Comparative Analysis of Ice Load Data using Strain Gauge Sensor and Fiber Optic Sensor on the IBRV ARAON in the Arctic Sea -2015 and 2016 Arctic Voyage Data-

Abstract The estimation of ice loads acting on a ship hull is one of the most critical concerns from a design point of view. To estimate the ice loads, various types of related research have been conducted, including full-scale measurement tests, model tests, and numerical model tests. To estimate the ice loads, ice load data recorded from a full-scale measurement test is necessary. The IBRV ARAON was used to conduct ice field tests in this study. To measure ice load data in ice field tests, strain gauges were installed on the inner hull plates and at the transverse frames of ARAON’s bow section. The measured strain data was analyzed to calculate ice loads using two approaches; i.e., the influence coefficient method and the calculation of shear force. This study focuses on estimating the local ice load, which is calculated by shear strains at transverse frames and comparing to local ice load calculated by the influence coefficient matrix. The level of local ice loads estimated from shear strain measurement was a little lower than those of hull plates. As a result, the method using shear strain data is recommended concerning the cost and simple procedures. Additionally, this study is intended to verify the performance and the potential of fiber optic sensors. For the verification of the results, the peak ice loads and stresses calculated from fiber optic sensors were analysed and it was a little higher than those from strain gauge sensors. The fiber optic sensor is considered more suitable for measuring ice load data in harsh environments. The presented results should be useful for future studies of local ice load estimation at the design part of a vessel. Also the analyzed results of strain data measured from fiber optic sensors can be helpful for the next ice field test.Chapter 1 Introduction 1 1.1 Background and Objectives 1 1.2 Organization of the Thesis 5 Chapter 2 Ice Load Measurement System 7 2.1 Electrical Strain Gauge Sensors 7 2.2 Fiber Optic Sensors 10 2.2.1 Structure of Fiber Optic Sensor 10 2.2.2 Basic Features of Fiber Optic Sensor 12 2.3 Fiber Bragg Grating Sensor for Measuring Strain 14 Chapter 3 Arctic Ice Field Tests and Measurement of Ice Load Data 17 Chapter 4 Analysis of Ice Load Data 25 4.1 Analysis procedures of Ice Load Data 25 4.1.1 Calculation Method for Stresses according to Types of Sensor 25 4.1.2 Influence Coefficient Method 27 4.1.3 Shear Strain Data at Transverse Frames 29 4.1.4 Concept of an Event and Peak Ice Load 32 4.2 Estimation of Local Ice Load by Influence Coefficient Method and Calculation of Shear Force 35 4.2.1 Local Ice Load by using Influence Coefficient Method 35 4.2.2 Local Ice Load from Shear Strain Data in Hull Frames 43 4.3 Estimation of Local Ice Load from Fiber Optic Sensors 51 4.3.1 Comparison of Stresses Calculated from Single and Rosette Gauge Sensors 51 4.3.2 Comparison of Local Ice Loads by Fiber Optic and Strain Gauge Sensors 58 Chapter 5 Conclusions 66 References 68Maste

Structural Health Monitoring Using Embedded Fiber Optic Strain Sensors

This dissertation involved several research activities with the common goal of developing a structural health monitoring methodology. The research activities encompass: composites fabrication, numerical modeling and a mechanical experimental program using a state-of-the-art sensing technology. The first part of the dissertation presents an analytical and experimental effort to characterize the bending response of sandwich composite plates. A general expression for the shear correction factor for laminated plates was derived using the principle of strain energy equivalence. It was proved that the first-order shear deformation theory (FSDT) can be confidently used in the elastic analysis of sandwich composite plates with lowdensity core using the proposed shear factor. A correlation between the experimental response of sandwich composite plates under transverse load and analytical predictions was conducted. The good agreement obtained provides an experimental validation of the developed analytical method and enhances the test method for simply supported sandwich composite plates subjected to a distributed load (ASTM D6416). The second part of the dissertation deals with structural health monitoring using embedded fiber optic strain sensors. A long-term monitoring of wood structural members of the AEWC Center new office building expansion was conducted using Extrinsic Fabry-Perot Interferometric (EFPI) fiber optic sensors embedded in a FRP laminate. A one-year cyclic variation of the longitudinal strain in the beams was observed, which is attributed to the variation of relative humidity during the year. The major research work of this dissertation presented a fatigue crack monitoring study of composite doubler plate joints using embedded fiber Bragg grating strain sensors was conducted. A methodology for the structural health monitoring and detection of delamination growth of composite joints based on strain measurements was developed. Secondary bonded woven Eglass/ vinyl ester composite doubler plate joints were subjected to fatigue tension loading. The feasibility of monitoring delamination using embedded sensors was investigated. The experimental plan, finite element modeling and the fabrication methodology of the specimens through Vacuum Assisted Resin Transfer Molding (VARTM) processing are presented. The proposed methodology allows detecting a one quarter inch delamination length, which is a common criterion used in marine construction for damage tolerance in service conditions

Overview of Fiber Optic Sensor Technologies for Strain/Temperature Sensing Applications in Composite Materials

This paper provides an overview of the different types of fiber optic sensors (FOS) that can be used with composite materials and also their compatibility with and suitability for embedding inside a composite material. An overview of the different types of FOS used for strain/temperature sensing in composite materials is presented. Recent trends, and future challenges for FOS technology for condition monitoring in smart composite materials are also discussed. This comprehensive review provides essential information for the smart materials industry in selecting of appropriate types of FOS in accordance with end-user requirements

DESIGN AND MODEL TEST OF STRUCTURAL MONITORING AND ASSESSMENT SYSTEM FOR TRIMARAN

Due to the unique structural design of multihull, the structural response on trimaran is often more complex than the response of monohull in navigation. In order to ensure the safety of trimaran navigation and predict the potential damage of local structure, the structure monitoring technology is applied. According to the structural characteristics of trimaran, structural monitoring and assessment system for multihull is designed and introduced in detail, and corresponding model test is taken to demonstrate its effectiveness. The self-propelled trimaran model is installed with sensors in different longitudinal positions to monitor the variety of structural responses in irregular waves. And three real-time structural strength assessment methods in the system are used respectively to indicate the structural state about hull longitudinal strength, local yielding strength and fatigue strength. The influence of different wave azimuths and monitoring positions on structural strength assessment is analysed. Finally, these measured data and analyses results will provide technical support for design and installation of the monitoring system on actual trimaran

Displacement and stress monitoring of a chemical tanker based on inverse finite element method

Real-time reconstruction of full field structural displacements, strains, and stresses by using surface strain measurements obtained from on-board strain sensors is commonly referred to as shape- and stress-sensing. For this purpose, a computationally accurate, robust, and rapid algorithm named as inverse Finite Element Method (iFEM) was recently developed. The main goal of this study is to perform displacement and stress monitoring of a typical chemical tanker mid-ship based on iFEM methodology. The numerical implementation of the iFEM algorithm is done by considering four-node inverse quadrilateral shell (iQS4) element. In order to demonstrate the capability of the current approach, a long barge that has a cross-section identical to a typical chemical tanker is modeled with iQS4 elements. Then, hydrodynamic loads of the barge for a certain frequency of waves are calculated by using in-house hydrodynamic software. Then, these forces are applied to a FEM model of barge and structural response is computed by using in-house finite element software. The results obtained from FEM analysis is utilized as a source to simulate in-situ strain data used in iFEM analysis as input. Finally, iFEM and FEM displacements are compared and the effects of locations and number of sensors on iFEM solution accuracy are discussed

Failure of carbon fiber yacht mast in heavy weather

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.Includes bibliographical references (p. 81-84).For many years Round the World racers and leading yacht owners have appreciated the benefit of carbon. Carbon fiber spars are around 50% lighter and considerably stronger than traditional aluminum masts. The result is increased speed, and the lighter mast also gives the boat a lower centre of gravity and so heeling and pitching is reduced. The recent spate of carbon mast failures has left concerns amongst the general yachting public about the reliability of the concept and ultimately the material itself. The lack of knowledge about loads acting on the mast prevents designers from coming with an optimum design. But a new program, the "Smart Mast" program, developed by two of Britain's leading marine companies, has been able to monitor loads acting on a mast in real-time with an optical fiber system. This improvement could possibly be a revolution in the design of racing yachts carbon masts and fill the design data shortage. Some other evolutions in the rigging design also appeared to be of interest, like for example the free-standing mast or a video system helping the helmsman to use its sails at their maximum.by Nicolas Meilhan.M.Eng

Failure monitoring of e-glass/vinylester composites using fiber grating acoustic sensor

This paper reports an application of an optical fiber sensor in a continuous and in situ failure testing of an E-glass/vinylester top hat stiffener (THS). The sensor head was constructed from a compact phase-shifted fiber Bragg grating (PS-FBG). The narrow transmission channel of the PS-FBG is highly sensitive to small perturbation, hence suitable to be used in acoustic emission (AE) assessment technique. The progressive failure of THS was tested under transverse loading to experimentally simulate the actual loading in practice. Our experimental tests have demonstrated, in good agreement with the commercial piezoelectric sensors, that the important failures information of the THS was successfully recorded by the simple intensity-type PS-FBG senso

Large-scale remotely interrogated arrays of fibre-optic interferometric sensors and fibre lasers

Abstract unavailable please refer to PD

Three dimensional shape and stress monitoring of bulk carriers based on iFEM methodology

Over the last few years, inverse finite element method (iFEM) is shown to be one of the most robust and general algorithms for the purpose of shape and stress sensing. This study concerns the application of iFEM methodology to a capsize bulk carrier and investigates an appropriate sensor placement configuration for better structural health monitoring of the vessel. The measured uniaxial strain data, e.g. the ones collected from fiber Bragg grating (FBG) sensors, are processed by the developed iFEM framework. For this purpose, hydrodynamic and finite element analyses are performed to generate simulated FBG sensor - strains data for the bulk carrier floating in head sea wave condition. Up to ten percent white noise is added on the numerical strain data to represent experimental strain measurements collected from real FBG sensors. The influence of FBG sensor locations as well as noise level in the strain measurements are examined versus the solution accuracy. Based on the displacement and stress comparison between iFEM and the reference solutions, it was observed that a sparse deployment of FBG sensors is sufficient to predict accurate bending response of the vessel. Hence, practical applicability of iFEM technology together with FBG sensors is demonstrated for the bulk carriers