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nozzle is heated to melt the material and ean be moved in both horizontal and vertical directions by numerical controlled mechanism, directly controlled by a computer-aided manufacturing (CAM) software package. The main materials for FOM include Acrylonitrile Butadiene Styrene (ABS); Medical grade ABS; Methyl methacrylate ABS; Polycarbonate; Investment casting wax [34]. The process ofthe FDM machine is fast and relatively low cost. In 2007, adooshan [35] used FDM technology to construct a wind tunnel model with Polycarbonate plastic material, which is an actual impact·rcsistant industrial·grade thermoplastic and is structurally strong. Traditionally, wind tunnel models are made of metal and are very expensive. FDM was used as a way to reduce time and cost. Figure 12 displays the wind tunnel model constructed by FOM. Figure 12: Wind Tunnel Model Constructed by FOM This wind tunnel model was tested by engineers to compare with the real values of this wind tunnel model with metal material. The most purpose of this test in the wind tunnel is forces and moments. The results displayed that the accuracy of the data is lower than that of a metal model due to surface finish and dimensional tolerances, but the FOM model is 36
quite accuratc for a testing level. This FDM model cost about $650 and took 4 days to construct, while the metal model cost about $1300 and took a month to design and fabricate. The conclusion was that FDM technology is a timely and cost effective way of producing test parts. In tbis wind tunnel model, the material needs to be strong enough to sustain the air force, which is on the nose cone and the edges of the wing tails. However, forces on a marine propeller are around all blades and nose cone and the fluid is much more dcnse. If a propeller needs to provide a large thrust for a vessel, this polycarbonate plastic material may not be strong enough. Selective Laser Sintering (SLS) is a better choice to produce a propellcr where higher strength is required. SLS [34] is a r'apid prototyping technology that uses a high power laser to fuse small particles of plastic, metal, ceramic or glass powcrs into a mass to build a desircd 3-dimensional object. The laser selectively fuses matcrial by scanning cross·sections, which will be used as the solid part of the object. The scanned parts are melted and become a solid. After each cross-section is scanned, the platen on which the object is built is moved down by one layer thickness, a new layer of material is applied on top of the solidified layer and the process is repeated until the object is completed. As shown in table 2, the SLS technology has a wide range of available materials. Using SLS technology, objects can be manufactured from high strength materials, such as uncoated or polymer-coated steel powders, which are unavailable for other teehnlogies. The layer thickness ofSLS is 0.001-0.004 inch,and laser diameter is 0.004-0.02 inch [36]. With the small heating diameter, thin process layer and high strength ofmaterial, propellers can be produced by SLS with a good accuracy, 37
Page 4: A Rapid Development Process for Mar
Page 7 and 8: Table of Contents Abstract ... Ackn
Page 9: List ofTables Table I: Required Inp
Page 12 and 13: Figure 46: Surface Dynamic Pressure
Page 14 and 15: a long time to analyze, draw, fabri
Page 16 and 17: Simulation work is now commonly don
Page 18 and 19: Early theoretical analysis applied
Page 20 and 21: ------------------------- provides
Page 22 and 23: As can be secn in Table I, the lift
Page 24 and 25: propeller geometry has to be entere
Page 27: avoid cavitation; however, it decre
Page 31: l" ........... ,... __ .... :l ,,_
Page 34: Table 2: Advantages and Disadvantag
Page 41 and 42: trend for many companies to reduce
Page 43 and 44: fluxes through a particular control
Page 45 and 46: known as a casting, is usually ejec
Page 47: Table 3: Prototyping Technology Mat
Page 54 and 55: For given values ofJ, Fn, Rn, En, t
Page 56: propeller geometry for impon into t
Page 59 and 60: Using OpenPVL_SW I a propeller desi
Page 64: o ...n".... 'Co 'OJ • • • DC)
Page 72 and 73: 3.3 Simulations using CosmosFloWork
Page 75 and 76: simulation domain are set to 6m and
Page 79: CosmosWorks can be used to check th
Page 82: Figure 33: Dynamic Pressure Distrib
Page 88: Chapter 4 Case Study: Simulation of
Page 94 and 95: The plots of RPM and thrust from ou
Page 96 and 97: Figure 46: Surface Dynamic Pressure
Page 98:
Figure 48: Deflection ofthe AUV Pro
Page 102:
In this simulation, two nose cones
Page 110 and 111:
Chapter 6 Propeller Fabrication by
Page 112 and 113:
Figure 60: Stratasys rDM 2000 After
Page 115 and 116:
Material options for Stratasys Fusi
Page 117 and 118:
Chapter 7 Conclusions and Future Wo
Page 119 and 120:
References III Burtner, E., 1953, "
Page 121 and 122:
[20] D'Epagnier, P.K., 2005, "A Com
Page 123 and 124:
Appendix 1\: The Part ofOpcnPVL_SW
Page 125:
Create all of the function commands
Page 131:
Appendix B: SolidWorks Macro lor th
Page 134:
'create loft swModcl.ClearSelcction
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