Strength Of Composite Materials Research Articles

Апробация методики сдвиговых испытаний геосинтетического композита «КАПЛАМ»

Purpose: to investigate the effect of different test methods on the shear properties of geomaterials and to determine the test method that provides the most consistent shear strength results. Demonstrate the need to include shear test methods for geosynthetic materials in state standards. Determination of interaction properties of geosynthetic composite “KAPLAM” with soil. Methods: a 300×375 mm shear machine was used to perform shear tests at the soil-geomaterial interface with normal loads ranging from 100 to 500 kPa. These tests were performed according to the American standard ASTM D5321. Results: the relationships obtained from the tests allow the identification of the test methodology that produces the most significant shear strength results and an understanding of the fundamental mechanisms underlying the observed shear strength. The need for further investigation of this methodology on other geosynthetics is identified. Practical relevance: overall, these results have important implications for the design of railway embankment slopes, ISDS lining systems and shear strength testing. The tests provide better modelling of field conditions and a more accurate representation of the shear strength of composite materials.

Multi-objective optimization of micro crystalline cellulose and montmorillonite filled poly lactic acid bio–composite and its characterizations

In this research study, the synthesis of poly lactic acid (PLA) based bio composite material factors contributions were investigated through the Taguchi-based grey relational analysis (GRA) technique. Effects of micro crystalline cellulose (MCC) and montmorillonite (MTT) nano clay filler, sorbitol (S) plasticizer, and temperature (T) operating factor on the PLA matrix through melt-mixing preparation method. The tensile strength (TS), Young modulus (YM), flexural strength (FS), flexural modulus (FM), hardness, impact strength (IS), water absorption (WA), and density properties of bio composite material were investigated for each experimental setup (orthogonal array, L16). Additionally, neat PLA and optimal sample structural, thermal, and morphological properties were examined through Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (X-RD), thermal gravimetry analysis/differential thermal gravimetry (TGA/DTG), and DSC and SEM analyses. The obtained result for optimal mechanical and physical properties of MCC/MTT/S/PLA bio composite was MCC at level 3 (6%), MTT at level 4 (9%), S at level 2 (10%), and T at level 4 (175 °C). Analysis of variance (ANOVA) shows that MTT has the greatest significant effect on mechanical and physical properties of MCC/MTT/S/PLA bio composite followed by MCC, T, and S. The confirmation test indicates that the improvement of weighted grey relational grade (GRG) from 0.7896 to 0.846 and the FTIR, XRD, thermal gravimetry/differential scanning calorimetry (TG/DSC), and scanning electron microscopy (SEM) results indicates that the good interaction between PLA and fillers, improvement of thermal and morphological properties of optimal (6MCC/9MTT/10S/175 °C) bio composite samples. Therefore, the multi-response characteristics of MCC/MTT/S/PLA bio composite can be highly improved by this technique.

Methodology for optimizing the radio absorption capacity and mechanical strength of composite structural materials

The possibility of impregnating high-strength fabrics under pressure with a modified binder is considered. The development of high-temperature composites that have not only high strength, but also microwave absorption properties is inextricably linked with new products being developed and the imposition of more stringent tactical and technical requirements on them. For the successful introduction of these composites into the field of mechanical engineering, one of the necessary conditions is the assessment of their stress-strain state at the design stage. This method allows producing the fabric for aircraft details with high strength. The purpose of the study is to evaluate the absorption of microwave waves and study the physical and mechanical characteristics of composites obtained by vacuum infusion.

Soybean protein “mechanically interlocked” bonding of polysaccharide and MXene to improve the strength and toughness of biomass adhesive

Simultaneously improving the strength and toughness of soybean protein adhesives is a huge challenge. The multi-scale enhancement strategy proposed in this study introduced MXene nanosheets and oxidized sodium alginate (OSA) to improve mechanical properties. The polymer network framework with high crosslink density dissipates energy by restricting the slip of the SPI molecular chains, and MXene act as stress dispersers in the polymer network in order to solve the challenge of the strength-toughness balance. The prepared biomass-based adhesives with high adhesion (dry/wet shear strength 1.93 MPa/1.33 MPa), high toughness (adhesion work 810.9 mJ), high thermal stability, high residual rate (92.53 %), low moisture absorption rate (11.18 %), and long storage time (12 d). Additionally, the application of SOM-5 adhesive reduces the burden of petrochemical resource extraction for adhesive production and contributes to the sustainable development of the wood industry. Most importantly, it presents an adoptable strategy for resolving the tension between strength and toughness of composite materials.

Development of polyurethane urea（PUU）– Waste rubber particles (WRP) composite materials for active ice-breaking of groove-filled asphalt pavement

The grooved-filled asphalt pavement has certain advantages in terms of pavement ice-breaking and anti-skid. However, the performances of the filling material limit its development. In this study, a polyurethane urea (PUU) - waste rubber particles (WRP) composite filling material was prepared by using a polyurethane (PU) and adding polyurea (PUa) with a similar microstructure as the cementing material, and adding WRP as the elastic reinforcing phase. The proportions of nine PUU-WRP composite materials were designed by changing the particle size and content of WRP, and then the filled composite materials were evaluated in terms of physical and mechanical properties, ice adhesion properties, interface bonding properties and aging resistance. The test results showed that the shore hardness, tensile strength, compression permanent deformation, and contact angle of PUU-WRP composite decreased as content of the WRP increased. Except the ice adhesion force results were the opposite. On the other hand, increased the WRP size resulted in increase in PUU-WRP composite’s shore hardness, compression permanent deformation, and ice adhesion force, while the tensile strength and contact angle were the opposite. The surface of the PUU-WRP composite material was hydrophobic, and the maximum contact angle was 102.3°. The reduction of WRP particle size and dosage was beneficial for reducing the ice adhesion force on the surface of PUU-WRP composite materials. The maximum interfacial shear and tensile strength of PUU-WRP composite material were 1.082 MPa and 0.244 MPa, respectively. After 42 days of UV aging, the maximum attenuation rate did not exceed 30 %. After the immersion test, the tensile strength attenuation of PUU-WRP composite material was basically controlled within 10 %. Finally, based on the fuzzy comprehensive evaluation (FCE) method, it was recommended to use WRP with a particle size of 0.6 mm and a dosage of 30 wt%-40 wt%.

The adjustable adhesion strength of multiferroic composite materials via electromagnetic loadings and shape effect of punch

Tunable and reversible dry adhesion possess great potential in a wide range of applications including transfer printing, climbing robots, wearable devices/electronics, and gripping in pick-and-place operations. Multiferroic composite materials offer new routines and approaches to achieve tunable adhesion due to their multi-field coupling effects. In this paper, the classical Johnson-Kendall-Roberts (JKR) adhesion model is extended to investigate the adhesive contact problem of a multiferroic composite half-space indented by an axisymmetric power-law shaped punch, whose shape index is denoted by n. The JKR-n adhesion models under the action of the power-law shaped punches with four different electromagnetic properties are set up by means of the total energy method. The explicit analytical expressions relating the indentation load and indentation depth to the contact radius are obtained, which can include the existing results in open literature as special cases. The generalized Tabor parameter and the interfacial adhesion strength applicable to multiferroic composite materials are defined. The effects of the shape index and the electromagnetic loadings on adhesion behaviors are revealed. It is found that both of them have prominent influences on the relationships among the indentation load, indentation depth and contact radius, the contact radius and indentation depth at self-equilibrium state, and the critical contact radius and indentation depth at pull-off moment. The pull-off force under the action of the conducting spherical punch subjected to non-zero electromagnetic loadings is dependent on material properties, which is different from the classical JKR result. More importantly, our analysis indicates that the pull-off force and the interfacial adhesion strength can be adjusted via altering the electromagnetic loadings and the shape index of the punch, which provides new approaches to achieve tunable adhesion.

Interfacial strength and its regulation in the carbon monofiber/epoxy binder system

The strength of polymer composite materials (CMs) is largely determined by the strength of interfacial interactions at a fiber/matrix interface. In this work the strength in a unit cell of CM carbon monofiber/cured epoxy matrix is investigated. The relevance of the work is due to direct measurements of strength at the monofiber/matrix interface, excluding defects of micro-droplet and technological errors associated with impregnation in a traditional assessment of polymer composite materials strength. Changes of surface morphology and energy characteristics of fibers in plasma chemical treatment process is shown. The study of fiber surface energy and formation of carbon monofiber/epoxy matrix interface of carbon fiber reinforced composite unit cell was carried out on the specially developed original device Drop-Sting test. Micro pull-out test was used to investigate the shear mechanical properties of interface and to determine the strength of carbon fiber reinforced composite unit cells before and after treatment in oxygen discharge plasma. It is shown that the increase in the strength of the monofiber/matrix interfacial interface after the treatment of carbon fiber in plasma occurs due to the increase in the surface energy and wettability of monofibers.

Effects of Ionizing Radiation on the Shear Bond Strength of Composite Materials to Dentin

Effects of Ionizing Radiation on the Shear Bond Strength of Composite Materials to Dentin

Vine copulas for accelerated prediction of composite strength variability

Composite materials are essential for many advanced engineering applications, but numerical quantification of strength variability can be computationally expensive. This paper proposes a novel methodology that drastically reduces the number of finite element simulations required to characterise composite material strength variability using the concept of vine copulas. This concept provides a flexible tool for the representation of high-dimensional dependencies. The methodology considers spatial scatter of three material variabilities: fibre volume fraction, fibre misalignment and fibre strength. First, the cross-correlation between stress, fibre volume fraction and fibre misalignment is fitted by a vine copula using results from a limited number of finite element simulations. Next, the vine copula is used to predict new conditional stress realisations when given realisations for the fibre volume fraction and fibre misalignment. This effectively replaces the finite element simulations with a vine copula that is much faster to evaluate. The methodology is verified by predicting the tensile failure load of a unidirectional composite coupon. Predictions are very similar to an exclusively finite element-based approach, while reducing the number of finite element simulations by a factor of 200.

Rate-dependent constitutive model and dynamic response of composite laminates for laser-induced delamination

Laser Bond Inspection is a new technology to quantitatively evaluate the interfacial strength in composite materials. Constructing an effective constitutive model, especially considering strain rate effects, is a critical factor for this technology. In this work, a reliable rate-dependent constitutive model of composite laminates for laser-induced delamination is established. Based on an orthotropic constitutive relationship, we introduce dynamic increase factors in different directions to adjust constitutive parameters. The dynamic increase factors are obtained through an adaptive matching model based on deep transfer learning. Then we effectively determine material rate-dependent constitutive relationship and ultimately achieve numerical simulation of laser-shocked composite laminates. Combining empirical testing with numerical simulation results, we investigate the dynamic response law of composite laminates under different laser parameters. The findings indicate that the rate-dependent constitutive model, effectively describes the mechanical behavior and dynamic response characteristics of composite laminates under laser shock. The dynamic response characteristics are determined by laser energy, pulse width, and spot size. Both laser energy and spot size affect the range of delamination, and pulse width mainly affects the depth of delamination.

Impact response of hybrid composites under varying environmental conditions: A comparative study

AbstractComposite materials are widely preferred in the aviation, automotive, construction and maritime industries due to their many superior properties. As a result of this widespread use, composite structures are inevitably subjected to various environmental conditions. Various environmental conditions may negatively affect the mechanical performance of the structure, and the structure may become unable to maintain its initial mechanical properties, especially in the face of critical loading, such as low‐velocity impacts. This research investigated the influence of various environmental conditions on the low‐velocity impact strength of composite materials. 12‐layer plate samples with epoxy matrix reinforced with woven glass fabric (GF), woven carbon fabric (CF), and hybrid fabric (HF), where the two fabrics are used together, were produced. Low‐velocity impact tests were conducted to these specimens at 20 and 40 J energy levels. Damages occurring in the material as a result of the low‐velocity impact test were interpreted using high‐resolution camera and optical microscope images. Force‐time and force‐ displacement curves were drawn and interpreted. It was concluded that as the impact energy values increased, the maximum force and displacement values also increased.Highlights The influence of various environmental conditions to which composite materials may be exposed on the dynamic response of the structure has been investigated. Various environmental conditions significantly affected the composite structure's impact behavior. While glass fabric (GF) composite samples were more affected by the seawater environment, carbon fabric (CF) composite samples were more affected by the HCl environment. Hybrid (HF) composite samples were affected by seawater and HCl in approximately equal amounts.

Research on compressive strength and thermal conductivity of lightweight phosphogypsum-based composite cementitious materials

Investigation of the mechanical and thermal properties of lightweight phosphogypsum-based cementitious materials can enhance the utilization rate of phosphogypsum-based composites and reduce building energy consumption. In this study, various amounts of hollow glass microspheres (HGMs) are incorporated into phosphogypsum-based composite cementitious materials to investigate their effects on mechanical and thermal insulation properties. Subsequently, comparisons are made between lightweight phosphogypsum-based composite cementitious materials produced by foaming and those with added HGMs. The research findings indicate that HGMs significantly mitigate the loss of compressive strength and notably reduce thermal conductivity, aligning with the development needs of lightweight and high-strength construction materials. Specifically, at a 20 % HGM dosage, the specimen exhibits a thermal conductivity of 0.2512 W·m−1·K−1, marking a 46.0 % decrease compared to specimens without HGMs. Additionally, the compressive strength measures at 25.45 MPa, reflecting a 36.4 % decline relative to specimens without HGMs. However, because of the uncontrolled pore structure and size in lightweight phosphogypsum-based composite cementitious materials produced by direct foaming, the decrease in compressive strength of foamed materials is greater than that of materials with added HGMs when the reduction in the coefficient of thermal conductivity is the same. Moreover, the compressive strength of phosphogypsum-based composite cementitious materials made with HGMs decreases more than that made with the addition of HGMs. This can be attributed to the uniform particle size of HGMs, contributing to a singular and complete pore structure within the phosphogypsum-based cementitious materials, thereby optimizing their performance.

Shear Strength of Organic Soils Modified by Mineral Materials

The paper presents the test results of the shear strength of composite materials, in which the base material was peat. The materials modifying the mineral part of the peat ground skeleton were fly ash and hydrated lime. The research was carried out for two groups. In group 1, the ratio of the mass of the peat skeleton to the mass of fly ash was equal to one, and in group 2, it was two. Hydrated lime content in the unit mass of the composite in group 1 was 2.4, 4.8 and 9.2%. In the second group, it was 1.6, 3.2 and 6.4%. The test results showed that the materials from group 1. (P/FA = 1) are characterised by the highest shear strength compared to materials from group 2. (P/FA = 2), regardless of the content of hydrated lime. It should also be noted that the shear strength of the materials of group 1 was significantly higher than the shear strength of the base material, which was peat.

Effect of carbon nanotubes on mechanical properties of aluminum matrix composites: A review

Abstract Carbon nanotubes (CNTs) are renowned for their low density, high elastic modulus, and exceptional electrical and thermal properties. The continuously developing applications of CNTs provide higher specific stiffness and strength for composite materials. The unique characteristics of CNTs make them ideal reinforcing particles in aluminum matrix composites (AMMCs), which generally exhibit excellent mechanical properties. CNTs/AMMCs are usually prepared using methods such as powder metallurgy, casting, spray deposition, and reactive melting. The uniform diffusion of CNTs in composites is crucial for enhancing the properties of CNTs/AMMCs. The properties of CNTs/AMMCs largely depend on the content, morphology, and distribution of reinforcements in the matrix and the interaction between reinforcements and the matrix. By adding an appropriate volume fraction of CNTs, the hardness, tensile strength, compressive strength, and electrical properties of CNTs/AMMCs were significantly improved. The effects of CNT content on the mechanical properties of CNTs/AMMCs, including the tensile strength, yield strength, compressive strength, stress–strain curve behavior, elastic modulus, hardness, creep, and fatigue behavior, were revealed. The design of microstructure, optimization of the preparation process, and optimization of composition can further improve the mechanical properties of CNTs/AMMCs and expand their application in engineering. The design concept of integrating material homogenization and functional unit structure through biomimetic design of novel gradient structures, layered structures, and multi-level twin structures further optimizes the composition and microstructure of CNTs/AMMCs, which is the key to further obtaining high-performance CNTs/AMMCs. As a multifunctional composite material, CNTs/AMMCs have broad application prospects in fields such as air force, military, aerospace, automation, and electronics. Moreover, CNTs/AMMCs have potential applications in cell therapy, tissue engineering, and other areas.

Evaluation of adhesive bond strength of restorative materials to hard tissues of deciduous teeth based on adhesion technique

Relevance. Treating caries in deciduous teeth remains one of the most complex challenges in pediatric dentistry. The bond strength between the enamel and dentin of deciduous teeth and restorative materials is crucial for the durability of hard tissue restorations in these teeth. This article evaluates the adhesive strength of restorative materials to the enamel and dentin of deciduous teeth using a universal adhesive system, both with and without prior etching with orthophosphoric acid.Purpose. To assess the adhesive bond strength of dental filling materials to the hard tissues of deciduous teeth, contingent upon the enamel and dentin etching techniques used with a universal adhesive system.Materials and methods. This study measured the adhesive strength of a composite filling material to the enamel and dentin of deciduous teeth using a universal adhesive system. The methods included both the absence of preliminary etching with 37% orthophosphoric acid (self-etch technique) and the application of preliminary etching of enamel and dentin with 37% orthophosphoric acid (total-etch technique). Sixty extracted deciduous teeth from children aged 6-8 years were used. Adhesive strength was assessed using the shear test of the filling material in cylinder form against the substrate surface.Results. Significant differences were observed in the adhesive bond strength of the composite material to the hard tissues of deciduous teeth when using 37% orthophosphoric acid before applying the adhesive system (total-etch technique) compared to no preliminary etching (self-etch technique). When filling carious lesions in deciduous teeth, if the defect is within the enamel, etching the surface with 37% orthophosphoric acid significantly (by two-fold) enhances the adhesive strength of the bond with the composite material using a universal adhesive. However, when repairing defects located deeper than the enamel layer in deciduous teeth, no statistically significant differences were observed in the adhesive strength with or without dentin etching. The optimal adhesive bond strength of composite materials to the hard tissues of deciduous teeth under laboratory conditions was attained by selectively etching the enamel with 37% orthophosphoric acid, followed by the application of a universal adhesive system to both the enamel and dentin.

Uneven exposure of compressed natural gas (CNG) and hydrogen (H2) cylinders: Fire and extinguishment tests

Vehicles that are powered by gaseous fuel, e.g., compressed natural gas (CNG) or hydrogen (H2), may, in the event of fire, result in a jet flame from a thermally activated pressure relief device (TPRD), or a pressure vessel explosion. There have been a few incidents for CNG vehicles where the TPRD was unsuccessful to prevent a pressure vessel explosion in the event of fire, both nationally in Sweden and internationally. If the pressure vessel explosion would occur inside an enclosure such as a road tunnel, the resulting consequences are even more problematic. In 2019 the authors investigated the fire safety of CNG cylinders exposed to localized fires. One purpose of the tests conducted in 2021 reported in this paper is to investigate whether extinguishment with water, e.g., from a tunnel deluge system, may compromise the safety of vehicle gas cylinders in the event of fire. Steel cylinders handles the situation with localizde fire and/or cooling with water well. Composite tanks can rupture if the fire exposure degrades the composite material strength, and the TPRD is not sufficiently heated to activate, e.g., if the fire is localized or if the TPRD is being cooled by water, which prevents its activation.

Influence of Recycled Aggregates and Silica fumes on Compression and Split Tensile Strength of Composite Materials

Influence of Recycled Aggregates and Silica fumes on Compression and Split Tensile Strength of Composite Materials

Crashworthiness Performance of Circular Hybrid Crash Box Due to Axial Load

In the previous study, hybrid crash box combines low-density and high strength of composite materials with aluminum materials had been developed. In this study, circular hybrid crash box with friction model is investigated. Crash box design is modelled by using computer simulation with ANSYS workbench. Composite carbon toray T300 – epoxy resin (CCE) and metal aluminum alloy 6063 (AA6063) is used as hybrid crash box material. Axial loading with a speed of 10 m/s is applied to circular hybrid crash box model by using impactor with mass of 100 kg. The orientation angle of composite lay-up and hybrid material configuration with two models of friction was running as 16 models. Energy absorption and deformation pattern were observed to determine crashworthiness performance. Based on the results, it can be denoted that the Al-Ko45 with friction model of 0.68 shows largest energy absorption of 7.53 kJ with specific energy absorption of 32.552 kJ/kg. The deformation pattern produces mixed mode with progressive crushing folding that can enhance energy absorption.

Study on dynamic mechanical properties and microstructure of basalt fiber reinforced coral sand cement composite *

This study investigates the impact of basalt fiber on the static and dynamic compression of coral-sand cement-based composites, as well as the mechanisms for strengthening and toughening. The samples of basalt fiber-reinforced coral sand cementitious composite (BFRCSCC) with varying fiber volume fractions (0%, 0.2%, 0.4%, 0.6%, 0.8%) underwent quasi-static mechanical tests and impact dynamic tests using an MTS universal testing machine and a split Hopkinson pressure bar (SHPB). This study investigates the mechanical properties of BFRCSCC, focusing on static and dynamic compressive strength, dynamic stress-strain curve, strain rate effect, failure strain, toughness analysis, and energy dissipation mechanism. In terms of microstructure, specimens of BFRCSCC were tested using scanning electron microscopy (SEM). The results indicate that basalt fiber can significantly enhance the quasi-static compressive strength (fc)and dynamic compressive strength (fd)of coral sand cement-based composite materials. When the basalt fiber content is 0.4%, the static and dynamic compressive strength of BFRCSCC increases by 28.78% and 37.25% respectively compared to ordinary concrete. The analysis from a micro perspective indicates that the incorporation of basalt fiber in the concrete matrix enhances the hydration reaction between cement and the BFRCSCC interface. The spatial structure formed by basalt fiber contributes to the excellent toughening effect on the mechanical properties of BFRCSCC. As the content of basalt fiber increases (≤0.4%), the bridging effect becomes stronger. The dynamic increase factor (DIF) and toughness index of BFRCSCC exhibit a significant positive correlation with the strain rate effect. Basalt fibers can help drive the hydration products to fill the cracks or voids in the cement matrix, thereby increasing the material's density and enhancing the impact resistance of coral concrete. This can be utilized in practical engineering projects with high dynamic load demands.

Enhancement of the bearing strength of pinned-joint composite materials

In this study, a different approach is used to enhance the bearing strength in continuous carbon fiber epoxy composite materials. In order to enhance the bearing strength, metal washers are inserted between laminae of composite material in the region of the pin. Two types of washer, one is stainless steel and the other is aluminum, are used in the preparation of specimens to carry out the bearing strength tests. In addition, three metal washer inserting configurations, as embedding one, two, or three washers in between carbon fiber layers, are tested in each group of specimens. The results show that the first bearing strength values obtained from the specimens with stainless steel washers increase considerably with respect to specimens with aluminum washers and the specimens without washers. The maximum strength of the specimens reinforced with one, two, and three stainless steel washers is approximately 185%, 405%, and 390% higher than the reference specimen, respectively. It is also observed that the maximum strength of the specimens reinforced with one, two, and three aluminum washers is 265%, 285%, and 320% higher than the reference specimen, respectively.