International Journal of Advanced Design and Manufacturing Technology
Volume:16 Issue: 4, Dec 2023

In this study, the compressive stresses of dodecahedron diamond lattice structures have been investigated. The finite element method has been used for Stress analysis. After the simulation, it was found that more stresses are applied at the junction of the struts of this structure due to the application of compressive force. For this purpose, the connection point of the structure’s struts was strengthened by spherical connections, and a new type of dodecahedron structure was created. The validation and effect of spherical connections in compressive stresses have been evaluated experimentally. Two types of diamond lattice structures are made of stainless steel 316L by the SLM method. The results show that in the same condition, the use of spherical connections with twice the diameter of the structure’s struts helps to strengthen the structure and increase its compressive strength by 18% compared to the simple structure.

The braking system in cars is directly deals with the issue of safety, and as a result, it is essential to pay attention to this matter. One of the materials used to make disc and brake pads in disc brakes is a ceramic material. This research aims to simulate and analyze the dynamic-thermal ceramic brake disc during the braking operation using the finite element method. Currently, the conventional brake disc is used in the Peugeot 206 car (domestic production), which has low efficiency in terms of life, wear, etc. Therefore, in this research, considering the significant production of Peugeot 206 car in the country, the disc and brake pads of this car have been selected, which were first modeled by Catia software, and after transferring the model to Abacus software and defining the types of ceramics and Cast iron was analyzed by finite element method. Compared the results of the Peugeot 206 ceramic brake disc and pad analysis were with the results of the standard (cast iron) discs in this car. The results showed that the maximum von Mises stress in the ceramic disc was 260.7 MPa, while the maximum von Mises stress in the cast iron disc was 293.3 MPa. The amount of heat produced in the ceramic disc during the braking action in 4 seconds was almost 84% less than the cast iron disc in the same period. Also, the results showed that the ceramic disc has a higher safety factor (1.98) than the cast iron disc (1.45).

The constant growth of energy consumption, increased fuel costs, non-renewable fossil fuel sources, and environmental pollution caused by increased emission of greenhouse gases, and global warming highlight the need for the analysis and optimization of main energy generation bases, i.e. power plants. The Artificial Neural Network (ANN) is a useful novel method for better processing information and controlling, and optimizing and modeling industrial processes. For the first time in this study, an ANN was designed and applied to data extracted from modeling and analyzing a 60 MW combined heat and power generation power plant. To this end, the error backpropagation network was selected as the optimal network, and the generator load or capacity, condenser pressure, and Feedwater temperature were considered inputs to the ANN. The energy and exergy efficiencies of the power plant and the overall energy and exergy losses of the cycle were considered outputs of the ANN. The ANN was coded and designed with the help of MATLAB. The Genetic Algorithm (GA) was used to obtain the optimal values of input parameters and the minimum losses and maximum efficiencies based on the first and second laws of thermodynamics.

The present study investigates the deformation of FGM plates under blast load. Hamilton's principle is used to obtain the dynamic Equations. The two constituent phases, ceramic and metal, vary across the wall thickness according to a prescribed power law. Boundary conditions are assumed to be Simply Supported (SS). The type of explosive loading considered is a free in-air spherical air burst and creates a spherical shock wave that travels radially outward in all directions. For the pressure time of the explosion loading, Friedlander’s exponential relation has been used. In order to determine the response analytically, the stress potential field function is considered. Using the Galerkin method, the final Equations are obtained as nonlinear and nonhomogeneous second-order differential Equations. The effect of temperature including thermal stress resultants and different parameters on the dynamic response have been investigated. Results have been compared with references and validated. Results showed that the amplitude of the center point deflection of the FGM plate is less than the pure metal plates when exposed to blast load, by increasing the volumetric index percentage of FGM, center point deflection is increased and in the FGM plates, deformation of symmetrical plates is smaller than the asymmetric plates. Also by applying the damping coefficient of the FGM plates, the amplitude of center point deflection is reduced, and by increasing the aspect ratio of the FGM plate, its center point deflection against explosion waves is reduced and by considering the effects of thermal resultant forces and moments, center point deflection is increased.

In this work, the effect of fine aggregates from two different sources on the quality and strength of concrete was determined using UPV measurements. The concrete samples were produced using a nominal mix ratio of 1: 1½: 3 and water-cement ratio of 0.55, with three different aggregate sizes (3/8, ½ and ¾ inches) of granite mixed separately with sand obtained from Ogun river and a local drainage in Abeokuta, Southwestern, Nigeria. UPV was measured through each sample on days 1, 7, 14, 21 and 28 after curing using Pundit lab+ equipment. Comparison of the actual compressive strength and estimated compressive strengths from equations generated for each sample type using the crushed samples on the 7th and 28th days respectively shows that most estimations were within the acceptable ±20% variation. Results show that there is no significant difference between the samples made from using either of the two fine aggregates.

The brake system must be reliable and display unchanging action throughout its use, as it guards the health and life of many people. Properly matched friction pair, a drum, and a brake pad have a great impact on these factors. The brake pads are far more complex components. New technologies make it possible to develop materials with various compositions and different proportions and connect them permanently in fully controllable processes. This elaboration shows that all these factors have a greater or lesser impact on the coefficient of friction, resistance to friction wear and high temperature, and the brake pad’s operating life. The friction materials are required to provide a stable coefficient of friction and a low wear rate at various operating speeds, pressures, temperatures, and environmental conditions. The aim of this work is therefore to investigate the possibility of using a Finite Element Analysis (FEA) approach to evaluate the braking performance of a heavy-duty elevator with different non-conventional pad materials including Composite Carbon fiber reinforced, Composite Epoxy SMC and SiC (silicon carbide). The results show that the performance of SiC (silicon carbide) is better than two other materials. In the braking system with SiC, the required time for stoppage of the system is lower than two other materials.

The attractive mechanical properties of 7075 alloy, such as its high strength-to-weight ratio and fracture toughness, have received special attention in the automotive and aerospace industries. However, welding as a fabrication process has a detrimental effect on this alloy’s properties which affects its mechanical performance. In this work, to compensate for the loss in mechanical properties caused by welding, proper heat treatment operations are adopted. To this end, 1.5 mm AA7075 sheets were first preheated and butt welded using the gas tungsten arc welding process. The welded sample was solution heat treated, quenched, and then artificially aged. Microhardness tests showed an increase of hardness in all zones of the aged specimen compared to those of the original welded blank before heat treatment. A maximum microhardness value of 180 HV was recorded in the heat-affected zone of the aged specimen. In addition, elongation at break, and strength (yield, tensile, and fracture) of the original welded blank increased by about 50% after the artificial aging operation.

In this study, we have synthesized nano Aluminum Fluoride (nAF) nanoparticles by the sol-gel method and studied the nano-sized morphology of crystals. In the other section, the PVC/NiAl2O3/AlF3 (nPNA) nanocomposite was successfully prepared and characterized by FT-IR, and HRTEM techniques. FTIR peaks of the PVC and nPNA have been shown spherical shape of PVC and also spherical shapes nanoparticles of nPNA loaded on PVC. A solvothermal method has been successfully introduced and applied for catalyst efficiency. This nanocomposite was used for the removal of Congo red dye. For this purpose, the morphology and the structure of crystals have been changed by modification on precursor gel. Meanwhile, precursor gel preparation and the interaction on the nano-sized area have been studied. This study exhibited that PVC/NiAl2O3/AlF3 (nPNA) nanocomposite is an effective catalyst for the synthesis of some organic derivatives. The results show that the as-prepared nanocomposite is an efficient catalyst and that PVC/NiAl2O4/AlF3 nanocomposite can be used in the next-generation of some organic reactions and faster production of various materials.

In this paper, the pressure distribution on the slippers of a mono-rail sled with vibration damping is investigated. Due to the many applications of sled testing in the aerospace industry, the study of system vibrations is highly noticeable. In this research, first, by mathematical modelling of the sled, the governing Equations are extracted and natural frequencies and vibration modes are obtained from the analytical method using the mass and stiffness matrix of the system. Then, using numerical simulation and validation methods with experimental results performed in wind tunnels, the modal analysis of the designed sled sample is performed. A difference of less than eight percent in both numerical and analytical methods proves the accuracy of the results. The results show that the role of the slipper in the vibrations created in the sled is very important due to the large torsional and transverse oscillations in different positions, and the highest static pressure occurs in the inner layer of the slipper.

Wheel/rail interaction is one of the most important research topics in railway engineering and generally includes impact response, vibrations, and track safety. Track structure failures caused by wheel/rail impact dynamic forces can lead to significant economic loss through damage to rails, ballast, fastening system, etc. Wheel/rail impact forces occur due to defects in wheels and/or rails such as wheel flats, irregular wheel profiles, rail corrugation, etc. A wheel flat can cause a large dynamic impact force as well as high frequency forced vibrations, which will eventually lead to damage to the train and track structure. In the present work, a freight train (3D model) was used to analyze the dynamic impact caused by the wheel flat using UM software. The effects of wheel flat depth and length (0, 0.2, 0.5, 1, 1.5, 2, and 3 mm) at two speeds of 50 and 80 km/h on wheel/rail dynamic forces have been investigated. The results showed that the presence of a wheel flat defect significantly increases the wheel/rail dynamic impact. For example, by increasing the wheel flat depth to 3 mm, the values of maximum force at speeds of 50 and 80 km/h have changed by about 235% and 400%, respectively.