مجله مهندسی ساخت و تولید ایران
سال ششم شماره 2 (خرداد و تیر 1398)

Nowadays Polymer Matrix Composites are replaced by metal as composite structures in petroleum industry due to their lightness and high strength ratio. Usually, the resin used to make these composite structures is a polyester resin and because of the use of this resin, in addition to its good physical and chemical properties, its price is lower than other resins. but one of the disadvantages of polyester composites is to expose it and to create a hazard in the petrochemical and refinery industries. Therefore, in order to solve this problem, four anti-inflammatory filler materials, including nanoclay with a weight percentage of 1,2,3%, aluminum hydroxide with a weight of 2,5,7,10%, magnesium hydroxide with a weight percentage of 2, 5,10,15% and zinc oxide with a weight percentage of 1,3,5,7%. In this research, the resistance to fire extinguishing by combustibility test (burning rate) and mechanical properties of composite by using tensile, hardness and impact tests is investigated. Finally, by comparing and checking the results, it was found that with 2% nanoclay weight, the maximum tensile strength, 58.33% improvement and with 39.11% hardness of glass / polyester composite would be improved. Also, by adding 2 wt% magnesium hydroxide, the impact strength is improved by 125%, and by adding 5% by weight of aluminum hydroxide, the burning rate of glass / polyester composite is reduced by 59.12%. It is the cause of the burning down rate in the sample containing aluminum hydroxide due to the reaction of hot forming and the release of water molecules.

In this research, the effect of graphene on the impact behavior of fiber metal laminates (FMLs) reinforced with hybrid of glass-Kevlar fibers, was investigated. FMLs including hybrid of glass-Kevlar fibers/ aluminum 2024 with different weight percent of graphene were made by hand lay-up method and subjected to impact charpy test. Also, before making composites, the surface of aluminum is modified using a chemical method to improve the bond between it and composite. The use of graphene reduced impact strength in the FMLs. Thus, by adding 0.25, 0.5 and 1 wt.% graphene to epoxy, 34.2, 41.8 and 58.86%, respectively, reduction were observed in the impact strength compared to the graphene-free sample. Increasing the amount of graphene in the composite, the degree and the probability of separation between the aluminum and the composite increased, and the FMLs showed a more brittle behavior. Thus, in the sample without graphene, the separation did not occurred, but with increasing graphene, the separation become more and finally for samples containing 1 wt.% graphene despite the separation between the aluminum and composite, brittle fracture in the composite and the subsequent failure of aluminum was observed. According to microscopic images, the presence of graphene and its agglomerate at the interface between aluminum and composite causes initiation and crack growth. Graphene also fills the cavities formed on the aluminum surface, which are formed to better interact with the resin by surface modification, and prevent the penetration of the resin and the proper bonding between the epoxy and the aluminum.

3D model reconstruction by stereo vision is divided into three steps: the camera calibration, matching, and triangulation algorithm. The matching can be considered as the most important and effective part of accuracy. In passive stereo vision, matching is done by algorithms that are often based on image features. These algorithms yield poor results in low or high textured regions. The matching problem can be resolved by adding a light source to stereo rig. In this paper, a 3D scanner is designed and built by combining passive stereo and a slit laser. The match point is obtained as intersection between the epipolar line and the laser stripe on the image. It is solved by mathematical formulas on pixel scale. Then the accuracy and ability of the system are investigated by relevant standards and the measurement indexes. The test samples have been scanned over 180 degree and the accuracy, repeatability, reproducibility and reliability of the system are reported. The results show an acceptable accuracy for small industrial parts using the proposed system.

The aim of this study is the using laboratory tests to evaluate the anti-wear performance, reduce friction and improve the heat transfer of powerful industrial oil in gearbox of rotary machines called Shell Omalla S2 G220 containing nano additives to the base oil. For this purpose, silica and alumina nano particles were selected to be added to the mentioned oil. In this study, concentrations of nano particles was 0.1, 0.2 and 0.4 wt% to prevent nanoparticle deposition problems on gear components. Surfactant Span 80 and an ultrasonic probe were used to disperse nanoparticles inside the base fluid and to achieve a stable nano-fluid. Then, the physical properties of the base oil and the nano lubricants including viscosity, viscosity index, density, pour point and ignition point were measured. The standard four ball wear test, friction coefficient and conduction heat transfer coefficient test were performed on the samples. After the experiments, the best combination of oil containing nanoparticles was selected in comparison with the base oil and charged to pump gearbox for the elemental analysis test. The results of this study showed 7.4% reduction in wear, 10% reduction in friction coefficient and 10.7% improvement in the conduction heat transfer coefficient. The results of the elemental analysis also showed abrasive elements of the internal components of the gearbox reduced significantly.

Thermoplastic composites are widely used in various industries due to its inherent properties. One of the most important parameters in the composite industry is the junction of composite components. In this research, the strength of joints of thermoplastic composites has been investigated empirically. Composite specimens are made of Commingled fibers which consist of glass/polypropylene, using a pultrusion process and as rectangular cross section profiles. For junction of the samples three methods are used including, bolted joint, ultrasonic weld and hot press. Based on the experimental results, the mechanical performance and failure of the ultrasonic weld and hot press methods were compared with the mechanical couplers. The results show that the ultrasonic bonded samples are better than the hot press method. In ultrasonic welding, the best strength is obtained for highest welding time of 1.8s, and for hot pressing the best result related to the maximum temperature of 200 ° C and the maximum pressure of 1.5 bar. The maximum force for bolted joint belongs to the specimens with a diameter to width ratio of 0.2 and a hole to width ratio of 1.25. Also, the results of the tensile test show that the junction strength for ultrasonic and hot pressing methods compared to the bolted joint increased by approximately 4 and 1.5 times, respectively.

Lost Foam Casting (LFC) with the ability to fabricate parts with complex shapes and without the need for secondary processes such as machining, has been very much considered. The foam used in LFC can have a direct influence on the defects that appear inside the piece and the quality of the product produced. In order to predict these defects and to study on proper foams for casting aluminum in this research, the process of foam casting for for the three polystyrene foam polystyrene and acrylonitrile butadiene styrene and poly lactic acid was simulated using Procast casting simulator software and the real casting process was performed for these three foam patterns. The Results obtained from mechanical properties tests and analysis of disadvantages of manufactured components in the simulation and experimental casting process indicate that the poly lactic acid foam can be used as a suitable foam for casting aluminum in LFC method with the least defects and the best mechanical properties than 2 more foams.