Fiberglass Samples Research Articles

Using Laser Point Scanning Thermography for Quality Monitoring of Products Made of Composite Materials

Introduction. Control of the presence of subsurface defects in products from composite materials is necessary for verification of products after release from production and in the process of operation. Aim of the Study. The purpose of the presented work is to estimate the parameters of subsurface defects using local laser thermography, suitable for quality control of both small objects and suspicious areas of large objects with curved surfaces. Materials and Methods. The laboratory setup on which this work was carried out includes a robotic arm, a COX CG640 thermal imager and a 3 W laser. The method was tested on a fiberglass sample with introduced delamination defect simulations located at different depths below the surface. By means of computer modeling rational parameters of thermographic control were selected, providing reliable detection of the defect at a depth of up to 3 mm under the surface of the composite sample. Results. Numerical modeling of surface temperature field induced by moving focused laser beam was carried out using COMSOL software package. It showed that laser beam with 3 W power moving at 5 mm/s provided the thermal contrast sufficient to detect the defects at the depth up to 3 mm. The obtained experimental data are in satisfactory agreement with numerical modeling both qualitatively and quantitatively. Experimental data were used to construct a regression model for determining defect depth based on the maximal thermal contrast and the time interval between heating and the contrast maximum. Discussion and Conclusion. The results obtained in this work allow us to propose a technique for detecting defects in fiberglass plastics and estimating their depth. The coefficient of determination for the obtained regression model was found to be equal to 0.95, and the mean square error of the metric was no more than 0.016 mm2. The use of a robotic arm to scan objects will make it possible to investigate objects with complex curved surfaces.

Effects of external influencing factors on the microstructure and physico-mechanical characteristics of glass-reinforced polymer composite material based on polyimide binder

The article presents the results of experimental studies of the effects of external influencing factors (natural exposure in climatic zones, such as a temperate climate and a climate with an industrial atmosphere, during accelerated climatic tests in a thermal humidity chamber, during thermal aging, exposure in technical environments) on the microstructure and physical and mechanical characteristics of a glass-reinforced polymer composite material grade VPS-72 based on polyimide binder grade VS-51. The state of the surface of fiberglass samples after exposure was studied for one year.

Study on recycling wind turbine blades into reinforcement for filaments used in 3D printing

Heavy applications like power production through wind energy requires light weight but strong material like composites with customizable properties. When the lifetime of the wind turbine blades ends, the parts are dumped in landfills and results in environmental pollution. Natural fibers are great option for improving the biodegradability of the conventional plastic which also ends up in the landfills. Fused Filament Fabrication (FFF) is chosen to combine the benefits of both materials, as the technique is highly customizable and sustainable. Wind turbine blade wastes are recycled using mechanical grinding. Recycled Fiber glass (FG) material is tested for contamination with Fourier Transform Infrared Spectroscopy (FTIR). Wood fiber (WF) is also added in order to improve biodegradability of the materials. Filaments are produced using a single screw extruder with various combinations of 9 wt% fiber content and recycled pellets. Tensile test shows comparable performance of reinforced filaments with recycled Polypropylene (PP) filaments. 6% WF + 3% FG sample withstood up to 380 MPa Young’s modulus.

Mathematical Models of Inelastic Behavior of Flat Fiberglass Samples under Three-Point Bending

Mathematical Models of Inelastic Behavior of Flat Fiberglass Samples under Three-Point Bending

Experimental Investigation on the Fatigue Behavior on Honeycomb Sandwich Composite Panels

This paper aims to study the dynamic behaviors of particular sandwich panels manufactured using three specifications of aluminum honeycomb core with fiberglass or aluminum face-sheet materials. Three groups of panels were designed and manufactured, each including three different sorts of samples, all fabricated with the same thickness. A cantilever fatigue test was conducted on specimens, and the results were collected and presented in curves to detect the factors that affect the panel's endurance. The finding showed that the specimens with aluminum skin had more probability of face-sheet/core delamination. Samples of fiberglass covers showed face-sheets cracks or cores cracks more than delamination failure, while samples of epoxy-filled cores experienced the specimen’s global crack. Generally, specimens with aluminum covers and epoxy-filled cores resisted fatigue load more than other specimens. The larger honeycomb cell-size specimens showed more probability to face-sheet/core delamination failures than samples with smaller cell-size cores.

Mechanical Investigation of S-Glass/Carbon Fibers Reinforced Epoxy Polymer Matrix Composites

Fiber-based hybrid composite materials are used for variety of industrial purposes going on from automotive to many engineering fields such as structural, aerospace because of unique properties compared over conventional materials. Fiber based hybrid composites have greatly long-drawn-out o varying applications in today's automotive industry reason behind is due their light weight, high strength, stiffness and ease of repair. This work aims to create a novel type of hybrid composite made by reinforcing S-glass (satin type) & carbon (twill form) in an epoxy matrix. Pure and hybrid composites are made by manual laying with 0° orientation of each fiber layer and the action has been tested with different combinations of each layer of S-glass and carbon and finally with a hybrid subjected to different mechanical stresses. The fiber matrix for the hybrid is created in a 50:50 ratio. Pure samples of fiberglass and carbon fiber-epoxy composites were compared to hybrid samples. The results showed that the hybrid samples outperformed the pure forms of the composite in mechanical tests, due to the presence of carbon fiber on the end faces of the sample, which offers the hybrid form's superior mechanical properties.

Ультразвуковой контроль качества пропитки стеклопластиковых элементов конструкций летательных аппаратов органическими смолами

Fiberglass products after molding and heat treatment are impregnated with the organosilicon resin to increase heat resistance followed by polymerization by heat treatment. A method for non-destructive quality control of the composite-profile products impregnation made of fiberglass plastics with the organosilicon resin is proposed. Results of experimental work are presented on the study of alteration in the longitudinal ultrasonic waves speed in structural elements of the aerial vehicles made of fiberglass before and after impregnation with the organosilicon resin, i.e. the MFSS-8 product. Besides, alteration in the longitudinal ultrasonic waves speed in the fiberglass samples violating the impregnation technology are demonstrated.

EVALUATION OF THE THERMAL AND MOISTURE AGING INFLUENCE IN AGGRESSIVE ENVIRONMENTS ON THE CHANGE IN THE OF THE MECHANICAL BEHAVIOR OF FIBERGLASS BY A SHORT BEAM BENDING TESTS BASED ON ACOUSTIC EMISSION TECHNIQUE

The work is aimed at experimental research and description of the mechanical behavior and degradation of the fibrous structural composite material strength properties during thermal and moisture aging in aggressive (operational) environments of different duration and temperatures. The object of the study was STEF structural fiberglass. STEF is a laminated fiberglass reinforced plastic obtained by hot pressing of glass fabric impregnated with a thermosetting binder based on combined epoxy and phenol-formaldehyde resins. After preliminary aging under various temperature-time conditions, fiberglass samples were tested at normal temperature for interlayer shear. To study the defect initiation and propagation during the deformation of fiberglass after preliminary aging under various temperature-time conditions and environments, the acoustic emission method is used in this work, which makes it possible to study the deformation stage structure and track the processes associated with the formation of defects in the structure of the fibrous composite. Influence of various media, such as industrial water, sea water and machine oil, at different durations (15, 30, 45 days) and temperatures (22°, 60° и 90 °С) on the processes of composite destruction and the implementation of various mechanisms damage accumulation during quasi-static interlaminar shear tests were obtained and analyzed. The paper presents the test results obtained by the acoustic emission signals processing. The data illustrating the stages of damage accumulation are presented and described, and the main mechanisms of damage to the composite structure under loading are analyzed. The results of a study of the microstructure of samples obtained using a stereomicroscope before and after thermal and moisture aging in aggressive media are described.

Study of Electromagnetic Shielding Properties of Composites Based on Glass Fiber Metallized with Metal Films

The article presents the results of an investigation of composites based on manufactured samples of fiberglass metalized with a submicron film made of brass, neusilber and non-magnetic SS304 stainless steel. It was found that, due to their characteristics, the samples of metallized fiberglass are an effective electromagnetic wave-absorbing filler for various building and construction materials; The developed metallized fiberglass samples are also useful for the creation of EMI-shielding building materials for protection from microwave radiation. With an increase in the proportion of metalized glass fiber, the electromagnetic shielding of the studied composites increases systematically. It is determined that at a concentration of 5 wt.% brass-metallized glass fiber, a test composite material with a thickness of 250 mm is able to shield up to 13.7 and 21.2 dB in the 4G and 5G ranges of cellular communication electromagnetic waves, respectively.

Исследование развивающихся повреждений при изгибном нагружении полимерных композиционных материалов и их идентификация методом акустической эмиссии

Polymer composite materials (PCM) reinforced with glass fibers are very important in many industries due to their unique properties (high chemical resistance and specific strength) with the economic efficiency of use. At the same time, the application of glass fabrics as reinforcing elements ensures high manufacturability. However, unlike crystalline materials, polymer composite materials are subject to the complex process of destruction, which requires the application of non-destructive control methods to get information about the nature of the resulting damage and the kinetics of their accumulation. The paper studies the deteriorations formed in the fiberglass samples molded using T-11-GVS-9 glass fabric and DION 9300 FR binder within static bending deformation accompanied by the acoustic emission (AE) method. In this work, the authors solved the problem of identifying the nature of damages in fiberglass using the Fourier spectra of the recorded AE signals. The authors used the clustering method to estimate their formation and development kinetics. Clustering was performed based on the Kohonen self-organizing map (SOM) algorithm using the values of peak frequencies of the Fourier spectra calculated for the recorded AE signals under static bending deformation of a fiberglass sample up to failure. To ensure the separability of the resulting damages according to the AE parameters, the authors used the loading rate that was ten times lower than that calculated according to the state standard. The study established that the application of frequency representation of AE signals recorded during the fiberglass destruction is effective when solving the task of identifying the nature of the resulting damages. As a result of the study, the authors found that the process of delamination formation during the bending of multilayer laminated plastics acts as a critical mechanism of destruction leading to a significant loss of the polymer composite strength properties.

CORRELATION DEPENDENCES OF THE BENDING STRENGTH OF POLYMER COMPOSITE MATERIALS MODIFIED IN A MICROWAVE ELECTROMAGNETIC FIELD ON THE MOISTURE CONTENT DURING EXPOSURE IN FULL-SCALE CONDITIONS

Experimental studies of the influence of external climatic factors, taking into account exposure, on the change in the bending strength of control and microwave – treated carbon and fiberglass samples in the cured state were performed. An increase in the limit stresses of three – point bending of experimental carbon fiber samples compared to the control ones was found by 7…12 %, and fiberglassby 4…7 %. It is shown that with an increase in exposure to 14 months, the strength of control samples of carbon and fiberglass decreases by an average of 10 %. At the same time, the strength of the prototypes is reduced only by 4.4 %. With an increase in the moisture content of both control and experimental samples, a decrease in their strength is observed. In this case, the linear correlation is average (from– 0.44 to – 0.615). It is established that for experimental samples, the influence of the amount of absorbed moisture on the strength is manifested to a much lesser extent. For carbon fiber, the reduction is 16.6 %, for fiberglass – 12 %.

Change of Rigidity of PCM Modified in an Ultrahigh Frequencies Electromagnetic Field under the Action of External Factors

Experimental studies of bending deformation of carbon - and fiberglass samples after 8-month exposure in full-scale conditions were performed and the modulus of transverse elasticity was determined. It was found that the influence of the external environment on fiberglass samples is more significant. For carbon fiber, there was an average decrease of 7.1%, and for fiberglass-by 14%. Modification of samples in ultrahigh frequencies (UHF) electromagnetic field reduces the negative influence of the environment: the values of the transverse elastic modulus of carbon fiber and fiberglass samples are reduced by 5% and 11%, respectively. It is shown that the UHF electromagnetic field in rational modes can increase the modulus of transverse elasticity of carbon fiber by (27-30)%, fiberglass – by (20.8-25.6)% with a significant increase in the uniformity of this parameter. Experimental studies of the bending deformation of carbon-and fiberglass specimens after 8-month exposure in natural conditions have been carried out, and the shear elastic modulus has been determined. It has been established that the influence of the external environment on fiberglass samples is more significant. For carbon fiber reinforced plastic, a decrease was noted on average by 7.1%, for fiberglass - by 14%. Modification of samples in a microwave electromagnetic field helps to reduce the negative influence of the external environment: the values ​​of the shear modulus of the prototypes of carbon fiber reinforced plastic and fiberglass are reduced by 5% and 11%, respectively. It is shown that the microwave electromagnetic field in rational modes allows increasing the transverse elastic modulus of carbon fiber reinforced plastic by (27-30)%, fiberglass - by (20.8-25.6)% with a significant increase in the uniformity of this parameter.

Tungsten Carbide Nanopowder Influence Study on Tensile Strength of GRP Specimens Made of Lavesan Glass Fabric and EPR 320 Momentive Epoxy

This paper presents the test results of fiberglass samples consisting of glass fiber Lavesan (Italy) and a binder - EPR 320 epoxy resin modified with tungsten carbide (WC) nanopowder. The positive effect of nanopowder on the tensile strength and the increase in tensile strength of more than 1.5 … 2.5 times with the addition of additives in the mass concentration of 1 … 4% to the mass of the resin are shown.

Investigation of the effect of tungsten carbide nanopowder additives on the strength properties of fiberglass, based on LAVESAN glass fabric and EPR 320 epoxy resin

The paper presents the results of tests for modulus of elasticity and tensile strength of fiberglass samples consisting of glass fiber Lavesan (Italy) and epoxy resin binder EPR 320 with hardener EPH 162, modified with WC tungsten carbide nanopowder, obtained from carbide waste. The positive effect of WC nanopowder on tensile strength and modulus of elasticity is shown. With the addition of nanoadditives in the mass concentration of 1 … 4% of the resin mass, the increase in tensile strength was more than 1.5 … 2.5 times, with no significant change in material elasticity.

Research of the damage accumulation and destruction processes of perforated composite plates

The main purpose of the research is to comprehensively study the regularities of deformation processes damage accumulation and destruction of modern composite materials in stress concentration zones. The object of research is fiberglass samples with four round holes. As a result of experimental studies loading diagrams were obtained for samples with different length of the working area. The paper presents graphs of the load dependence on the longitudinal deformation. According to the data obtained it can be noted that the longer the length of the working area of the sample the earlier the failure occurs. The deformation was obtained using the optional Vic-3D “virtual extensometer” non-contact optical video system. In the experiments process curves of longitudinal deformations were plotted. From these data it is possible to estimate the maximum longitudinal deformations occurring near the hole. Also in the work numerical modeling of the process of deformation and destruction of perforated plates was carried out in the software engineering complex Ansys. The calculated data obtained confirm the experimental results of the research.

Исследование микротвердости матрицы стеклопластиков по толщине образцов, отформованных различными способами

On specimens made of fiberglass with a thickness of 2.2, 5.4 and 11 mm, obtained by autoclave molding, studies were carried out to assess the regularities of changes in the values of the microhardness of the matrix along the thickness of the specimens. The carried out studies have established that the value of the microhardness of fiberglass samples along their thickness from the front surface of the sample to the reverse surface changes according to a parabolic law with maximum values in the core, and that with an increase in the thickness of the sample, the value of the microhardness of the matrix also increases. An assessment of the stability of the values of the microhardness of the matrix in different places of a fiberglass sheet with a length of 3 m, as well as sheets of the same thickness, molded individually and in a five-layer package, is given. It was found that the methods of forming sheets of fiberglass within the framework of the experiment did not affect the values of the microhardness of the matrix.

ИДЕНТИФИКАЦИЯ ИСТОЧНИКОВ АКУСТИЧЕСКОЙ ЭМИССИИ В ПОЛИМЕРНОМ КОМПОЗИЦИОННОМ МАТЕРИАЛЕ В УСЛОВИЯХ ЦИКЛИЧЕСКОГО РАСТЯЖЕНИЯ

The structure of polymer composite materials (PCM) provides high mechanical properties but, at the same time, is highly sensitive to the formation of internal defects. Therefore, when designing, manufacturing products, and assessing their reliability in service, much attention is paid to the methods of non-destructive testing, among which the method of acoustic emission (AE) has proven itself to study structural changes in material under external influence. The paper deals with the identification of typical damages in fiberglass samples made of T11-GVS9 glass fiber cloth and DION 9300 FR binder and tested under cyclic tension using the AE method. In the work, the authors solved the problem of selecting the AE informative parameters and used a clustering method to identify the nature and the formation kinetics of the AE sources. The authors performed clustering using the Kohonen self-organization map (SOM) with the Fourier spectra calculated for the AE signals recorded during cyclic tests. Based on the peak frequencies analysis of the produced clusters, the researchers determined their nature and calculated the periods of critical accumulation. When characterizing the AE sources, the authors used the peak frequencies analysis of the wavelet spectra performed for different levels of decomposition. The authors determined the damage accumulation stages of samples during testing based on own research and research by other authors’ results. The study established that registration of AE signals identified as adhesion failure can be used to identify the onset of the material destruction and characterized the local formation of micro-damages in the matrix and fracture of fibers can be used to predict the destruction of PCM.

Reinforced materials for radio engineering modified with carbon nanotubes

The paper presents the results of studies of the influence of carbon nanotubes (CNTs) on radio engineering (reflection coefficient), electrophysical (surface electrical resistance), thermomechanical and strength properties of fiberglass based on epoxy binder. The compositions and technological parameters of the manufacture of fiberglass samples are proposed. The change in the electrophysical and radio technical characteristics of fiberglass samples with increasing concentrations of CNTs is shown.

Calculation and experimental research of mechanical characteristics of composite materials

Research and use of composite materials for scientific experiments, engineering activities, as well as industrial purposes has expanded significantly, since the development of technologies for the production of composite materials has made it possible to create and research new types of their physical and chemical properties, reinforcement schemes and fiber lengths, etc. This paper presents the results of computational and experimental studies of the elastic and damping properties of a composite material. The studies were carried out on samples of laminated fiberglass, the dimensions of which are 160 × 16 × 4 mm, cut in three directions, in the direction of the warp, weft and at an angle of 45 degrees, five samples were cut in each direction. To study the mechanical properties of the obtained cantilever samples, the electrodynamic shaker was used. The study of damping properties was carried out by the Oberst method based on the experiment of the frequency response characteristics of cantilever samples. The determination of Young's moduli of laminated fiberglass samples was carried out by the dynamic method, and also the theory of vibrations of continuous systems was used. The experimental data obtained are compared with the results of numerical solutions performed by the finite element method (FEM). Geometric and finite element models were constructed and the natural frequencies and vibration modes of the samples were determined. Frequency and phase response characteristics are given. To reduce the error according to the results of the experiment, statistical processing was carried out. The values of the mathematical expectation and the standard deviation of the mechanical loss coefficient are calculated. The estimation of the measurement error was made on the assumption of the normal distribution of the error.

Deformation and failure of polymer composite materials under preliminary cyclic and low-velocity impacts

The paper presents the results of an experimental study of the behavior of samples of polymer composite materials under complex mechanical loads. A technique has been developed for the experimental assessment of changes in the residual strength and stiffness properties of layered composites for various parameters of preliminary cyclic and low-velocity impacts. Corresponding experimental data were obtained for fiberglass samples with various layouts. In accordance with the considered method for analysis of the obtained data, a fatigue sensitivity diagram has been introduced, which contains the characteristic sections of the change in the residual static strength and its threshold values, and is used to study the processes of damage accumulation and fracture of composites at various loading parameters. The results of a study of the effect of preliminary shock tension on the processes of deformation and fracture of fiberglass samples are presented. As a result of the analysis of the influence of a preliminary three-point impact bending on the mechanical characteristics of fiberglass specimens during tension, a threshold value of impact sensitivity was noted, until which a decrease in the residual strength of fiberglass was not observed. A change in the mechanisms of destruction of the samples under static tension with an increase in the energy of preliminary impact is noted.