Finite Element Analysis of Foundation Pile Anchor Support System

16 - Design, construction and installation of support structures for offshore wind energy systems

To minimize the assembly stress and thermal stress introduced by the support structure, and ensure the high surface accuracy and high thermal stability of space mirror. An ultra-lightweight design of secondary mirror was carried out for some space remote sensor, and three tangential bipods were used for quasi-kinematic support. Firstly, the design principle of quasi-kinematic support structure was investigated, and advantages of bipod kinematic support were analyzed from the angle of degree of freedom decoupling. Based on structure designed above, the finite element model was established. Taking surface accuracy of the mirror as optimization objectives, the integrated optimization method was adopted to extract the structural parameters with high sensitivity on the surface accuracy in the flexible support structure, and parameters optimization design was carried out. Finally, the static and dynamic characteristics of the optimized mirror assembly were analyzed. The analysis results showed that the surface shape accuracy (RMS) of the mirror assembly is better than 1 nm under a load case of 1g gravity when the optical axis is level. Surface accuracy (RMS) is better than 2 nm under the load case of 4℃ uniform temperature rise. The first-order natural frequency of the secondary mirror assembly is 587 Hz. The optimized mirror support structure can well unload the additional deformation caused by the support structure, and has good dynamic stiffness, which verifies that the designed mirror and its support structure are reasonable, and the optimization design method is reliable. This paper provides a reference and idea for the design of flexible support structure of space mirror.

Cathodic protection (CP) anode bed grounding resistance calculating formulae, given by CP standards, are reviewed firstly. Underground assumptions and limitations of these grounding calculating formulae are analyzed, which means formula method may encounter problems when designing anode beds in high soil resistivity area. Based on finite element analysis (FEA) method, a new grounding resistance calculation method is suggested, which is can be treated as more suitable and flexible for anode bed grounding resistance calculation in high soil resistivity condition. The main steps of FEA method, geometric model building, meshing, boundary condition and solver setting, and grounding resistance calculating according to Ohmic law, are clearly presented. In order to introduce the FEA method in detail, a realistic anode bed design program for Northwestern China area, where soil resistivity is always very high, is demonstrated. Based field soil resistivity survey data by Wenner 4-pin method, the candidate anode bed site, named Station A, is regarded as optimal site, and Barnes’ soil layer analysis method is used to predict soil resistivity distribution in depth direction. Both formula method and FEA method are used to calculate grounding resistance. The following comparison results show that formulae from COR-GS-023, GB21448-2008, РД 153-39.4-039-99 standards and FEA method give out almost the same grounding resistance results under the assumption of uniform soil resistivity, which also, from another angle, verifies the correctness of FEA method. But for FEA method, designers can include realistic soil resistivity distribution function and any anode rod layout plan in calculation model. So, FEA method can be treated as a more flexible tool to calculate CP anode bed grounding resistance.

Private Sector-led Urban Development Projects. Management, Partnerships and Effects in the Netherlands and the UK

Alternative conceptual design of a magnet support structure for plasma fusion devices of stellarator type

Effects of support-structure design and postpolymerization protocols on dimensional changes in three-dimensionally printed complete dentures.

Support point determination for support structure design in additive manufacturing

Parametric design optimisation of tree-like support structure for the laser-based powder bed fusion of metals

When in shallow waters, not only the risers, but also the structures and equipment are submitted to different conditions from the ones related to deepwater applications. OGX has developed offshore applications in shallow waters in Campos Basin, Brazil, using a FPSO with Lazy S riser configuration, based on the Midwater Arch systems (MWA). MWA systems are feasible due to OGX application scenario, but they present some disadvantages, such as: high compliance of the buoyant section to the FPSO, large static offset (common issue in shallow waters applications), which makes the MWA carry the risers that are clamped at the top; high manufacturing and installation costs, associated to the high weight of the structure, which includes large and heavy buoys; limitation regarding transportation, sometimes requiring heavy duty trucks, and consequently, more expensive ones. These disadvantages could be avoided by using another type of support structure, but it depends on the application conditions. Aiming to optimize the Lazy S configuration for new applications in shallow waters, a viability study of a most simplified concept of support, fixed and less compliant, was carried out considering as a standard scenario the Waimea field (under development), located in Campos Basin, Brazil. As a result of this study, OGX and Wood Group Kenny developed the conceptual project of an innovative design of Riser Support Structure (RSS). Therefore, this paper addresses the technical challenges that were faced during the design of this new concept of Riser Support Structure for shallow waters in offshore applications, including issues regarding the required structural safe response and aspects comprising installation and some decommissioning considerations. Regarding the design, this paper discusses the structural analyses performed to validate the RSS, which include VIV and Finite Element Analyses, presenting its main results, and the critical issues encountered during these analyses. They include issues such as: Overstress due to combined loads; stress concentration in important structural components; and stress concentration due to impact load (issue recognized during dynamic analysis to simulate the pile driving operation).

This study delves into the design and deformation patterns of support structures in urban deep excavation projects, aiming to optimize the design of these structures to ensure their safety and stability. Initially, experimental research on steel-cement soil composite beams reveals their bending resistance and ductility under various loading conditions, confirming the effectiveness of the Soil Mixing Wall method in enhancing the stability of support structures. Subsequently, theoretical calculations using the method of elastic support points were conducted and validated through a deep excavation project in Xi’an, demonstrating that this method accurately calculates the trends of horizontal displacement in support structures. Additionally, FLAC3D numerical simulations are utilized to analyze the patterns of horizontal and vertical displacement during the excavation process. The simulation results generally align with the actual measured data, showing that the support structures optimized by the elastic support points method effectively control horizontal displacement (maximum displacement of 47.8 mm) and vertical displacement (maximum heave of 67.3 mm), validating the effectiveness of the numerical simulation methods. This research not only provides theoretical and practical guidance for deep excavation projects but also holds significant reference value for the design and construction of similar engineering projects.

The anti-scuffing bearing capacity of gears is a significant issue for their service lives, especially for the cases with heavy loads or high speeds. Generally, the anti-scuffing bearing capacity is evaluated according to the surface contact temperature that can be calculated with either analytical methods or finite element analysis (FEA) methods. The analytical methods usually apply the theory of Blok to efficiently obtain the results by simplifying some actual physical conditions, which are well considered in the FEA methods with accurate results but more computation time. Conversely, a new efficient and accurate analytical method is proposed by introducing the actual lubricant film thickness and continuous heat transfer for the theory of Blok. These two physical conditions are the key issues for the calculation of the two parts of surface contact temperature, flash temperature and bulk temperature, respectively. For the calculation of flash temperature, elastohydrodynamic lubrication (EHL) is introduced to consider the lubricant film thickness for the theory of Blok, and the result is obtained by solving the Reynolds equation efficiently with the finite difference method. For the bulk temperature, the result for a contacting point on the gear tooth surface is directly obtained according the theory of Blok, and the continuous heat transfer among the adjacent contacting points is considered with Gaussian heat morphology, which can accurately construct the bulk temperature field distribution in the contact region. The proposed method is validated as in good agreement with the FEA method and with less computation time.

PurposeThe purpose of this paper is to report the design of a lightweight tree-shaped support structure for fused deposition modeling (FDM) three-dimensional (3D) printed models when the printing path is considered as a constraint. Design/methodology/approachA hybrid of genetic algorithm (GA) and particle swarm optimization (PSO) is proposed to address the topology optimization of the tree-shaped support structures, where GA optimizes the topologies of the trees and PSO optimizes the geometry of a fixed tree-topology. Creatively, this study transforms each tree into an approximate binary tree such that GA can be applied to evolve its topology efficiently. Unlike FEM-based methods, the growth of tree branches is based on a large set of FDM 3D printing experiments. FindingsThe hybrid of GA and PSO is effective in reducing the volume of the tree supports. It is shown that the results of the proposed method lead to up to 46.71% material savings in comparison with the state-of-the-art approaches. Research limitations/implicationsThe proposed approach requires a large number of printing experiments to determine the function of the yield length of a branch in terms of a set of critical parameters. For brevity, one can print a small set of tree branches (e.g. 30) on a single platform and evaluate the function, which can be used all the time after that. The steps of GA for topology optimization and those of PSO for geometry optimization are presented in detail. Originality/valueThe proposed approach is useful for the designers and manufacturers to save materials and printing time in fabricating complex models using the FDM technique. It can be adapted to the design of support structures for other additive manufacturing techniques such as Stereolithography and selective laser melting.

Premature failures of stator insulation account for a large percentage of repairs of marine generator systems. The failure mechanisms of such faults have been presented in many parts of the literature. Partial discharge activity, thermal degradation, thermal cycling, harmonics and transients are some examples of such failure mechanisms. Whilst there has been an insight into the failure mechanisms, there is still no definite answer to how these defects manifest in the first place. Most of the failures that have been identified within literature are on end windings, especially slot ends. Some failure mechanisms have also been linked with thermal cycling. Frequent and rigorous stop/start cycles stress coils by inducing mechanical forces between elements of the coil and housing owing to differential thermal expansion. This differential expansion is dependent on the rate of rise of temperature and also the different coefficients of thermal expansion of the materials. The present paper will evaluate the thermal degradation of insulation systems used on marine generators using Finite Element Analysis (FEA) methods. On board temperature measurements of stator coils during a high speed run are used as one of the parameters within the FEA simulations, to investigate if there is any risk of differential thermal expansions during such an operational cycle. Different ramp rates are also analyzed within the FEA simulations to understand the effect of uneven thermal expansions and the risk of material degradation of the insulation in coils on marine systems. A brief review of the standards available for thermal cycling and testing are also presented within the paper.

Support structure and optical alignment technology of large-aperture secondary mirror measured by back transmission method

The high-temperature superconducting magnet (HTS) is one of the core technologies of a superconducting maglev. The effects of multiphysics fields including electromagnetic, mechanical, and thermal should be taken into consideration in design. Traditional design methods rely on the initial configuration and the engineer's experience and only consider the design for the heat conduction performance or the structure strength, which often significantly increases the weight. To solve the above problems, based on COMSOL Multiphysics software, the mathematical model of topology optimization of the main support was established with electromagnetic force and thermal stress as the input loads. The objective functions were assigned to total strain energy and heat leakage, combined with stress value and volume fraction constraint conditions. The solid isotropic material with penalization (SIMP) method was used to carry out the topological analysis of multiphysics. Finally, the innovative structure of main support is obtained. Through finite element analysis of multiphysics fields, the heat leakage, the max Von-Mises stress, and weight were taken as evaluation indexes to compare the optimal structure performance. The results show that the method adopted in this paper can reduce the heat leakage by 61.7% while reducing the weight of the main support by 85%, and the max Von-Mises stress does not exceed the yield limit of the material. The work of this paper provides a theoretical foundation for the engineering design of the heat conduction structure of a HTS magnet.