Pneumatic Microextrusion-Based Additive Biofabrication of Polycaprolactone Bone Scaffolds: Part II – Investigation of the Influence of Polymer Flow Parameters

2021 ◽  
Author(s):  
Mohan Yu ◽  
Logan Lawrence ◽  
Pier Paolo Claudio ◽  
James B. Day ◽  
Roozbeh (Ross) Salary
Keyword(s):  
Mechanical Performance ◽  
Research Work ◽  
Biological Tissues ◽  
Direct Write ◽  
Bone Scaffolds ◽  
Flow Parameters ◽  
Material Deposition ◽  
Flow Pressure ◽  
Physical Phenomena ◽  
Head Temperature

Abstract Pneumatic micro-extrusion (PME), a direct-write additive manufacturing process, has emerged as a high-resolution method for the fabrication of a broad range of biological tissues and organs. However, the PME process is intrinsically complex, governed by complex physical phenomena. Hence, investigation of the effects of consequential parameters would be an inevitable need. The goal of this research work is to fabricate biocompatible, porous bone tissue scaffolds for the treatment of osseous fractures, defects, and eventually diseases. In pursuit of this goal, the objective of this study is to investigate the influence of material deposition factors — i.e., (i) deposition head temperature, (ii) flow pressure, and (iii) infill pattern — on the mechanical performance of PME-fabricated bone scaffolds. It was observed that the deposition head temperature as well as the flow pressure significantly affected scaffold diameter (unlike scaffold height). In addition, material deposition rate increased significantly as a result of an increase in the deposition temperature; this phenomenon stems from a reduction in Polycaprolactone (PCL) viscosity. Furthermore, there was a direct correlation between the amount of deposited mass and scaffold stiffness. Overall, the results of this study pave the way for future investigation of PME-deposited PCL scaffolds with optimal functional properties for incorporation of stem cells toward the treatment of osseous fractures and defects.

Investigation of the Regenerative Potential of Human Bone Marrow Stem Cell-Seeded Polycaprolactone Bone Scaffolds, Fabricated Using Pneumatic Microextrusion Process

2021 ◽  
Author(s):  
Logan Lawrence ◽  
James B. Day ◽  
Pier Paolo Claudio ◽  
Roozbeh (Ross) Salary
Keyword(s):  
Stem Cell ◽  
Structural Integrity ◽  
Biological Tissues ◽  
Direct Write ◽  
Osteosarcoma Cell ◽  
Bone Scaffolds ◽  
Depth Analysis ◽  
Cell Scaffold ◽  
Material Process

Abstract Pneumatic MicroExtrusion (PME) is a direct-write additive manufacturing process, which has emerged as a robust, high-resolution method for the fabrication of a broad spectrum of biological tissues and organs. However, the PME process is intrinsically complex, governed by bio-physio-chemical phenomena as well as material-process interactions. Hence, investigation of the influence of consequential factors on bone scaffold fabrication as well as investigation of cell-scaffold interactions would be an inevitable need. The objective of the work is to investigate the biocompatibility as well as the histological properties of PME-fabricated porous bone scaffolds, composed of polycaprolactone (PCL). To achieve this objective, a media extraction of the scaffold material was tested for cytostatic or cytotoxic activity with the aim to: (i) assess the fabricated scaffolds’ feasibility of use in regenerative medicine, and (ii) determine their structural integrity in a modelled in-vivo environment. In addition, the scaffolds were inoculated with an established osteosarcoma cell line (SAOS-2) and cultured for seven days to investigate the scaffold architecture and cell integration potential. A histological examination was performed on the seeded scaffolds for further in-depth analysis of cell-scaffold interaction. Overall, the results of this study pave the way for future investigation of stem cell incorporation into PME-fabricated PCL scaffolds toward the treatment of osseous fractures and defects.

Characterization of the Functional Properties of Pcl Bone Scaffolds Fabricated Using Pneumatic Microextrusion

2021 ◽  
Author(s):  
Mohan Yu ◽  
Ye Jien Yeow ◽  
Logan Lawrence ◽  
Pier Paolo Claudio ◽  
James B. Day ◽  
...  
Keyword(s):  
Bone Tissue ◽  
Process Parameters ◽  
Mass Density ◽  
Research Work ◽  
Biological Tissues ◽  
Tissue Scaffolds ◽  
Influential Factor ◽  
Material Transport ◽  
Layer Height ◽  
Physical Phenomena

Abstract Pneumatic micro-extrusion (PME) is a direct-write additive manufacturing process, which has emerged as a robust, high-resolution method for the fabrication of a broad spectrum of biological tissues and organs. PME allows for non-contact multi-material deposition of functional inks for tissue engineering applications. In spite of the advantages and engendered potential applications, the PME process is inherently complex, governed by not only complex physical phenomena, but also material-process interactions. Consequently, investigation of the influence of PME process parameters as well as the underlying physical phenomena behind material transport and deposition in PME would be inevitably a need. The overarching goal of this research work is to fabricate biocompatible, porous bone tissue scaffolds for the treatment of osseous fractures, defects, and diseases. In pursuit of this goal, the objectives of the work are: (i) to investigate the influence of seven consequential scaffold design factors and PME process parameters on the mechanical properties of fabricated bone tissue scaffolds; (ii) to explore the underlying dynamics behind material transport in the PME process, using a 3D computational fluid dynamics (CFD) model. To investigate the effects of the design and process parameters, a series of experiments were designed and conducted. Layer height was identified as the most significant factor in this study. An increase in the layer height led to less overlap between subsequent layers, which allowed for more shrinkage and ultimately a reduction in scaffold diameter. In addition, print speed appeared as an influential factor in this study. An increase in the print speed resulted in a decline in linear mass density and thus in the extent of fusion between subsequent deposited layers. Besides, it was observed that there was a strong correlation between deposition mass and compression modulus. Overall, the results of this study pave the way for future investigation of PME-deposited PCL scaffolds with optimal functional and medical properties for incorporation of stem cells toward the treatment of osseous fractures and defects.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

Investigation of the Effects of Design and Process Parameters on the Mechanical Properties of Biodegradable Bone Scaffolds, Fabricated Using Pneumatic Microextrusion Process

2020 ◽  
Author(s):  
Mohan Yu ◽  
Ye Jien Yeow ◽  
Logan Lawrence ◽  
Pier Paolo Claudio ◽  
James B. Day ◽  
...  
Keyword(s):  
High Resolution ◽  
Process Parameters ◽  
Testing Machine ◽  
Ccd Camera ◽  
Biological Tissues ◽  
Morphological Properties ◽  
Color Temperature ◽  
Layer Width ◽  
Bone Scaffolds ◽  
Four Levels

Abstract Pneumatic micro-extrusion (PME) is a direct-write additive manufacturing process, which has emerged as a robust, high-resolution method for the fabrication of a broad spectrum of biological tissues and organs. In the PME process, a high-pressure flow is injected into a cartridge, which contains a bioink material, resulting in pressure-driven material deposition on a free surface via a converging conical micro-capillary. In this study, PCL powder was loaded into the cartridge, maintained at 120 °C. The flow pressure was set to 550 kPa. Laminar molten PCL flow was deposited on a glass surface (steadily and uniformly kept at 45 °C), using a 200 μm nozzle. A porous, cylindrical scaffold was designed (honeycomb-filled), having a diameter and height of 10 mm and 3 mm, respectively. To investigate the effects of the design and process parameters, a series of experiments were designed and conducted where print speed was varied at four levels in the range of 0.30–0.45 mm/s with 0.05 mm/s increments. In addition, similarly, layer height and layer width were changed at four levels in the range of 125–200 μm with 25μm increments. Finally, infill density was set at four levels in the range of 0.20–0.35 with 5% increments. As a result, 16 experimental runs were characterized, each replicated four times. Of each of the PME-fabricated samples, an image was acquired (both horizontally and vertically) using a high-resolution CCD camera. Illumination was provided by an LED ring light (being of a brightness in the range of 30,000–40,000 Lux as well as a color temperature of 6000 K). Subsequently, the acquired images were analyzed using in-house digital image processing algorithms, forwarded with the aim to characterize both the diameter and the height of the fabricated bone scaffolds. The veracity of the image-based measurements was corroborated, using offline caliper measurements. Furthermore, the compression properties of the fabricated bone scaffolds were measured using a compression testing machine; the samples were subjected to a compression load, applied with a velocity of 0.08 mm/s. Overall, the results of this study pave the way for future investigation of PME-deposited PCL scaffolds with optimal mechanical and morphological properties for incorporation of hBMSCs toward the treatment of osseous fractures and defects.

Study of the Proper Sintering Conditions of Anionically-Polymerized Polyamide 6 Matrices for the Fabrication of Greencomposites

2012 ◽  
Vol 713 ◽  
pp. 121-126
Author(s):  
A. Alfonso ◽  
J. Andrés ◽  
J.A. García
Keyword(s):  
Material Characterization ◽  
Mechanical Performance ◽  
In Situ Polymerization ◽  
Research Work ◽  
Polyamide 6 ◽  
Liquid Composite Molding ◽  
Thermoplastic Matrix ◽  
Composite Molding ◽  
Long Fiber Thermoplastic

The present research work assesses the manufacture of long fiber thermoplastic matrix composite materials (GreenComposites). Thermoplastic matrices are too viscous to be injected into the conventional LCM (Liquid Composite Molding) molds, and then epoxy, polyester or vinylester resins are used. Nevertheless, the groundbreaking anionic polymerization of caprolactam allows such a synthesis of a thermoplastic APA6 matrix inside the mold. This matrix is sintered from the starting monomers, and presents high mechanical performance and recyclability. In order to do the reactive injection in a LCM mold, it is necessary to control the polymerization mechanism of such a thermoplastic matrix. This paper puts special emphasis on detecting and solving all problems which arose during synthesis. For instance, moisture values were assessed for all starting reactants, since humidity keeps polymerization from occurring. It is thought that once the synthesis and the resulting material characterization are well controlled, the manufacture of GreenComposites through in situ polymerization, as well as addition of state-of-the-art fabrics such as basalt, can proceed successfully.

SUSTAINABLE ULTRA-HIGH-PERFORMANCE GLASS CONCRETE FOR INFRASTRUCTURES

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Arezki Tagnit-Hamou ◽  
Nancy A. Soliman
Keyword(s):  
High Performance ◽  
Glass Powder ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Low Cost ◽  
Research Work ◽  
High Strength ◽  
Quartz Powder ◽  
Ultra High Performance Concrete ◽  
Powder Particles

This paper presents research work on the development of a green type of ultra-high-performance concrete using ground glass powders with different degrees of fineness (UHPGC). This article presents the development of an innovative, low-cost, and sustainable UHPGC through the use of glass powder to replace cement, and quartz powder particles. An UHPGC with a compressive strength (fc) of up to 220 MPa was prepared and its fresh, and mechanical properties were investigated. The test results indicate that the fresh UHPGC properties were improved when the cement and quartz powder were replaced with non-absorptive glass powder particles. The strength improvement can be attributed to the glass powder’s pozzolanicity and to its mechanical performance (very high strength and elastic modulus of glass). A case study of using this UHPGC is presented through the design and construction of a footbridge. Erection of footbridge at University of Sherbrooke Campus using UHPGC is also presented as a full-scale application.

scholarly journals HSM Spindle Model Updating With Physical Phenomena Refinements

2013 ◽  
Author(s):  
David Noel ◽  
Sebastien Le Loch ◽  
Mathieu Ritou ◽  
Benoit Furet
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Model Updating ◽  
Research Work ◽  
Behavior Modeling ◽  
Specific Device ◽  
Sensibility Analysis ◽  
Physical Phenomena ◽  
Good Agreement ◽  
Do So

The modeling of High Speed Machining (HSM) spindles is a complex task due to the numerous physical phenomena involved in the dynamic behavior. Modeling is still rarely used in the industry, although sophisticated research work has been achieved. The boundary conditions of rotor models, which correspond to the ball bearings, are crucial and difficult to define. Indeed, they affect the dynamic behavior of the rotor in a non-linear and sometimes in an unpredictable way. The aim of the paper is to determine a relevant spindle model, i.e. the adequate level of complexity. To do so, a dynamic bearing model is introduced and the axial model of a spindle is established in relation to the preloaded bearing arrangement. Then, the operating stiffness of the spindle has been obtained experimentally with a new specific device that applies axial load and measures the resulting displacement, whatever the spindle speed. The model updating with the experimental data combined to sensibility analysis have led to the model refinement with additional physical phenomena, in order to account for non-linearities observed experimentally. The parameters of the model are also identified experimentally. As a result, a relevant spindle model is obtained and validated by the good agreement between simulations and experiments.

scholarly journals Curvilinear Variable Stiffness 3D Printing For Improved Mechanical Performance

2021 ◽  
Author(s):  
Sadben Khan
Keyword(s):  
3D Printing ◽  
Mechanical Performance ◽  
Variable Stiffness ◽  
Fused Filament Fabrication ◽  
Work Cell ◽  
Material Deposition ◽  
Stiffness Design ◽  
Open Hole ◽  
Line Scanner ◽  
Novel Design

<div>Continuous Curvilinear Variable Stiffness (CCVS) is proposed as a novel design technique to generate Variable Stiffness design for improving the performance of composite panels featuring open-hole cut-outs. Compared to existing VS design techniques, CCVS steers the fibers around the cut-out without breaking at the holes using only a single design variable the geometry. The technique utilises a numerical method known as Source Panel method, which is typically utilised in the fluid dynamics world. Utilising this technique, the performance of an open hole ASTM D5766 coupon manufactured using Fused Filament Fabrication (FFF) was improved 16-38% depending on the ratio of the hole to the width of the specimen. The technique was further</div><div>improved on to allow for arbitrary geometries such as fuselage cut-outs. A fuselage cut-out case was examined, and it was shown that a CCVS design can improve the performance over a QuasiIsotropic design by 57%. To validate CCVS, it is necessary to first manufacture and validate the part. This was done by developing a robotic 3D printing work-cell capable of 5 axis of material deposition of both thermoplastic and pre-impregnated carbon fiber. Finally, an in-process inspection technique was developed using a laser line scanner in the work-cell for the purposes of quality control. </div>

scholarly journals Numerical investigation of friction crush welding aluminium and copper sheet metals with flanged edges

2021 ◽  
Vol 309 ◽  
pp. 01015
Author(s):  
Ashu Kumar ◽  
Gurinder Singh Brar
Keyword(s):  
Temperature Distribution ◽  
Mechanical Performance ◽  
Experimental Testing ◽  
Research Work ◽  
Dissimilar Materials ◽  
Copper Sheet ◽  
Thermomechanical Model ◽  
Nonlinear Transient ◽  
New Material ◽  
Stress Flow

Aluminum alloys are the most attractive solutions for many industries including aerospace, marine, and other transportation sectors where lightweight construction is required. Friction Crush Welding (FCW) is a new material joining process that simultaneously creates a mechanical lock and a metallurgical seal at the interface between similar and dissimilar materials. In this research work presents the development of numerical modelling to predict the temperature distribution and mechanical performance of aluminum and copper similar joints in the FCW of sheet metal section. An explicit nonlinear transient finite element thermomechanical model is develop using ABAQUS based on the coupled Euler-Lagrange method to simulate FCW of AW5754 and Cu-DHP alloys. The Johnson-Cook materials law is adopted in the FEM. Numerical investigations of the FCW process was performed to reduce experimental testing times, which can be long and expensive. Temperature distribution and von misses stress flow patterns are observed at the top surface of the weld. Numerical simulation data correlate with experimental data in the literature.

Analysis and Numerical Simulation of the Mechanical Performance of FDM Samples With Variable Infill Values

2017 ◽  
Author(s):  
Steffany N. Cerda-Avila ◽  
Hugo I. Medellín-Castillo ◽  
Dirk F. de Lange
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Prediction Models ◽  
Mechanical Performance ◽  
Numerical Models ◽  
Research Work ◽  
Tensile Tests ◽  
Geometrical Shape ◽  
Cad System ◽  
Fem Method

The prediction of the mechanical properties of AM parts is very important in order to design and fabricate parts not only of any geometrical shape but also with variable or customized mechanical properties. A limited number of investigations have focused on the analysis and prediction of the mechanical properties of AM parts using theoretical and numerical approaches such as the Finite Element Method (FEM); nevertheless, their results have been not accurate yet. Thus, more research work is needed in order to develop reliable prediction models able to estimate the mechanical performance of AM parts before fabrication. In this paper the analysis and numerical simulation of the mechanical performance of FDM samples with variable infill values is presented. The aim is to predict the mechanical performance of FDM components using numerical models. Thus, several standard tensile test specimens were fabricated in an FDM system using different infill values, a constant layer thickness, one shell perimeter, and PLA material. These samples were measured and modelled in a CAD system before performing the experimental tensile tests. Numerical models and simulations based on the FEM method were then developed and carried out in order to predict the structural performance of the specimens. Finally the experimental and numerical results were compared and conclusions drawn.

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