Characterization of Spectral Response of a FBG Sensor Embedded in a Metallic Structure Using Laser Solid Freeform Fabrication

2006 ◽  
Author(s):  
Hamidreza Alemohammad ◽  
Ehsan Toyserkani
Keyword(s):  
Solid Freeform Fabrication ◽  
Spectral Response ◽  
Element Model ◽  
Metallic Structure ◽  
Metallic Structures ◽  
Freeform Fabrication ◽  
Fbg Sensor ◽  
Fbg Sensors ◽  
Laser Solid Freeform Fabrication

This paper focuses on spectral response characterization of fiber Bragg grating (FBG) sensors embedded in metallic structures using laser solid freeform fabrication (LSFF). Fiber Bragg grating sensors are capable of measuring temperature, strain and pressure and can be embedded in metallic structures to monitor thermal and structural loads. Due to the sensitivity of the FBG sensors to high temperatures and stresses, the embedding process using LSFF is a challenging task. In the present work, a finite element model is developed to predict the stress and temperature fields adjacent to the fiber optic sensor embedded the metallic structure. The FE results are transferred to opto-mechanical model of the FBG sensor to predict the change in the spectral response of the sensor. Finally, the finite element model is verified using an existing analytical model which predicts the temperature field and melt pool geometry in LSFF process.

Characterization of Permeability for Solid Freeform Fabricated Porous Structures

1999 ◽  
Author(s):  
Merve Erdal ◽  
Levent Ertoz ◽  
Selçuk Güçeri
Keyword(s):  
Solid Freeform Fabrication ◽  
Pore Geometry ◽  
Fluid Viscosity ◽  
Porous Structures ◽  
Permeability Measurement ◽  
Porous Flow ◽  
Freeform Fabrication ◽  
Fused Deposition ◽  
Order Of Magnitude

Abstract Fused deposition based solid freeform fabrication technique allows manufacturing of potential functional preforms for subsequent Resin Transfer Molding. In this study, the transport property (permeability) of solid freeform fabricated porous preform geometries are investigated. Specifically the effect of pore geometry and network on the permeability is sought. Wet (saturated) permeability experiments were performed for various pore geometries with different viscosity liquids. For all fluids and preform structures investigated in this study, the porous flow exhibited Darcian behavior. The permeability is affected by changes in order of magnitude of fluid viscosity, the effect considerably significant in low porosity preforms. Current work concentrates on dry permeability measurement and development of numerical permeability models for ordered pore geometries (as produced through SFF) that will be compared with experimental results.

Effect of Preheating on the Delamination and Crack Formation in Laser Solid Freeform Fabrication Process

2008 ◽  
Author(s):  
Masoud Alimardani ◽  
Ehsan Toyserkani ◽  
Jan Paul Huissoon
Keyword(s):  
Thermal Stresses ◽  
Crack Formation ◽  
Solid Freeform Fabrication ◽  
Fabrication Process ◽  
Experimental Results ◽  
Stress Fields ◽  
Thin Wall ◽  
Freeform Fabrication ◽  
Micro Cracks ◽  
Laser Solid Freeform Fabrication

This paper presents a numerical-experimental investigation on the effects of preheating the substrate on the potential delamination and crack formation across the parts fabricated using the Laser Solid Freeform Fabrication (LSFF) process. For this purpose, the temperature distributions and stress fields induced during the multilayer LSFF process, and their correlation with the delamination and crack formation are studied throughout the numerical analysis and the experimental fabrication of a four-layer thin wall of SS304L. A 3D time-dependent numerical approach is used to simulate the LSFF process, and also interpret the experimental results in terms of the temperature distribution and the thermal stress fields. The numerical results show that by preheating the substrate prior to the fabrication process, the thermal stresses throughout the process domain substantially reduce. Accordingly, this can result in the reduction of potential micro-cracks formation across the fabricated part. Preheating also decreases the transient time for the development of a proper melt pool which is an important factor to prevent poor bonding between deposited layers. The experimental results are used to verify the numerical findings as well as the feasibility of preheating on the reduction of the micro-cracks formed throughout the fabrication process.

Preparation and characterization of hydroxyapatite suspensions for solid freeform fabrication

2002 ◽  
Vol 28 (3) ◽  
pp. 299-302 ◽  
Author(s):  
Jiemo Tian ◽  
Yong Zhang ◽  
Xinmin Guo ◽  
Limin Dong
Keyword(s):  
Solid Freeform Fabrication ◽  
Freeform Fabrication

Characterization of Printable Micro-Fluidic Channels for Organ Printing

2012 ◽  
Author(s):  
Yahui Zhang ◽  
Howard Chen ◽  
Ibrahim T. Ozbolat
Keyword(s):  
Oxygen Transport ◽  
Fluid Transport ◽  
Solid Freeform Fabrication ◽  
Structural Formation ◽  
Freeform Fabrication ◽  
Filament Diameter ◽  
Organ Printing ◽  
Scaffold Degradation ◽  
Tissue Scaffolding

Organ printing is a complex and challenging process in execution due to the lack of fundamental understanding of tissue and organ formation, and problems associated with giving the organ-conforming 3D shapes. One of the major challenges is the inclusion of blood vessel-like channels between layers to support cell viability in terms of nutrients and oxygen transport. Tissue scaffolds have been widely used in generation of replacement tissue by providing mechanical support and fluid nutrients, but complications with scaffold degradation and the corresponding adverse effects on extra cellular matrix still present major challenges. This paper introduces a new approach in tissue scaffolding for cellular assembly to minimize these problems. This research investigates the manufacturability of novel printable micro-fluidic channels, where the micro-fluidic channels support mechanical integrity as well as enable fluid transport in 3D. A pressure-assisted solid freeform fabrication platform is developed with co-axial needle dispenser unit to print hollow hydrogel filaments, which will later be used to support nutrients and oxygen transport through the printed cell assembly. The dispensing rheology is studied and the effect of material property on structural formation of hollow filaments is analyzed in this paper. Sample structures are printed through the computer-controlled system. In experiments with sodium alginate, 4% CaCI2-4% alginate solution combination results in the smallest core and filament diameter. In experiments with chitosan on the other hand, 3% chitosan-1% NaOH combination brings the smallest core and filament diameter.

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