Showing papers on "Spar published in 2023"

Coupled dynamic analysis of horizontal axis floating offshore wind turbines with a spar buoy floater

Abstract: Coupled dynamic analysis of a floating offshore wind turbine (FOWT) is predicted with in-house ITU-WAVE computational tool. The hydrodynamic parameters are approximated with time marching of boundary integral equation whilst aerodynamic parameters are solved with unsteady blade element momentum method. In addition, forces on FOWT due to mooring lines are predicted with quasi-static analysis whilst hydrodynamic viscous effects are included with Morison equation. FOWT’s blades are considered as an elastic structure whilst tower is considered as a rigid structure. The effects of steady wind speed on surge motion spectrum decrease the spectrum amplitude over wave frequency ranges, but this effect is not significant. The duration of time domain simulation plays significant role in the region of surge and pitch resonant frequencies. The numerical results of in-house ITU-WAVE computational code for eigenfrequencies of blades, aerodynamics and hydrodynamics parameters are validated against other numerical results which shows satisfactory agreements.

Preliminary Results of a Structural Health Monitoring System Application for Real-Time Debonding Detection on a Full-Scale Composite Spar

Abstract: The present paper reports the outcomes of activities concerning a real-time SHM system for debonding flaw detection based on ground testing of an aircraft structural component as a basis for condition-based maintenance. In this application, a damage detection method unrelated to structural or load models is investigated. In the reported application, the system is applied for real-time detection of two flaws, kissing bond type, artificially deployed over a full-scale composite spar under the action of external bending loads. The proposed algorithm, local high-edge onset (LHEO), detects damage as an edge onset in both the space and time domains, correlating current strain levels to next strain levels within a sliding inner product proportional to the sensor step and the acquisition time interval, respectively. Real-time implementation can run on a consumer-grade computer. The SHM algorithm was written in Matlab and compiled as a Python module, then called from a multiprocess wrapper code with separate operations for data reception and data elaboration. The proposed SHM system is made of FBG arrays, an interrogator, an in-house SHM code, an original decoding software (SW) for real-time implementation of multiple SHM algorithms and a continuous interface with an external operator.

Provendo melhorias na geração de código para GPUs na SPar

Abstract: Neste trabalho são apresentados resultados parciais do estudo que está sendo conduzido para prover melhorias na geração de código paralelo para GPUs na SPar. Foram paralelizadas quatro aplicações de processamento de Stream utilizando a versão original da SPar, e a versão modificada. A versão contendo novas otimizações obteve melhora de até 718% no desempenho de aplicações computacionalmente intensivas para GPUs.

Análise de Correlação no Esforço de Desenvolvimento de Aplicações Paralelas

Abstract: Neste trabalho, foram analisadas diversas métricas, voltadas para uma aplicação de processamento de vídeo, utilizando as interfaces FastFlow, TBB e SPar. Os resultados revelam que utilizando a SPar e o FastFlow é possível desenvolver uma aplicação paralela eficiente com menos esforço, ao contrário do TBB. Em trabalhos futuros planejamos incluir mais aplicações no dataset a fim de confirmar os resultados.

Mechanical Testing of Connections Blind Bolted to the Thick Glass-Fiber-Reinforced Polymer Spar Cap of a Decommissioned GE37 Wind Turbine Blade

Abstract: Millions of tons of glass-fiber-reinforced polymer (GFRP) composite wind turbine blades are expected to age out of service over the next 30 years. Research is being conducted on repurposing these structures as new civil infrastructure products. The GFRP material in these decommissioned wind blades has been shown to retain significant strength and stiffness for second-life applications. However, for repurposing as new products, they will need to be connected to other structural members. The connections employed for this need to be designed, evaluated, and tested prior to their use. Here, we present the results of detailed testing of bolted connections for load-carrying appurtenances that will carry the phases and shield wires (e.g., insulators, crossarms, davits, guy wires, posts) to the spar cap of an 11-year-old 1.5 MW GE37 wind blade, intended for use as a repurposed transmission pole (i.e., a BladePole). Details of ASTM-type pull-out and bearing capacity tests using different types of blind bolts, and tests of a full-scale steel bracket connection called a “universal connector,” are reported. The effects of the different blind bolts, pin diameters, and loading directions relative to the composite laminate structure (longitudinal or transverse) for both the coupon- and full-scale connector bracket tests are described. The ability to design and construct robust connections for repurposed wind blade structures was demonstrated.

Метод підтвердження ресурсних характеристик металевої лопаті несучого гвинта вертольота за результатами випробувань

Abstract: The helicopter main rotor blade is the basic product that determines the reliability and service life of the helicopter as a whole. The problem of predicting and ensuring the specified blade life is an urgent problem considered at the stage of its design. The analysis of the design, structural materials and design and technological solutions of the main rotor blade (RB) of the Mi-8 helicopter has been carried out. A brief description of the main rotor blade of the Mi-8 helicopter is presented. The analysis was carried out and a standard flight cycle (SFC) of the helicopter was developed. The type of bench equipment for carrying out bench fatigue tests of the blade has been selected and justified. The loads on the main rotor blade for the SFC are determined. To determine the fatigue life of a blade, it is necessary to know the characteristics of the stress-strain state. The calculation of the stress-strain state (SSS) of a blade by the finite element method (FEM) using the ANSYS system is presented. The characteristics of the stress-strain state of the spar of the regular and irregular parts of the rotor blade of a helicopter are determined using the ANSYS system. The use of numerical methods for calculating the characteristics of the stress-strain state can significantly reduce the time and cost of designing a blade. The paper presents the results of calculating the regular part of the main rotor blade of the Mi-8 helicopter in the hover mode in the case of its loading with aerodynamic and inertial load from rotation, as well as the force from its own weight. With the help of the ANSYS system, a finite element model of the regular part of the blade was developed, consisting of a set of beam elements of variable section, a calculation was carried out taking into account the geometric nonlinearity of the structure's behavior, and an analysis of the results obtained was carried out. To describe the response of materials to an external action, a model of an elastically deformable isotropic body was used with the assignment of the corresponding elastic constants of the material. The analysis of the calculation results includes the determination of reactions at the attachment points, the values of the maximum displacements of structural elements and stresses in dangerous sections. Dangerous sections are determined and the values of the longitudinal force and bending moment in these sections are calculated. The assessment of the static strength of the blade by the safety factor was carried out. When evaluating the static strength, the equivalent stresses according to Mises were considered as the maximum design stresses. To assess the fatigue strength, we analyzed the distribution of the main tensile stresses in the power elements over typical stress concentrators. The maximum level of the main tensile stresses in the dangerous section indicates that the blade material operates in the zone of high-cycle fatigue. A technique for calibrating strain gauge channels has been developed. The calculation of the characteristics of the rotor blade of a helicopter is based on the requirements set forth in the technical literature, regulatory documents. When performing work, the requirements of the Aviation Rules, Part 29 (AP - 29) were taken into account. These studies were the basis for the development of a method for confirming the resource characteristics of a helicopter main rotor blade based on the results of flight and bench tests.

Predicting fatigue crack growth in complex geometries using numerical methods

Abstract: Fatigue cracks growth in three different wing spar geometries is simulated using xFEM, as the most suitable numerical method for this purpose. The goal of this analysis was to find out how crack paths affect number of cycles, i.e. fatigue life, so that the optimal geometry can be defined. The extended finite element method was applied using Morfeo/Crack for Abaqus software. Results provided better understanding and prediction of multiple cracks propagation in complex 3D structures and provided data for the optimal design of wing spar.

Delamination and Skin-Spar Debond Detection in Composite Structures Using the Inverse Finite Element Method

Abstract: This work presents a novel strategy for detecting and localizing intra- or inter-laminar damages in composite structures using surface-instrumented strain sensors. It is based on the real-time reconstruction of structural displacements using the inverse Finite Element Method (iFEM). The iFEM reconstructed displacements or strains are post-processed or ‘smoothed’ to establish a real-time healthy structural baseline. As damage diagnosis is based on comparing damaged and healthy data obtained using the iFEM, no prior data or information regarding the healthy state of the structure is required. The approach is applied numerically on two carbon fiber-reinforced epoxy composite structures: for delamination detection in a thin plate, and skin-spar debond detection in a wing box. The influence of measurement noise and sensor locations on damage detection is also investigated. The results demonstrate that the proposed approach is reliable and robust but requires strain sensors proximal to the damage site to ensure accurate predictions.

Impact of Prehabilitation on Postoperative Mortality and the Need for Non-Home Discharge in High-Risk Surgical Patients

Abstract: Objective: To determine if a preoperative multidisciplinary prehabilitation program (Surgical Prehabilitation and Readiness [SPAR]) reduces postoperative 30-day mortality and the need for non-home discharge in high-risk surgical patients. Background: The preoperative period is an important target for interventions (e.g. SPAR) that can improve postoperative outcomes for older patients with comorbidities. Methods: Surgical patients enrolled in a prehabilitation program targeting physical activity, pulmonary function, nutrition, and mindfulness were compared to historical control patients from 1 institution’s American College of Surgeons (ACS) NSQIP database. SPAR patients were propensity score matched 1:3 to pre-SPAR NSQIP patients and their outcomes compared. The ACS NSQIP Surgical Risk Calculator was used to compare observed to expected ratios (O/E) for postoperative outcomes. Results: 246 patients were enrolled in SPAR. A six-month compliance audit revealed that overall patient adherence to the SPAR program was 89%. At the time of analysis, 118 SPAR patients underwent surgery with 30 days of follow up. Compared to pre-SPAR NSQIP patients (n=4028), SPAR patients were significantly older with worse functional status and more comorbidities. Compared to propensity score-matched pre-SPAR NSQIP patients, SPAR patients had significantly decreased 30-day mortality (0% vs 4.1%, p=0.036) and decreased need for discharge to post-acute care facilities (6.5% vs 15.9%, p=0.014). Similarly, SPAR patients exhibited decreased observed 30-day mortality (O/E: 0.41) and need for discharge to a facility (O/E: 0.56) compared to their expected outcomes using the ACS NSQIP Surgical Risk Calculator. Conclusion: The SPAR program is safe, feasible, and may reduce postoperative mortality and the need for discharge to post-acute care facilities in high-risk surgical patients.

Research on the application of improved NSGA-II in the structure design of wind turbine blade spar cap

Abstract: Introduction: The blade is one of the most important parts of a wind turbine. Blade design is a complicated process involving many design links and mutual couplings. To efficiently obtain the Pareto Front and optimal blade, a novel methodology combined the improved NSGA-II with Thin-Walled Beam Theory and Classic Laminated Theory has been developed. Methods: In the optimization study, the design parameters are the thickness distribution of the spar cap and a parametric model based on blade production process is developed. The objective function is on the minimization of mass and the maximization of flap-wise stiffness. As a practical engineering application research, a 15 MW wind turbine IEA-15-240-RWT developed by NREL is used as a reference model. Results: Laws on the number of variables, blade profiles, design loads and natural frequencies present in the design have been studied through Pareto fronts obtained from multi-objective optimization results. Discussion: These laws have important implications for practical engineering design work. Meanwhile, the results show that the new methodology is effective for blade structure design, and that this approach can be easily extended to study the design of influence laws for more design parameters or more complex blade design problems.

Quantitative interlink wear estimation method for the mooring chain

Abstract: Long-term operation of mooring systems is one of the challenging issues of floating structures such as floating offshore wind turbines. The nondestructive testing and condition monitoring techniques can achieve a rational operation by predicting the degradation. However, as contrasted with fatigue only few studies on the effect of nonuniform volume loss of mooring chain links due to wear can be found because of difficulties to estimate wear amounts quantitatively. This chapter introduces the quantitative interlink wear estimation method by applying it to a spar-type floating structure and utilizing the observations. The method is presented which consists of the material test, derivation of an interlink wear estimation formula with Finite element analysis, and calculation of mooring chain response with coupled dynamic analysis. Additionally, by using a 3-D rigid-body link model, it was found that the interlink wear amount can be calculated closer to the chain diameter measurements.

Influence of Vertical Plates on the Pitching Motion of a SPAR Wind Floater in Waves

Abstract: One of the concerns about using a heave plate on a SPAR floater is that the pitch response will be inadequately minimized. This weakness will result in excessive misalignment conditions in the floater wind. The vortex ring state phenomenon is a more complex effect and the most common potential issue. This issue may result in over-performance of wind turbine system components. A time domain based experimental test was developed in this study to investigate the extent to which the number and configuration of vertical plates influence pitch response, which is useful for improving wind energy extraction performance. Because the vertical plate configuration is an important key parameter, the following arrangements are proposed to be investigated: solid plates, three-perforated plates, and six-perforated plates. 3VP-S, 3VP-3H, 3VP-6H, 4VP-S, 4VP-3H, 4VP-6H, 5VP-S, 5VP-3H, and 5VP-6H are the modified SPARs. The ballasting area is where the modified vertical plate of the base SPAR is located. In 120 regular wave cycles, the effects of the proposed model's pitch response, pitch reduction percentage, wave steepness, natural period, and viscous damping were evaluated. The wave tank was used to test ten different scenarios. The 4VP-6H, 5VP-3H, and 4VP-S models were identified to provide better estimates than other modified models. The perforated plate is confirmed to be more effective at reducing pitch motion than the solid plate and base SPAR. The increase in pitch response is consistent with the increase in applied wave parameters. The model was also initiated to be in dominant stand-by mode for all wave parameters. Because of the reduced volume caused by the SPAR body modification, the percentage reduction in pitch motion increases with decreasing wave loads. When compared to the base SPAR, the proposed model's pitch reduction percentage ranges from 19 to 56%. In all scenarios, the wave steepness relationship is inversely proportional to the pitch reduction percentage. Furthermore, none of the proposed models are closer to the natural frequency than the base SPAR, resulting in the lowest resonance. The perforated plate also dampens more effectively than the base SPAR. This is primarily due to the geometry of the vertical plate and its configuration layout. Finally, as the most recent conceptual design in wind floater SPAR, the 4VP-6H model is deeply recommended.

Analisis Tegangan Bilah Turbin Angin Komposit Berpenguat Spar Ganda

Abstract: The design of wind turbine blades requires structural design and material selection that can withstand aerodynamic loads. The required structural criteria for wind blades are strong and lightweight. Modeling and analysis of stress values were carried out using MSC Patran/Nastran software. The selected material is an E-Glass fiber composite with epoxy resin matrix and has 8 layers with different fiber directions in each layer with fiber direction arrangement [0°/±45°/90°]. The turbine blade model without a spar is compared with the double spar turbine blade. The results found that the stress of the double spar blade had a lower stress value with a maximum tensile stress of 8.83 MPa, while on the blade without spar the maximum tensile stress was 10.6 MPa, while the maximum compressive stress on the double spar blade was 8.68 MPa, the maximum compressive stress on the blade without spar was 11 MPa.

Hydrodynamic Investigation on Floating Offshore Wind Turbine Platform Integrated with Porous Shell

Abstract: As the siting of wind turbines increasingly transitions from shallow water to offshore deep-water locations, improving the platform stability of floating offshore wind turbines is becoming a growing concern. By coupling a porous shell commonly used in traditional marine structures, with a FOWT (floating wind turbine platform), a new spar-buoy with a porous shell was designed. A numerical model investigating the coupling effect of the aero-hydro-mooring system is developed, and the results of the motion response are compared with the OC3-Hywind spar. The motion response of the two platforms was simulated in the time-domain with the incident wave period varied in the range of 5~22 s. The exciting wave force with added mass and radiation damping of the spar with the porous shell is compared with the OC3-Hywind spar. The results demonstrate that the motion response amplitude of the spar with the porous shell decreases in all three main motion freedoms (i.e., surge, heave and pitch, etc.), among which the heave motions are most significantly attenuated. The study shows that the coupling of porous shells with a floating platform to achieve the reduced motion responses is feasible and can be an innovative structure for the development of deep-sea offshore floating wind turbines.

Dynamic Analysis of a Novel Installation Method of Floating Spar Wind Turbines

Abstract: This paper presents the performance of a new, floating, mono-hull wind turbine installation vessel (Nordic Wind) in the installation process. The vessel can transport pre-assembled wind turbines from the marshalling port to the offshore installation site. Each assembled turbine will be positioned over the pre-installed floating spar structure. The primary difficulty lies in examining the multibody system’s reactions when subjected to combined wind, current, and wave forces. Time-domain simulations are utilized to model the interconnected system, incorporating mechanical coupling between components, the mooring system for the spar, and the installation vessel. The primary objective is to focus on the monitoring and connection stages preceding the mating operations between the turbine and the floating spar. Additionally, it involves examining the impacts of wind, current, and wave conditions on the motion responses of the installation vessel and the spar, as well as the relative motions at the mating point, gripper forces, and mooring forces. The simulations show that the resulting gripper forces are reasonable to compensate. The relative motion at the mating point is not significantly affected by the orientations of the turbine blades, but it is influenced by the prevailing wave conditions. In addition, vessel heading optimization can minimize the relative motions at the mating point and gripper forces. Given the examined environmental conditions, the presented installation concept exhibits a commendable performance.

Reciprocal hydrodynamic response estimation in a random spreading sea

Abstract: Direct estimation of the hydrodynamic response of an offshore structure in a random spreading sea can lead to large computational costs. In this paper the actual spreading sea is replaced by an idealised diffuse wave field and the diffuse field reciprocity (DFR) relationship is derived analytically and verified against diffraction analysis for offshore application. The DFR approach provides an analytical expression for the estimation of the wave loading spectrum in a spreading sea. It is very efficient because only the added damping coefficients are required. Furthermore, if normalised to the peak amplitude of a spreading sea, an upper bound response can be obtained using the reciprocal approach. And this is demonstrated using a spar type floating wind turbine. Given that the hydrodynamic coefficients are routine outputs for offshore structural design, engineers would obtain the upper bound response without additional computational cost using this new approach.

Spar Österreich büßt Ergebnis ein

Abstract: Spar Österreich hat die Marktführerschaft trotz Inflation und Krise zwar auf hohem Niveau gehalten. Doch Investitionen in Preise und hohe Energiekosten ließen das Ergebnis der Handelsgruppe schmelzen.