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Opto-Mechanical Design Process
Published in Paul Yoder, Daniel Vukobratovich, Opto-Mechanical Systems Design, 2017
Paul R. Yoder, David M. Stubbs, Kevin A. Sawyer, David Aikens
In the 3D process, a CAD model of the hardware generates cross-section slices (or layers) for the machine to apply successively on top of each other to create the model. There are many types of 3D printers capable of creating realistic plastic models on the market. Some manufacturers are developing means for depositing and fusing metals and metal alloys in a similar manner. The products of the latter efforts are expected to be usable in place of conventionally machined hardware in opto-mechanical instruments in the near future.
Static analysis and design of deep foundations
Published in An-Bin Huang, Hai-Sui Yu, Foundation Engineering Analysis and Design, 2017
Precast concrete piles are typically made with steel reinforcement and pre-stressing tendons to obtain the tensile strength required to survive handling and driving, and to provide sufficient bending resistance. The piles can be made with a constant or tapered cross-section. A wide variety of sizes and geometry in cross-section and length can be accommodated. The cross-section can be circular, square, or polygonal. Long concrete piles can be difficult to handle and transport. Splicing of precast concrete pile sections requires special arrangements.
Biofabrication
Published in Karen J.L. Burg, Didier Dréau, Timothy Burg, Engineering 3D Tissue Test Systems, 2017
Layer-by-layer fabrication (bottom row of Figure 2.3) is one of the most versatile methods of scaffold development. In RP or solid free-form fabrication (SFF), a small element of material can be placed at specific locations to build the structure one element at a time. 3D objects are built using a layering technique in which a computer-aided design (CAD) system generates a series of cross-sections. Each cross-sectional layer of the scaffold is deposited onto the previous layer resulting in the completed design (Agrawal and Ray 2001; Liu and Ma 2004). The advantage of RP systems is the potential for fine control of the microstructure and macrostructure of the scaffold.
IBEM for Impedance Functions of an Embedded Strip Foundation in a Multi-Layered Transversely Isotropic Half-Space
Published in Journal of Earthquake Engineering, 2018
Zhenning Ba, Jianwen Liang, Vincent W. Lee, Liming Hu
Figure 9 depicts the dynamic impedance functions of the foundation in the single-layered TI half-space for three different cross sections versus ω* ranging from 0.0 to 9.0. The semicircular, rectangular, and trapezoidal cross sections are considered. The half-width and depth of the three foundations are all equal to a. The width of the bottom of the trapezoidal foundation is equal to 3a. The modulus ratios are ni = 0.5 and mi = 0.3 and the depth of the layer is H/a = 2.0. From Fig. 9, one can see that the dynamic impedance functions are very sensitive to the cross section of the foundation. Generally, the values of the impedance functions are largest for the trapezoidal foundation, second largest for the rectangular function, and smallest for the semicircular function. The oscillation of the impedance functions is also very different for different cross sections, which may be because the variation of the cross section alters the dynamic interactions between the TI layer and foundation.
Data model for additive manufacturing digital thread: state of the art and perspectives
Published in International Journal of Computer Integrated Manufacturing, 2019
Renan Bonnard, Jean-Yves Hascoët, Pascal Mognol
The fifth step is the generation of an AM system interpretable language, called a build file (Pratt et al. 2002). In this step, information specific to AM processes is introduced into the digital thread. Such information as support structure location, hatching, and process specifics are given. To prepare for manufacturing, the 3D model is sliced into multiple two-dimensional cross-sections. Some formats, such as slice layer interface and common layer interface (CLI), are presented in this research. During the slicing of the 3D model, geometric, process, material, and machine information are taken into account to generate parameters for each layer.
Three-Dimensional Numerical Study on Thermal-Hydraulic Performance of Twisted Mini-Channel Using Al2O3-H2O Nanofluid
Published in Heat Transfer Engineering, 2020
Elham Hosseinirad, Morteza Khoshvaght-Aliabadi, Faramarz Hormozi
There are a few studies on the twisted duct, particularly in small scales. In the following, some of these studies on the non-circular and circular twisted tubes are mentioned. Pozrikidis [11] performed a numerical study on the flow through a twisted square tube with helical grooves using finite difference techniques. He observed the secondary flow growing in the cross section and improving the axial flow rate by the helical grooves. Bhadouriya et al. [12] investigated heat transfer and friction factor characteristics of air flow in an annulus region with the twisted square channel. The range of Reynolds number was 400–60,000. They demonstrated that the heat transfer and pressure drop increased inside twisted square channel as compared with the straight square channel at all Reynolds numbers. Finally, correlations for the Nusselt number and friction factor were developed. In the other study [13], they studied air flow inside the twisted square channel for both laminar and turbulent regimes (for Re =600–70,000). Correlations were also proposed for the Nusselt number and friction factor at both laminar and turbulent regimes. Based on the considered performance index, guidelines were proposed for design and choice of the twisted square channel according to Prandtl number and Reynolds number. Yang et al. [14] investigated the effects of geometric parameters, such as the aspect ratio and twist pitch of the twisted elliptical tube on the thermal and hydraulic characteristics of water flow. Their results indicated that the twisted tube can increase the heat transfer rate and pressure drop. The maximum heat transfer coefficient and friction factor were obtained for lower twist pitch and greater aspect ratio. Tan et al. [15] carried out an investigation on the pressure drop and heat transfer of water flow inside the twisted elliptical tube. They demonstrated that the heat transfer rate and pressure drop can increase inside the twisted elliptical tube compared with those obtained inside the straight circular tube. Their results showed that the thermal and hydraulic specifications were enhanced in larger axis ratio and smaller twist pitch. Khoshvaght-Aliabadi and Arani-Lahtari [16] investigated the effect of the different ratios of twist pitch to channel length and cross-section shape of the twisted mini-channel on the heat transfer and flow field of air, water, engine oil, and ethylene glycol. The studied cross-section shapes were circular, elliptic, half-circular, square, rectangular and triangular. They found the highest value of performance evaluation criteria inside half-circular cross-section for air flow, while liquid fluids had the highest values inside square twisted mini-channel. Cheng et al. [17] investigated the flow and heat transfer characteristics of water inside the twisted oval tube for the Reynolds number in the range of 50–2000. They studied the effect of the flattening and twisted pitch ratio on the heat transfer and pressure drop of flow. Their results explained that the heat transfer and pressure drop increased inside the twisted oval tube than the smooth tube. The performance evaluation criteria increased with decreasing the twisted pitch ratio and increasing the flattening.