Strength Of Composite Materials Research Articles

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

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.

PEMANFAATAN WASTE PENGOLAHAN AIR SEBAGAI AIR UMPAN BOILER PT. NLP

NLP isafurniture manufacturing company that uses three types of wood, namely mahogany, pine, and teak. Handling and processing sawdust waste is a challenge that needs to be overcome effectively so that the waste can become a product that has added value. The value-dded product in question is souvenir craft. The utilization of coarse sawdust can be mixed with epoxy resin to form composite materials, which can be used as the basic material for souvenir crafts. It is known that the strength of composite materials increases with the increasing composition of the resin in composite materials, and the character of composite materials If the composition of sawdust is higher, the resulting composite material will be opaque and lighter. Then the manufacture of composite materials will use a ratio of 1:1. Regional attributes, cultural elements, innovation in form, design, and ease of application are important factors to consider when designing a product for souvenirs. The collected data is needed to be translated into the interpretation of product requirements to be used in making the Objective Tree and Morphological Diagrams. Evaluation of alternative product designs is carried out by considering the minimum risks.

INFLUENCE OF FILLERS ON THE STRUCTURE AND PROPERTIES OF POLYMER MATRIX

Purpose. Enhancement of the mechanical properties of the polymer matrix through the incorporation of finely dispersed fillers, namely aluminum oxide and talc, as potential modifiers.
 Research methods. Research was conducted on polymer specimens subjected to tensile testing according to DSTU EN ISO 527-5:2018. The tests were performed using a URM-5 tensile testing machine with a maximum force of 50 kN. Metallographic analysis was carried out using a KEYENCE VHX microscope at magnifications of 50 and 500. The microstructure of the polymer matrix was assessed through etching-free procedures.
 Results. The study demonstrates that the incorporation of finely dispersed aluminum oxide particles increased the strength parameter from 4.69 MPa to 13.07 MPa, as compared to the unfilled sample. Additionally, it was observed that the introduction of finely dispersed talc particles at a concentration of 0.75 % by mass led to an enhancement in strength values from 4.69 MPa to 12.74 MPa, in comparison to the unfilled sample.
 Scientific novelty. A polymer matrix with enhanced mechanical properties was achieved through the addition of fillers acting as modifiers. The optimal concentration of aluminum oxide and talc additives was determined. By comparing the results with previous studies involving aluminum oxide and talc at various concentrations in different types of polymer matrices, it can be concluded that the investigated concentrations of modifiers with epoxy resin ED-20 led to the production of a polymer composite with superior mechanical characteristics. The obtained results underscore the significant potential of aluminum oxide and talc as effective modifiers for improving the strength and other crucial properties of composite materials.
 Practical value. The obtained results highlight the significant potential of utilizing aluminum oxide and talc as modifiers for polymer matrices to enhance their mechanical characteristics. From a practical standpoint, the use of these fillers can exert a substantial impact on the development of new composite materials with improved properties, finding application in composite reinforcement production. Considering the heightened strength and resilience of the resulting materials, these composites can be effectively employed to create lighter and stronger structures in construction and other industries. Additionally, their application may lead to reduced repair and maintenance costs due to increased durability and resistance to mechanical loads. Thus, the implementation of the obtained results could have a substantial influence on the practice of composite material manufacturing, ensuring the creation of products with enhanced characteristics for various applications.

Influence of unidirectional composite failure envelope shape on predicting compressive failure of a laminate with a filled-hole

In recent decades, several computational models have emerged at the mesoscale for predicting the failure development and strength of composite materials. Nevertheless, the intricate failure mechanisms of composites pose a formidable challenge in developing models capable of consistently reproducing diverse sets of experimental data. Furthermore, the absence of standardised multiaxial tests has hindered consensus on failure envelopes and criteria for composites. In this work, an in-house constitutive model implemented in a finite element code is employed to predict the failure strength of several filled-hole compressive carbon/epoxy experimental tests, varying in stacking sequences, sizes, bolt preloads, and other parameters. The influence the selected failure criterion has on the predictions is analysed. The findings indicate a large impact of the failure envelope on both the failure compressive strength and developed failure mechanisms. Therefore, the correct adjustment of the failure criteria can be as relevant as defining accurately the material input parameters. These results emphasise the importance of accurately establishing failure envelopes, rather than overemphasising the development of complex models.

Modulating adhesion strength in multi-ferroic composite materials: Insights from adhesive contact with arbitrary profile indenters

Adhesion control is a critical aspect of various applications, from industrial adhesion devices to the locomotion of insects on ceilings and walls. Multi-ferroic materials, which encompass mechanical, electrical, and magnetic properties, offer approaches for reversible adhesion control. This study presents a comprehensive theoretical framework for adhesive contact in multi-ferroic composite materials when subjected to axisymmetric rigid indenters with arbitrary profiles. We analytically derive the physical fields for various contact models, including Hertz contact, Johnson–Kendall–Roberts (JKR), and Maugis–Dugdale (MD) adhesive models. The obtained energy release rates indicate that the electric and magnetic potentials can modulate adhesion strength. The Griffith energy balance relation is employed to derive the indentation forces and penetration depths, which can be extended to a range of common indenters. Notably, the classical approximations fail when using small spherical indenters, but the study provides valid alternatives. The influence of amplitude and wavelength on contact behavior is explored, with greater effects observed for larger or smaller values. For cosine-shaped indenters, equivalence to flat-ended cylindrical punches is established under specific conditions. The study also reveals that the power indices for power-law-shaped indenters change the influence of electric and magnetic potentials on pull-off forces. These findings provide a theoretical fundament associated with the biomimetic and artificial adhesive systems and the modern testing techniques.

Mechanical impact on biomineralization: Enhancing the strength of composite materials

A recent study published in Nature Communications introduces a novel mechanically-mediated reaction involving ZnO nanoparticles that autonomously react, forming Zn/S mineral microrods within an organogel. These microrods selectively reinforce synthetic polymer composites, offering a unique approach to material strengthening. The method provides a distinctive pathway for mechanical mineralization in composite materials.

Study of the Influence of Fillers on the Impact Strength of Composite Materials with an Ice Matrix

Study of the Influence of Fillers on the Impact Strength of Composite Materials with an Ice Matrix

Enhancement of magnetic activation on the backfilling performance of coal gangue-based composite materials

ABSTRACT The large accumulation of coal gangue has resulted in significant environmental contamination and detrimental impacts. Utilizing it as a filler material in coal mining operations may successfully address this issue. It may be used to efficiently alleviate this issue by filling up coal mines. The wettability of magnetized solution on the coal gangue surface and the phase composition, microstructure, and pore structure of hydration products of coal gangue-based composite material (CGCM) at different ages were analyzed by means of contact angle (CA), X-ray diffraction (XRD), thermogravimetry (TG/DTG), mercury intrusion (MIP), and scanning electron microscopy (SEM) in order to control the fluidity and mechanical properties of backfilling materials. Simultaneously, an investigation was conducted on the slump expansion, setting time, and compressive strength of composite filler materials derived from magnetized coal gangue. The findings indicate that the application of a magnetic field reduces the interaction force among the molecules in the mixing water. Consequently, this leads to an improvement in the wettability of the coal gangue particle surface. Thus, the fluidity of the backfilling slurry is improved. The permeability and diffusion characteristics of magnetized water surpass those of regular water, The rate of dissolving and hydration reactions of the cementitious active material in the slurry is increased, resulting in a noticeable reduction in the setting time of the slurry. In the backfilling body, magnetized mixing water can encourage the formation of dicalcium silicate (C2S), tricalcium silicate (C3S), and Ca (OH)2. Higher amounts of C-S-H gel and Aft are produced by the pozzolanic action with SiO2, which enhances the pore structure. Thus, the mechanical qualities of the filler body are enhanced. The study findings provide novel insights into the coal gangue backfill mining and offer an environmentally friendly and efficient approach for the large-scale processing and exploitation of coal gangue.

Interface enhancement and distribution of carbon fibers in injection welding

AbstractInjection welding is an excellent adhesive‐free bonding method for thermoplastic resins, demonstrating outstanding connection effectiveness. The incorporation of carbon fibers (CFs) significantly enhances the weld shear strength at the injection interface. This study aims to investigate the reinforcement effect of CF‐reinforced thermoplastic composites (CFRTP) during the injection welding process. And explore the influence of the amount of added CFs on the weld shear strength. Polyamide 6 (PA6)/CF composites with CF contents of 10 wt% and 30 wt% were subjected to injection welding for the first and second molding cycles, respectively. It was observed that the reinforcement effects varied considerably depending on the combinations studied. Under the optimal combination and process parameters, the weld shear strength of PA6/CF composites reached 63 MPa, equivalent to 90% of the shear strength (70 MPa) of the original PA6/CF material. Polarized light microscopy and scanning electron microscopy were utilized to analyze the distribution of CFs at the interface and the reinforcing mechanism during tensile fracture. The significance of maintaining uniform CF content during the welding process of PA6/CF composites was emphasized.Highlights Preparation of PA6 composite materials with different carbon fiber contents. Achieving high welding shear strength of composite materials through injection welding. Identified the optimal injection welding conditions to achieve the highest strength. The positive effect of specific fiber distribution on welding strength was analyzed.

Investigation of Empennage Location Effect to the Unmanned Aerial Vehicle (UAV) Structure Characteristic

Over the past few decades, unmanned aerial vehicles, commonly known as UAVs, have been widely used in a number of consumer and military applications, such as surveillance, tracking, monitoring, and aerial photography. Fixed-wing and rotary UAVs are the two primary categories in UAV. Interestingly, the hybridization of fixed-wing and rotary UAV gives better performance in terms of energy consumption and the needs of runaway. Designing new hybrid fixed wing-rotary UAV or hybrid vertical take-off and landing (VTOL) is challenging especially to identify the critical location in the UAV and material selection. Therefore, the objective of this research is to study the effect of empennage location and material selection on the structural strength of a hybrid VTOL UAV. The SolidWorks software was employed to design a 3D model of the UAV with different empennage locations, as well as perform a simulation of the structural strength of fibre glass, carbon fibre and kenaf for the hybrid VTOL UAV. The simulation analysis presents stress (Von Mises). The results show that the fibre glass (4.342 N/m2) at top empennage gives the best performance as compared to other parameters. In conclusion, this study is necessary to give a better picture of structural strength of composite materials and best design location in hybrid VTOL UAV for future research.

Epoxy resin mechanical properties in composition with copper (I) oxide particles, encapsulated by polylactide with variable thickness

The required functional and mechanical properties are necessary for design the polymer compositions with dispersed fillers. The mechanical properties of such polymer composition can be changed by encapsulated filler particles shell thickness varying. The paper shows that the presence of polylactide polymer shell and its thickness on the surfaces of copper (I) oxide particles significantly affect the strength of polymer composite material based on ED-20 epoxy resin. That is due to the interaction between encapsulated particles and the matrix polymer, in contrast to noncapsulated particles. In addition, a change in particle size due to increasing shell thickness also affects the strength properties of the composition. It is shown that the elastic modulus of the filled epoxy composite does not depend on the shell thickness on the particle surfaces.

High injection molding welding strength and cross-sectional analysis of carbon fiber composite materials

In this study, carbon fibers, commonly used as reinforcement materials, were added to polyamide (nylon) PA6 to fabricate carbon fiber-reinforced thermoplastic composites (CFRTP), which were then subjected to injection molding welding. The aim of this research was to investigate the positive influence of carbon fibers on injection molding welding strength and explore the optimal injection conditions. Three different joining combinations and various injection parameters were examined. The tensile fracture surfaces after welding were observed using polarized microscopy and scanning electron microscopy. The reinforcing mechanism of carbon fibers was analyzed. Ultimately, the optimal conditions were determined as a mold temperature of 120°C, an injection temperature of 380°C, and an injection velocity of 150 mm/s. The addition of carbon fibers exhibited significant strengthening effects on the injection molded joints, and it also provided the potential for injection molding welding between resins with poor compatibility.

Prediction Ability Analysis of Phenomenological Strength Criteria for Composites

The article examines and assesses the phenomenological strength theory of composite materials. A comparative analysis of the theoretical envelopes was conducted for each criterion. A unified form of the phenomenological strength criterion was established. The study specifically examined the effects of altering the interaction parameter on the Tsai-Wu criterion’s theoretical envelope. Based on the available experimental data, the study plotted the failure envelopes of each strength criterion under planar composite stress states. The variation of these envelopes across various stress quadrants was highlighted. As a result of the examinations, four typical phenomenological strength criteria were chosen. The composites’ off-axis tensile and biaxial loading test data were used to evaluate the predictive power objectively. The results showed that not all stress states’ test results agreed with the predictions of the phenomenological strength theory. The criterion proposed by Norris and Tsai-Hill performed better at accounting for the material’s different compressive and tensile characteristics. The other criteria tended to be conservative under particular circumstances. Simultaneously, the Hoffman criterion matched the test data more closely over a broader range of stress states. Overall, this study clarified the limitations and applicability of various strength criteria in composite material strength prediction.

Flexural Strength Analysis of Laminated Composites Using Clam Shell Powder and Bagasse Powder

Composites are materials that have specific properties based on their constituent materials. The constituent materials consist of binders and reinforcements. Reinforcing materials come from synthetic fibers and natural fibers. Natural fibers can be waste that is wasted in the environment. These wastes include bagasse waste and clam shells. These wastes are made into fibers. Resin is mixed with fiber and blowing agent, then stirred until evenly distributed and poured into the mold, resulting in a composite material. This study aims to obtain the strength of composite materials due to three-point bending loading with the laminate fiber layer method. The manufacture of this test specimen uses bagasse powder and clamshell powder formed with a casting system. This material consists of 4 layers. The first and third layers are clamshell powder, and the second and third layers are bagasse powder. The fiber sizes of the specimens are 300mesh, 400mesh, and 500mesh. The fiber fraction ratio was 10% and 15%. The models were laminated and tested for three-point bending. The best results were found in the 500 mesh fiber size specimen, with a fraction ratio of 85% resin and 15% clam shell powder and bagasse. The maximum stress obtained was 63.46 MPa and strain 0.59 mm, with a bending force of 487.42 N.