نشریه علوم و فناوری کامپوزیت
سال دوازدهم شماره 1 (پیاپی 43، بهار 1404)

Biodegradable sandwich panels, as a new generation of environmentally friendly structures, have attracted considerable attention due to their ability to return to nature at the end of their service life. In this study, the flexural behavior of such panels was numerically investigated using the finite element method. The panel structure consists of flax fiber-reinforced skins and cores with various geometric configurations made from composite, wooden, and aluminum materials. Simulations were performed under identical loading conditions. The main objective was to evaluate and compare the mechanical performance of different core configurations in terms of stress distribution and energy absorption capacity. The results indicated that the combination of core shape and material has a significant influence on the flexural behavior of the panels. Overall, cores with curved geometries such as C-shaped and W-shaped exhibited superior performance compared to other shapes, while R-shaped and X-shaped cores showed the weakest results. Furthermore, although aluminum cores provided more uniform stress distribution, wooden and composite cores demonstrated better energy absorption performance. These findings can serve as a basis for the optimal design of biodegradable sandwich panels in structural applications.

Functionally graded materials (FGMs) are an advanced class of heterogeneous materials whose mechanical properties vary continuously through the thickness due to gradual changes in the volume fractions of constituent phases. This study investigates the transient thermoelastic response of a porous functionally graded rectangular plate subjected to a time-dependent thermal shock within the framework of the Lord–Shulman generalized thermoelasticity theory. A comprehensive three-dimensional numerical analysis is carried out using the state-space method in conjunction with the Lord–Shulman model. The coupled governing equations for stress components, displacements, temperature, and heat flux are solved through the differential quadrature method combined with numerical inversion of the Laplace transform, under simply supported boundary conditions. The parametric study explores the influence of porosity type, porosity coefficient, time, and gradation parameter on the spatial distribution and magnitudes of temperature, displacement, and stresses. The results reveal that these parameters significantly affect the transient thermoelastic behavior of the functionally graded plate. Furthermore, optimizing the volume fraction distribution and porosity characteristics can enhance the performance of porous FGM structures. These findings underscore the critical role of structural and material parameters in controlling coupled thermal–mechanical responses and provide practical insights for the optimal design of FGMs in advanced engineering applications.

In this study, the optimization of 3D printing process parameters for the fabrication of CNT/ABS nanocomposites was investigated using the Taguchi method. The primary objective was to optimize the mechanical properties, weight, printing time, and material consumption of the fabricated parts. To achieve this, key printing parameters—including printing temperature, printing angle, infill percentage, printing speed, infill pattern, carbon nanotube (CNT) weight fraction, and layer thickness—were systematically examined to identify the most optimal configuration. Experimental results revealed that infill percentage and layer thickness had the most significant influence on tensile strength and Young’s modulus; specifically, increasing the infill percentage and decreasing the layer thickness led to notable improvements in these properties. Furthermore, by optimizing these parameters and precisely adjusting the printing angle, the part weight was reduced, and both printing time and filament consumption were optimized. Additionally, the ratio of strength to the product of weight, printing time, and filament length was introduced as an effective index for evaluating the overall printing performance.

In the present research, the forced vibration of a truncated conical nanoshell in contact with fluid under harmonic load has been investigated. Classical plate theory along with modified stress couple theory has been used for shell analysis. The energy method and Hamilton's principle have been used to determine the governing equations. The applied pressure from the fluid to the shell has been determined by using the fluid potential function and using the velocity boundary conditions at the contact surface of the fluid and the shell. Also, to determine the vibration response, the method of hypothetical modes along with the Galerkin technique has been used. Finally, for a sample nanoshell, numerical results have been determined with the help of MATLAB software, and the numerical results of forced vibration and the effect of various parameters such as aspect ratios, cone apex angle, external force parameters, and fluid density on the vibration response of the system have been analyzed.

In this study, the significance of fiber–metal laminates (FMLs) as a new generation of engineering materials with superior properties such as high strength, good ductility, and enhanced damage resistance was investigated. Due to their combined metallic–composite performance, these structures are widely applied in marine and aerospace industries. Three types of laminates, including GLARE, BARAL, and a novel hybrid glass/basalt–aluminum configuration with a constant FML 5-3/2 lay-up, were fabricated. The metallic layers consisted of 5052-H32 aluminum alloy, while the composite layers were reinforced with unidirectional glass, basalt, and glass/basalt hybrid fibers in a vinyl ester matrix. To evaluate the mechanical behavior, tensile, flexural, and low-velocity impact tests were performed at three energy levels. The results showed that GLARE exhibited the highest tensile strength of 315 MPa, BARAL displayed a more brittle behavior with 281 MPa, and the hybrid laminate presented an intermediate performance with 287 MPa. Under flexural loading, the maximum stresses were measured as 285 MPa for GLARE, 250 MPa for BARAL, and 227 MPa for the hybrid laminate. In the impact tests, the primary energy absorption mechanisms were identified as plastic deformation of the aluminum layers and interfacial delamination. The use of vinyl ester resin instead of conventional epoxy, along with the employment of 5052-H32 aluminum alloy and the incorporation of a glass/basalt hybrid configuration, introduced a distinctive approach compared to conventional practices, with the comparative results highlighting their significant influence on mechanical response and energy absorption capacity.

Aluminum matrix composites reinforced with Mg₂Si particles are considered advanced engineering materials due to their desirable mechanical and thermal properties, such as high specific strength and hardness. However, machining these composites is often accompanied by challenges such as severe tool wear, mainly due to the presence of hard and brittle phases. In this study, the effects of machining parameters and tin (Sn) additive on tool wear behavior during the turning of Al–Mg₂Si composites were experimentally and statistically investigated. Two types of composites—one without additive and the other containing 1 wt.% Sn—were fabricated using the in-situ casting method. Machining tests were performed under four levels of cutting speed, feed rate, and depth of cut, and in both dry and wet conditions, based on the Taguchi design with an L16 orthogonal array. Tool wear was evaluated in terms of wear morphology and wear area using a scanning electron microscope (SEM) and ImageJ software. The results indicated that adhesive wear was the dominant mechanism in both composites, and the addition of Sn significantly reduced tool wear. Taguchi analysis and multiple regression modeling revealed that depth of cut had the most significant effect on tool wear. The optimal machining condition was identified as a 0.5 mm depth of cut, 0.08 mm/rev feed rate, 710 rpm spindle speed, and wet cutting. Additionally, an alternative condition with 1 mm depth of cut and 0.12 mm/rev feed rate was suggested for improved productivity.