Mechanic of Advanced and Smart Materials

Abstract Phononic crystals are a kind of advanced materials that are created by alternating arrangement of one or more inclusion materials in a different host material. In this research, the effect of the dimensional parameters of inclusions on the band gap of tungsten-rubber phononic crystal plate has been investigated. The shape of the inclusion under investigation is a hollow cylinder and the lattice type is square. The analysis of the above structure was done based on the finite element method and with aid of Comsol software. The band structures of the phononic crystals have been obtained for 10 different dimensions of the inclusion (inner and outer diameter of the hollow cylinder). The results showed that to achieve the widest band gap, the outer and inner diameters of the cylinder should be 4.5 and 3.77 mm, respectively. In this case, the band gap can be obtained from the frequency of 281.5 to 1076.5 Hz, and the total width of the band gap is 795 Hz.

Abstract This experimental study investigated the effect of machining parameters on the surface roughness of bone during the grinding process. Bone grinding is commonly used in neurosurgery, spinal operations, and heel spur removal. Despite using CNC machines and robotic systems in this field, selecting optimal process parameters to achieve desirable surface quality remains a significant challenge. In this research, bovine femur bone samples were subjected to experimental trials. Four parameters were examined, including spindle speed, feed rate, depth of cut, and tool diameter. The Sobol sensitivity analysis method was implemented using Python programming to assess surface roughness's sensitivity to these parameters. Subsequently, response surface methodology (RSM) in Minitab software was employed for results analysis and process optimization. The findings revealed that tool diameter, depth of cut, and osteon orientation had the most substantial influence on surface roughness. The optimum roughness value of 1.47 µm was obtained under specific conditions: spindle speed of 3000 rpm, feed rate of 60 mm/min, depth of cut of 0.1 mm, tool diameter of 8 mm, and across osteon orientation. The sensitivity analysis confirmed the dominant role of tool diameter in both longitudinal and across osteon orientations.

Abstract In the present study, the vibrational analysis of a three-layer sandwich plate with an auxetic core under aerodynamic forces with simply supported boundary conditions has been investigated. In this sandwich plate, the middle layer, or the so-called core, is made of auxetic material. The plate is subjected to aerodynamic forces on one side. To reduce the intensity of vibrations in the structure, the plate has been reinforced with carbon nanotubes. For the analysis and modeling of the plate’s vibrations, the modified shear deformation plate theories were employed, and the aerodynamic force exerted by the airflow on the plate was assumed based on first-order piston theory. Using Hamilton's principle, the governing equations for the vibrational behavior of the sandwich plate were derived, and the Galerkin weighted residual method was utilized to solve these equations. To demonstrate the validity of the obtained relationships and the proposed solution method, the results of this study were compared with results published in reputable journals and numerical solutions obtained using the finite element method through commercial software. Finally, the effects of various parameters such as the geometric dimensions of the sandwich plate, the dimensions of the auxetic core, aerodynamic pressure, and the volume fraction of carbon nanotubes on the vibrations of the structure were examined and analyzed.

Abstract In this article, research on the process of induction hardening on the Saina vehicle’s Tulip part, which is made of 1055 steel, was investigated. The input parameters discussed in this article include induction power, hardening time and cooling fluid pressure, and in the output parameter, surface hardness and effective case depth were investigated. Using the test design table extracted from the Minitab software and the analyzes performed with the response surface method, the mathematical and statistical equations governing the process were extracted, and using the analysis of variance table, the ineffective parameters of the process were removed and the final regression equation and other required information was extracted. Then the optimization of the process according to the desired values to achieve the desired surface hardness and effective case depth were done by providing a suitable range of induction power settings, induction time and cooling fluid pressure, which helped to reduce destructive tests and increase the quality assurance of parts.

Abstract The entry of air into hydraulic power systems presents a key challenge for both stationary and mobile machinery. Given the performance limitations of conventional online deaeration methods, this research was conducted to design, fabricate, and optimize an air-oil separator unit. To simulate the turbulent flow and the physical separation mechanism, a three-dimensional, two-phase numerical model was developed, integrating the Volume of Fluid (VOF) and Discrete Phase Model (DPM) approaches. A laboratory-scale hydro-pneumatic test rig was designed and fabricated to validate the numerical model. A comparison between experimental and numerical results revealed a discrepancy of approximately 2.5% for separation efficiency and 5.6% for pressure drop, thereby confirming the model's validity for analyzing the variables affecting the separator's performance. The results indicated that separation efficiency exhibits a non-linear behavior, with an optimal inlet velocity range of 3.5 to 5.5 m/s establishing a balance between high efficiency (87.5–90%) and an acceptable pressure drop (735–1150 Pa). Furthermore, the geometric analysis identified optimal ranges for key parameters. Accordingly, optimal values for the conical section angle (5–6°), cylindrical diameter (36–40 mm), and air outlet diameter (18 mm) yielded separation efficiencies of 89%, 90%, and 90%, respectively. These findings provide a quantitative and reliable framework for the optimal design of air-oil separators, demonstrating that an effective balance between efficiency and energy consumption can be achieved by selecting appropriate geometric parameters. The implementation of this approach is expected to enhance the reliability and service life of hydraulic systems significantly.