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Based on the engineering examples, the software Flac3d5.0 was used to simulate the deep foundation pit under natural and rainstorm conditions. The load was applied on the north side of the foundation pit, and the influence of the adjacent high-rise buildings on the foundation pit deformation was considered. The results show that the measured value is larger than the simulated value and the deformation law is more consistent. There is obvious deformation in the upper and middle part of the retaining pile under the action of rainstorm, and four kinds of reinforcement plan are developed for the deformation danger area. Based on the comparison of horizontal displacement, shear stress and bending moment of the pile after reinforcement, the advantages and disadvantages of the reinforcement plans are obtained, and effective reinforcement position of deep foundation pit is given. [ABSTRACT FROM AUTHOR]

Abstract A fully blade resolved CFD model with a RANS formulation using the k − ω SST turbulence model was used to study the tidal turbine performance in the presence of two support structures with cylindrical and elliptical cross-sections. The integrated rotor force coefficients were higher in the presence of the cylindrical support structure than the elliptical support due to the higher opposing thrust from the cylinder in the channel increasing the local flow velocity near the top half of the rotor. The angle of attack on the blade decreases as it approaches the support structure due to the reduction in stream-wise flow velocity just ahead of the support structure. This drop is higher for cylindrical support than the elliptical support due to its larger opposing thrust to the flow causing a larger drop in stream-wise velocity. The drop in the angle of attack due to the presence of support structures causes a significant drop in the blade sectional forces as it approaches the support structure. The presence of rotor also causes a drop in the forces on the support structure. The mean stream-wise force coefficients of the cylindrical and elliptical support structures are 0.21 and 0.12 respectively, which are much lower than if they were in open water without a rotor. In case of both the support structures, the stream-wise sectional forces behind the rotor swept area are lower than that in open-water whereas the mean cross-stream forces are higher. The thrust from the rotor and the support structure has a direct influence on the wake velocity. The velocity deficit just in-front of the support structure is 20% higher for the cylindrical support than the elliptical support due to its higher opposing thrust to the flow, and further downstream, the case with cylindrical support has higher velocity deficit followed by elliptical support and then the case with no support structure. Highlights • Implementation of fully blade resolved RANS formulation with k − ω SST turbulence model to study the interaction effects between turbine rotor and two different support structure shapes. • Integrated rotor force coefficients were higher in the presence of the cylindrical support structure than the elliptical support structure. • Presence of rotor causes a drop in the mean stream-wise force coefficients of the support structures. • The velocity deficit just in-front of the support structure is 20% higher for the cylindrical support than the elliptical support. [ABSTRACT FROM AUTHOR]

Here, the new expressions for the mutual inductance and the magnetic force between two Bitter coils (thick coil and pancake) with the inverse radial current densities are presented. These types of coils are used for producing the high magnetic fields. For producing strong magnetic fields, the coils are extremely heated, so that they could be cooled to avoid this problem. During a water‐cooled magnet trip, the induced current in coil changes as a function of decay time constant which is determined by the self‐inductance and the resistance of the water‐cooled magnet. Moreover, such high fields develop the strong magnetic forces which can cause the mechanical stress upon the supporting structure. This way the precise evaluation of these electrical quantities between coils must be calculated to optimise the support structure of Bitter coils. With the newly presented approach, these quantities are obtained in an analytical and semi‐analytical form expressed over elliptical integrals and simple integrals. For validating this method, the comparative improved filament method is used. [ABSTRACT FROM AUTHOR]

A diffuser-augmented hydrodynamic turbine (DAHT) is composed of three main components: a diffuser, a rotor, and a support structure. The design of the support structure plays a crucial role in the performance of the DAHT. It has a significant influence on both the rotor and diffuser performance. However, research on this specific topic is currently limited. In this study, the influence of various parameters such as support distance, the number of columns comprising the support structure and the aspect ratio of support section on the performance of the DAHT is analyzed using blade-resolved Computational Fluid Dynamics (CFD) numerical simulations. Reynolds-Averaged Navier-Stokes (RANS) equations are performed and the k- ω SST turbulence model is utilized to predict the performance of the DAHT. The accuracy of the CFD model is verified by experiments. The results indicate that support structures may significantly reduce the acceleration ratio and power coefficient of the DAHT. With a column number of 3, a support distance of 0.1 and an aspect ratio of 1, the acceleration ratio decreases by approximately 22% and the power coefficient decreases by approximately 26%. It is recommended to choose a front support with a larger aspect ratio and maintain an appropriate support distance. • A blade-resolved Computational-Fluid-Dynamics model of a diffuser-augmented hydrokinetic turbine is established. • Flume experiment is carried out to verify the CFD model. • Support distance, the number of columns and the aspect ratio on the diffuser-augmented hydrokinetic turbine are evaluated. • Suggestions on support structure are put forward. [ABSTRACT FROM AUTHOR]

This paper presents a description of an effective method for determining loads due to waves and current acting on the supporting structures of the offshore wind turbines. This method is dedicated to the structures consisting of the cylindrical or conical elements as well as (truncates) pyramids of polygon with a large number of sides (8 or more). The presented computational method is based on the Morison equation, which was originally developed only for cylindrically shaped structures. The new algorithm shown here uses the coefficients of inertia and drag forces that were calculated for non-cylindrical shapes. The analysed structure consists of segments which are truncated pyramids on the basis of a hex decagon. The inertia coefficients, CM, and drag coefficients, CD, were determined using RANSE-CFD calculations. The CFD simulations were performed for a specific range of variation of the period, and for a certain range of amplitudes of the velocity. In addition, the analysis of influence of the surface roughness on the inertia and drag coefficients was performed. In the next step, the computations of sea wave, current and wind load on supporting structure for the fifty-year storm were carried out. The simulations were performed in the time domain and as a result the function of forces distribution along the construction elements was obtained. The most unfavourable distribution of forces will be used, to analyse the strength of the structure, as the design load.

This paper presents a restoration solution of increased vibration of the fan plant's support structure. Based on vibrodiagnostic tests and dynamic analysis, a technical solution of the problem is given with additional steel bracing. There is particular emphasis on the diagnosis and forming of a dynamic model.

A super-span tunnel that has the characteristics of a large excavation area, a small high-span ratio and a significant spatial effect exhibits a complex mechanical response during the excavation process. In this paper, taking the Badaling Great Wall station in Beijing, China as the engineering background, a case study of field monitoring a super-span tunnel has been presented. A typical monitoring section was selected in the super-span transition section of the tunnel and the deformation and forces of both the surrounding rock and the support structures were systematically monitored. The dynamic evolution and the spatial distribution characteristics of the monitoring data, including the internal displacement of the surrounding rock, the tunnel displacement, the contact pressure between the surrounding rock and the primary supports, the contact pressure between the primary and secondary supports, the axial forces in the bolts and cables, the internal forces in both the steel arches and the secondary supports and the internal stresses of the surrounding rock, were analyzed. The results of the monitoring and the analyses have shown that the deformation and the forces acting on both the surrounding rock and the tunnel’s lining are directly related to the construction procedures, the geological conditions and the locations in the super-span tunnel. According to the results, a few suggestions to improve the construction of the tunnel have been proposed.

In the laser powder bed fusion processes for metal additive manufacturing, a support structure is needed to fix the part to the base plate and to support overhanging regions. Currently the importance of support structure for a successful build process is often underestimated and some effects are not yet well understood. Therefore, this study investigates the fracture behavior and mechanical properties of thin additive manufactured struts using the titanium alloy Ti-6Al-4V and specific machine parameters for support structures. Tensile tests were performed for different strut diameters and the fracture surfaces were analyzed using a laser microscope and a scanning electron microscope. Additionally, the porosity was examined with micro-CT scans. The results were compared with a different set of parameters used for solid parts. The experiments revealed that struts produced with support parameters had no significantly lower tensile strength than the comparative parts. Despite that, some porosity and around two percent of defects on the fracture surface for parts using the solid parameter set have been found. Parts with support parameters show no porosity, even though the energy density is around 30% lower compared to the solid parameter set.

This paper investigates efficient design of offshore wind turbine (OWT) support structures under ultimate loads and proposes three schemes to overcome excessive computer time due to many required external loads. The first is the assumption of a rigid support structure to find blade wind forces, so that these forces are only dependent on wind profiles, which limits different cases in the structural analyses. Since the blade information is often confidential in turbine companies, this two-stage analysis allows the hub force to be the input data for the support structure design. The second is using a few control loads to perform the steel design between the second and the second-last design cycles. The third is using parallel computational procedures, since all loading cases can be independently executed in different CPU cores and computers. The test cases, with 5044 loading cases, indicate that the proposed method is fully parallel and can complete the design procedures using a few personal computers within several days. Test cases include IEC 61400-3, tropical cyclone, and seismic loads; although there are many loads to be considered, steel design is governed by a limited number of load cases, which are discussed in this paper.

In household refrigerators, the rotational speed of a reciprocating compressor can be appropriately adjusted according to the temperature inside of the refrigerator. The lower rotational speed reduces the power consumption of the compressor. However, several natural frequencies of the compressor exist in the low rotation region, and besides, the unbalance force arising from the piston motion acts on the internal drive unit. Thereby the vibrations of the compressor are likely to be larger due to the resonance in the low rotation region. In this study, a method for supporting the drive unit inside the shell, which is called “the self-standing support” is newly proposed in order to reduce the vibration of the compressor drastically. In the proposed method, a spherical support element is utilized instead of coil springs to support the drive unit. And the drive unit can maintain a stable self-standing state by acting restoring moment due to the gravity while it is directly placed on the shell. The natural frequencies of the compressor can be greatly reduced by decreasing the support stiffness for the drive unit in comparison with the support method using coil springs. Furthermore, in designing the drive unit, the application point of the exciting force is matched with the center of percussion to the contact point on the spherical support. As a consequence, the periodic restraining force acting on the contact point can be minimized. By these two features, it is possible to considerably reduce the vibration transmission from the drive unit to the shell. In the present study, a simplified model for a reciprocating compressor is treated, and the effectiveness of the self-standing support is investigated analytically and experimentally.

The support structure being the object of the analysis presented in the article is Tripod. According to the adopted assumptions, it is a foundation gravitationally set in the water region of 60 m in depth, not fixed to the seabed, which can be used for installing a 7MW wind turbine. Due to the lack of substantial information on designing and strength calculations of such types of structures in the world literature, authors have made an attempt to solve this problem within the framework of the abovementioned project. In the performed calculations all basic loads acting on the structure were taken into account, including: the self mass of the structure, the masses of the ballast, the tower and the turbine, as well as hydrostatic forces, and aero- and hydrodynamic forces acting on the entire object in extreme operating conditions.

This paper presents a procedure of determining the causes of increased vibration of a fan plant and its support structure in the PUC 'Subotička toplana'. Excessive vibrations were observed following the installation of the frequency converter, thus a methodological approach of testing-analysis-diagnosis has been applied. Based on the definition of the causes of this problem, the paper also suggests possible repair procedures.

The authors are developing multi degree of freedom micro spherical ultrasonic motor using wire stator for vascular endoscope. Spherical ultrasonic motor with 20 times model is used to confirm the driving characteristics as experimental equipment. Wire stator is designed by assuming the introduction to a vascular endoscope and transient response analysis is performed by the finite element method compared with 20 times model. In this study, the authors improve new support structure on waveguide and investigate new influence of the attenuation of the traveling wave transmitted on the wire stator by analyzing and changing the condition of the model. In the future, the authors will measure the amplitude of the wire stator by experiment and verify the accuracy of the simulation. [ABSTRACT FROM AUTHOR]

Aero-engine blade-off event could cause serious malfunction and endanger flight safety,which is an important issue widely concerned for a long period.This paper presents a comprehensive review on the regulation requirements,the major research methods and status at home and abroad.Firstly,the relevant certification regulations and standards about aero-engine structure safety due to blade-off event were overviewed and the research gaps between the abroad and the domestic were compared.Then,the simulation and experimental methodologies on aero-engine supporting structures undertake abnormal load due to blade-off event were discussed as major issue.Finally,the safety certification verification technology system for aero-engine support structures during blade-off event was proposed. [ABSTRACT FROM AUTHOR]

Notwithstanding the widespread use and large number of advantages over traditional subtractive manufacturing techniques, the application of additive manufacturing technologies is currently limited by undesirable support material waste. Support structures are unavoidable when manufacturing objects with overhangs in extrusion-based Additive manufacturing, leading to extra build time and material waste. In a manufacturing process, different parameters such as cooling fan speed, print speed and print temperature can make a great contribution to printable overhang angle size. In this study, effects of these parameters on printable overhang angle size are studied theoretically and experimentally. First, theoretical analysis of printable overhang is conducted. Then experiments of overhangs with 20°, 30°, 40° and 50° are carried out with regard to different parameters on an FDM printer. According to the results, the printable threshold overhang angle varies substantially with printing conditions. The findings of this paper can then be applied for setting a lower threshold overhang angle for reducing support waste in the future. The findings can also provide some reference for future research in high-precision printing by adjusting relevant print parameters. [ABSTRACT FROM AUTHOR]

Radiation embrittlement of materials of support structures (SS) for reactor pressure vessel (RPV) of WWER types is considered. The features of radiation embrittlement of SS materials are connected with low irradiation temperature no exceeding 90 °C and also with a use of the steels which are usually applied for different building structures and have not a high resistance to the radiation embrittlement. The experimental date on standard mechanical properties and fracture toughness have been obtained for various steels and weld metals in the initial and irradiation conditions. SEM investigation of fracture surface of fractures toughness specimens and investigation with atomic-tomography method have been performed. The model for prediction of material radiation embrittlement as a function of the neutron fluence and the impurity (Cu and P) content is developed. The irradiation temperature effect is considered on various mechanisms of radiation embrittlement of a material. [ABSTRACT FROM AUTHOR]

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of the two support structures, thin-wall tooth contact (TC) and solid-gap (SG), on the Ti-6Al-4V parts fabricated by powder bed fusion electron beam additive manufacturing were investigated. In the Y-plane of the overhang, equiaxed β′ microstructure formed initially and gradually grew into a wider columnar structure with its width about 3 times of that iRn the solid section. Fine α/α′ and β phases were identified within the β′ grains, in which the content of α′ increases from the bottom to the top of the part and α/α′ phase presents strong textures of 0   0   0   1 and 1   1   2 ¯   0 parallel to the build-direction. In addition, more defects were observed in the overhang than the solid, especially at the interface between the solid and the overhang sections which also induced the stress concentration. Compressive residual stresses were revealed in the parts with some points showing minor tensile residual stresses. Compared to the SG part, the TC part had a lower Vickers hardness. The solid part under the SG part acted as a heat sink and enhanced heat dissipation during the manufacturing process, which affected the thermal gradient and improved the microstructures and mechanical properties in the overhang. The teeth in the TC part did limit the occurrence of the wrapping phenomenon. Taking advantages of the two designs, a new support design, SG support with teeth at the tip-end of overhang, is recommended. [ABSTRACT FROM AUTHOR]

Increasing the surface porosity of a support membrane has been proposed as an effective way to improve the water permeability of thin-film composite (TFC) reverse osmosis (RO) membranes by reducing the diffusion pathway in the active layer. In this work, we prepared a highly porous microstructured (HPμS) support membrane with a suitable mechanical strength to enhance the water permeability of an RO membrane. The HPμS support membrane was prepared by increasing the thermodynamic instability of a 10 wt% polymer solution and thereby facilitating rapid desolvation. The rapid desolvation formed the narrow and regularly arranged pore structure in the sublayer, and we proposed the mechanism for the sublayer structure formation based on analyses of the thermodynamic properties of such a binary system. Owing to the narrow and regular structure, the HPμS support membranes showed the exceptional mechanical strength, which was comparable to the strength of support membranes used for conventional RO membranes. Also, the HPμS support membranes successfully endowed an in-house RO membrane with the performance (water permeability of 4.68 L m −2  h −1  bar −1 and NaCl rejection of 98.3%) surpassing commercial RO membranes and thin-film nanocomposite membranes recently reported in the literature. [ABSTRACT FROM AUTHOR]

Manufacturing-oriented topology optimization has been extensively studied the past two decades, in particular for the conventional manufacturing methods, for example, machining and injection molding or casting. Both design and manufacturing engineers have benefited from these efforts because of the close-to-optimal and friendly-to-manufacture design solutions. Recently, additive manufacturing (AM) has received significant attention from both academia and industry. AM is characterized by producing geometrically complex components layer-by-layer, and greatly reduces the geometric complexity restrictions imposed on topology optimization by conventional manufacturing. In other words, AM can make near-full use of the freeform structural evolution of topology optimization. Even so, new rules and restrictions emerge due to the diverse and intricate AM processes, which should be carefully addressed when developing the AM-specific topology optimization algorithms. Therefore, the motivation of this perspective paper is to summarize the state-of-art topology optimization methods for a variety of AM topics. At the same time, this paper also expresses the authors’ perspectives on the challenges and opportunities in these topics. The hope is to inspire both researchers and engineers to meet these challenges with innovative solutions. [ABSTRACT FROM AUTHOR]

The high-luminosity LHC upgrade target is to increase the integrated luminosity by a factor of 10, resulting in an integrated luminosity of 3000 fb-1. One major improvement foreseen is the reduction of the beam size at the collision points. This requires the development of 150-mm single aperture quadrupoles for the interaction regions. These quadrupoles are under development in a joint collaboration between CERN and the US-LHC Accelerator Research Program. The chosen approach for achieving a nominal quadrupole field gradient of 132.6 T/m is based on the Nb3Sn technology. The coils with a length of 7281 mm will be the longest Nb3Sn coils fabricated so far for accelerator magnets. The production of the long coils was launched in 2016 based on practice coils made from copper. This paper provides a status of the production of the first low grade and full performance coils and describes the production process and applied quality control. Furthermore, an outlook for the prototype assembly is provided. [ABSTRACT FROM AUTHOR]

This paper presents a topology optimization formulation that accounts for construction in stages. Unlike in common topology optimization procedures, the loading and support conditions during construction are considered in addition to the final situation for which the structure is intended. The main purpose is to generate optimized layouts that can be built without temporary supports or scaffolds, as required for example in the design of segmental bridges. Another field of application which can benefit from this formulation is the design for manufacturing by layers, for which the staged construction is interpreted as a layer-by-layer fabrication process. By slicing the design domain and considering several fabrication stages, we obtain optimized designs that are influenced by the building direction and by the excessive deformation of unsupported layers. Demonstrative examples in 2-D and 3-D show that the amount of temporary scaffolds which are required for supporting during construction can be reduced significantly. Finally, we apply the layered approach to the design of hybrid void-support-solid layouts that can exhibit superior balance between performance and constructability compared to void-solid topologies. [ABSTRACT FROM AUTHOR]

In the present research, by using a numerical model, some analyses were performed on flows around a T-shape spur dike and a support structure located at its upstream under different wing to length ratios of T-shape spur dike in the order of 0.25, 0.50, 0.75 and 1.00. In order to verify numerical model, physical model data were used in presence of a single T shape spur dike. Results from numerical model are desirably in agreement with those of physical one because the regression between both data is 0.86 up to 0.92. In this research, all hydraulic parameters of flows, streamlines and dimensions of flow separation zones were studied in order to select the most practical model. Increased W/L results in 7%-12% increase in the length of flow separation zone and in 2% increase in the width of this zone compared to W/L=0.25. [ABSTRACT FROM AUTHOR]

Selective laser melting (SLM) technology was recently introduced to fabricate dental prostheses. However, the fatigue strength of clasps in removable partial dentures prepared by SLM still requires improvement. In this study, we attempted to improve the fatigue strength of clasps by adding support structures for overhanging parts, which can generally be manufactured at an angle to be self-supporting. The results show that the fatigue strength of the supported specimens was more than twice that of unsupported specimens. Electron back-scattered diffraction analysis revealed that the supported specimens exhibited lower kernel average misorientation values than the unsupported specimens, which suggested that the support structure reduced the residual strain during the SLM process and helped to prevent micro-cracks led by thermal distortion. In addition, the supported specimens cooled more rapidly, thereby forming a finer grain size compared to that of the unsupported specimens, which contributed to improving the fatigue strength. The results of this study suggest that the fatigue strength of overhanging parts can be improved by intentionally adding support structures. [ABSTRACT FROM AUTHOR]

3D printing is a new promising technology capable of creating intricate food shapes. To stabilize the mechanical properties of the complex printed food it may require support structures. The 3D shape of chocolate was designed with different support structures (cross support, parallel support and no support) and its effect on the snapping properties was investigated. This study also determined the relationship between the physical properties of chocolate used for printing and the quality of the printed 3D constructs. The dimensions (wall thickness, height, and diameter), weight as well as physical properties (melting properties, flow behaviour, snap ability) of the 3D printed chocolate were evaluated. The nozzle temperature before deposition was maintained at 32 °C in order to extrude the melted state of the sample as the flow behaviour curves indicated that the melting of chocolate started between 28 °C to 30 °C. Incorporation of Magnesium Stearate (MgST) in the chocolate formulation aid in material lubrication and increase flow efficiency during deposition. Results showed that there was a minor difference between the predetermined diameter and the actual output diameter for each sample suggesting similarity between the printed 3D structure and the pre-designed 3D model. Wall thickness of printed item varied along the height due to uneven deposition of chocolate as the layer height increased. The breaking strength of the sample was strongly related to the additional support structure, with 3D chocolate with cross support structure requiring the highest force (N) to break the sample. Industrial relevance The development and production of food with 3-Dimensional printing (3DP) technology has potential to create and produce food in a more advanced format that will be a new paradigm shift in the food industry. Through 3D printing, personalised food can be created in terms of shape and nutritional composition. To firmly establish this promising technology as a powerful tool for engineering food it is required a thorough understanding of the supply ingredients and strategies to enhance printability. This study demonstrates the use of flow enhancer and inclusion of support structure in the designed shape were key factors influencing printability capacity of chocolate (edible ink chosen as a model). [ABSTRACT FROM AUTHOR]

Although 3D-printing is common in dentistry, the technique does not produce the required quality for all target applications. Resin type, printing resolution, positioning, alignment, target structure, and the type and number of support structures may influence the surface roughness of printed objects, and this study investigates the effects of these variables. A stereolithographic data record was generated from a master model. Twelve printing processes were executed with a stereolithography Desktop 3D Printer, including models aligned across and parallel to the printer front as well as solid and hollow models. Three layer thicknesses were used, and in half of all processes, the models were inclined at 15°. For comparison, eight gypsum models and milled polyurethane models were manufactured. The mean roughness index of each model was determined with a perthometer. Surface roughness values were approximately 0.65 µm (master), 0.87−4.44 µm (printed), 2.32−2.57 µm (milled), 1.72−1.86 µm (cast plaster/alginate casting), and 0.98−1.03 µm (cast plaster/polyether casting). The layer height and type and number of support structures influenced the surface roughness of printed models (p ≤ 0.05), but positioning, structure, and alignment did not.

To obtain reliable estimations of the dynamic responses of high-rising marine structures such as offshore wind turbines with obvious nonzero initial conditions, traditional frequency-domain methods cannot be employed because they provide only steady-state results. A novel frequency-domain transient response estimation method for offshore wind turbines is presented in this paper. This method builds upon a recent, significant theoretical development, which found that expressions of external loads in the frequency domain can be obtained by discretizing their eigenvalues and corresponding complex coefficients rather than directly by discrete Fourier transform (DFT) analysis, which makes it possible to deal with nonzero conditions in the frequency domain. One engineering advantage of this approach is its computational efficiency, as the motion equations of the system can be solved in the frequency domain. In order to demonstrate this approach, a case of a monopile-supported wind turbine with nonzero initial conditions was investigated. The numerical results indicate that the approach matches well with the time-domain method, except for a small, earlier portion of the estimated responses. A second case study of a sophisticated, jacket support wind turbine, involving practical issues such as complex external loads and computation efficiency, is also discussed, and comparisons of the results with the time-domain method and traditional frequency-domain method using the commercial software ANSYS are included here.

This paper investigates the structural monitoring concept and data analysis strategy using an example of an operating offshore wind turbine in the North Sea. As part of the data evaluation strategy; a design verification is shown for the bending moments calculated from monitoring data, operational modal analysis is performed to identify the first three dominant natural frequencies. Then an FE Model is prepared and validated with the identified natural frequencies so that, the model fairly represents the as built healthy physical structure. Finally, variation of the natural frequencies are traced for increasing sea bed scouring (change in boundary condition). This study is done to make up for the absence of such monitored events and as part of the introduced data evaluation strategy to initiate thresholds for damage sensitive global parameters. [ABSTRACT FROM AUTHOR]

The clearance feature is the key issue in the direct manufacturing of nonassembly mechanism by selective laser melting (SLM). Although support structures can prevent warpage and collapse of overhanging surfaces within the clearance feature during the laser beam irradiation, the motion performance of mechanism is however reduced. Taking the avoidance of an overhanging surface within the clearance as the goal in this study, the critical building angle of overhanging structure was determined as 40°, and influences of process parameters on clearance size were studied. Furthermore, optimized structures of kinematic pairs were proposed to reduce the overhanging surfaces. Finally, the optimized kinematic pairs were applied to a typical mechanism. The result shows that mechanism can be manufactured perfectly by using the optimized kinematic pairs and process parameters without considering the overhanging surfaces within clearance feature. [ABSTRACT FROM AUTHOR]

By accounting for almost 25% of the capital cost of an OWT (offshore wind turbine), optimisation of support structures provides an efficient way to reduce the currently high cost of offshore wind energy. In this paper, a structural optimisation model for OWT support structures has been developed based on a coupled parametric FEA (Finite Element Analysis) and GA (Genetic Algorithm), minimising the mass of the support structure under multi-criteria constraints. Contrary to existing optimisation models for OWT support structures, the proposed model is an integrated structural optimisation model, which optimises the components of the support structure (i.e. tower, transition piece, grout and monopile) simultaneously. The outer diameters and section thicknesses along the support structure are chosen as design variables. A set of constraints based on multi-criteria design assessment is applied according to standard requirements, which includes vibration, stress, deformation, buckling, fatigue and design variable constraints. The model has been applied to the NREL (National Renewable Energy Laboratory) 5 MW OWT on an OC3 (Offshore Code Comparison Collaboration) monopile. The results of the application of the integrated optimisation methodology show a 19.8% reduction in the global mass of the support structure while satisfying all the design constraints. It is demonstrated that the proposed structural optimisation model is capable of effectively and accurately determining the optimal design of OWT support structures, which significantly improves their design efficiency. [ABSTRACT FROM AUTHOR]

Summary: We present an approach for controlling the undercut and the minimal overhang angle in density based topology optimization, which are useful for reducing support structures in additive manufacturing. We cast both the undercut control and the minimal overhang angle control that are inherently constraints on the boundary shape into a domain integral of Heaviside projected density gradient. Such a Heaviside projection based integral of density gradient leads to a single constraint for controlling the undercut or controlling the overhang angle in the optimization. It effectively corresponds to a constraint on the projected perimeter that has undercut or has slope smaller than the prescribed overhang angle. In order to prevent trivial solutions of intermediate density to satisfy the density gradient constraints, a constraint on density grayness is also incorporated into the formulations. Numerical results on Messerschmitt–Bolkow–Blohm beams, cantilever beams, and 2D and 3D heat conduction problems demonstrate the proposed formulations are effective in controlling the undercut and the minimal overhang angle in the optimized designs. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Access shaft is of critical importance to tire construction and operation of underground rock caverns. It usually has a relatively large cross-section and penetrates through fill materials, soil layers, and weathered rocks before reaching the caverns excavated in solid bedrock. In this paper, tire design and construction of vertical shafts are reviewed in terms of diameter, depth, geological conditions, and support structure. Three shaft alternatives, namely alternative I: vertical shaft with spiral roads, alternative II: upper shaft with spiral roads & lower tunnels, alternative IE: plain shaft, are proposed based on a simplified geological profile of tire Jurong formation, Singapore. The advantages and limitations of the three types of shafts are discussed. The key issues relating to shaft design and construction, such as the shaft sinking, water control, support structure, are also discussed with a series of solutions provided, such as the sequential excavation, pre-grouting and diaphragm walls. [ABSTRACT FROM AUTHOR]

We present an approach for controlling the undercut and the minimal overhang angle in density based topology optimization, which are useful for reducing support structures in additive manufacturing. We cast both the undercut control and the minimal overhang angle control that are inherently constraints on the boundary shape into a domain integral of Heaviside projected density gradient. Such a Heaviside projection based integral of density gradient leads to a single constraint for controlling the undercut or controlling the overhang angle in the optimization. It effectively corresponds to a constraint on the projected perimeter that has undercut or has slope smaller than the prescribed overhang angle. In order to prevent trivial solutions of intermediate density to satisfy the density gradient constraints, a constraint on density grayness is also incorporated into the formulations. Numerical results on Messerschmitt-Bolkow-Blohm beams, cantilever beams, and 2D and 3D heat conduction problems demonstrate the proposed formulations are effective in controlling the undercut and the minimal overhang angle in the optimized designs. [ABSTRACT FROM AUTHOR]

The high luminosity Large Hadron Collider (LHC) upgrade target is to increase the integrated luminosity by a factor 10, resulting in an integrated luminosity of 3000 fb−1. One major improvement foreseen is the reduction of the beam size at the collision points. This requires the development of 150-mm single-aperture quadrupoles for the interaction regions. These quadrupoles are under development in a joint collaboration between CERN and the US-LHC Accelerator Research Program. The chosen approach for achieving a nominal quadrupole field gradient of 132.6 T/m is based on the Nb3Sn technology. The coils with a length of 7281 mm will be the longest Nb3 Sn coils fabricated so far for accelerator magnets. The production of the long coils was launched in 2016 based on practise coils made from copper. This paper provides a status of the tooling development and production of the first copper coil, from winding, curing, and reaction heat treatment. In addition, an overview of the upcoming coil vacuum impregnation and the development of the magnet assembly including a prototype production schedule are provided. [ABSTRACT FROM PUBLISHER]