Twill Weave Research Articles

Experimental investigation on the thermal characteristics of Kevlar/hemp intraply hybrid composites: Influence of various weaving designs

In this work, several weaving designs of intra-ply woven fabric Kevlar/hemp fiber (KHE) reinforced epoxy hybrid composites are developed and their thermal characteristics are examined. Thermogravimetric analysis showed that intra-ply hybrid of plain and basket weave designs possessed highest thermal stability. The different weaving patterns of KHE hybrid composites have no effect on the glass transmission temperature (Tg) value as inferred from the differential scanning calorimetry results. The thermomechanical analysis clearly demonstrates the superior dimension stability of the hybrid composites with basket weave. Dynamic mechanical analysis reveals that twill weave KHE have exhibited the maximum storage modulus (2021 MPa), loss modulus (210 MPa) and lower tan delta (0.3090) values compared to all other composites. Based on the obtained results, it is denoted that all the fabricated KHE hybrid composites displayed improved thermal performance. It may be suitable for applications in thermal insulation panels, fire-resistant clothing, and automotive underbody shields.

Investigating the Effect of Weave Type and Filament Count on Electrical Conductivity of Polyethylene Terephthalate (PET) Fabrics Coated with PEDOT Polymer

The rapid development of smart and wearable textiles has been driven by the need for smaller and lighter electronic circuits. To make textile surfaces conductive, various methods have been developed, with vapor-phase polymerization being a preferred method due to its smoothness, conductivity, and ease of application. This study investigates the effect of fundamental characteristics of textile fabrics, such as weave type and filament count, on electrical conductivity. Fabrics woven with different filament counts and weave types were coated with PEDOT polymer using vapor-phase polymerization. The results showed that the fabric woven with 150F288 yarns and a 3/1 twill weave exhibited lower electrical resistance, attributed to the microfibrous structure of the yarn and the twill's staggered structure. Despite increases in resistance values after performance tests, the electrical resistance values remained within a sufficient conductivity range. This research contributes to the understanding of how fabric characteristics affect the electrical conductivity of coated textiles, paving the way for the development of smart electronic textiles.

Effect of spandex linear density and twist multiplier on the properties of core spun yarn and denim fabric

AbstractThe utilization of core‐spun yarns with spandex has achieved significant interest over the past decade because of their exceptional stretchability, resilience, and comfort features. The main objective of this study was to evaluate the effects of changing the spandex denier and twist multiplier on the physio‐mechanical properties of 16 Ne core spun yarn and the produced denim fabric using these yarns as weft. Core‐spun yarns were produced from three different spandex deniers at various TM values, where cotton roving was used as the sheath. Fabrics were manufactured using an air‐jet weaving machine with the core spun yarn as weft and 100% ring cotton yarn as warp (12 Ne) following the identical 3/1 twill weave pattern. Results reveal that using different spandex percentages shows better results at different TM parameters. Both yarn and fabric were attained at a twist multiplier of 5.0, 5.5, and 6.0 for 40, 70, and 105 D, respectively. Additionally, it was discovered that the yarn produced using lower spandex denier gives higher tenacity for yarn and fabric. However, the yarn produced using a higher spandex denier gives higher elongation percentage for yarn, higher tear strength, recovery, and lower growth percentage fabric.Highlights Influence of spandex denier and twist multiplier on the physio‐mechanical properties of core‐spun yarn and the resulting denim fabric. The higher spandex denier exhibited greater tear strength, better recovery, and lower fabric growth percentages. Increasing the twist multiplier initially increased the tenacity and elongation percentage of yarns and fabrics, followed by a decrease. Higher spandex percentages reduced hairiness and increased with higher twist levels. Higher spandex denier indicates the need for tailored TM settings based on spandex denier to achieve desired fabric properties.

Thermal Degradation and Chemical Analysis of Flame-Retardant-Treated Jute Fabrics.

Jute is an inherent lignocellulosic fiber, consisting of hemicellulose, α-cellulose, and lignin. Industrial ventilation, automotive composites, upholstery, carpets, military uniforms, hospital furnishings, and curtains necessitate the integration of flame-retardance properties into jute fibers. In this investigation, seven weave-structured jute fabrics were treated using an organophosphorus-based flame-retardant (FR) chemical (ITOFLAM CPN) and a crosslinking agent (KNITTEX CHN) by the pad-dry-cure method. The thermal stability, degradation and pyrolysis behavior of jute was measured using a thermogravimetric analyzer (TGA). Surface morphology and element distribution were scrutinized utilizing a scanning electron microscope (SEM) and an energy-dispersive spectrometer (EDS). The ATR-FTIR (Attenuated Total Reflection-Fourier Transform Infrared Spectrometer) technique has been employed for analyzing the composition of chemicals in the jute fabrics. According to the protocols specified in ISO 14184-1, free formaldehyde detection was carried out on the jute fabrics. The flame-retardance property was significantly improved on all of the jute fabrics after FR treatment. FTIR and SEM-EDS studies revealed the presence of FR chemical deposition on the surface of the jute fabrics. TGA analysis indicated that the fabrics treated with FR exhibited premature degradation, leading to the generation of more char compared to untreated samples. The jute fabrics specifically demonstrated a notable enhancement in residual mass, exceeding 50% after FR treatment. However, it is noteworthy that the FR-treated fabrics exhibited an elevated level of free formaldehyde content, surpassing the permissible limit of formaldehyde in textiles intended for direct skin contact. The residual mass loss percentage after ten washes of FR-treated fabrics remained in a range from 32% to 36%. Twill weave designed fabrics (FRD4 and FRD5) clearly showed a lower thermal degradation temperature than the other weaves used in this study.

Manufacture of a Nanocomposite of Carbon Fibre and Nanotubes and Epoxy Resin

Nanocomposite material have been manufactured by the manual contact method, using nanotubes and carbon fibres as the basis for manufacturing the nanocomposite and epoxy resin as the matrix. The CVD method was used to manufacture the carbon nanotubes on the carbon fibre with twill and plain weaves. Additionally, the mechanical properties of the nanocomposite with twill and plain weave were obtained from the tensile tests, and the density was obtained experimentally. The carbon nanotubes, CNTs, grew perpendicular to the surface of the carbon fibres, CF. The average diameter was 117 μm and the average length was 23.87 μm. The nanocomposite made of carbon nanotubes, carbon fibre and epoxy resin, CNT/CF/Epoxy with single layer twill weave had a thickness of 0.57 mm, while the plain weave nanocomposite had 0.56 mm. The densities obtained of the CNT/CF/Epoxy material were 1.03 g/cm3 with the plain weave and 1.08 g/cm3 with the twill weave. While the densities of the composite material, CF/Epoxy, where 1.21 g/cm3 and 1.19 g/cm3 with plain and twill weave. The densities of the CNT/CF/Epoxy were 14.28% and 9.14% lower than the densities of the CF/Epoxy, both with the plain and twill weave. From the tensile tests the mechanical properties obtained of the CNT/CF/Epoxy with twill weave were a modulus of elasticity of 31 GPa and a maximum stress of 153.47 MPa and with the plain weave the modulus of elasticity was 25.10 GPa and the maximum stress was 121.71 MPa. Both composite and nanocomposite materials were investigated with twill weave, and it was found that the best results of the mechanical properties were obtained with the nanocomposite, the increase of the modulus of elasticity and the maximum stress were 23.82% and 2.16% respectively.

Influence of Reinforcement Architecture on Behavior of Flax/PLA Green Composites under Low-Velocity Impact.

The main goal of this study is the comparison of different reinforcement architectures on the low-velocity impact behavior of green composites. The study includes the comparison of unidirectional, basket weave, and twill weave flax/PLA composites, they are subjected to unidirectional tensile tests, drop-weight impact tests, and after-impact compression tests. Results show that the unidirectional composite demonstrates superior tensile strength and initial modulus due to reduced fiber crimp, while basket weave exhibits the highest energy absorption capability and strain capacity attributed to its higher fiber-weight ratio and fiber crimp. Unidirectional composite also shows a larger impacted damage area compared to basket weave and twill weave, attributed to its internal architecture. Residual compressive strength across all composites decreased by 40% compared to the reference sample. However, the reduction in stiffness after impact was different, UD/PLA composite stiffness was reduced by 30% while the reduction in BW/PLA and T/PLA composites was about 20%.

Evaluating the optimum abrasive water jet machinability for CARALL composites with various fiber orientations

AbstractCarbon Fiber Reinforced Aluminum Laminated (CARALL) composites are widely used in aircraft structures due to their ability to be produced in different shapes with desired properties and their high impact resistance properties. As with other layered composite materials, processing of CARALL composites by conventional manufacturing methods results in many damage mechanisms such as fiber breakage, deformation in the hole region, stress concentration, resin‐fiber separation and microcracks. One of the modern manufacturing methods, Abrasive Water Jet (AWJ), is a processing method in which the material is removed by abrasion and almost any material can be cut without thermal degradation. There are no experimental studies in the literature on the drilling of CARALL composites by modern manufacturing methods. The aim of this study is to investigate the impact of machining parameters on the output variables (kerf taper angle (K), roundness error (Re) and material removal rate (MRR)) as well as the effect of fiber orientation on the drilling of CARALL composites with different fiber orientations on an AWJ machine. PROMETHEE‐GAIA weighted by Entropy Weighting Method were used to ascertain the optimum levels of control factors. CARALL composites with different fiber orientations were drilled with an 8 mm diameter AWJ with three different water pressures, three different nozzle feed rates. With PROMETHEE‐GAIA multi‐criteria optimization method, the optimum levels of the factors that provide both minimum Re and K values and maximum MRR value were obtained with twill woven material, 1680 mm/min feed rate and 1680 bar water pressure.Highlights CARALL composite materials with two different fiber orientations (twill weave and UD) were used. CARALL composite materials were drilled at different machining parameters. Abrasive water jet was used in drilling experiments. Optimum drilling parameters were determined to achieve minimum roundness error, minimum kerf angle and maximum material removal rate. PROMETHEE‐GAIA was used as a multi‐criteria decision‐making method.

Performance of Flax/Epoxy Composites Made from Fabrics of Different Structures

Flax fibers have been shown to have comparable mechanical properties to some conventional synthetic fibers. Flax fabrics with different textile structures show differences in resistance against mechanical loads mainly rooted in fabric orientation and the resultant resin impregnation. Thus, in this study, flax fabrics with three different textile structures, fine twill weave, coarse twill weave and unidirectional, were used as reinforcements in an epoxy matrix. The surfaces of the fabrics were chemically treated using an alkaline treatment, and the alterations in fabric crystallinity index (CrI) were determined using X-ray diffraction (XRD). Experimental results confirmed that textile structures and CrI had significant effects on the mechanical properties of composites. Although an increment in CrI, resulting from chemical treatment, always enhanced tensile and flexural properties, it adversely affected damage development once composites were exposed to impact load. In terms of textile structures, unidirectional fabric outperformed woven fabrics in tensile and flexural properties while in impact properties, the latter had a better performance inducing less damage development. Finally, the mechanism of damage development in different composites was discussed in detail using Scanning Electron Microscopy (SEM) images. It is envisaged that the results of this study will provide an insight that will lead to the proper choice of the optimal kind of flax fabric for different applications.

Effect of warp yarn paths on the symmetrical cyclic bending fatigue properties of 3D woven composites

AbstractIn this study, the symmetric cyclic bending fatigue properties of three‐dimensional (3D) woven composites under the condition of R = −1 were investigated. Three types of 3D preform structures with different warp yarn paths were designed, and a bending fatigue testing fixture suitable for 3D woven composites under R = −1 conditions was developed. In addition, the bending fatigue properties, damage mechanisms, and failure modes of three composites were studied. The results showed that the warp yarn paths were responsible for the differences in quasi‐static bending properties. The bending fatigue properties were related to the warp yarn paths and applied stress. Satin woven (SW) structure had the highest bending fatigue failure strain value, followed by the twill woven (TW) structure, and the plain woven (PW) structure had the lowest. The bending fatigue limits of PW, TW, and SW structures were 40% (136 N), 40% (210.5 N), and 16% (119.4 N) stress levels, respectively. The bending fatigue failure mode of 3D woven composites was softening failure under the condition R = −1.Highlights The warp yarn paths significantly affects the quasi‐static bending properties. A symmetrical cyclic bending fatigue testing fixture was developed. The symmetrical cyclic bending fatigue life of 3D woven composites was obtained. SW composites have the highest bending fatigue failure strain value. The symmetrical cyclic bending fatigue failure modes were softening failures.

An experimental study of physical, mechanical, and thermal properties of Rattan fiber reinforced hybrid epoxy resin laminated composite

The primary objective of this research was to observe the physical, mechanical and thermal properties of rattan fiber reinforced hybrid epoxy resin laminated composites. The hybrid composites were fabricated utilizing rattan fiber, carbon fiber, jute fiber and epoxy resin as matrix materials. This study employed two types of rattan fibers, namely plain weave and twill weave. These rattan fibers were combined with carbon fibers and jute fibers separately, forming R3C2, R′3C2, R3J2 and R′3J2 composites. The fabrication process involved conventional hand lay-up followed by high-temperature treatment and pressure application under a hydraulic press to ensure effective curing and minimize voids within the final composites. These were compared with the properties of monolithic laminates. Mechanical properties, including tensile, flexural and hardness characteristics, were assessed to evaluate the impact of rattan fibers in hybrid composites. Failure modes of the fractured tensile specimen were examined using Scanning Electron Microscopy (SEM). Additionally, water absorption behavior and fire retardant painting test were conducted. The results showed that hybrid composites reinforced with plain weave rattan fiber (R3C2 & R3J2) exhibit superior tensile strength, flexural strength and hardness. In comparison to R5 composites, the tensile strengths of these samples have improved by 104.36% and 349.68%, respectively. Moreover, the flexural strengths of R3C2 and R3J2 composites exhibit significant enhancements of 218.41% and 90.9%. These composites also excel in the Shore D Hardness test. Hence, it can be concluded that the hybrid composites reinforced with rattan fibers demonstrate enhanced physical, mechanical, and thermal properties.

A preliminary step toward intelligent forming of fabric composites: Artificial intelligence-based fiber distortions monitoring

This work presents a prototype of an intelligent quality inspection tool for application to fibers distortion monitoring in the fabric composites forming processes. To this end, a series of hemisphere draping tests on a typical commingled fiberglass/polypropylene twill weave were conducted at the dry form, and the defects (in-plane and out-of-plane) for each formed part were inspected via camera vision. By gathering data from around 30 samples and over 1200 images from different forming regions, different machine-learning algorithms were trained and validated. As an application scenario in a smart factory, the developed simple AI tool would be used by an operator, or a robot, to scan different areas of the formed parts and identify ‘defected’ (fail) versus ‘non-defected’ (pass) scenarios. It was found that the K-nearest neighbors and Support Vector Machine models detect the defects with an error rate of less than 5% in the present case study, regardless of the background noise in the images such as external objects, marks on samples, or blurriness.

Mechanical strength measurement of needle-shaped CaSO4 microcrystals by a three-point bend test

A simple method for direct measurement of the mechanical strength of needle-shaped microcrystals of calcium sulfate, CaSO4, is proposed. The microcrystals, with a length from 30 to 50 μm and transverse dimensions from 1 to 3 μm, can act as reinforcing filler in various structural and building composites to improve their mechanical properties. The method is based on a three-point bend test, adapted to microscopic objects. The CaSO4 microcrystals were placed on a substrate, which was a twill-weave filter mesh consisting of intertwined steel fibers with diameter of ∼25 μm. Due to the twill weave, the mesh surface is characterized by a periodic distribution of protrusions and depressions. The protrusions act as supports for the placing of microcrystals, and the depressions provide the possibility of deformation and destruction of microcrystals under the action of an increasing vertically acting force, which is applied to the microcrystal through the indenter of the dynamic ultra-micro hardness tester. The moment of destruction of the microcrystals is observed to be dependent on the force on the displacement of the indenter. The measured values of the mechanical strength of CaSO4 microcrystals varied in a range from ∼3.5 to ∼6.0 GPa. The experimental strength values are in good agreement with the values obtained from the results of numerical analysis of the stressed state formed in the volume of CaSO4 microcrystals during the three-point bend test.

Electromagnetic shielding performance of copper wire/carbon fiber fabric reinforced composite materials

In order to enhance the electromagnetic (EM) shielding performance of carbon fiber composites, copper meshes were combined with carbon fiber fabric to design and fabricate eight types of copper wire/carbon fiber (Cu/C) fabric composite materials. Characterization and analysis of the conductivity and electromagnetic shielding performance of the Cu/C fabric composite materials were conducted. The results demonstrated that the number of layers of carbon fiber fabric had a significant impact on the EM shielding performance of the composite materials. Furthermore, the plain weave copper mesh composite exhibited higher EM shielding performance compared to the square plain weave and twill weave copper mesh composites. The optimal SE of the samples occurs in different frequency ranges at different densities. For the low-frequency range, the 60-mesh copper wire exhibits the best SE, while the 40-mesh copper wire demonstrates better SE for the high-frequency range. Additionally, the bonding of the copper mesh with the resin is also a potential factor influencing the electromagnetic shielding performance of the material. These findings provide valuable insights for the future design of electromagnetic shielding composite materials.

Material-Structure Integrated Design and Optimization of a Carbon-Fiber-Reinforced Composite Car Door

This paper develops a material-structure integrated design and optimization method based on a multiscale approach for the lightweight design of CFRP car doors. Initially, parametric modeling of RVE is implemented, and their elastic performance parameters are predicted using the homogenization theory based on thermal stress, exploring the impact of RVE parameters on composite material performance. Subsequently, a finite element model of the CFRP car door is constructed based on the principle of equal stiffness, and a parameter transfer across microscale, mesoscale, and macroscale levels is achieved through Python programming. Finally, the particle generation and updating strategies in the Multi-Objective Particle Swarm Optimization (MOPSO) algorithm are improved, enabling the algorithm to directly solve multi-constraint and multi-objective optimization problems that include various composite material layup process constraints. Case study results demonstrate that under layup process constraints and car door stiffness requirements, plain weave, twill weave, and satin weave composite car doors achieve weight reductions of 15.85%, 14.54%, and 15.35%, respectively, compared to traditional metal doors, fulfilling the requirements for a lightweight design. This also provides guidance for the lightweight design of other vehicle body components.

Influence of fabric structures and temperature on the mechanical properties of quartz braids

Herein, quartz fiber braids with different structures (plain, twill, satin, broken twill) were woven to explore the influence of structures on the performance of fabrics. The influences of high temperature and structure on the mechanical properties of quartz fiber braids were investigated in detail. As the temperature increased to 1000°C, the mechanical properties of quartz fiber decreased by around 90% due to its crystallization. Among the different fabric structures tested, quartz fabrics with satin and broken twill structures possessed good tensile properties (400 MPa) at room temperature. However, as the temperature and duration of heat treatment increased, the tensile performance of broken twill weave fabrics decreased by 50 MPa. In summary, the study demonstrates that quartz fibers and their fabrics possess significant potential for applications in high temperature environments, with the ability to withstand elevated temperatures for short durations, thereby enhancing their performance and extending their range of applications.

Study on the impact of weaving patterns of vibrating screen mesh on the performance of fluid flow through moving screens

Screen is a core component of the linear vibrating screen and is closely linked to the efficiency of drilling fluid recovery. This study aims to analyze the impact of different vibration frequencies and amplitudes on the fluid flow performance through screen with different weaving patterns. Analysis reveals that when the motion direction of the screen is opposite to the flow direction of the drilling fluid, higher screen velocity corresponds to increased drilling fluid permeation velocity and reduced pressure. Plain weave screen exhibits the highest fluid permeation velocity, maintaining the lowest negative pressure. Vortices concentrate mainly around the screen wires at the back of the screen, with herringbone twill weave screen showing improved vortex distribution compared to plain weave screen. Increasing vibration amplitude and frequency enhances screen motion, amplifying variations in pressure and pressure drop coefficients during the motion cycle. With increased amplitude and frequency, the average pressure drop coefficient of the screen rises, making it more challenging for drilling fluid to permeate through the screen. Herringbone twill weave screen demonstrate lower pressure drop coefficients than plain and twill weave screen, indicating superior drilling fluid permeation performance. Field experiments confirm that, compared to plain weave screen, drilling fluid filtered through herringbone twill weave screen results in significantly lower water content in cuttings. The findings of this study provide theoretical insights for the analysis and design of linear vibrating screen meshes in drilling fluid applications.

Investigating Stacking Configuration and Fiber Hybridization Effects on Low-Velocity Impact Behavior in Twill Woven Carbon/Flax Composites

In this study, experimental research has been done to investigate and analyze the effects of fiber hybridization and stacking configurations on the impact performance of carbon/flax bio-hybrid composite laminates. A total of four composite laminates with pure carbon, sandwich, symmetric, and asymmetric stacking configurations were manufactured and investigated in terms of low-velocity impact test with varying energies between 30J and 75J. Both qualitative and quantitative analysis were performed to analyze the damage and failure patterns in the composite layups and were compared with the pure carbon-based layup to identify the effects stacking configuration. The experimental findings showed the symmetric layup having a consistent distribution of flax fiber layers, showed the most enhanced performance as compared to the carbon-based layup Moreover, damage and failure modes differed among layups and increased with varying impact energies. Furthermore, to enable the thorough comparison of the configurations, Composite Performance Index (CPI) was developed, which suggests that bio-hybrid configurations when designed optimally with a suitable number of evenly distributed flax layers, can equal or exceed the performance of a pure carbon fiber configuration.

Tensile mechanical properties and damage analysis of layered woven GFRP composite bolts

Composite bolts have become one of the research focuses in screw threads joints due to their lightweight, high-strength, and wave transmission properties. We elucidate the differences in tensile properties, damage processes, and tensile failure forms between two types of layered woven GFRP composite bolts through tests and numerical simulations. It was found that the tensile strength of layered plain woven bolts is 40% higher than layered twill woven bolts. The failure forms of both types of bolts are related to their layered woven structure. The fracture surface of plain bolts is planar, while the fracture surface of twill bolts is apex shaped. Subsequently, a refined thread stretching model was established to study the effect of loading speed on the tensile property of screw threads. It was found that the tensile strength of plain woven screw threads and twill woven screw threads at a loading speed of 1 mm/min was 11% and 6% higher than that at 3 mm/min, respectively. The results show that the bolts and screw threads with layered plain woven have stronger tensile strength than those with layered twill woven, and a decrease in loading speed within a certain range can improve the tensile strength of the screw threads.

Application of Profilometric Measurements in an Assessment of Woven Fabrics Surface Geometry

ABSTRACT The surface roughness of the textile materials is one of the crucial features influencing the appearance and functionality of fabrics and products made of them. The surface roughness of textile materials can be measured using the contact or non-contact methods. In the presented work, the non-contact method using the MicroSpy® Profile profilometer was applied to assess the quality of surface of the cotton woven fabrics of plain and 3/1S twill weave. Determination of surface geometry parameters and functions was done using the Mark III software according to the DIN EN ISO 4287 standard. Results showed that the twill woven fabric is characterized by greater roughness than the plain woven fabric. The profiles created along the warp and weft have different shapes dependably on fabric weave. The autocorrelation function reflects the weave pattern of the woven fabrics. Performed investigations confirmed that the non-contact method of measurement of fabric surface geometry by means of the profilometer provides very detailed and complex data about the fabrics’ surface quality.

Експериментальне визначення зміни капілярної утримної здатності сітчастих розділювачів фаз

The subject of this study is the process of loss of capillary holding capacity (CHC) as a result of a violation of the balance of external and internal forces on the phase interface (PI) "liquid - gas" of the capillary in the cell of the mesh phase separator (MPS) of the capillary means for ensuring the integrity of the fuel (CMEIF) with a long service life in chemically aggressive fuel components (FP): nitrogen tetroxide (NT) and asymmetric dimethylhydrazine (NDMH). The goal is to improve the selection of design parameters of the CMEIF through the refinement of traditional approaches to the calculation of the CHC MPS depending on the term of their operation. Task: to determine the rate of corrosion of the main structural material of the MPS - steel nets of the twill weave type, and its effect on the structural and geometric characteristics of the nets; to perform an experimental determination of the change in the MPS CHC; to improve the mathematical model for determining the MPS CHC, considering the term of their operation as part of the fuel system of space flight vehicles (SFV). The methods used are as follows: to determine the rate of corrosion - metallographic studies and measurement of the geometric dimensions of mesh samples; to determine the change in CHC - the bubble method. The following results were obtained. The coefficient of the maximum corrosion rate was determined. A new, refined dependence of the average value of Bo cr on the temperature of the FP was obtained. Linear regressions of changes in the approximated values of CHC MPS depending on the duration of their operation were obtained. An increase in the average arithmetic value of the wetting contact angle θ in the NDMG over 31 years of MPS operation was determined. An improved mathematical model for determining the CHC of MPS was obtained, considering the period of their operation in JSC and NDMH. Conclusions. The scientific novelty of the obtained results is as follows: for the first time, comprehensive studies were carried out to determine the rate of corrosion of the main structural material of MPS after a long period of their stay (from 14 to 31 years) in FP (NT and NDMG) and under their pairs, the results of which revealed regularities of flow corrosion processes in the liquid and gas phase, established corrosion rates and deduced coefficients, the application of which improves the engineering methods of calculating the main parameters of MPS; the physical model for calculating Bo kr received further development; the physical model for calculating the CHC has been improved, which makes it possible to calculate the value of the static CHC of the MPS with greater accuracy than it was before and to make the final design of the designed CMEIF more perfect and reliable.