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Abstract- In this study thermal properties of Woofd Plastic Composite (WPC) were measured using Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG). The investigated specimens were: high density polyethylene (HDPE), wood particle and WPC. DSC test showed that adding wood particle to HDPE matrix cause a decrease in the area under the DSC curve. The result revealed that WPC have a heat of fusion less than unfilled HDPE and are more stable when temperature increases. The melting point temperature did not changed significantly. The heat of capacity of HDPE, wood particle and WPC were obtained using DSC test. An enhancement in the temperature led to a linear increase in the heat of capacity of wood particle. HDPE and WPC showed similar behavior too. But WPC specimen had a heat of capacity more than wood particle and less than HDPE. The heat capacity of WPC by rule of mixture has a good agreement to experimental results. Adding wood to plastic identify higher WPC thermal stability by TG. The extrusion process was modeled and the throughput temperature was calculated using themal equation. The model was used to carry out high throughput by incresing screw speed. These help to produce defectless extruded WPC in continous production.

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The tadpole shrimp of genus Triops is a well-known living fossil whose fundamental morphology has been unchanged for 220 million years. We collected specimens of Triops cancriformis in temporary water bodies near the southern part of Urmia Lake (in the Fall of 2005). Some biological characteristics of this Triops were investigated. The feeding re-gime of T. cancriformis was found to be related to the fauna and flora of the temporary pools. Invertebrates and animal detritus were found to constitute major part of the feed-ing regime. The existence of Triops cysts and particles in the gut also showed certain de-gree of cannibalism. Morphological and histological investigations showed that the popu-lation of T. cancriformis was female and there was only one male among 400 samples col-lected. Observation of sperm among follicle ducts of a few samples indicated some degree of hermaphrodity, but the animal seemed to reproduce mainly through parthenogenesis. Fecundity, varying from 100 to 2500 cysts, was with a few exceptions related to the body size. The average cyst diameter was 40085 m.

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SMA training in constant stress causes stabilized response. Since in engineering applications alloy stress isvariant,the aim of this study is to investigate SMAs response in some range of stresses.In this study, six SMA wires were trained in 30, 50, 100, 150, 200 and 250 MPa. At the next step, their recoverable strains were evaluated in 0-250 MPa.It was found that SMA wires that trained in 30, 150 and 200 MPa showedtow-way shape memory effect (TWSME). Also recoverable strains in stresses higher than 100 MPa are independent of training and in order to have better performance, stresses higher than 100 MPa are required. SMA wires trained in 180 and 200 MPa resulted in unstable behavior.

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In this research drying kinetics, moisture diffusivity and determination of most appropriate mathematical modeling and activation energy of Mazafati dates species were studied under a cabinet solar dryer.Drying experiments were carried out at three air temperatures of 50, 65, and 80ºC and three air velocities of 1.0, 1.5, and 2.0 m/s. Effect of temperature and air velocity evaluated on drying time and shrinkage by using a completely randomized statistical design. Results showed that the effects of temperature and air velocity are significant on drying time. The average increase of temperature from 50ºC to 80ºC caused the drying time to decrease by 70.77%. For determination of most appropriate model, the highest value of R² and the lowest values of c² and RMSE were used. For mathematical modeling, eight empirical models were fitted on experimental data and the best model was selected. The result of regression analysis showed that Page model has the best fitting with data. Moreover, the lowest and highest value of moisture diffusivity were obtained as 4.309×10^-10 and 0.0188×10^-9  m²/s at temperatures of 80^°C and 50^°C, respectively. Also the values of activation energy in the drying of Mazafati dates species were found between 31.22 to 42.27 kJ/mol.  

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In this study, the corrugated composite beam is actuated by shape memory alloy wire (SMAw). SMAw was placed on the surface of composite beam. Martensite to austenite transformation occurs by increasing of SMAw temperature. After transformation, SMAw length decrease and beam actuated. Beam displacement, force and current are measured and by A/D board transferred to computer. For evaluation of temperature in SMAw, the Heat transfer differential equation is used. Also Brinson’s model is used for modeling of SMA behavior. The results show that SMA behavior in Brinson’s model is good agreement whit experiments. But in lower temperatures than martensitic transformation state, the SMA stress is equal to zero in experiment unlike Brinson’s model. Also considering the SMA training and DSC test, for some temperatures in the experimental results, the start and end transformation temperatures are different to Brinson’s model. The results show as using SMAw in the corrugated composite, smart structures can be achieved that in corrugation direction is irritable, whereas in Perpendicular to the direction, corrugated composite bending strength is high that lead to using this structure in engineering application.

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In the pultrusion process, continuous fibers reinforcement in roving forms are drawn through a pultrusion die. Therefore, the fibers reinforcement in the final product are generally oriented in the longitudinal axis. In this research, for manufacturing of composite rods, on the basis of previous studies and researches, the E-glass fiber-polyethylene prepregs were produced firstly. Then due to the Design of Experiments (DOE), the pultruded rods with unidirectional and helically-wound layers were produced by using the prepregs. In this study, mechanism of the pull-winding process is created as a secondary process during the main process to improve the mechanical and physical properties in the other directions. One of the most important issues in the thermoplastics pultrusions is the fibers impregnation quality with the polymer base. The fiber volume fractions of the productions are found by the burn tests. The density of the specimens is found by the liquid displacement method. The microscopic images were taken from cross-section of the pultruded rods to investigate the fiber impregnation and the void distribution. Due to the surveys conducted, the fiber volume fractions in the pultruded rods was increased, using the pull-winding technique, and also the void content of these rods was decreased.

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Nowadays, study on the bistable composites due to the using of them in morphing structure has become more and more important. Unidirectional composites have different thermal expansion coefficients in longitudinal and transverse directions. This difference in thermal expansion coefficient is caused the composites to bend like bimetals due to the raise in temperature and bistable composites are derived. In this research, in order to study effects of fabrication method the square-shaped bistable composites laminates with asymmetric layers were prepared and investigated. Different kinds of bistable composite laminates were fabricated by thermoplastic PVC and glass fibers and the effects of composites laminate's dimensions and mold's temperature were investigated. The maximum height of the bistable composite laminate is selected as the output of experiments. The results derived from ANOVA analysis showed that the dimensions of the laminates has the highest effects on bistability height and the effects of mold temperature are very low. It was also determined that with the larger dimensions of composite laminates and lower mold's temperature, the heights of bistability were higher. Also, these bistable composite laminate were simulated in ABAQUS and the simulation results were compared with the experimental results. The results indicated that simulation method anticipated the higher bistability height rather than the experimental results and the difference between these results are less than 10% in all specimens.

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This paper presents a numerical model for predicting pressure, impregnation and pulling force in pultrusion die which circular cross section witch two reinforcement fibrous tows pass through it. Pulling force and degree of impregnation are the most important parameters associated with pultrusion process that determine production cost and quality of pultruded profile respectively. Main idea in this approach is obtaining characteristic equations in purely polymer region and purely fibrous region and establishing relations between them by using conservation law. The superiority of this approach compared to other methods is ability to considering both straight and conical part of the die, calculating pulling force, ability of investigating influence of a variety of parameters such as those associated with die geometry, material rheology and process parameters. In this paper the influence of fibers position and fibers radius on pulling force, impregnation and pressure inside die is investigated. Due to the ability of simultaneous calculation of force and impregnation, this model can be used to establish an optimum condition between cost and quality of produced profiles.

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In the present study, the available methods of predicting the sound transmission loss through infinitely long double-walled cylindrical shells with porous layer are developed to analytically compute the sound transmission loss in triple-walled sandwich cylindrical shells in the presence of an external fluid flow. Loves’ shell theory and Lee’s method based on Biot’s theory are used to describe the motions of thin isotropic triple-walled cylindrical shell and wave propagation in the porous media, respectively. The vibro-acoustic problem for the most complicated configuration of the triple-walled sandwich cylindrical shell is formulated and solved by the transfer matrix method with appropriate boundary conditions. The total transmission loss in a diffuse field is calculated and validated by considering the effect of total internal reflection. Then the transmission loss of triple-walled cylindrical shell is compared with its double-walled counterpart of the same weight. The results generally show a superior performance in sound insulation for the case of triple-walled shell, considerably at mid-high and high frequency regions. Moreover, ten typical configurations, which involve different coupling methods between the walls and porous layers, are considered to completely study the effect of various configurations on the sound transmission properties. As will be shown, a configuration with the largest number of air gaps in its structure provides better performance in sound transmission reduction almost at the entire frequency range. The effects of external fluid flow and azimuthal angle are also studied on the sound transmission loss.

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In this paper, an investigation was done on modulated IR thermography for detection and evaluation of artificial subsurface defects in composite materials. In this method, In order to stimulate the test specimen, the heat flux is applied periodically over the surface of the specimen and the thermal response is decomposed by the Fourier transform method in order to extract its amplitude and phase images. The non-uniform backgrounds in the obtained images often reduce detection ability, In order to improve the evaluation of this method, an edge detection filter and a morphological attribute profile were applied to the images. Experimental investigations were applied for different frequencies on specimens made with common controlled defects in composite materials. Interpretation of the results were utilized in the calculation of defects’ size and location, it was observed that in specimen with 2 mm thickness delamination defect with a minimum size of 20*10 mm, dry fiber and inclusion defects with a minimum size of 50*40 mm is detected and is measured. The same geometry and the artificial defects used in experiments, were considered in the finite element analysis. The results of finite element analysis were found to have an agreement with the experimental results and can be used to find the optimum parameters in investigation of modulated IR thermography for detection of defects on composites.

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Memory-shaped polymers are thermally induced subsets of intelligent materials that require thermomechanical behavior to accurately understand their function. In this study, polymeric memory scaffolds were fabricated using polylactic acid by molten labeling method in three reticular honeycomb, rhombic and elliptical form. Parameters such as longitudinal dimensions and wall thickness of printed scaffolds compared to the designed scaffolds and solutions were presented to enhance the printing accuracy. Built-in scaffolds can be a good option for stent use. Formal memory properties experiments with 30% axial strain were performed to study the shape memory behavior of polymer on scaffolds. The results showed that the percentage of shape recovery in scaffolds with symmetric angular grid networks was higher than elliptical reticular stents. The minimum percentage of longitudinal recovery belonged to the elliptical reticular stent and was 74.5%. The percentage of longitudinal recovery of honeycomb and rhododendron reticular stents is approximately equal to 80.3%. The results of this study can be used to optimize the stent grid geometry to increase the retrieval force to resolving vascular clogging.

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Bistable composites have gained increased attentions in industry, especially in the aerospace industry, due to their unique feature of shape-changing without the need for continuous energy. The advantage of using these structures is their ability to package in small size, whilst deploying in long lengths and high stiffness ratio along the length. This unique feature, along with the advantages of other fiber reinforced composites such as high strength, light weight and high rigidity, has made them a good choice for many applications such as deployable booms and antennas for satellites.
In this paper, the bistablility of shell structures at different time-temperature conditions are investigated. To explain the mechanical behavior of the Bistable Tape Springs (BiTSs) in different conditions, an analogous 2D model consist of rigid linkages, elastic springs and viscous dampers is proposed. The relationships between the force and energy through the transition path for the 2D model were established and the non-dimensional strain energy paths for different initial parameters were obtained, accordingly. As a case study, four BiTSs made of composite materials are fabricated and subjected to a particular thermo-viscoelastic condition to verify all stability behaviors of the 2D LSD model under thermo-viscoelastic conditions.

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