Optimization of Bolted Connection in Steel Corbel Attach to RC Column of MRT Viaduct

MRT is one of the backbones of a city’s public transportation system, capable of carrying large crowds. The use of a portal frame in the design of an MRT train station has raised significant concerns about how the portal frame’s load will be supported by the extended structure element known as a corbel. A corbel is a protruding structural element that supports weights like primary beams and girders. Engineers must then decide how to properly bolt the steel corbel structure to the concrete pier segment or columns. Generally, most corbel structure designs were constructed of concrete; however, in this study corbel design was made of steel so that the steel portal frame could rest on the corbel structure, allowing for more usable area on the platform, such as kiosks and other amenities. Optimization of end plate thickness and beam web thickness is carried out. Manual calculations are used in addition to FEA modeling to examine the bolt’s deflection, shear, bearing, tension, slip, and block tearing resistance. When using Eurocode, all three loadings, transverse force, vertical force, and transverse moment, produce values that are 10% lower than the British Standard. As a result, designers can optimize their designs using Eurocode.

Determination of the PIC700 Ceramic’s Complex Piezo-Dielectric and Elastic Matrices from Manageable Aspect Ratio Resonators

Achieving good piezoelectric properties, such as the widely reported d33 charge coefficient, is a good starting point in establishing the potential applicability of piezoceramics. However, piezoceramics are only completely characterized by consistent piezoelectric-elastic-dielectric material coefficient matrices in complex form, i.e., including all losses. These matrices, which define the various alternative forms of the constitutive equations of piezoelectricity, are required for reliable virtual prototyping in the design of new devices. To meet this need, ten precise and accurate piezoelectric dielectric and elastic coefficients of the material, including all losses, must be determined for each alternative. Due to the difficulties arising from the coupling of modes when using the resonance method, this complete set of parameters is scarcely reported. Bi0.5Na0.5TiO3-based solid solutions are already commercially available in Europe and Japan. Here, we report a case study of the determination of these sets of material coefficients (diα, giα, eiα and hiα; sE,Dαβ and cE,Dαβ; εTik and εSik; and βTik and βSik), including all losses, of the commercial PIC700 eco-piezoceramic. Plate, disk, and cylinder ceramic resonators of a manageable aspect ratio were used to obtain all the material coefficients. The validation procedure of the matrices is also given by FEA modeling of the considered resonators.

Mechanical modeling of a stitched sandwich thermal protection structure with ceramic-fiber-reinforced SiO2 aerogel as core layer

Ceramic-fiber-reinforced SiO2 aerogel (CFRSA) composite was used as core layer to prepare a stitched sandwich thermal protection structure (SSTPS). Mechanical properties of the SSTPS were experimentally investigated and compared with that of CFRSA, including flatwise tension, flatwise compression, edgewise compression and shear. Research results showed that the SSTPS can greatly improve the mechanical properties of CFRSA. To further understand the non-linear, tension-compression asymmetric and transversely isotropic properties of the SSTPS, inner configurations were investigated by X-ray computed tomography and scanning electron microscopy. Mechanical models were established to predict the overall properties of the SSTPS through performance of each component, including theoretical model and finite element analysis (FEA) model. Mixed series-parallel spring models were constructed to theoretically predict the effective elasticity modulus of the SSTPS. Representative volume element (RVE) was selected for FEA modeling of the SSTPS, which can not only predict the equivalent elastic modulus of SSTPS, but also predict the nonlinear flatwise compression behavior. In order to verify whether the mechanical properties of large area SSTPS under complex stress can be represented by the properties of uniform materials through RVE analysis, four-point bending test and FEA modeling were carried out on a large scale SSTPS specimen. Results showed that when analyzing the macro bending behavior of large area SSTPS, the method of equivalent SSTPS to uniform material were of relatively high accuracy and efficiency.

CFD/FEA Co-Simulation Framework for Analysis of the Thermal Barrier Coating Design and Its Impact on the HD Diesel Engine Performance

Thermal barrier coatings (TBCs) have been investigated both experimentally and through simulation for mixing controlled combustion (MCC) concepts as a method for reducing heat transfer losses and increasing cycle efficiency, but it is still a very active research area. Early studies were inconclusive, with different groups discovering obstacles to realizing the theoretical potential. Nuanced papers have shown that coating material properties, thickness, microstructure, and surface morphology/roughness all can impact the efficacy of the thermal barrier coating and must be accounted for. Adding to the complexities, a strong spatial and temporal heat flux inhomogeneity exists for mixing controlled combustion (diesel) imposed onto the surfaces from the impinging flame jets. In support of the United States Department of Energy SuperTruck II program goal to achieve 55% brake thermal efficiency on a heavy-duty diesel engines, this study sought to develop a deeper insight into the inhomogeneous heat flux from mixing controlled combustion on thermal barrier coatings and to infer concrete guidance for designing coatings. To that end, a co-simulation approach was developed that couples high-fidelity computational fluid dynamics (CFD) modeling of in-cylinder processes and combustion, and finite element analysis (FEA) modeling of the thermal barrier-coated and metal engine components to resolve spatial and temporal thermal boundary conditions. The models interface at the surface of the combustion chamber; FEA modeling predicts the spatially resolved surface temperature profile, while CFD develops insights into the effect of the thermal barrier coating on the combustion process and the boundary conditions on the gas side. The paper demonstrates the capability of the framework to estimate cycle impacts of the temperature swing at the surface, as well as identify critical locations on the piston/thermal barrier coating that exhibit the highest charge temperature and highest heat fluxes. In addition, the FEA results include predictions of thermal stresses, thus enabling insight into factors affecting coating durability. An example of the capability of the framework is provided to illustrate its use for investigating novel coatings and provide deeper insights to guide future coating design.

Flaw Design for d-c EP Monitoring of Crack Initiation and Growth During Full-Size Pipe Experiments

A design for flaw placement in a full-scale pipe test was developed to both detect crack initiation and measure crack growth rate upon internal pressurization of a pipe exposed to a sulfide stress cracking (SSC) environment. The objective of this work was to model different sizes of longitudinally oriented, inside diameter (ID) surface flaws and lay them out on the pipe in such a manner that (1) the flaws experience their target stress intensity factor (K) value at a chosen value of internal pressure, (2) the stress interaction between flaws is minimized, and (3) the flaw layout is optimized for detecting both crack initiation and growth using a direct-current (d-c) electric potential (EP) technique. The approach to the flaw design and layout used finite element analysis (FEA) modeling and consisted of optimizing K-profiles. First, the K-profiles were optimized by designing curved-bottom flaws such that the target K along the flaw front occurred along most of the flaw length. Then, stress interactions between the flaws were checked to confirm minimum interactions were achieved and that the proposed flaw layout around the pipe circumference was acceptable. In addition, the FE models were used to predict strains on the pipe outside surface. Finally, global (single large current supply), local (individual small current supplies) and hybrid (individual medium-sized current supplies at larger distance) approaches to the d-c EP measurements were evaluated to select which methodology would be most appropriate to detect both crack initiation and growth of the flaws. The results of the analysis show that optimizing all these design factors provides a solid basis for achieving experimental success.

Design Optimization and Application of Hybrid Bit to Reduce a Well Cost in Geothermal Field

Hybrid bit is one of the innovations developed for very hard and abrasive formations such as in geothermal field. This bit eliminates the risk of losing cones, reduces tripping time, and increaseas ROP to reduce the well cost. The stage of data processing by calculating the UCS formation using D-BOS software and design optimization based on 9-7/8" bits simulations in granodiorite formations. The 1st phase was to determine the 4 best out of 7 hybrid bit designs that were selected from the highest ROP obtained, the most stable cutter cutting force, and the lowest vibration by comparing the results of FEA modeling of 1 ft drilling simulation. The 2nd phase is to choose 1 of the best from the 4 selected by doing 50 ft of drilling dynamics simulation which is assessed by directional capability, the durability, and the lowest MSE. In this study to improve drilling optimization in geothermal field, it was found that the Z616 hybrid bit design was the most optimal one. Based on 1st phase simulation, this bit was able to produce ROP of 6.38 mph, a stable cutter cutting force, very low average lateral 2.109 g and axial vibration 0.329 g. Furthermore, for the 2nd phase simulation of 50 ft, seen from the comparison of directional capability, this bit has a 0.91 deg/100 ft DLS in rotating mode, and 6.5 deg/100ft DLS in sliding mode means quite stable when drilling in rotary mode and easy to make some angle in slide mode. By its durability, the average value of lateral acceleration is 10 g, and the lateral force is 6 klbf. By MSE side, this bit also produces the lowest average MSE value of 769 psi. From the economic view, this bit can save USD 198,625 - USD 564,712 of a well cost.

Mechanical and Finite Element Analysis of an Innovative Orthopedic Implant Designed to Increase the Weight Carrying Ability of the Femur and Reduce Frictional Forces on an Amputee’s Stump

This study was designed to test the hypothesis that: “A properly designed implant that harnesses the principle of the incompressibility of fluids can improve the weight carrying ability of an amputee’s residual femur and reduce the frictional forces at the stump external socket interface.” The hypothesis was tested both mechanically on an Amputee Simulation Device (ASD) and through Finite Element Analysis (FEA) modeling software. With the implant attached to the femur, the FEA and ASD demonstrated that the femur carried 90% and 93% respectively of the force of walking. Without the implant, the FEA model and ASD femur carried only 35% and 77%, respectively, of the force of walking. Statistical calculations reveal three (3) degrees of separation (99% probability of non-random significant difference) between with and without implant data points. FEA modeling demonstrates that the normal contact forces and shear forces are pushed the distal weight-bearing area of the amputee stump, relieving the lateral stump of frictional forces. The ASD mechanical and FEA modeling data validate each other with both systems supporting the hypotheses with confidence intervals of three degrees of separation between with implant and without implant models.