In this study, using design of experiments, the effect of the total weight percentage of graphene nanosheets and nano clay and their weight ratio and weight percentage of compatibilizer (PPg-MA) on the Tensile properties of polypropylene/ graphene/ nano clay/ PP-g-MA nanocomposites were investigated. Design of experiments and analysis of experimental data with Minitab 16 software and response surface methodology were carried out. Making nanocomposites, based on the melt mixing was performed. All combinations and pure states materials were mixed together in a co-rotating twin-screw extruder and then injection molded into standard Tensile test samples. The Tensile properties of all samples including Tensile strength, Young's modulus and elongation at break was studied experimentally. Statistical models provided by response surface methodology had good agreement with experimental findings. Statistical analysis showed that with increasing the percentage of nanoparticles, Tensile strength and elongation at break of nanocomposites reduced. Also increasing the percentage of nanoparticles increase the stiffness of nanocomposites without compatibilizer, however, with the increasing amount of compatibilizer, reduced modulus. Compounds morphology by Scanning Electron Microscopy (SEM) was performed. Micrographes showed better dispersion of the particles in lower percentages.

The idea of combining low weight and good mechanical properties has led to efforts to develop a new light fiber/metal laminate (FML) in the last decade. FMLs are hybrid composites consisting of alternating thin layers of metal sheets and fiber-reinforced epoxy prepregs. In this study, the effect of fiber orientation on Tensile properties of this material is investigated both analytically and experimentally. An analytical constitutive model based on classical lamination theory by using Kirchhoff-Love assumption, which incorporates the elastic-plastic behavior of the aluminium alloy was applied. Test results show that fiber sheet, with zero angle in laminates, improve the Tensile strength. The composite layers with different fiber orientation change specimens' mode of fracture. Good agreement is obtained between the model predictions and experimental results.

In this study, the mechanical properties of composite produced using high -density polyethylene (as a matrix) and olive mill sludge (as filler) was studied. Composite samples were prepared using different content of olive mill sludge between 15 to 45% (w/w). Effect of maleic anhydride grafted polyethylene as coupling agent on the mechanical properties of the composites was also studied, and the properties of these composites were compared with composites without coupling agent. Material compounding was performed using extruder and then standard samples were fabricated using injection molding technique. Mechanical properties including the Tensile properties (Tensile strength and modulus of elasticity) and impact strengths were measured. The results showed that the Tensile modulus of elasticity of polyethylene/olive mill sludge were significantly higher than pure polyethylene samples and the highest Tensile strength was measured on samples prepared using 30% olive mill sludge and incorporating coupling agent. The impact strength of the composite containing 15% olive mill sludge was superior to pure polyethylene but at higher dosages of the sludge, the impact strength was reduced. Adding coupling agent (MAPE) to the mixture of the composite resulted in improving the mechanical properties of composites, which implies the development of matrix / sludge plant olive adhesion.

The study of mechanical behavior of the structural steel S400 under quasi- static and dynamic loading has been the subject of this investigation. In order to obtain different stress - triaxiality conditions the specimens were notched with 1. 1.5. 2 and 3.5 mm notch radius. The results of fractography show as the velocity of tension increases, ductility reduces and a ductile-brittle transition occurs under certain stress triaxiality or strain rates. The observation of load-time history diagrams and SEM micrographs show that, as far as the fracture is ductile, any increase in velocity leads to the reduction of fracture load which is presumed to be due to reduction of plastic deformation. in brittle fracture, however, the velocity increase results in increase in fracture load which is thought to he due to micro-cracks formed at different level near to the fracture surface of specimens the so called crack shielding and crack branching at high deformation velocities. Notch radius also proved to be highly effective on fracture mechanism which is due to notch strengthening. The change in grain size of some of the specimens shows that the ductile to brittle transition in fracture mechanism can be postponed by a suitable heat-treatment scheme up to a certain strain rate.

In this research trunk fibers of date palm tree were utilized as the reinforcement for epoxy matrix composites. Composite samples were produced using the fibers with the cut length of 1, 2 and 3 cm and with three levels of fiber volume percentage (FVP) by the hand molding method and were subjected to Tensile and three-point bending tests. The results showed that fiber length, in the range of the research parameters, didn’ t have a significant effect on the Tensile and flexural properties. In general, adding date palm fibers (DPFs) didn’ t improve Tensile strength compared with the pure matrix, which may be due to week bonds between fibers and matrix and existence of structural defects in the samples. A fairly good agreement was observed between theoretical Tensile moduli calculated using Tsai-Pagano model and experimental values. The results of bending test showed that adding 7. 5 volume percent of DPFs leads to the improvement in flexural strength of the composites, however, in the higher FVP (10. 7) it decreases which is due to the increase in fibers volume and thus less penetration of resin into them and deterioration of structural integrity of the samples. Moreover, by adding DPFs to epoxy the Tensile modulus of the composite increased. This increase was observed in samples containing 7. 5 and 10. 7 FVP with a maximum value of 3. 7 GPa in 7. 5 FVP (105 %enhancement).

Home-made single screw extruder was designed and constructed with screw length to diameter ratio 20:1 operating at different screw speeds ranging from 7-28 rpm and at different temperatures. The extruder was used to produce rod composite samples composed of low density polyethylene and short E-glass fibre. The effects of fibre contents and extruder operating variables on the Tensile modulus and ductility were investigated. The Tensile modulus increased with fibre weight percent up to 10.52 wt% as residual fibre content (20 wt% prepared sample before processing) and had a value of 827 MPa, then slightly decreased to lower values due to bad wettability and poor distribution/dispersion of fibres in the LDPE matrix. The clear decrease in fibre content after processing (residual fibre content) which is about 40-55% is due to the sticking of fibres in hopper or in the different extruder zones. On the other hand, ductility as percentage elongation-at-break decreased significantly at low fibre concentration then decreased in lower rate at higher fibre contents. Operating variables of the extruder were found to affect the Tensile properties of LDPE/glass fibre composites by affecting the interfacial adhesion between the two components. This effect was clear from the analyzed data of the modulus efficiency factor KE.

Oxidized Polyacrylonitrile fibers (OPF) are made by thermal stabilization of polyacrylonitrile (PAN) fibers and are used as precursors materials for production of carbon fibers. In this paper, effect of adding these fibers on Tensile properties of polymer matrix composites was studied. So thirteen kind weights of epoxy matrix composite reinforced with one of the carbon, Kevlar and glass fabrics including OPF by hand lay up method as four layers with different layering were made. For making of composites epoxy Bisphenol F resin and polyamine hardener were used and the resin to fiber fraction was selected as 60 percent. Then Tensile properties and failure cross section of them were studied. Results showed that by increasing OPF to carbon, Kevlar and glass fabric ratio; the Tensile and modulus strength decreased but in more than 50 weight percent ratios failure strain increased. Study of the fail cross section showed that composites made with one of the carbon, Kevlar, glass fabrics including OPF have lateral, explosive and edge delamination failure modes respectively and with increasing the OPF to carbon, Kevlar and glass fabric transverse failure mode happens.

The effects of Li on the microstructure and mechanical properties of Type A380 aluminum casting alloys have been examined. It is shown that, as the Li content is increased up to 0.1 wt.pct in the base alloy (Al-8.5 wt.%Si-3.5 wt. %Cu-1 wt.%Fe), Li successfully modifies the morphology of the b-Al5FeSi and eutectic Si phases from coarse intersected and branched platelets into finer and fibrous ones. The 0.06%wt Li-containing alloy exhibits higher strength and elongation, presumably due to both finer b-Al5FeSi and eutectic Si phases. In amounts greater than 0.06%wt lithium, Reduction of the strength and elongation can be due to increasing porosity and creation of other undesirable phases.