جستجوی مقالات مرتبط با کلیدواژه "impact strength" در نشریات گروه "مواد و متالورژی"

Two phases nanocomposite based polyamide 6/nitrile butadiene rubber reinforced by nano clay has gained wide application in various industries. Since friction stir processing is one of the fabricating methods for nanocomposites, in this paper, the response surface methodology (RSM) was used to investigate the effect of rotational speed, traverse speed and shoulder temperature on the tensile and impact strength. At first, a number of trail runs were performed in order to determine the limits of the process parameters. Analysis of variance was used to investigate the process parameters and mathematical models. Comparison of the results of these methods with experimental results indicated that RSM results had a lower percentage of error. Using a mathematical model, the effect of the mentioned parameters on tensile and impact strength was investigated to obtain optimum conditions. Results indicated that with an increase in rotational speed tensile strength and impact strength increased. With increase in traverse speed, tensile strength and impact strength decreased. Simultaneous optimization of the input parameters for maximization of the output responses led to a tensile strength of 31.3MPa and impact strength of 70.3 j/m was achieved at the rotational speed of 1200 rpm, traverse speed of 20 mm/min and shoulder temperature of 125 °C.

In this article the effects of carburizing heat treatment on girth weld with containing titanium oxide and titanium carbide nanoparticles (X-65 grade of gas pipeline) is evaluated. The charpy results show that in the carburized sample containing titanium oxide and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium carbide and titanium carbide nanoparticles), has been respectively increased by 6% and 42%. Also, the ultimate strength carburized sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium oxide and titanium carbide nanoparticles) has been respectively increased by 20% and 28%. The results show that the fatigue life in both carburized nano-alloy samples has been increased. The fatigue life in the carburized sample of titanium carbide nanoparticles has increased more than that of titanium oxide nanoparticles. The fatigue test results show that in the carburized sample containing titanium carbide nanoparticles compared to the tempered sample containing titanium oxide nanoparticles, fatigue life (150-N force) has been increased by 20%. In this loading the fatigue life (tempered sample containing titanium carbide nanoparticles compared to the no heat treatment sample) has been increased by 31%. The results show that the residual stress in both carburized nano-alloy samples has been decreased The hole drilling strain gage results show that in the tempered sample containing titanium oxide oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium oxide nanoparticles and titanium carbide nanoparticles), hoop residual stresses has been respectively decreased by 9% and 6%.

Nowadays increasing application of Sandwich panels in various structures as like as aerospace and ship is due to excellent high strength to weight ratio, sound insulation and thermal properties. The study of failure mechanism in composites and especially sandwich panels are investigated as cutting edge. In this research, the acoustic emission data of low velocity impact tests has been used to study the impact strength and various defects created in glass / polyester-polyurthane foam composite sandwich panels with 3 different types of Lay-up technique. The analysis of the acoustic data and the study of the force-displacement diagrams and the visual images of the specimens after the various impacts of 20, 38 and 60 J have been studied. For this purpose, the obtained force-displacement diagrams and acoustic energy in each frequency range during the impact tests are interpreted and their relation to the types of failure mechanism, such as matrix cracking, fiber breakage and debonding in this type of sandwich panel has been extracted. Also, by studying the force-displacement diagrams and investigating the maximum reaction force and elastic return strength, acoustic events in signals has been verified. The results showed that the impact resistance of the cross-ply lay-up was30 to 40% higher than other specimens in the all impact tests.

Polypropylene has a poor toughness and impact strength. So, it needs to modification for some applications. Addition of elastomers to PP to enhance the toughness is a traditional way, but it causes to decrease of the modulus and tensile strength of products. In this research a hybrid composite system including PP, thermoplastic elastomer, nanoparticle and compatibilizer was prepared by melt mixing method. The interaction effect of nanoparticle, thermoplastic elastomer, and compatibilizer on the tensile and impact properties of composites were studied using the experimental design technique; response surface methodology. The results of microscopy analysis showed that the blends were two-phase, where thermoplastic elastomer was dispersed phase. The elastomeric particle size was in the range of 100-400 nm and by increasing the rubber content, rubber particle size increased. Nanosilica dispersed in the presence of compatibilizer had a particle size between 40-90 nm, while the lack of compatibilizer created some agglomerations of nanoparticles. As elastomer content increased, the strain of failure and impact strength of nanocomposites increased, while the Young modulus and tensile strength were decreased. Addition of nanosilica to the PP in the absence of compatibilizer lowered the tensile and impact strengths. While, addition of nanosilica along with compatibilizer improved the tensile modulus of blends. According to the experimental design results, some mathematical relations were presented to predict the mechanical properties. The optimal hybrid nanocomposite had significantly higher impact strength than pure PP while their moduli were in the same order.

In this study, mechanical properties, including elastic modulus and impact strength of nanocomposites based on polypropylene and polyethylene, linear low-density blends, in the presence of titanium oxide nanoparticles have been studied. 0, 2 and 4 wt% titanium dioxide nanoparticles were added to the basic ingredients polypropylene / polyethylene linear low density with a fixed ratio of 60/40 wt. % to reach the final composition that was prepared using an extruder. Tensile and impact tests were carried out in order to determine the elastic modulus and impact strength of compounds. It was observed that the presence of titanium dioxide nanoparticles at 2 wt. %, elastic modulus and impact strength compared to the basic polypropylene/polyethylene linear low-density increase and the presence of higher level of titanium dioxide nanoparticles up to 4 wt. % decrease mechanical properties of compounds. It was also seen that usilng low weight percent of nano particles, increase impact strength of the samples up to 7 percenrt.

Epoxy resin has high capacity in order to properties enhancement. Since, polymer's morphology has a great effect on mechanical properties of polymers, there are many attempt to find relation between mechanical properties and morphology in polymers and it is an interesting area for researchers. To understand the relation between morphology and mechanical properties, knowing deformation mechanism and fracture is necessary. In this paper we aim to investigate the effect of liquid elastomer addition on fracture resistance of epoxy resin. For this purpose, the history of liquid elastomer addition and toughening mechanism have been reviewed.

In the this work, the effect of nano-graphene, as a platelet reinforcement, on the mechanical (tensile and impact strength) and rheological properties of general purpose polystyrene was investigated. Styrene-butadiene-styrene (SBS), was used as a compatibilizer and its effect on the improvment of nano-graphene distribution was also studied. The range of studied concentration were 0.01, 0.02 and 0.05 wt.% for graphene and 5 and 10 wt.% for SBS. The samples were prepared by melt blending method in a corotating twin screw extruder. The morphology of the samples was characterized through transmission electron microscopy (TEM) and X-ray diffraction (XRD). Further more, the mechanical properties of the all samples were analysied by tensile and impact strength tests. The rheological properties was investigated under small amplitude oscillatory shear (SAOS). The results of XRD and TEM showed a better dispersion and distribution of nano-graphene for the compositions having SBS. For all the nanocomposites with SBS the brittle failure disappeared and cold drawing area increased. The highest elongation at break and impact strength was obtained for the composition with 5 wt.% SBS and 0.05 wt.% graphene. Also, for this system the impact strength improved more than 6 times compared to pure PS. While mechanical properties improved even with low amount of graphene in the presence of SBS, the rheological measurement showed that complex viscosity reduced in these compositions which is a favorable phenomena from processing point of view.