJet 3D-Printed Composites Inspired by Space-Filling Peano Curves

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3516
Author(s):  
Changlang Wu ◽  
Truong Tho Do ◽  
Phuong Tran
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Volume Fraction ◽  
General Rule ◽  
Second Order ◽  
Compression Tests ◽  
Space Filling ◽  
First Order ◽  
Loading Direction ◽  
3D Printed

This paper proposes a design of novel composite materials inspired by the Peano curve and manufactured using PolyJet 3D printing technology with Agilus30 (flexible phase) and VeroMagentaV (rigid phase) materials. Mechanical properties were evaluated through tensile and compression tests. The general rule of mixture (ROM) for composites was employed to approximate the tensile properties of the hybrid materials and compare them to the experimental results. The effect of reinforcement alignments and different hierarchies are discussed. The results indicated that the 5% inclusion of the Peano reinforcement in tensile samples contributed to the improvement in the elastic modulus by up to 6 MPa, but provided no obvious enhancement in ultimate tensile strength. Additionally, compressive strengths between 2 MPa and 6 MPa were observed for compression cubes with first-order reinforcement, while lower values around 2 MPa were found for samples with second-order reinforcement. That is to say, the first-order reinforcement has been demonstrated more effectively than the second-order reinforcement, given the same reinforcement volume fraction of 10% in compression cubes. Different second-order designs exhibited slightly different mechanical properties based on the ratio of reinforcement parallel to the loading direction.

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