Ship Hull Diagnostics with the Use of Remotely Operated Underwater Vehicle

NDT World ◽  
2015 ◽  
Vol 18 (3) ◽  
pp. 12-15 ◽  
Author(s):  
Третьяков ◽  
Evgeniy Tretyakov ◽  
Бритвин ◽  
Vladimir Britvin ◽  
Вельтищев ◽  
...  
Keyword(s):  
Crack Detection ◽  
Flaw Detection ◽  
Surface Preparation ◽  
Steel Structures ◽  
Ship Hull ◽  
Contact Method ◽  
Remotely Operated Vehicle ◽  
Sh Waves ◽  
Dry Dock ◽  
Diagnostics System

Introduction. Nowadays ship hull diagnostics is carried out in dry-dock or using divers in the road. The both technologies are time consuming, labour and material resource demanding. Specialists from Bauman Moscow State Technical University have developed a diagnostics system that allows the ship hull underwater part inspection to be performed without calling at dry-dock and without divers. The system includes the following main elements: remotely operated vehicle that contains diagnostics tools; hydro acoustic navigation system; software; and diagnostics technology. Method. The technology is based on an acoustic method of non-destructive testing (NDT). SH-waves with elastic vibrations excitation by non-contact method are used without necessity of thorough surface preparation before testing. SH-waves are also used for flaw detection within damaged areas (areas of different thicknesses). As the research has shown, the mirror-shadow technique with bottom signal attenuation as a criterion for corrosion crack detection is most effective. The minimum detectable deep of the corrosion cracks is 1.5–2 mm. The proposed diagnostics technology uses electromagnetic acoustic transducers (EMAT) with a 5 MHz frequency. Results. The diagnostics system was successfully tested in the pool. The test results confirmed the system’s ability to perform automatic metal diagnostics with wall thickness measurements and defect detection within areas of corrosion. Discussions. Nowadays the system is under the process of Russian Maritime Register of Shipping approval. It is planned to develop a system with arc welding tools for underwater objects repair. Prospects of diagnostics system usage for the various underwater steel structures including ones located on the Russian Federation Arctic shelf are under consideration.

Framework for Flaw Detection: Application to Dynamic Crack Detection in Flat Membranes

2008 ◽  
Author(s):  
Daniel Rabinovich ◽  
Dan Givoli ◽  
Shmuel Vigdergauz
Keyword(s):  
Inverse Problem ◽  
Crack Detection ◽  
Flexible Structures ◽  
Flaw Detection ◽  
Forward Problem ◽  
Dynamic Crack ◽  
Computational Framework ◽  
Time Harmonic ◽  
Present Context ◽  
Flat Membranes

A computational framework is developed for the detection of flaws in flexible structures. The framework is based on posing the detection problem as an inverse problem, which requires the solution of many forward problems. Each forward problem is associated with a known flaw; an appropriate cost functional evaluates the quality of each candidate flaw based on the solution of the corresponding forward problem. On the higher level, the inverse problem is solved by a global optimization algorithm. The performance of the computational framework is evaluated by considering the detectability of various types of flaws. In the present context detectability is defined by introducing a measure of the distance between the sought flaw and trial flaws in the space of the parameters characterizing the configuration of the flaw. The framework is applied to crack detection in flat membranes subjected to time-harmonic and transient excitations. The detectability of cracks is compared for these two cases.

Immunity of the second harmonic shear horizontal waves to adhesive nonlinearity for breathing crack detection

2021 ◽  
pp. 147592172110571
Author(s):  
Fuzhen Wen ◽  
Shengbo Shan ◽  
Li Cheng
Keyword(s):  
Crack Detection ◽  
Guided Waves ◽  
Lamb Waves ◽  
Second Harmonic ◽  
Sh Waves ◽  
High Order Harmonic ◽  
Thin Walled Structures ◽  
Harmonic Shear ◽  
Contact Acoustic Nonlinearity ◽  
Shear Horizontal

High-order harmonic guided waves are sensitive to micro-scale damage in thin-walled structures, thus, conducive to its early detection. In typical autonomous structural health monitoring (SHM) systems activated by surface-bonded piezoelectric wafer transducers, adhesive nonlinearity (AN) is a non-negligible adverse nonlinear source that can overwhelm the damage-induced nonlinear signals and jeopardize the diagnosis if not adequately mitigated. This paper first establishes that the second harmonic shear horizontal (second SH) waves are immune to AN while exhibiting strong sensitivity to cracks in a plate. Capitalizing on this feature, the feasibility of using second SH waves for crack detection is investigated. Finite element (FE) simulations are conducted to shed light on the physical mechanism governing the second SH wave generation and their interaction with the contact acoustic nonlinearity (CAN). Theoretical and numerical results are validated by experiments in which the level of the AN is tactically adjusted. Results show that the commonly used second harmonic S0 (second S0) mode Lamb waves are prone to AN variation. By contrast, the second SH0 waves show high robustness to the same degree of AN changes while preserving a reasonable sensitivity to breathing cracks, demonstrating their superiority for SHM applications.

scholarly journals A Self-Organizing Fuzzy Logic Classifier for Benchmarking Robot-Aided Blasting of Ship Hulls

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3215 ◽  
Author(s):  
M. A. Viraj J. Muthugala ◽  
Anh Vu Le ◽  
Eduardo Sanchez Cruz ◽  
Mohan Rajesh Elara ◽  
Prabakaran Veerajagadheswar ◽  
...  
Keyword(s):  
Fuzzy Logic ◽  
Robotic System ◽  
Ship Hull ◽  
Integrated System ◽  
Ship Hulls ◽  
System Solution ◽  
Maintenance Work ◽  
Dry Dock ◽  
Self Organizing

Regular dry dock maintenance work on ship hulls is essential for maintaining the efficiency and sustainability of the shipping industry. Hydro blasting is one of the major processes of dry dock maintenance work, where human labor is extensively used. The conventional methods of maintenance work suffer from many shortcomings, and hence robotized solutions have been developed. This paper proposes a novel robotic system that can synthesize a benchmarking map for a previously blasted ship hull. A Self-Organizing Fuzzy logic (SOF) classifier has been developed to benchmark the blasting quality of a ship hull similar to blasting quality categorization done by human experts. Hornbill, a multipurpose inspection and maintenance robot intended for hydro blasting, benchmarking, and painting, has been developed by integrating the proposed SOF classifier. Moreover, an integrated system solution has been developed to improve dry dock maintenance of ship hulls. The proposed SOF classifier can achieve a mean accuracy of 0.9942 with an execution time of 8.42 µs. Realtime experimenting with the proposed robotic system has been conducted on a ship hull. This experiment confirms the ability of the proposed robotic system in synthesizing a benchmarking map that reveals the benchmarking quality of different areas of a previously blasted ship hull. This sort of a benchmarking map would be useful for ensuring the blasting quality as well as performing efficient spot wise reblasting before the painting. Therefore, the proposed robotic system could be utilized for improving the efficiency and quality of hydro blasting work on the ship hull maintenance industry.

scholarly journals Carboline’s systems approach to the maintenance of coating systems for steel structures in the oil and gas industry

2019 ◽  
Vol 121 ◽  
pp. 02003
Author(s):  
Gennadiy Konovalov
Keyword(s):  
Oil And Gas ◽  
Systems Approach ◽  
Protective Coatings ◽  
Surface Preparation ◽  
Steel Structures ◽  
Oil And Gas Industry ◽  
Internal Stresses ◽  
Gas Industry ◽  
Low Levels ◽  
Protective Systems

The article discusses options for optimal repair systems with several advantages compared with competitive solutions in the market of protective coatings. The proposed materials have a high tolerance to the degree of surface preparation, compatibility with old protective systems, as well as low levels of internal stresses arising in the repair layer of coating, which significantly reduces the risk of pulling off the old protective coatings after repair.

Surface Pretreatment of Fiber-Reinforced Plastics via VUV Radiation

2017 ◽  
Vol 742 ◽  
pp. 70-73
Author(s):  
Christoph Schmüser ◽  
Kira Rosanova ◽  
Christopher Dölle
Keyword(s):  
Surface Energy ◽  
Power Plants ◽  
Adhesive Bonding ◽  
Surface Preparation ◽  
Transport Sector ◽  
Contact Method ◽  
Fiber Reinforced ◽  
Release Agent ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics

Fiber-reinforced plastics (FRP) are of great importance for the transport sector, the aerospace industry, for wind power plants, in the building sector and in the field of sports and leisure applications. Optimization of the adhesive bonding process for FRP structures, especially the surface preparation prior to bonding, will be of a central importance in forthcoming expansion of FRP use. In this connection the key problem depends on the FRP polymer matrix. In the case of duroplastic matrix the main problem is the presence of release agent on the surface of joining components. For the thermoplastic matrix such as polypropylene (PP), the main problems are the low surface energy and the inertness of its surface. Conventional pretreatment methods, such as manual grinding, shall be replaced by energetic radiation technics like VUV lamps (vacuum ultraviolet spectral range: 100 – 200 nm). This approach is a non-contact method, characterized by high treatment homogeneity and material-saving properties, combined with no further fibers to be released. The surface of the thermoplastics is activated by the incorporation of oxygen, release agent contamination on the thermoset is cleaned or modified [1 - 8]. The results of the VUV surface activation of PP and CFRP with regard to the incorporation of functional groups, increase of surface energy, matrix degradation and the adhesion increase of adhesive bonds are presented. In addition, studies on the release agent coating and the release agent modification by VUV radiation are presented. The work is completed by considerations concerning possibilities to accelerate the process (in particular, wavelength dependence, influence of an inert gas or the moisture content). Finally, an evaluation of the VUV pretreatment is carried out on the basis of two specific applications.

APPLICABILITY OF A NEW SURFACE PREPARATION METHOD FOR STEEL STRUCTURE USING LASER

2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Hiroshi Ogami ◽  
Katashi Fujii ◽  
Yukio Manabe ◽  
Kohei Ota ◽  
Asuo Yonekura
Keyword(s):  
Preparation Method ◽  
Surface Condition ◽  
Surface Preparation ◽  
Steel Structure ◽  
Steel Structures ◽  
Laser Cleaning ◽  
Coating Film ◽  
Test Results ◽  
Corrosion Prevention ◽  
Accelerated Corrosion

Surface preparation is very important in re-painting of steel structures so as to extend the effective term of corrosion prevention. Though grinding or blasting have been widely used to remove rust and old coating film on steel surface, both these methods have difficulty in completion of rust-removal and cause some problems such as dust scattering, noise, etc. In order to solve these problems, this paper presents the laser cleaning method which instantaneously sublimes/evaporates the rust on the surface of steel structure. The authors investigate the effects and the applicability of laser cleaning using the specimens made by accelerated corrosion method. The test results confirmed that the laser cleaning can remove the rust almost much as using sand blast, and the salt on the surface of steel can also be evaporated as good as the rust. Moreover, this method seems can be applied on wet surface condition because the moisture and water on the surface of steel can also be evaporated.

Investigation of Wall Thinning Measurement in Steel Plates by Electromagnetic Acoustic Resonance

2008 ◽  
Vol 580-582 ◽  
pp. 113-116 ◽  
Author(s):  
Kinya Mitani ◽  
Masahito Mochizuki ◽  
Masao Toyoda
Keyword(s):  
Resonance Spectrum ◽  
Steel Structures ◽  
Resonance Method ◽  
Acoustic Resonance ◽  
Steel Plates ◽  
Contact Method ◽  
Wall Thinning ◽  
And Control ◽  
Coupling Medium ◽  
Basic Investigation

Development of a non-contact method for measuring the degree of corrosion is highly desired by those who are involved in the maintenance and control of steel structures. Increasingly, it is expected that application of an electromagnetic acoustic technology that does not require a coupling medium will meet this demand. Various problems have been reported regarding measuring thickness of a corroded material using the resonance method. In order to clarify these problems, it is important to make evaluations based on the resonance spectrum that corresponds to the thickness of each plate. In this paper, experiments using grooved specimens for a basic investigation were performed and a new method for wall-thinning measurement based on the resonance spectrum amplitude was proposed. In addition, examination was performed by using a numerical simulation about this method’s detection principle.

Sign in / Sign up

Export Citation Format

Share Document