Detection and Quantification of Delamination Failures in Marine Composite Bulkheads via Vibration Energy Variations

This paper proposes a new vibration-based structural health monitoring method for the identification of delamination defects in composite bulkheads used in small-length fiber-based ships. The core of this work is to find out if the variations of vibration energy can be efficiently used as a key performance indicator for the detection and quantification of delamination defects in marine composite bulkheads. For this purpose, the changes of vibrational energy exerted by delamination defects in sandwich and monolithic composite panel bulkheads with different types of delamination phenomenon are investigated using a non-destructive test. Experiments show that the overall vibration energy of the bulkheads is directly dependent on the damage conditions of the specimens and therefore, the variations of this parameter are a good indicator of the incorporation of delamination defects in composite bulkheads. Additionally, the overall vibration energy changes also give interesting information about the severity of the delamination defect in the panels. Hence, this methodology based on vibratory energy can be used to accurately determine delamination defects in medium-sized composite bulkheads with the advantages of being a simple and cost-effective approach. The findings of this research possess important applications for the identification of delamination failures in composite components such as bulkheads, turbine blades, and aircraft structures, among others.

Recent Industrial Developments of Marine Composites Limit States and Design Approaches on Strength

To further exploit the potential of marine composites applications in building ship hulls, offshore structures, and marine equipment and components, design approaches should be improved, facing the challenge of a more comprehensive and explicit assessment of appropriately defined limit states. The structure ultimate/limit conditions shall be verified in principle within the whole structural domain and throughout the ship service life. What above calls for extended and reliable materials characterization on the one hand and for accurate and wide-ranging procedures in structural analyses. This paper presents an overview of recent industrial developments of marine composites limit states assessments and design approaches, as available in open literature, focusing on pleasure crafts and yachts as well as navy ships and thus showing a starting point to fill the gap in this respect. After a general introduction about composites characterization techniques, current design practice and rule requirements are briefly summarized. Both inter-ply and intra-ply failure modes and corresponding limit states are then presented along with recently proposed assessment approaches. Three-dimensional aspects in failure modes and manufacturing methods have been identified as the main factors influencing marine composite robustness. Literature review highlighted also fire resistance and hybrid joining techniques as significant issues in the use of marine composites.

Assessing efficiency of conducting industrial special economic zone Lotos

The article highlights the importance of creating and operating the special economic zones in Russia in order to increase the investment attractiveness and competitiveness of the entities and strategically important industries in the Russian Federation. Traditionally, shipbuilding has been a priority economic activity in the Astrakhan region, which has led to creating an industrial special economic zone Lotоs, whose purpose is defined as formation of a local chain of shipbuilding and machine-building products in the south of Russia. The effectiveness of special economic zones is an integrated characteristic of the management company's ability to achieve the goals of creating and operating a special economic zone. As a result of the analysis of investment attrac-tiveness of the industrial special economic zone Lotоs, the problem areas of the management company's activities were identified: creating infrastructure facilities and attracting residents and investors. The substantial characteristic of investment projects of the residents (type of economic activity and its compliance with the objectives of the industrial special economic zone Lotоs, expected period and volume of investment, employment status, level of multiplicative effect on the regional economy) allowed formulating a conclusion about the necessity of differentiation of the state support for the investment projects of residents. There have been given the substantial characteristics of the projects of the residents: Shipbuilding Plant Lotos, JSC; Hexa-Lotos, LLC; Svoi, LLC; MedInTech, LLC; Atef-Russ, LLC; Marine Composite Shipbuilding, LLC; InProect, LLC; Protelux Lotоs, LLC; Stroyliderplus Lotоs, LLC; Helios Systems, LLC; Azka Composite, LLC; Naval Design International, LLC; Roza, LLC, etc. There have been offered the recommendations for the management company on developing a strategy for attracting residents and investors and establishing special preferential treatment for investment projects that are of strategic importance for the development of the regional economy and international cooperation are proposed.

Thermal and Mechanical Coupled Analysis of Marine Composite Cryogenic Pipeline

Marine composite cryogenic pipeline is one of the key equipment for offshore gas explorations, which is mainly used in the transmission of liquefied natural gas. Due to the harsh marine environment and extreme temperature of transmission medium, the marine composite cryogenic pipeline needs to bear both the tensile and bending loads caused by marine environments and the ultra-low temperature load caused by transmission medium. Due to the extremely low temperature of liquefied natural gas, about −163 °C, the structure and the composed material of cryogenic pipelines will be faced greatly challenges. Previous studies have considered mechanical properties or temperature loading separately. In this research, the structural performance of the marine composite cryogenic pipeline under the combined action of mechanical loads and thermo-load is studied with numerical methods. The framework of the coupled mechanical and thermo-analysis for the structure of composite cryogenic pipeline is established. The numerical results show that the temperature distribution has great impacts on the structural responses of the cryogenic pipeline. The coupled mechanical and thermo analysis of the cryogenic pipeline is proved to be necessary. The established method and framework provide a reference for the engineering design and application of the marine composite cryogenic pipeline.