Composite Marine Propeller Research Articles

Acoustic emission monitoring of composite marine propellers in submerged conditions using embedded piezoelectric sensors

Flexible composite marine propellers can aid the marine industry in reducing carbon emissions and underwater radiated noise pollution. The structural integrity of the blades can be assessed using structural health monitoring. One of these methods is the measurement and analysis of damage-induced acoustic emission signals. This paper experimentally investigates the feasibility of using embedded piezoelectric sensors for the measurement of acoustic emissions throughout a submerged flexible composite marine propeller blade. A full-scale glass-fibre reinforced polymer blade has been manufactured with 24 embedded sensors. While suspended in artificial seawater, acoustic emissions were simulated on the blade. The measurements show that the embedded piezoelectric sensors can measure acoustic emissions while the blade is submerged. Further, the distance from source to sensor over which the acoustic emission is measurable was investigated. For a noise level of 40 dB and a source amplitude of 70 dB between 100 and 250 kHz, an average maximum measurable distance of 124 mm was obtained. For higher frequencies, the distance drops and for lower noise levels the distance increases.

A Succinct Review on the Numerical and Experimental Performance Evaluation Techniques for Composite Marine Propellers

A Succinct Review on the Numerical and Experimental Performance Evaluation Techniques for Composite Marine Propellers

Acoustic emission monitoring of composite marine propeller blades using embedded piezoelectric sensors and hydrophones

The marine industry is increasingly considering the use of flexible composite marine propellers for their potential to reduce carbon emissions and underwater radiated noise. Given the early stage of development of flexible composite propellers, there are unknowns on their structural degradation. Structural health monitoring (SHM) can provide additional insight into the occurrence and propagation of degradation in these structures. A passive and lightweight method of SHM is the measurement and processing of acoustic emissions (AE) that are induced by different degradation mechanisms. The current research investigates the measurement of AE signals in composite marine propeller blades using embedded piezoelectric sensors. A full-scale glass-fibre polymer composite propeller blade is suspended in a tank filled with artificial seawater. The propeller blade contains 24 embedded piezoelectric sensors that were installed between laminas during manufacturing. Additionally, the tank includes an array of hydrophones for validation of the results. AE signals are simulated on the blade using underwater pencil lead breaks. The measured AE signals are assessed for their amplitude and frequency content. The results demonstrate the feasibility of measuring AE signals in composite marine propeller blades using embedded piezoelectric sensors and hydrophones.

Numerical analysis of the performance of a composite marine propeller blade subject to structural blade oscillations

High-fidelity Large Eddy Simulations (LES) are conducted over the oscillating marine propeller blades to investigate the effects of blade oscillation on the unsteady flow behaviour as well as to analyse the performance of the composite marine propeller blades. The accuracy of the results is first verified against the reference experimental results. A nonlinear frequency-domain solution or harmonic solution method is also applied to this study, based on a high-fidelity LES model, in addition to the traditional time-domain solution method to investigate the capabilities of the frequency-domain method in predicting the unsteady flow parameters, vortex generation, and hydrodynamic damping to determine the stability of the propeller blades. Results obtained reveal that the oscillation of the blade has a great impact on the vortex generation process which could impose implications on the performance and structural integrity of the composite marine propeller blades.

A Review on Recent Development in Advanced Composite Marine Propellers

Abstract: The present status of research and technological development in the field of composite marine propeller. There is an increasing interest in the marine industry to use composite to improve the hydrodynamics and structural performance of naval structure. Composite materials have high strength to weight and stiffness to weight ratio. The use of composites considerably increased to optimize the physical and organizational reliability of such sea vessels and decrease the expense of establishment and utilisation

Deformed shape estimation for flexible composite marine propellers by image registration

Deformed shape estimation for flexible composite marine propellers by image registration

Automated manufacture of optimised shape-adaptive composite hydrofoils with curvilinear fibre paths for improved bend-twist performance

Composite marine propellers improve hydrodynamic efficiency by inducing bend-twist coupling and allowing for passive pitch changes. One critical limitation, however, is the extent to which a composite propeller blade can deform and cause a pitch change without incurring structural failure. Recent numerical studies showed that curvilinear tows could improve the structural response of a composite blade by lowering its deflection or stress and strain required to induce a pitch change, but no experimental validation has been carried out before. The current study, thus, presents the manufacture of composite sandwich hydrofoils made with steered tows using automated fibre placement and validates the curvilinear tow benefits. Two hydrofoils were optimised with straight and curved fibre path layups, respectively and were manufactured for mechanical testing. The manufacturing complications arising from steering curvilinear tows in a three-dimensional convex mould are also discussed in the paper. The study found that significant tow buckling occurred near the tool cavity edge due to excessive steering radius during manufacture. The follow-up structural cantilevered tests showed that the experimental results were consistent with the FE predictions despite the presence of some manufacturing defects. The experiment agreed that the hydrofoil manufactured with curved tows achieved a similar tip twist but a significant reduction in deflection and critical principal strains compared to the hydrofoil made with straight tows. The use of a foam core reduced the overall weight of the sandwich hydrofoils by about 25% compared to that of a fully-carbon composite hydrofoil, and the numerical analysis showed that the core shear failure induced by transverse shear stresses was unlikely to occur.

Performance Prediction of Composite Marine Propeller in Non-Cavitating and Cavitating Flow

The purpose of this study is to compare the performance of specific composite propellers with different ply angles from a cavitation inception speed (CIS) perspective. Composite propellers have a relatively large deformation compared to existing propellers manufactured using nickel aluminum bronze alloys. Therefore, it is necessary to understand the correlation between the stacking method of the composite materials and the propeller performance in order to design composite propellers that provide sufficient strength and generate the desired deformation. In addition, in the case of composite propellers, the deformation is closely related to the CIS because it can delay or accelerate the occurrence of tip vortex cavitation (TVC). Fluid-structure interaction (FSI) analysis of the model-scale composite propellers is performed using a coupled computational fluid dynamics (CFD)-finite element method (FEM) to examine the influence of the lamination direction on the deformation of the composite propeller. Finally, a hydroacoustic analysis of the noise generated and propagated by a composite propeller in non-cavitating and cavitating flows is conducted. The study found that some deformed parameters of the propeller affect the performance, the deformation of the composite propeller itself has no significant effect on the sound pressure level, and the volume change of cavitation has a decisive effect on the variation of the sound pressure level radiated from the composite propeller. These results can improve the feasibility, conceptual design, performance, and manufacturing methods for composite propellers.

Feasibility evaluation for development of composite propellers with embedded piezoelectric sensors

Marine propellers made of fibre-reinforced composites have demonstrated the potential to outperform metallic propellers in terms of efficiency and under-water noise radiation. For full realisation of this potential in a tailored design process with realistic constraints, accurate information on the hydrodynamic loads acting on composite marine propellers and the structural integrity is of key importance. It is conceptualised that this information can be acquired without disturbing propeller hydrodynamics using a network of piezoelectric sensors embedded inside the blade. In this paper, feasibility of this concept has been investigated numerically and experimentally. Hydrodynamic loads on a composite propeller obtained from numerical simulations were used to assess the sensitivity of piezoelectric sensors in measuring the dynamic strain field due to the blade deformation. Subsequently, 25 small-scale carbon-epoxy composite samples were manufactured with embedded piezoelectric wafer sensors of different sizes, and subjected to non-destructive and destructive loading scenarios. Feasibility of measuring strains at different frequency ranges and damage-induced acoustic emissions was quantitatively assessed from these experiments. Furthermore, the influence of the embedded sensors on the ultimate strength and toughness of the specimens was investigated. It was found that at least 92% of the studied propeller blade would have dynamic strains measurable up to the first four harmonics by the considered piezoelectric sensors. In a four-point bending setup, it was additionally demonstrated that the embedded piezoelectric sensor captured damage-induced acoustic emissions up to specimen failure with an average signal to noise ratio of 17 dB. The results indicate that embedded piezoelectric sensor networks can have the capability to measure both low-frequency dynamic strains in composite marine propeller blades and damage-related acoustic emissions.

Numerical Fluid-Structure Interaction Analysis for a Flexible Marine Propeller Using Co-Simulation Method

Carbon fibre composite has exceptionally high strength, low density and corrosion resistance in the marine environment compared to conventional materials. These characteristics make it a favourable alternative material to be considered for manufacturing marine screw propellers. Despite these advantages, the flexibility of the material leads to a significant change in blade geometry due to loads acting on blades which alter hydrodynamic performance. A two-way coupled fluid-structure interaction analysis is required to accurately capture its hydrodynamic performance due to the reduced stiffness and material anisotropy. The present study focuses on numerical investigation for the hydro-elastic based performance analysis of a composite marine propeller in open water condition. The procedure involves the coupling of Reynolds-Averaged Navier-Stokes Equation based computational fluid dynamics solver with the finite element method solver using co-simulation technique. The open water characteristics, including thrust coefficient, torque coefficient and open water efficiency, are discussed as a function of advance ratio. This paper presents a comparison of the hydrodynamic performance and structural responses between a carbon fibre composite propeller and a conventional steel propeller which are geometrically identical. The results for the composite propeller show a significant improvement in hydrodynamic performance compared to the metallic propeller while remaining structurally safe throughout the tested range.

Analysis on the particularity of model test for composite marine propellers

Objectives Compared to traditional metal rigid propellers, the rigidity of composite marine propellers is lower, and the deformation of the blade under fluid-structure interaction has an obvious effect on hydrodynamic and noise performance. It is therefore particular to the composite propeller model test. Methods Dimensional analysis is used to build a special similarity relation and conversion method for the hydrodynamic and noise performance of the composite propeller. To meet the requirements of the model test, the special test technology is analyzed according to the processing of the composite propeller model and its fluid-structure interaction characteristics. Results The composite propeller model test, besides satisfying the similarity relation to the metal propeller model test, also essentially satisfies the similarity relation of the blade's hydrodynamic deformation. Conclusions Unlike traditional metal propellers, the composite propeller offset, mechanical properties and dynamic deformation of the blade must be collected in the test, so as to select a reasonable model scale and propeller model material. Meanwhile, not only must the same dimensionless advance coefficient between the model and full-scale propeller be kept, but also the combined similarity of stiffness characteristics and Mach number of the blade tip must be met.

Effect of hydrodynamic twisting moment on design and selection of flexible composite marine propellers

The capability of enhancing the efficiency by exploiting the elastic response of composite propeller has been a controversial research point. Contradictory findings are noticed as some studies concluded that composite propeller does not outperform metallic propeller while other succeeded to obtain efficiency improvement at certain operating conditions. This research investigated geometric aspects and hydrodynamic parameters that govern elastic response, and introduced criteria for assessing propeller model, to be used as composite propeller. Parametric study was performed on a case of propeller VP1304 varying two geometric design variables of propeller, namely, pitch and skew distribution. Hydrodynamic twisting moment resultant from pressure load was defined as the effective hydrodynamic output parameter suitable for preliminarily predicting blade structural behaviour. Comparison of moderate and high skew models in term of nondimensional twisting moment showed that increasing blade skew reduced pitching moment at low advance coefficients which is advantageous while; at high advance coefficients, skew resulted in unfavorable increase of de-pitching moment. Accordingly, recommendations for optimization process at both design and off-design conditions was presented.

FSI-based structural optimization of thin bladed composite propellers

Lamination of thin bladed composite marine propellers necessitates dropping layers following thickness variation to produce lighter propeller with good elastic damping. Composite blade is subjected to multiaxial loads resulted from nonuniformly distributed hydrodynamic pressure that cause the blade to undergo combined structural response of bent and twist therefore, strength evaluation of such tapered laminate is a highly nontrivial process that include significant fluid–structure interaction (FSI). This research aims to investigate the strength of composite propeller using unconstrained stacking-sequence optimization based on fully coupled CFD-FEA analysis. Different hub idealization techniques were studied to determine the most accurate treatment in predicting stress and deformation of the blade. Composite model configured for propeller VP1304 after modification on blade thickness and, initial analysis on balanced-stacking of [0, 90, 45,−45] were set as a benchmark for optimization process targeting to minimize failure index; calculated according to Puck failure theory considering fiber and matrix failure as well as delamination. Delamination is evidenced to be utmost critical mode of failure whereas, the optimization resulted in an optimum laminate with unbalanced nonsystematic stacking that succeeded to; reduce interlaminar stresses, avoid failure and, reduce maximum value of IRF (Inverse Reserve Factor) by 50% compared to the predefined balanced-stacking benchmark.

Numerical analysis on propulsive efficiency and pre-deformated optimization of a composite marine propeller

The objectives of this paper are to numerically investigate the performance of a composite propeller through bidirectional FSI algorithm combining CFD and FEM, and to improve its propulsive efficiency by a pre-deformated method. Numerical results are presented for the composite propeller which has been modeled by unidirectionally stacking with glass-fiber reinforced composites. The propulsive efficiency of the composite and rigid propellers with different advance coefficients J has been compared. The results show that the efficiency of the composite propeller is obviously higher than that of the rigid propeller when J≤0.8, which is attributed to the decrease of pitch angle caused by the bend-twist coupling effects. But for the design condition J=0.851 and the cases with J 0.851, the efficiency of the composite propeller is significantly lower than that of the rigid propeller, which is because the angle of attack αcomposite is deviated from the optimal angle of attack αdesign more than that for the rigid case αrigid. Based on the optimization by the proposed pre-deformated method, the efficiency improvement of the composite propeller at the conditions with J≥0.851 could be obtained, and the composite material used in this work can meet the strength requirement of the designed propellers.

Mechanical, Structural and Dynamic Characterisation of Water Aged Composite Marine Propeller

Mechanical, Structural and Dynamic Characterisation of Water Aged Composite Marine Propeller

Improving hydrodynamic efficiency of composite marine propellers in off-design conditions using shape memory alloy composite actuators

The bend-twist coupling of fibre-reinforced composite laminates has been studied extensively to introduce self-adjustment in pitch angle of marine propellers for improving the hydrodynamic efficiency in off-design conditions. A recent study has shown that for full-scale propellers designed against material failure, the twist generated in the deformed blade due to this effect is not sufficient to cause any noticeable change in the hydrodynamic efficiency. In this paper, we study the use of shape memory alloy (SMA) for inducing variable twist in composite propellers for achieving the same. Prestrained SMA fibres are embedded in the composite in the martensite phase. When SMA fibres are heated upto the austenite phase, a large recovery stress is developed due to the shape memory effect. This stress is used to create twist in the propeller blade through appropriate positioning of the SMA actuators. A full-scale propeller of 4.2 m diameter, made of graphite epoxy with Nitinol fibres as SMA, is considered. The study establishes for the first time that using SMA composite actuator elements, it is possible to generate sufficient twist that can cause the desired improvement in the hydrodynamic performance of full-scale marine propellers at off-design conditions over a wide range of advance ratio.

Numerical Investigation of a Marine Propeller Blade for Material Effect and Stress Behaviour

The process of designing a marine propeller for under water applications involves various complex analyses. Analysis is of iterative in nature which makes it cumbersome and inefficient to understand. A part of the research work entitled in this paper is concerned with the material effect and stress behavioural characteristics of a marine propeller blade subjected to cantilever condition. Designing and analysing the behaviour of an anisotropic composite material is one of the most important technologies in the area of marine propulsion. Based on FEM the conventional and composite material marine propeller blades are analysed. To simulate the blade layup and to determine the stress characteristics, ANSYS software with shell 181 elements is taken for reference. A study has also been carried out for determining the stress and deformation pattern arising due to varying ply layup and material. The obtained numerical results are then compared and summarised in. Computational efficiency and integrity of the presently adapted method in this work are determined by several case studies.

Numerical analysis and performance comparison of the same series of composite propellers

Composite marine propeller, due to its potential advantage of reduced weight and noise reduction, has increasingly attracted the attention of researchers. In the current work, the performance and efficiency of the 438x series of composite propellers are studied based on the finite element method (FEM) and the computational fluid dynamics method (CFD). The influence of blade skew angle on the hydro-elastic performance, cavitation and efficiency of composite marine propeller are discussed. The performance differences are compared between composites series propellers and metal series propellers. According to the performance characteristics of the same series of composite propellers, a fast and effective design method is proposed.

Finite element modelling and model updating of small scale composite propellers

The application of composite materials in marine propellers is a relatively recent innovation. Methods have been presented to analyse the hydro-elastic behaviour of these type of propellers and in some studies these methods have been validated as well. Differences between measured and predicted responses are typically explained from inaccuracies in structural or fluid modelling. It is beyond all doubt that for an accurate finite element (FE) model a correct modelling of the fibre orientations and material properties is required. Both subjects are addressed in this work. An approach is presented in order to accurately define the element dependent fibre orientations in doubly curved geometries like (marine) propeller blades. In order to improve the structural response prediction this paper presents an inverse method based on experimental and numerical results which can be used for structural identification and FE model updating. In the developed approach the residual between measurement results obtained with static experiments and results obtained with an FE model is minimized by adapting the stiffness properties in the FE calculation. This method has been successfully applied to two small scale composite propellers. The obtained material properties have been determined with a relatively high confidence level. A verification by means of measured and calculated eigenfrequencies show also that accurate results are obtained with the inverse method. Therefore, this paper gives a positive answer on the research question whether it is possible to determine the stiffness properties of small scale composite marine propeller blades from a static experimental data.

Hydro-elastic aspects of a composite marine propeller in accordance with ply lamination methods

In a composite material, stiffness and strength in a desired direction can be controlled via the combination and stacking of materials. As such, the application of composite materials has spread to almost every industry. To utilize this advantage in the design of a marine propeller with complex geometry, accurate and practical analysis tools that consider both the hydroelastic behavior and ply-stacking structure of composite materials are required. Therefore, steady and unsteady BEM–FEM FSI algorithms of a composite propeller blade and a simple finite element model that considers the lamination modulus of fiber materials have been introduced in this study. In addition, a comparative study using CFD–FEM-based FSI analysis and numerical investigation of the hydroelastic behavior of a composite propeller in the ship wake field have been performed based on the present methodology.