Опыт применения композитных материалов в судостроении

Introduction. Polymer composite materials (PCM) are used to improve the mechanical properties and increase the working period of products. For the processing of products made of PCM, the use of electrophysical processing methods is standard. One of these methods is copy-piercing electrical discharge machining (EDM). The use of such methods for processing PCM is due to its high physical and mechanical characteristics and the complexity of processing by blade methods. Considering the fact that the PCM element is a binder – epoxy resin, which is destroyed at the edges of the resulting holes and grooves during EDM, PCM can be considered difficult to process. During the EDM of holes in PCM products, the temperature rises, and inefficient cooling often occurs in the processing zone. The paper is devoted to theoretical simulation in the Ansys package, which makes it possible to evaluate the impact of flushing method on the efficiency of the EDM of PCM products based on numerical simulation in finite element analysis software systems. The aim of the work is to increase the productivity of the processes of EDM for PCM products. Methods. Experimental studies were carried out according to the method of a classical experiment on a copy-piercing electrical discharge Smart CNC machine. The workpiece was processed at a constant voltage U = 50 V, pulse on-time Ton = 100 µs and current: I = 10 A. For theoretical simulation of the flow, the ANSYS CFX 20.1 software was used. Flow distribution simulation was carried out at three processing depths (2 mm, 10 mm, 15 mm), as well as at three nozzle inclination angles (15°, 45°, 75°). Results And Discussion. The analysis of the data obtained showed that in the case of the EDM of PCM, the angle of the location of the flushing nozzles should be taken into account in order to increase the productivity of processing deep, blind holes. It is established that the highest performance value is achieved when the nozzles are located at an angle of 15˚. The laminar motion prevails. With this arrangement of the nozzles, the value of the liquid pressure and the removal of the sludge are stable both with the EDM of PCM to a depth of 2 mm, and when processing to a depth of 15 mm. It is noted that for processing holes with a depth of 10 mm or more, it is worth considering the angle of inclination of the flushing nozzle for effective processing, it is necessary to remove eroded particles from the gap. In the process of conducting an experimental study, when processing holes with a depth of 15 mm, sticking of sludge to the electrode-tool was observed, as well as the closure of the EDM process, the occurrence of secondary discharges in the processing zone, which caused the processing to stop.

In the past few years there could be seen an increasing use of polymer composite materials in the marine industry. Polymer composite materials reach 70% in the volume of parts and structures of ships and marine equipment. The most intensive growth in the implementation of composite materials can be observed abroad. The problem of complete or partial absence of domestic original reinforcing fibers and polymer matrices is revealed. The necessity to define the limiting factors for using the polymer composite materials in the shipbuilding industry of the Russian Federation is substantiated. A study of domestic and foreign literature, industry regulations was carried out, in which the deductive methods, analysis and synthesis were used. The ecosystem of organizing the technological process from the polymer composite materials in the production of structures and parts of marine equipment is considered. The specific features of the technological process are listed, and a formula that describes the speed of the infusion process and determines the parameters on which the process depends is given. It has been found that the main documents regulating the use of polymer composite materials in shipbuilding are focused on the production processes in the 1970s. Nowadays, a competitive struggle for the orders and deadlines forces to use computer-aided design systems for creating 3D models of parts and structures in designing complex structures. There have been defined the restraining factors that have a negative impact on the development of technological processes of working up and introducing the polymer composite materials in in the national industry. The results of the study will further serve to form methodological materials and options for designing technological processes for the processing of polymer composite materials in the Russian industry.

The article considers issues of identifying the causes and factors that have a significant impact on the occurring and development of the warping process in monolithic products made of polymer — composite materials (PCM) obtained by the method of multidirectional layering of uncured PCM — semi-finished product (prepreg) and subsequent high-temperature molding in an autoclave. Warping is understood as a defect of a PCM product in the form of distortion of its configuration (deformation) under stresses arising during the polymerization of the binder prepreg at a high temperature (1800C) and cooling the product to room temperature. Flat samples made of glass-based prepregs have been researched. The selecting schemes of equilibrium stacking of samples of monolithic panels has been carried out. The influence of the binder content in the prepreg on the deformations in non-equilibrium layouts of the panel samples has been evaluated. It is shown that the most significant factors influencing the occurrence of warpage of monolithic PCM panels are: the weaving pattern of the prepreg reinforcing base, the amount of binder deposited in the prepreg, the direction of stacking monolayers in the panel, the edge effect and the shape of the product surface. It was found that the warpage of the sample occurs along the direction of unbalanced shrinkage of the binder. For balanced stacking, compensation in the direction of binder shrinkage and symmetry with respect to the central layer are necessary; more binder in the prepreg reduces the amount of warpage, but only slightly. The development of constructive and technological recommendations based on the results obtained will lead to a reduction in the terms of development of PCM products.

The mechanical properties of polymer composite materials used in shipbuilding are examined in this article. The samples from polymer composite materials based on glass fibers and polyester resin were made for this purpose. The manufacturing samples technique from polymer composite materials for mechanical test operation is represented here. The influence of woven roving fabric layers number ratio to the number of glass-fiber mat layers under testing samples for expansion, compression and 3 point bending has been determined by mechanical tests method. As the data processing result obtained in the experiment course it has been determined that the number of woven roving fabric layers increase with polymer composite materials increases the breaking load and tensile ultimate strength and decreases these values under compression and 3 point bending. The results obtained in this article are the basis for identifying polymer composite materials mechanical properties with different reinforcement schemes in case of their application in ship structures such as a material for transport vessels superstructure .

In the last decades there is increasing the need to apply polymer composite materials in different industries, particularly in shipbuilding. There are developing single structures made from polymer composite materials to be used on board ships. The article focuses on technology of manufacturing slabs from polymer composite materials to carry out mechanical testing in the laboratory special standard units. Mechanical properties of polymer composite materials depend on molding technologies. There has been described a technology of sample manufacturing from polymer composite materials reinforced with glass fiber mat with fiberglass plastics. The technique of testing the specified samples for tensile strength has been considered. The sizes and shapes of the samples as well as the technological parameters of the manufacturing process have been validated, depending on the standard requirements and the technological features of the testing machine. The physical and mechanical properties of the components that make up the composite materials are considered. The sequence of stacking layers for preparation of plates from composite materials is indicated. The dimensions of the plates for cutting out finished samples are determined, depending on the method of production. The way of laying plates from composite materials has been chosen on the base of economic considerations and conditions of accessibility. The obtained results of mechanical properties can be used in solving problems of application of polymer composite materials in shipbuilding, for example, in manufacturing superstructures of some dry cargo vessels.

Modern production requires new technological solutions that meet the requirements of environmental safety, saving energy resources while increasing the efficiency of technological processes. The paper presents the results of a study of the polymer composite materials in the form of fiberglass rebar curing with the use of a microwave unit. Microwave technologies were used for the polymer composite materials curing (at the electromagnetic field oscillation frequency of 2450 MHz), thermosetting epoxy resins and glass fibers were used as binders and fillers. A uniform temperature distribution over the volume of polymer composite materials in the form of rods (of 20 and 40 mm diameters) was formed using the microwave installation electrodynamic systems. It is shown that the microwave radiation energy as a heat source makes it possible to realize a qualitatively new level of polymer composite materials production, characterized by the ability to produce products with higher physical and mechanical characteristics. In addition, microwave installations significantly save energy consumption compared to traditional installations for the fiberglass rebar production. The calculation of microwave installation parameters and fiberglass rebar heat treatment technological modes are presented as well as data on the temperature distribution over the rods cross-section. The obtained results can be used in technological production processes of the polymer composite rod materials heat treatment.

The results of the review of the types of polymer composite materials used in domestic shipbuilding for the production of ship hulls and structures are presented. It has been established that the construction of vessels with a hull length of more than 70 m from polymer composite materials is currently not carried out for several reasons: limitation of length by the requirements of the rules of classification societies, lack of a single universally recognized worldwide methodology for calculating the strength parameters of composite hulls, high cost, restrictions on the use of composites by the requirements of international conventions and codes in the field of fire safety security. It is determined that polymer composite materials based on glass fibers and epoxy (or polyester) resin as a binding medium are most often used for the manufacture of ship structures in domestic shipbuilding. Molding is most often used as manufacturing methods, and vacuum infusion is used if special equipment is available. This is due to cost savings, the need for the introduction of complex and expensive vacuum infusion systems, ventilation systems for production facilities and heating of layers of composite materials in the production of elements of marine power plants and structures. With the reduction in the cost of materials such as carbon fiber, basalt-reinforced complexes, hydrocarbon fiber, and others, the prospect of using composites opens up not only for small-scale, but also large-tonnage displacement vessels for the manufacture of hull structures and superstructures, internal combustion engine parts, and other elements. The disadvantages of polymer composite materials such as high cost, difficult disposal and non-compliance with fire hazard, according to the requirements of international maritime codes and conventions, are considered, which may be a direction for future research.

The article presents the results of the analysis of the influence of the composition and structure of polymer composite material (PCM) with enhanced vibration damping properties on its characteristics. Experimental samples of PCM of various composition having enhanced vibration damping properties were made and their main physical, mechanical and vibration-absorbing properties were investigated. Factors affecting the level of properties of manufactured experimental samples were determined. The optimalvariant of the composition and structure of PCM with enhanced vibration-absorbing properties has been determined.

The possibility of regulating the content of composite material components that is polymer matrix (PM) and reinforcing filler is revealed. It found out that weak interfacial adhesion between reinforcing fibers and a polymer matrix leads to getting a polymer composite material (PCM) with low physical and mechanical characteristics. To eliminate this drawback, a method of influencing reinforcing materials is chosen – a low-energy ion flow at reduced pressure, which makes it possible to improve their capillary wettability, create conditions for strong interaction with the matrix, and regulate the PM–reinforcing filler ratio. Therefore, an urgent task is to study the ratio of PCM components in order to reduce the weight of composite products while maintaining their strength characteristics. Ultra-high molecular weight polyethylene (UHMW PE) fibers such as D800 and PCM based on UHMW PE and ED-20 epoxy resin are selected as research objects. A study of the wettability of UHMW PE fiber surface by spreading time of epoxy resin drop has shown that after exposure to the low-energy ion flow, the interaction of the polymer binder with the fibrous material increases due to activation of its surface when additional functional groups appear. Modification of the low-energy ion flow leads to an increase in the capillarity of UHMW PE material, the height of epoxy resin increases by more than 5 times due to the appearance of hydroxyl groups on the surface of the material. The thermomechanical characteristics of PCM with varying polymer matrix content have shown that the use of modified low-energy ion flow and UHMW PE materials as reinforcing components can reduce the binder content by 10%, while increasing the thermal stability of the composite by 5.5%. The mechanical characteristics of PCM based on modified UHMW PE materials have increased values. The conducted studies allowed to find out that the use of low-energy ion flow makes it possible to reduce the binder content in PCM and at the same time obtain the best mechanical characteristics.

Object and purpose of research. The object of the study is polymer composite materials (PCM) used for manufac-turing hull structures of ships and vessels. The main purpose is to find the ways of fire protection of ships and vessels built from these materials. Materials and methods. The results of experimental studies and standard tests on the fire resistance of PCM structures, as well as methods of heat and mass transfer processes simulation in ship premises during fires, were used to determine the thermal characteristics affecting these structures. Main results. The ways of improving the fire safety of ships and vessels with PCM hull structures are determined. The list of problems to be solved in this area is outlined. Also this study has recommendations to improve the fire protection of the ships being designed, under construction and in operation. Conclusion. The structural PCM used in indigenous practice does not meet the current requirements of the International Maritime Organization (IMO) for Maritime Safety for fire protection of high-speed vessels and the requirements for fire protection of Navy ships. Ships that are in service and built using these materials do not provide additional measures to reduce their fire hazard. Fires on such ships can lead to disastrous consequences. It is necessary to solve this problem as soon as possible. The recommendations proposed in this paper on how to solve it, based on a large amount of experimental research, and they have great practical significance.

As the demand for reliability and durability in polymer materials used in friction units and sealing systems continues to grow, it is essential to develop composites that exhibit enhanced tribological and mechanical properties. Polytetrafluoroethylene (PTFE) is a popular choice due to its exceptional antifriction qualities; however, its limited wear resistance restricts its application in extreme environments. To address this, we explored the modification of PTFE with cerium dioxide (CeO2) fillers to enhance its performance. The objective of this study was to examine how the mechanochemical activation of cerium oxide influences the properties and structure of PTFE, ultimately aiming to improve its mechanical and tribological characteristics. We employed traditional processing methods for polymer composite materials (PCM) based on PTFE. The mechanochemical activation of CeO2 was conducted using a planetary mill, and we utilized various analytical techniques, including X-ray diffraction analysis, differential scanning calorimetry, and IR spectroscopy, alongside mechanical and tribological testing to evaluate the structure and properties of the composites. Our findings revealed that incorporating 2 wt.% of CeO2 into PTFE significantly increases the degree of crystallinity and the enthalpy of melting of the PCM when using the mechanically activated filler. Notably, tribological tests indicated a remarkable 254-fold increase in wear resistance for the PCM with mechanically activated CeO2, while the friction coefficient remained consistent with that of the initial polymer. Additionally, IR spectroscopy analysis of the friction surfaces of the PCM indicated the formation of perfluorocarboxylate salts during wear, suggesting the occurrence of tribochemical processes. In conclusion, the developed PCM based on PTFE with mechanically activated CeO2 demonstrates enhanced mechanical and tribotechnical properties, positioning them as promising materials for use in friction units and sealing systems.

Currently, developments of the so-called Smart-constructions are relevant as they enable a real-time monitoring of changes in required values. Smart designs are widely used in the construction, automotive and aerospace industries. Technologies of creating products from polymer composite materials make it possible to introduce various sensors directly into the structure of a material, thereby create systems monitoring the state of structures. The most recommended for such implementation are fiber-optic sensors, which have a number of advantages over other sensors (luminescent, strain gauge, piezoelectric ones). However, when introducing the fiber-optic sensors, there is a number of difficulties, which are primarily associated with fragility of the optical fiber and lead to the breakdown of fiber-optic lines. As a result, it is necessary to develop a Smart-layer that will protect the optical fiber leads and will not significantly change the physical and mechanical characteristics. This paper aims to determine the stiffness and strength characteristics of samples made of polymer composite materials: reference samples, samples with embedded fiber-optic sensors, samples with embedded Smart-layers. In this work, a Smart-layer is understood as a coating that protects the fiber-optic sensors at the stage of implementation into a structure. The paper considers the following configurations of the Smart-layer: polymer reinforced mesh, polyamide and polyurethane layer. We analyzed and compared the influence of the embedded optical fiber and various configurations of the Smart-layer in the composite structure on the physicomechanical characteristics of the samples obtained under quasi-static loading (tension, compression, and interlayer shear). For a more detailed analysis of using the fiber-optic sensors and various configurations of the Smart-layer, the corresponding loads were simulated to assess their mechanical behavior. Based on the obtained physical and mechanical characteristics, a specific configuration of the Smart-layer was selected and justified for further researches.

Polymer composite materials (PCM) are used extensively and are viewed as candidates for application in various industries, including nuclear power. Despite a variety of methods and procedures employed to investigate the mechanical characteristics of PCMs, the use of the laboratory sample mechanical test results to design and model large-sized structures is not always fully correct and reasonable. In particular, one of the problems is concerned with taking into account the scale parameter effects on the PCM strength and elastic characteristics immediately in the product. The purpose of the study is to investigate the scale effects on the mechanical characteristics of glass reinforced plastics using phenolformaldehyde and silicon-organic binders and a fabric quartz filler. Samples of four different standard sizes under GOST 25604-82 and GOST 4648-2014 were tested for three-point bending using an LFM-100 test machine to estimate the scale effect. The thicknesses of the model samples were chosen with regard for the wall thicknesses of full-scale products under development or manufactured commercially and the test machine features, and varied in the limits of 1.6 to 7.5 mm. The tests showed that strength decreased as the sample thickness was increased to 3 mm and more both at room and elevated (200 to 500 °C) temperatures, which can be described by an exponential function based on the Weibull statistical model. The values of the Weibull modulus that characterizes the extent of the scale effect on the strength of the tested materials were 4.6 to 6.7. The average bend strength in the sample thickness range of 3 mm and less does not vary notably or tends to increase slightly as the thickness is increased. This fact makes it possible to conclude that estimation of allowable stresses in a thin-wall product requires the use of test results for samples with a thickness that is equal to the product wall thickness since standard samples may yield overestimated allowable stress values and lead, accordingly, to incorrect calculations of the strength factor. The results obtained shall be taken into account when defining the allowable levels of operation for full-scale products and structures of polymer composites based on the laboratory sample strength data as well as when estimating their robustness as a characteristic of the product’s fail-safe operation.

Polymer composite materials (PCM) are used extensively and are viewed as candidates for application in various industries, including nuclear power. Despite a variety of methods and procedures employed to investigate the mechanical characteristics of PCMs, the use of the laboratory sample mechanical test results to design and model large-sized structures is not always fully correct and reasonable. In particular, one of the problems is concerned with taking into account the scale parameter effects on the PCM strength and elastic characteristics immediately in the product. The purpose of the study is to investigate the scale effects on the mechanical characteristics of glass reinforced plastics using phenolformaldehyde and silicon-organic binders and a fabric quartz filler. Samples of four different standard sizes under GOST 25604-82 and GOST 4648-2014 were tested for three-point bending using an LFM-100 test machine to estimate the scale effect. The thicknesses of the model samples were chosen with regard for the wall thicknesses of full-scale products under development or manufactured commercially and the test machine features, and varied in the limits of 1.6 to 7.5 mm. The tests showed that strength decreased as the sample thickness was increased to 3 mm and more both at room and elevated (200 to 500 °C) temperatures, which can be described by an exponential function based on the Weibull statistical model. The values of the Weibull modulus that characterizes the extent of the scale effect on the strength of the tested materials were 4.6 to 6.7. The average bend strength in the sample thickness range of 3 mm and less does not vary notably or tends to increase slightly as the thickness is increased. This fact makes it possible to conclude that estimation of allowable stresses in a thin-wall product requires the use of test results for samples with a thickness that is equal to the product wall thickness since standard samples may yield overestimated allowable stress values and lead, accordingly, to incorrect calculations of the strength factor. The results obtained shall be taken into account when defining the allowable levels of operation for full-scale products and structures of polymer composites based on the laboratory sample strength data as well as when estimating their robustness as a characteristic of the product’s fail-safe operation.

The development of modern shipbuilding requires using new structural materials, superior to traditional ones. Polymeric composite materials are among the most promising. The article studies the mechanical properties of multilayer polymer composite materials made of glass fabrics under tension and the effect of the number of layers of glass mat on the tensile strength of the material. The technology of manufacturing samples from polymer composites reinforced with fiberglass plastic is being considered. The size and shape of the samples, the technological parameters of the manufacturing process, which depend on standard requirements, and the technological features of the testing machine are substantiated. It has been stated that fiberglass is the cheapest and most common type of composite materials, which does not require special maintenance, the cost of maintenance of fiberglass structures being significantly lower than that of steel structures. The method of testing the tensile strength of the samples has been studied. For conducting experiments, samples of glass mat brand EMC-600-1250-E were used. According to the study results, the mathematical dependence of tensile strength on the number of layers was established, and the most important stages of statistical processing of test results were laid out using the Minitab 18.1 software package. A graph of the relationship between the number of layers and tensile strength is presented. For all the examined samples the ultimate strength will depend on the number of layers. The results of mechanical properties can be used in solving problems associated with the application of polymer composite materials in shipbuilding, for example, in manufacturing superstructures of dry cargo vessels.