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The air and structural loads of a 5-ton class light helicopter (LH) rotor in a 2.24 g pull-up maneuver are investigated using a coupling between the computational structural dynamics (CSD) and computational fluid dynamics (CFD) methods. The LH rotor is characterized by a five-bladed system with elastomeric bearings and inter-bladed dampers. The periodic trim solution along with the converged CFD/CSD delta airloads obtained in steady-level flight (advance ratio of 0.287) are used to perform the transient CSD maneuver analysis. The resulting vehicle attitude angles and velocity profiles of the aircraft are then prescribed in the quasi-static (QS) CFD maneuver analysis. It is demonstrated that the present QS approach provides an effective means for the maneuver loads' analysis. The important flow behaviors such as BVI (blade–vortex interaction)-induced oscillations and the negative pitching moment peaks met in maneuver flight are captured nicely with the proposed method. Either the vortex trajectories or the surface pressure distributions are examined to identify the sources of the oscillations. A loose CFD/CSD coupling (LC) is used to predict the blade elastic motions, structural moments, and pitch link loads at the specified maneuver revolution of the rotor and also to correlate these with the transient CSD-based predictions. A reasonable correlation is obtained. The LC results show more pronounced 5P (five per revolution) oscillations on the structural response than those of the CSD-based methods. [ABSTRACT FROM AUTHOR]

Copyright of Aeronautical Science Bulletins / Repüléstudományi Közlemények is the property of National University of Public Service 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.)

Increased volumes of freight turnover in international transportation require the situational adaptation of the existing wagon fleet to the transportation of containers, which are commonly used at present. The research presented in this article substantiates the possibility of transporting containers in open wagons. It has been found that taking into account the possible displacements of containers in the body, the stresses at the operating modes can be twice as high as the permissible ones if an open wagon is part of the combined train. In this regard, it is proposed that a detachable multifunctional module for securing containers in the open wagon body be used. The detachable module is fixed through the fitting stops, either stationary or hinged, in the body. The rationale for the choice of the detachable module profile, as well as the results of its strength calculation, is given. The strength of the open wagon body during container transportation has been studied taking into account the proposed fastening diagram. The results of the calculations have shown that the maximum stresses in the body do not exceed permissible values. The results of the study will contribute to improvement in the efficiency of container transportation and the transport industry as a whole. Also, these results may be useful developments for designing modular vehicles. [ABSTRACT FROM AUTHOR]

The air and structural loads of a 5-ton class light helicopter (LH) rotor in a 2.24 g pull-up maneuver are investigated using a coupling between the computational structural dynamics (CSD) and computational fluid dynamics (CFD) methods. The LH rotor is characterized by a five-bladed system with elastomeric bearings and inter-bladed dampers. The periodic trim solution along with the converged CFD/CSD delta airloads obtained in steady-level flight (advance ratio of 0.287) are used to perform the transient CSD maneuver analysis. The resulting vehicle attitude angles and velocity profiles of the aircraft are then prescribed in the quasi-static (QS) CFD maneuver analysis. It is demonstrated that the present QS approach provides an effective means for the maneuver loads’ analysis. The important flow behaviors such as BVI (blade–vortex interaction)-induced oscillations and the negative pitching moment peaks met in maneuver flight are captured nicely with the proposed method. Either the vortex trajectories or the surface pressure distributions are examined to identify the sources of the oscillations. A loose CFD/CSD coupling (LC) is used to predict the blade elastic motions, structural moments, and pitch link loads at the specified maneuver revolution of the rotor and also to correlate these with the transient CSD-based predictions. A reasonable correlation is obtained. The LC results show more pronounced 5P (five per revolution) oscillations on the structural response than those of the CSD-based methods.

This paper demonstrates the influence of pile head freedom on the thermomechanical performance of a belled pile. Field tests on the belled pile response to a cooling–heating cycle and incremental structural construction are carried out. The temperature changes, axial strain profiles, and pressures at the pile toe are recorded through the buried instruments. The variation in the degrees of freedom, tensile forces, and inferred pile head settlements along the pile depth for different test procedures are analyzed using the measured data. The degree of freedom close to the pile head calculated from strain rates decreases with the structure mass with a gradient of −2.8×10−5/kN. The reducing effect of the incremental superstructure on pile freedom decreases along with the orientation of the pile depth. Compared with the inferred thermal displacement of the pile without an applied structural load, the values decrease by about 10% when the pile was subjected to incremental floors, and an elastic recoverable characteristic response to cooling–heating-recovery phases is observed. Compared with the equal-diameter pile, the belled pile showed a significant constraint close to the toe. Mechanical loads can decrease the cracking risk because of a possible tensile force under cooling conditions. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology 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.)

Increased volumes of freight turnover in international transportation require the situational adaptation of the existing wagon fleet to the transportation of containers, which are commonly used at present. The research presented in this article substantiates the possibility of transporting containers in open wagons. It has been found that taking into account the possible displacements of containers in the body, the stresses at the operating modes can be twice as high as the permissible ones if an open wagon is part of the combined train. In this regard, it is proposed that a detachable multifunctional module for securing containers in the open wagon body be used. The detachable module is fixed through the fitting stops, either stationary or hinged, in the body. The rationale for the choice of the detachable module profile, as well as the results of its strength calculation, is given. The strength of the open wagon body during container transportation has been studied taking into account the proposed fastening diagram. The results of the calculations have shown that the maximum stresses in the body do not exceed permissible values. The results of the study will contribute to improvement in the efficiency of container transportation and the transport industry as a whole. Also, these results may be useful developments for designing modular vehicles.

• Closed-form equations are developed for an OSWEC's pitch-pitch and surge-pitch added mass, radiation damping, and excitation forces/torques, which can be used to determine the system's response amplitude operator (RAO) and foundation loads. • The proposed model is benchmarked against numerical simulations using WAMIT and WEC-Sim; excellent agreement is found. • The flat plate assumption, inherent to the theoretical model, was examined through comparison with numerical solutions over a range of plate thickness. • A case study demonstrates the ability of the analytical model to quickly (less than one second per frequency) sweep over a domain of OSWEC dimensions, illustrating the model's utility in the early phases of design. This study presents theoretical formulations to evaluate the fundamental parameters and performance characteristics of a bottom-raised oscillating surge wave energy converter (OSWEC) device. Employing a flat plate assumption and potential flow formulation in elliptical coordinates, closed-form equations for the added mass, radiation damping, and excitation forces/torques in the relevant pitch-pitch and surge-pitch directions of motion are developed and used to calculate the system's response amplitude operator and the forces and moments acting on the foundation. The model is benchmarked against numerical simulations using WAMIT and WEC-Sim, showcasing excellent agreement. The sensitivity of plate thickness on the analytical hydrodynamic solutions is investigated over several thickness-to-width ratios ranging from 1:80 to 1:10. The results show that as the thickness of the benchmark OSWEC increases, the deviation of the analytical hydrodynamic coefficients from the numerical solutions grows from 3 % to 25 %. Differences in the excitation forces and torques, however, are contained within 12 %. While the flat plate assumption is a limitation of the proposed analytical model, the error is within a reasonable margin for use in the design space exploration phase before a higher-fidelity (and thus more computationally expensive) model is employed. A parametric study demonstrates the ability of the analytical model to quickly sweep over a domain of OSWEC dimensions, illustrating the analytical model's utility in the early phases of design. [ABSTRACT FROM AUTHOR]

Two‐bladed wind turbines (WTs) are recently discussed as a potential alternative to reduce the cost of energy in offshore wind farms which have a higher cost compared to onshore wind farms. However, the dynamic response and performance of these WTs are different from the three‐bladed WTs. In this study, new and comprehensive models for rigid and teetered rotor WTs are developed in FAST and emulated with a setup of the previous simulation‐based works. Then, the power quality issues are discussed and compared for two‐bladed WTs with rigid and teetered rotors as the main contribution of this study. The performance of a WT with different rotors is evaluated and compared in terms of power fluctuations, voltage fluctuations, flicker emission level. In addition, the structural loads of the turbine are studied and compared with both rotor types. This was done in emulation and simulation by varying linear horizontal and logarithmic vertical wind shear as well as utilising a turbulent wind time series without shear. The study presents results obtained by simulation and by emulation, using a scaled‐down WT emulator. It presents conclusions as to which type of rotor offers better performance for various operating conditions. [ABSTRACT FROM AUTHOR]

Knowledge of loads acting on running specific prostheses (RSP), and in particular on running prosthetic feet (RPF), is crucial for evaluating athletes’ technique, designing safe feet, and biomechanical modelling. The aim of this work was to develop a J-shaped and a C-shaped wearable instrumented running prosthetic foot (iRPF) starting from commercial RPF, suitable for load data collection on the track. The sensing elements are strain gauge bridges mounted on the foot in a configuration that allows decoupling loads parallel and normal to the socket-foot clamp during the stance phase. The system records data on lightweight athlete-worn loggers and transmits them via Wi-Fi to a base station for real-time monitoring. iRPF calibration procedure and static and dynamic validation of predicted ground-reaction forces against those measured by a force platform embedded in the track are reported. The potential application of this wearable system in estimating determinants of sprint performance is presented.

This article investigates the impact of the pitch-to-stall and pitch-to-feather control concepts on horizontal axis wind turbines (HAWTs) with different blade designs. Pitch-to-feather control is widely used to limit the power output of wind turbines in high wind speed conditions. However, stall control has not been taken forward in the industry because of the low predictability of stalled rotor aerodynamics. Despite this drawback, this article investigates the possible advantages of this control concept when compared to pitch-to-feather control with an emphasis on the control performance and its impact on the pitch mechanism and structural loads. In this study, three HAWTs with different blade designs, i.e., untwisted, stall-regulated, and pitch-regulated blades, are investigated. The control system is validated in both uniform and turbulent wind speed. The results show that pitch-to-stall control enhances the constant power control for wind turbines with untwisted and stall-regulated blade designs. Stall control alleviates the fore-aft tower loading and the blades flapwise moment of the wind turbine with stall-regulated blades in uniform winds. However, in turbulent winds, the flapwise moment increases to a certain extent as compared to pitch-to-feather control. Moreover, pitch-to-stall control considerably reduces the summed blade pitch movement, despite that it increases the risk of surface damage in the rolling bearings due to oscillating movements with a small amplitude.

The knowledge of loads acting on Running Specific Prostheses (RSP), and in particular, on Running Prosthetic Feet (RPF) is crucial for evaluating the athlete’s running technique, designing RPF, and developing models of the runners. The aim of this work was to develop a set of instrumented RPF (iRPF) suitable for track data collection of start, sprinting, and whole run-in and take-off of long jump. The system allows measuring with a portable data logger forces acting on the foot clamp on multiple steps of the athlete without modifying the RSP behavior: The method involves strain gauge bridges applied to each RPF in a configuration that allows decoupling the loads parallel and normal to the foot clamp during the stance phase. Comparison with literature data and validation against force platform data gave confirmation of the validity of the method in the estimation of determinants of sprint performance.

As oil or gas field moves deeper offshore area, offshore offloading operations such as Tandem or Side-by-Side arrangement between two floating structures take place in many locations throughout the world and also have many hydrodynamic problems. Therefore, the researches on the motion response and hydrodynamic force including first and second order between two floating structures are needed to have the more safe offloading operability in waves. In this paper, prediction of wave induced motion responses and structural loads at midship section with hydrodynamic interaction effect between two offshore floating structures in various heading waves are studied by using a linearized three-dimensional potential theory. Numerical calculations using three-dimensional pulsating source distribution techniques have been carried out for hydrodynamic pressure distribution, wave exciting force, twelve coupled linear motion responses, relative motions and wave loads of the barge and the ship in oblique waves. The computational results give a good correlation with the experimental results and also with other numerical results. As a result, the present computational tool can be used effectively to predict the wave induced motions and structural loads of multiple offshore floating structures in waves. [ABSTRACT FROM AUTHOR]

Due to the growing penetration of renewables, Wind Turbines (WT) are becoming increasingly crucial for grid balancing services, such as Frequency Containment Reserve (FCR). This study proposes an adaptive operational strategy that optimally accommodates the power reserve and controls the active power based on grid frequency uncertainties and stochastic wind variations. The proposed approach includes an end-to-end solution, considering fixed and percentage reserve methods, from estimating an appropriate reserve margin to the real-time computation of generator torque and pitch control setpoints in response to grid frequency variations. A real-time look-up table is incorporated to actively adjust the reserve and adapt the deloading rotor speed-power curve based on a short-term estimation of the grid frequency using a deep-learning technique. Applying the proposed strategy improves WTs' FCR contribution by at least 3.3 times reserve in MW. Moreover, adaptive fuzzy-PI pitch-torque controllers are suggested to enhance the WT dynamic response and ensure smooth provision of FCR. Simulation results of a 5 MW-NREL offshore model show the improvement of the fuzzy-PI in power reference tracking, rotor speed regulation, and average studied mechanical load parameters in the range of 2.14–11.69%, 11.1%, and 8.81%, respectively, for an average of 250 kW reserve, confirming an overall improvement. • Adaptive strategy for Wind Turbines optimizes power reserve and controls active power, considering the grid frequency uncertainties. • End-to-end solution estimates reserve margin and computes generator torque and pitch control setpoints in real time for different wind conditions. • Real-time look-up table adjusts reserve and adapts rotor speed-power curve using a deep-learning approach predicting grid frequency changes. • Proposed strategy improves contributions of wind turbines in the reserve market by at least 3.3 times reserve in MW. • Fuzzy-PI controllers enhance WT dynamic response and ensure smooth frequency containment reserve (FCR) provision in all operating regions. [ABSTRACT FROM AUTHOR]

This paper presents a novel type of variable speed wind turbine with a new drive train different from the variable speed wind turbine commonly used nowadays. In this concept, a synchronous generator is directly coupled with the grid, therefore, the wind turbine transient overload capability and grid voltage support capability can be significantly improved. An electromagnetic coupling speed regulating device (EMCD) is used to connect the gearbox high speed shaft and synchronous generator rotor shaft, transmitting torque to the synchronous generator, while decoupling the gearbox side and the synchronous generator, so the synchronous generator torque oscillations during a grid fault are not transmitted to the gearbox. The EMCD is composed of an electromagnetic coupler and a one quadrant operation converter with reduced capability and low cost. A control strategy for the new wind turbine is proposed and a 2 MW wind turbine model is built to study the wind turbine fault ride-through capability. An integrated simulation environment based on the aeroelastic code HAWC2 and software Matlab/Simulink is used to study its fault ride-through capability and the impact on the structural loads during grid three phase and two phase short circuit faults.

Seakeeping analysis has progressed from the linear frequency-domain 2D strip method to the nonlinear time-domain 3D panel method. Nevertheless, the violent free surface flows such as slamming and green water on deck are beyond the scope of traditional panel methods based on potential theory. Recently, Computational Fluid Dynamics (CFD) has become an attractive numerical tool that can effectively deal with the violent free surface flows. ABS, as a classification society, is putting forth a significant amount of effort to implement the CFD technology to the advanced strength assessment of modern commercial ships and high-speed naval craft. The main objective of this study is to validate the CFD technology as a seakeeping tool for ship design considering fully nonlinear three-dimensional slamming and green water on deck. The structural loads on a large container carrier were successfully calculated from the CFD analysis and validated with segmented model test measurements.

Tidal Current Turbine (TCT) blades are highly flexible and undergo considerable deflection due to fluid interactions. Unlike Computational Fluid Dynamic (CFD) models Fluid Structure Interaction (FSI) models are able to model this hydroelastic behavior. In this work a coupled modular FSI approach was adopted to develop an FSI model for the performance evaluation and structural load characterization of a TCT under uniform and profiled flow. Results indicate that for a uniform flow case the FSI model predicted the turbine power coefficient CP with an error of 4.8% when compared with experimental data. For the rigid blade Reynolds Averaged Navier Stokes (RANS) CFD model this error was 9.8%. The turbine blades were subjected to uniform stress and deformation during the rotation of the turbine in a uniform flow. However, for a profiled flow the stress and deformation at the turbine blades varied with the angular position of turbine blade, resulting in a 22.1% variation in stress during a rotation cycle. This variation in stress is quite significant and can have serious implications for the fatigue life of turbine blades.

• It performs a literature review on the effect of climate change on structural loads. • Various loads, including wind, snow, temperature, and multi-hazard, are considered. • A wide range of urban infrastructure from different regions is included. • It summarizes research findings aimed at building climate-resilient infrastructure. Climate change is one of the pressing problems of today's world, with its unequivocal effects. The modern urban infrastructure has also borne the brunt of the devastating impact of changing climate. The increasing number of structural failures under extreme environmental loads has been reported throughout the globe, with state-of-the-art design and maintenance practices proved to be insufficient under the dynamically changing climate, demanding more resilient design standards and maintenance procedures. This review article synthesizes the research findings aimed at building climate-resilient civil infrastructure considering the design and service phase of various structures, the durability of structural components and materials, and adaptation and mitigation practices. The paper performs a systematic literature review of the effect of climate change on various structural loads, including wind, snow, temperature, and multi-hazard, in various urban infrastructures from different regions of the globe. The findings in this review can serve as valuable information to suitably revisit and improve design and maintenance practices and build more climate-resilient urban infrastructure. [ABSTRACT FROM AUTHOR]

To enable further growth of wind turbine dimensions and rated power, it is essential to decrease structural loads that wind turbines experience. Therefore a great portion of research is focused on control algorithms for reduction of wind turbine structural loads, but typically wind turbine rotor is considered to be perfectly symmetrical, and therefore such control algorithms cannot reduce structural loads caused by rotor asymmetries. Furthermore, typical approach in the literature is to use blade load measurements, especially when higher harmonics of structural loads are being reduced. In this paper, improvements to standard approach for reduction of structural loads are proposed. First, control algorithm capable of reducing structural loads caused by rotor asymmetries is developed, and then appropriate load transformations are introduced that enable presented control algorithms to use load measurements from various wind turbine components. Simulation results show that proposed control algorithm is capable of reducing structural loads caused by rotor asymmetries. [ABSTRACT FROM AUTHOR]

As the modern wind turbines (WTs) become larger in size, the structural loads experienced by the WTs increase dramatically, which would shorten the working life of the WTs and increase the maintenance cost. To mitigate such problem, this study proposes a non‐linear pitch control strategy including tower load reducing objective for the WTs operating in the above‐rated wind speed region. The proposed non‐linear controller consists of a rotor speed regulator, a tower oscillation damper and a lead compensator. The rotor speed regulator and tower oscillation damper are designed separately based on inverse system method, which is a powerful tool in solving the control problem of non‐affine non‐linear system. The lead compensator is utilised to compensate for the phase lag of the pitch angle command caused by the pitch actuator. Furthermore, light detection and ranging (LIDAR) preview measurements are introduced to provide wind information for the proposed controller in order to improve its control performance. The simulation results with the aero‐elastic model of fatigue, aerodynamics, structures and turbulence (FAST) show that, the proposed non‐linear controller outperforms the baseline gain‐scheduled proportional–integral controller. The proposed non‐linear controller can work well in the whole above‐rated wind speed region, and is easy to implement for application. [ABSTRACT FROM AUTHOR]

The pitch actuator of the offshore wind turbine has a high failure rate, and this fault will lead to aerodynamic imbalance on the floating system, especially when the 10 MW wind turbine is applied. In this paper, the impact of actuator faults on the floating platform motion and turbine structure is investigated. The 10-MW OO-Star semi-submersible platform is used as the reference structure. The fault discussed in this study involved one blade seizing, followed by an emergency shutdown. Coupled non-linear aero-hydro-servo-elastic simulations were carried out in the time domain using OpenFAST. The platform motions and structural loads caused by the fault were compared with the normal operating conditions. The effects of the pitch rate at the initial fault on the loads of the critical components are presented. The results revealed that imbalanced loads due to blade seizing can lead to particularly large excitations of the dynamic responses of the wind turbine. The maximum lateral nacelle acceleration is increased by 27.9%. In addition, the parametric study on the effects of the pitch rate for feathering blade was carried out. It was found that the pitch rate of 8 deg/s is favorable to alleviate the structural loads. • The blade pitch actuator fault significantly excites the low-frequency motions of the 10-MW floating offshore wind turbines. • The roll and sway motions are also stimulated by the rotor aerodyanmic imbalance. • The blade flapwise bending moment, tower-top bending moment, shaft bending moment, and nacelle acceleration are amplified. • During the emergency shutdown after the fault, the blade pitch rate of 8 deg/s is favorable to feathering the blade. [ABSTRACT FROM AUTHOR]

In this paper a methodology that enables detailed studies of the momentary slamming pressure distribution and the related structural loads is presented. The methodology involves pressure measurements, spatial and temporal pressure distribution reconstruction, and finite element analysis. Using a set of model experiments with a high-speed planing craft towed in irregular waves, the methodology is applied to evaluate different slamming pressure models regarding their ability to accurately represent the structure loads. The slamming equivalent uniform pressure model used in the prevailing semi-empirical design methods, and non-uniform time-dependent pressure models used in a method for direct calculation, are considered. It is concluded that for smaller structure members, typically found in densely spaced metal structures, the uniform pressure model performs well with respect to accurately representing the structure loads. However, for larger members found in modern sandwich structures, the underestimation of structure loads is significant, especially with respect to the shear forces. The non-uniform pressure modeling technique is concluded to be promising regarding its ability to accurately represent the structure loads, regardless of structure member size. The presented methodology is concluded to be a useful tool in further research regarding the evaluation and development of methods for high-speed craft structural design. [ABSTRACT FROM AUTHOR]

Purpose -- This paper aims to correlate the flexible multibody analysis for the performance, blade airloads, rotor pitch control angles, and blade structural loads of a full-scale utility helicopter rotor in low-speed forward flight with wind tunnel test and flight test data. Design/methodology/approach -- A nonlinear flexible multibody dynamics analysis code, DYMORE, is used to analyze the performance and aeromechanics of a utility helicopter rotor in low-speed forward flight. The main rotor system is modeled using various multibody elements such as rigid bodies, nonlinear elastic beams, mechanical joints, and elastic springs/dampers. The freewake model is used to capture rotor wakes more elaborately in low-speed forward flight. Findings -- Fair to good correlations of rotor performance such as figure of merit in hover, rotor power, propulsive force, and lift in low-speed forward flight are achieved with sweeps of the thrust, rotor shaft tilting angle, and advance ratio, against wind tunnel test data. The blade section normal forces from the mid-span to outboard are fairly or well correlated with flight test data, but the normal force at the inboard blade station is under-predicted. The trimmed pitch control angles are reasonably predicted; however, the lateral cyclic pitch control angle is moderately under-predicted. The flap bending moments are compared fairly with measurements; however, the oscillations of the lead-lag bending and torsion moments are not captured well. Practical implications -- Reasonable predictions of the performance and aeromechanics of the rotor in low-speed forward flight will allow the flexible multibody dynamics to be used for the rotorcraft comprehensive analysis, in place of expensive flight and wind tunnel tests of the rotor. Originality/value -- Up to now, the stand-alone flexible multibody dynamics without the aid of external aerodynamic analysis has not been widely used for the analyses of rotor performance and aeromechanics in low-speed forward flight. However, the present flexible multibody dynamics analysis directly integrated with the freewake model gives fair to good correlation of the rotor performance and aeromechanics predictions in low-speed forward flight. [ABSTRACT FROM AUTHOR]

Abstract: A modelling framework for determining structural dynamic loads in airframe components has been developed. This paper addresses the flight dynamics and structural modelling tools of the framework and presents the first validation results. Validation of the calculated component strains has been done by means of comparison with strain gauge measurements on the aft-pylon engine frame during scheduled operational flights. Results show a good agreement for the 3/rev vibrations of the component. Trend analyses provides insight in weight, flight speed and altitude dependencies. The proposed framework is capable of calculating structural dynamic loads of an airframe component in a relatively simple and cost-effective way. [Copyright &y& Elsevier]

Copyright of Automatika: Journal for Control, Measurement, Electronics, Computing & Communications is the property of Taylor & Francis Ltd 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.)

Abstract: A method to compute structural loads on surface ships coupling a CFD solver with rigid or elastic representations of the ship hull is presented. One-way and two-way coupling approaches were used for the cases when the ship was considered elastic, in which the forces obtained from the CFD solver were used to compute the structural loads. In the two-way coupling method the hull deformation influenced the CFD solution, while in the one-way coupling method this feedback was not needed. The flow field around the ship was calculated with the URANS/DES overset solver CFDShip-Iowa version 4, with the structural response obtained using modal superposition. Predictions of ship motions and structural loads were compared with available experimental data for the S175 containership, obtained from a segmented elastic model. Predicted heave and pitch transfer functions in regular waves matched well with the experimental values. The computations showed that slamming events greatly affected the vertical bending moment amplitude, showing sharp peaks for the rigid model. The elastic models predicted well the ringing of the structure and showed that the ringing was mainly triggered by bow flare slamming. The one-way coupled approach with a virtual mass correction provided a solution that in some aspects had almost the same quality as the two-way coupled solution, at a fraction of the cost. [Copyright &y& Elsevier]

Abstract: A wind load code has to provide information on the appropriate design wind actions for different purposes: the design of the cladding, the design of the support of the load bearing structure and the design of the load bearing structure itself. Strictly speaking, for each task a different pressure coefficient is required. The paper presents a concept that recently has been adopted in the draft of ISO 4354. Basic idea is to specify non-simultaneous extremes for the local pressures in tables and give additionally figures for simultaneous pressure distributions. All pressure coefficients are introduced as appropriate fractile values of the extremes. The simultaneous distributions are identified with the LRC-method. [Copyright &y& Elsevier]

Downbursts are transient phenomena that produce wind profiles that are distinctly different from synoptic boundary layers. Wind field data from Computational Fluid Dynamics (CFD) simulations of isolated downburst-like impinging jets, are used to investigate structural loads of tall buildings due to these high intensity winds. The base shear forces and base moments of tall buildings of heights between 120 and 250 m produced by downburst winds of various scales are compared with the forces from the equivalent boundary layer gust winds, with matched 10-metre wind velocity. The wind profiles are mainly functions of the size of the downburst and the radial distance from the centre of the storm. Wind forces due to various downburst profiles are investigated by placing the building at different locations relative to the storm center as well as varying the size of the downburst. Overall it is found that downbursts larger than approx. 2,000m in diameter might produce governing design wind loads above those from corresponding boundary layer winds for tall buildings. [ABSTRACT FROM AUTHOR]

Database-assisted design (DAD) is a relatively new concept whereby archived pressure time series from wind tunnel experiments are used directly in structural analysis software for the design of a structure. The US National Institute of Standards and Technology (NIST) is currently creating an aerodynamic database of wind-induced pressure time series on the envelope of various low buildings. In order for DAD to be of practical use, simple interpolation schemes must be used to cover the wide range of low building geometries a designer may desire since only relatively few geometries could be included in any database. The approach investigated herein consists of using a set of re-scaled pressure time series from an aerodynamically similar building at the same wind angle and in the same terrain. The set of reference time series are corrected by adjusting their mean and rms. pressure coefficients with artificial neural network models which have captured the variability of these statistical parameters. The use of the re-scaled time series is a simple way to get the correct spatial correlations for the interpolated building without resorting to more elaborate simulation schemes. However, interpolation must be limited to situations where the spatial correlations are similar. The methodology was applied to two test cases with reasonable success. [Copyright &y& Elsevier]

Knowledge of loads acting on running specific prostheses (RSP), and in particular on running prosthetic feet (RPF), is crucial for evaluating athletes' technique, designing safe feet, and biomechanical modelling. The aim of this work was to develop a J-shaped and a C-shaped wearable instrumented running prosthetic foot (iRPF) starting from commercial RPF, suitable for load data collection on the track. The sensing elements are strain gauge bridges mounted on the foot in a configuration that allows decoupling loads parallel and normal to the socket-foot clamp during the stance phase. The system records data on lightweight athlete-worn loggers and transmits them via Wi-Fi to a base station for real-time monitoring. iRPF calibration procedure and static and dynamic validation of predicted ground-reaction forces against those measured by a force platform embedded in the track are reported. The potential application of this wearable system in estimating determinants of sprint performance is presented. [ABSTRACT FROM AUTHOR]

This article investigates the impact of the pitch-to-stall and pitch-to-feather control concepts on horizontal axis wind turbines (HAWTs) with different blade designs. Pitch-to-feather control is widely used to limit the power output of wind turbines in high wind speed conditions. However, stall control has not been taken forward in the industry because of the low predictability of stalled rotor aerodynamics. Despite this drawback, this article investigates the possible advantages of this control concept when compared to pitch-to-feather control with an emphasis on the control performance and its impact on the pitch mechanism and structural loads. In this study, three HAWTs with different blade designs, i.e., untwisted, stall-regulated, and pitch-regulated blades, are investigated. The control system is validated in both uniform and turbulent wind speed. The results show that pitch-to-stall control enhances the constant power control for wind turbines with untwisted and stall-regulated blade designs. Stall control alleviates the fore-aft tower loading and the blades flapwise moment of the wind turbine with stall-regulated blades in uniform winds. However, in turbulent winds, the flapwise moment increases to a certain extent as compared to pitch-to-feather control. Moreover, pitch-to-stall control considerably reduces the summed blade pitch movement, despite that it increases the risk of surface damage in the rolling bearings due to oscillating movements with a small amplitude. [ABSTRACT FROM AUTHOR]

• Fluid–Structure Interaction method for predicting high-speed water entry problem is • Comparison between CFD and FSI of high-speed water entry of cylinder are investigated. • Detailed description of von Mises stress over the cylinder at high entry velocity is presented. • The effects of the water-entry velocity on the cavity evolution, motion, and structural response of the cylinder are analyzed. This paper describes an investigation of the motion, structural response, and cavitation bubble evolution of a cylinder in the high-speed water entry (HSWE) process using a fluid-structure interaction (FSI) method. The effectiveness and accuracy of the FSI method are verified by comparison with experimental results available in the literature. The results show that the cylinder structure is deformed when considering the coupling effect between the fluid and the structure, and the impact load during water entry presents obvious fluctuation characteristics. Meanwhile, the von Mises stress distribution on the two end faces of the cylinder is in a ring shape and propagates as the structure deforms. Moreover, the cavitation bubble dynamics, motion and structural loads of the cylinder under different water entry velocities are investigated. The load at the initial stage is greater with the increase of the water entry velocity, which in turn leads to more significant fluctuation characteristics, thereby increasing the deformation of the structure. [ABSTRACT FROM AUTHOR]