Calculation and Experimental Technique for Determining the Damping Properties of Composite Materials

2022

KEM

Reinforced plastics are widely used in various fields of technology for a wide variety of structures. They provide high strength at low density, resistance to aggressive media, low material intensity of production, high manufacturability, the ability to regulate heat and electrical conductivity over a wide range, the ability to repair without the use of special equipment, they perform in a broad range of temperatures and stresses. Reinforced polymer composites with the use of fiberglass-based textile materials as reinforcement are the most used due to their availability, low cost and high strength properties. This scientific paper presents the results of specimen tests with a substrate of various types of steel, adhesive compositions as bonding material, and fiberglass as reinforcing material. The influence of the properties of the substrate and coating materials, and the ratio of their thicknesses on the theoretical strength of the composite element was investigated. The results obtained will make it possible to clarify the design schemes and dependencies in the design and repair of structural elements with reinforced polymer coatings.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Computational and Experimental Evaluation of the Tensile Strength of a Reinforced Polymer Coating with a Substrate

2022

KEM

“…To reduce the vibration loads of mechanical engineering products, various methods are used: improving the structural and kinematic schemes [2,6,7], replacing dynamic processes with static ones [8,9], using vibration damping coatings [10][11][12][13], etc.…”

Section: Introductionmentioning

confidence: 99%

“…One of the effective methods for reducing the effect of shock and vibration loads on the bearing capacity of mechanical structures is the use of structural elements made of composite materials [11,[14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Effect of Vibration on the Bearing Capacity of Composite Materials

2022

KEM

Polymer coatings are increasingly used in mechanical engineering. In particular, sheet composite elements are created on their basis. But the question of the influence of vibration loads on the bearing capacity of composite structures remains relevant. This work presents the results of an experimental study of the operation of composite structures when exposed to vibration loads. The choice of the parameters of the test bench is due to the frequencies of natural vibrations of the specimens under study. The frequencies were determined using generally accepted approximations. A test bench was developed for carrying out measurements. A vibration-absorbing foundation was used, a support frame with the element was attached on elastic suspensions to the outer frame. A scheme for cutting sheet elements for tensile testing was developed. Nine sheet elements made of reinforced polymer material were tested. The influence of the number of loading cycles on the material ultimate strength is investigated. It was established that the presence of a reinforced polymer coating leads to a decrease in the vibration amplitude when approaching the resonance frequencies. This is due to the internal deformation of the polymer coating. After removing the vibration load, no cracks were found on the specimens.

Assessment of the adhesion strength of composite curved elements

IOP Conf. Ser.: Mater. Sci. Eng.

2021

Modern composites have good strength properties. But insufficient adhesive strength often leads to the delamination of a coating. The Poisson’s ratio, modulus of elasticity, and thermal coefficient of linear expansion are of particular importance among the characteristics of materials that determine different properties of the coating and metal. The ratio of metal and coating thicknesses is also important. The work suggests that the temperature deformations associated with the polymerization of a coating influence the process of delamination of the reinforced polymer coating. Evaluation of the potential of the proposed calculated dependencies was carried out according to the results of experiments. A polymer coating consisting of «Sprut-Plus» adhesive composition and a filler (T-11-GVS-9 glass fabric) was applied to a surface of St.3 steel. For experimental studies, the reinforced polymer coating was kept in water and machine oil for 100 days. The thickness of the coating was taken to be 10 mm, and the thickness of the metal - from 3 to 6 mm. Calculated and experimental dependences of radial stresses on the relative thickness of the polymer coating are obtained. An increase in radial stresses at the interface between the layers of the metal and the reinforced polymer coating after holding the composite material in water has been established; it does not exceed 10%. Analysis of the results showed that the destruction of the adhesive metal-polymer joint is more likely than that of the polymer-polymer adhesive joint. In addition, the radial stresses are at their maximum at the interfaces. Prospects for further research in this direction are associated with express methods of repairing metal structures of complex configuration. It is necessary to increase the efficiency and reliability of calculations of curved elements consisting of metal with a reinforced polymer coating. This can be achieved by a combination of experimental and theoretical research.