In this study, we investigated the bonding mechanism of surface-treated steel with an Al-Si alloy in order to produce steel-aluminum (STL-Al) hybrid composite materials by cast-bonding. The results showed that there are differences in the phase and properties of the hybrid composite materials bonded specimens depending on the surface treatment of the steel sheet used, and that the bonding conditions can be controlled further by detailed conditions of the surface treatment. Based on the interfacial bonding strengths measured here, the galvanized surface treatment induced metallurgical bonding to form a reaction layer on the bonding surface and was determined to be the most effective surface treatment.

Background: a humidity sensor is used to sense and measure the relative humidity of air. A new composite system has been fabricated using environmental pollutants such as carbon black and low-cost zinc oxide, and it acts as a humidity sensor. Residual life of the sensor is calculated and an expert system is modelled. For properties and nature confirmation, characterization is performed, and a sensing material is fabricated. Methodology: characterization is performed on the fabricated material. Complex impedance spectroscopy (CIS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) are all used to confirm the surface roughness, its composite nature as well as the morphology of the composite. The residual lifetime of the fabricated humidity sensor is calculated by means of accelerated life testing. An intelligent model is designed using artificial intelligence techniques, including the artificial neural network (ANN), fuzzy inference system (FIS) and adaptive neuro-fuzzy inference system (ANFIS). Results: maximum conductivity obtained is 6.4×10⁻³ S/cm when zinc oxide is doped with 80% of carbon black. Conclusion: the solid composite obtained possesses good humidity-sensing capability in the range of 30–95%. ANFIS exhibits the maximum prediction accuracy, with an error rate of just 1.1%.

A high performance and light-weight wound composite material wheel has been developed and is intended to be used for many purposes. One of these applications is marine current turbine (MCT). Traditionally, major problems influencing the design and operation of MCTs are fatigue, cavitation and corrosion due to the sea water. Considering these factors, implementation of composite materials, especially Kevlar fiber/epoxy matrix, in MCTs is explained in this paper. This novel design pattern of composite material marine current turbine (CMMCT) shows many advantages compared to conventional turbines. This paper investigated several factors which should be considered during this novel turbine design process such as the composite material selection, filament winding of composite wheel and turbine's structural and cavitation analysis. The power coefficient of CMMCT by using CFD is also obtained and the experimental facilities for testing CMMCT in a water towing tank are briefly described.

The present work studies the tribological properties of new hybrid material composed from high porosity open cell aluminum alloy (AlSi10Mg) skeleton and B83 babbitt infiltrated into it. The porous skeleton is obtained by replication method applying salt (NaCl) as space holder. The reinforcing phase of the skeleton consists of Al2O3 particles. The skeleton contains Al2O3 particles as reinforcement. The microstructure of the obtained materials is observed and the tribological properties are determined. A comparison between tribological properties of nominally nonporous aluminum alloy, high porosity open cell skeleton, babbitt alloy and the hybrid material is presented. It is concluded that new hybrid material has high wear resistivity and is a promising material for sliding bearings and other machine elements with high wear resistivity.

The aim of this paper is analysis of the possibility of determining the internal structure of the fibrous composite material by estimating its thermal diffusivity. A thermal diffusivity of the composite material was determined by applying inverse heat conduction method and measurement data. The idea of the proposed method depends on measuring the timedependent temperature distribution at selected points of the sample and identification of the thermal diffusivity by solving a transient inverse heat conduction problem. The investigated system which was used for the identification of thermal parameters consists of two cylindrical samples, in which transient temperature field is forced by the electric heater located between them. The temperature response of the system is measured in the chosen point of sample. One dimensional discrete mathematical model of the transient heat conduction within the investigated sample has been formulated based on the control volume method. The optimal dynamic filtration method as solution of the inverse problem has been applied to identify unknown diffusivity of multi-layered fibrous composite material. Next using this thermal diffusivity of the composite material its internal structure was determined. The chosen results have been presented in the paper.

Several recent earthquakes have indicated that the design and construction of bridges based on former seismic design provisions are susceptible to fatal collapse triggered by the failure of reinforced concrete columns. This paper incorporates an experimental investigation into the seismic response of nonductile bridge piers strengthened with low-cost glass fiber reinforced polymers (LC-GFRP). Three full-scale bridge piers were tested under lateral cyclic loading. A control bridge pier was tested in the as-built condition and the other two bridge piers were experimentally tested after strengthening them with LC-GFRP jacketing. The LC-GFRP strengthening was performed using two different configurations. The control bridge pier showed poor seismic response with the progress of significant cracks at very low drift levels. Test results indicated the efficiency of the tested strengthening configurations to improve the performance of the strengthened bridge piers including crack pattern, yield, and ultimate cyclic load capacities, ductility ratio, dissipated energy capacity, initial stiffness degradation, and fracture mode.

The composite materials as FRP (Fiber Reinforced Polymers), which are characterized by benefits resulting from the combination of high strength reinforcement (as carbon, glass, steel or aramid fibers) with synthetic matrix are increasingly used to reinforce existing structures. Reinforcing System as FRCM (Fibre Reinforced Cementitious Matrix), which includes, among others, Ruredil X Mesh Gold System, is much less commonly used. However, the uniform and practical methods for calculating composite reinforced structures are not determined. Especially when considering the real conditions of structure exploitation, which requires further research in this field. In the paper the initial loading level influence on the efficiency of reinforced concrete beams strengthen using system Ruredil X Mesh Gold was investigated.

The paper presents the results of experimental-numerical tests of firing at aluminum composite materials. The test materials were manufactured by pressure infiltration of porous ceramic preforms made of -Al2O3 particles in the amount of 30% and 40% by volume. The EN AW-7075 alloy was chosen as the material matrix, and the steel 7.62×39 mm (M 43) FMJ (Full Metal Jacket) intermediate ammunition was selected for firing. In the result of the experiment, the samples were perforated with a clear difference in the muzzle diameter. The projectile with fragments caused damage to up to three reference plates placed behind the samples (witness plates) in composites with 40% of particles by volume. The mechanics of crack propagation during ballistic impacts of the projectile was characterized based on microstructure studies. Then, using numerical analysis of impact load, the examination of composite materials puncture in the ABAQUS environment was carried out. The Finite Element Method (FEM) was employed for the discretization of geometric models using Hex elements. The Johnson-Cook constitutive model describing the relationship between stress and strain in metal-ceramic composites was applied for the analyses. Numerical models were then subjected to numerical verification using smoothed particle hydrodynamics (SPH). Based on the obtained results, it was found that the hybrid FEM/SPH method correlates significantly with the experimental results.