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Showing 149 results for Asadi


Volume 16, Issue 88 (6-2019)
Abstract

Carrot is a good source of carotene, water-soluble vitamins and amino acids. Carrot powder is used because of its high nutritional value, highly desirable flavor, sweetness and appropriate color to improve the quality of bakery products and all types of cakes. In this study, Balangu seed gum was used to improve the characteristics of carrot cake. So, firstly, the carrot cake batter containing different percentages of Balangu seed gum (at four levels 0, 0.5, 1.0, and 1.5%) was prepared and their viscosity was measured. Then the cakes were cooked and their physicochemical properties including weight, ash, moisture, volume, density, crumb color and sensory characteristics were measured. Carrot cakes batter was a non-Newtonian fluid and shear-dependent and time-dependent type. With increasing Balangu seed gum percentage in carrot cake formulation, the viscosity of batter increased (P<0.05). With increasing the Balangu seed gum from 0 to 1.5 %, cakes batters viscosity at shear rate of 40 s-1 ware increased from 16.93 to 32.88 Pa.s (P<0.05). The moisture content and volume of cakes were increased with increasing gum percentage (P<0.05). With increasing Balangu gum brightness of cakes increased due to increasing volume, in addition decreased yellowing of the samples (P<0.05). The L*, a* and b* indexes for sample containing 1.5 % gum were 82.00, 4.12 and 60.24, respectively. Carrot cake containing 1.5% Balangu seed gum significantly had more acceptability than other samples (P<0.05).
 

Volume 16, Issue 89 (7-2019)
Abstract

Layer by layer self - assembly technique is one of the newest methods to produce multilayer films relying on the placement of the liquid layers on solid substance. The purpose of this studies  is to manufacture multilayer kraft  based on protein biopolymers (zein and whey isolated protein) containing of green tea phenolic compounds by utilizing layer by layer self - assembly technique and evaluation antibacterial, physical-mechanical properties and release of phenolic compounds from coated kraft at refrigerator temperature in pH of 4.5 and 7. The minimum inhibitory concentration of green tea powder demonstrates that Escherichia coli (5mg/ml) compared to Listeria monocytogenes (10mg/ml) is more sensitive. The results of physical properties of krafts coated paper showed that thickness, grammage and bulk density increased by coating process. Also, the presence of zein in outer layer caused a significant reduction in WVP and increased air resistance. Evaluation of phenolic compounds release from coated krafts demonstrated that release rate in acidic food stimulant was more than the neutral stimulants. Also, release content of kraft paper with zein as outer layers respect to whey isolated protein was higher in the first days and continued in a longer time. Log reduction value of coated Kraft with active bilayer zein against Escherichia coli and Listeria monocytogenes was 0.25 and 0.06 respectively. According to the results of this study, active zein bilayer kraft is recommended as a carrier of phenolic compounds for the packaging of food products

Volume 17, Issue 1 (2-2013)
Abstract

Today the reverse logistics is one of the most important subjects in supply chain area. The control of return process beside the forward supply chain permits the organization to avoid of additional costs. This paper at the first approach introduces the major success factors which result from interview with experts in this area and although stemmed from major resources in automotive reverse logistics and then it utilizes the Interpretive Structural Modeling (ISM) methodology to understand the mutual influences among the barriers so that those driving success factors, which can aggravate few more factors and those independent factors, which are influenced by driving factors are identified. By analyzing the success factors using this model, we may extract crucial factors that influence the reverse logistics activities. It can be observed that there are some factors, which have both high driving power and dependency, thus they need more attention. Finally, the implications for practice and future research are discussed.

Volume 17, Issue 1 (1-2015)
Abstract

In this research, rehydration behavior of dried figs was studied at different temperatures (25, 60, 70, 80, and 90°C). The rehydration kinetic was examined using the four most frequently used empirical models, namely, Weibull, Peleg, first-order, and exponential association models. The Weibull model gave the highest coefficient of determination (R2) and the lowest values of root mean square error (RMSE), sum of squared error (SEE), and chi-square (χ2) was considered the best. In all models examined, the equilibrium moisture content showed statistically significant differences as compared to the rehydration temperature. The temperature dependence of kinetic constants was described in terms of Arrhenius relationship. The average activation energy for the four models was 24.362 kJ mol-1. During the rehydration process hardness of dried figs decreased, which was further confirmed by microscopic evaluation. Scanning electron microscopy (SEM) images of rehydrated figs indicated porous structure proposing the presence of free water.

Volume 17, Issue 1 (3-2017)
Abstract

In this article the vibration analysis of a viscoelastic cantilever beam with piezoelectric layers under aeroelastic force and base excitation is investigated. The beam viscoelastic material is assumed to obey the Kelvin-Voight model. Also the piezoelectric layers are located at the top and bottom beam surfaces with series connections. The aeroelastic force based on piston theory is considered to act as an external force on the beam and also the base excitation is assumed to be random. In this research the cantilever beam with two piezoelectric layers are considered as a mechanism to harvest the bending vibration energy. First, the Galerkin method is used to convert the governing partial differential equation into a set of ordinary differential equations. Then the resulted nonlinear ordinary differential equation coupled with electrical circuit equation of piezoelectric layer are solved numerically by Rung-Kutta method. Finally, by analyzing the response of the governing equations, the influence of the system parameters on the vibration behavior of beam and output voltage are discussed. Results show that the increase of fluid velocity increases vibrational energy system which leads to increase of both vibration amplitude and output voltage. In addition, it was shown that structural damping has a significant impact on the output voltage.

Volume 17, Issue 2 (5-2013)
Abstract

In this study, we developed a Joint Replenishment Problem (JRP) model; In addition, JRP was introduced through capacitated vehicle to send the parts. The model was developed as an Integer-non linear model. Cost function consists of the major ordering cost, the minor ordering cost and the holding cost. Previous studies had not considered transaction cost; therefore, we considered transaction cost, which depends on the number of different parts in the order. Demand for parts was considered as constant and the model was solved by using a genetic algorithm. For calculating variable, we developed the present algorithm in the literature. We solved the model for two conditions, with dispatch volume restriction and without dispatch volume restriction. The results showed that the dispatch volume increases both the cycle time and the total cost. The model was solved for one of the major manufacturers of SAPCO. We considered the problem with 12 strategic parts of this company. The model was investigated through the real data gathered from the SAPCO Company. Finally, for model validation, the results were compared with the traditional ordering system of SAPCO, in which the parts are ordered separately. It was shown that the proposed system has better performance than the traditional ordering system. Validation of Model was performed by the numerical example that has been solved in the literature. Keywords: Joint replenishment, Automotive parts, Genetic algorithm, Inventory.

Volume 17, Issue 2 (7-2017)
Abstract

Soil erosion, as a complicated natural phenomenon, is a global challenge threatening soil and water resources. Therefore, accurate understanding of soil erosion and sediment transport processes and their interactions is necessary for prediction of soil erosion.To distinguish between the dominant processes involved in soil loss, soil erosion has been classified into rill and interrill erosion. Rainfall-induced detachment and transport of sediment have a fundamental contribution to interrill and sheet erosion. Instead of the observation of natural rain showers, simulation of rainfall is widely used for better understanding of processes involved in soil erosion and their interactions. Rainfall intensity is variable during a natural rain showers, such that peak rainfall intensity in an event can exceed the mean event intensity by an order of magnitude. Variations of rainfall intensity during a rainfall event is called ‘event profile’. However, the available information is inadequate to understand its effects on runoff and soil loss processes. Thus, this study was aimed to quantify the effect of event profile on runoff and soil loss in rainfall-induced erosion. The experiments were based on the use of simulated rainfall on disturbed soils in a small laboratory detachment tray. Since kinetic energy controls runoff and soil loss processes, the effects on the soil surface of rainfall events with the same average intensity may be different. Hence to study only the effects of event profile, we used four simulated rainfall events, each with a different profile but all delivering the same total kinetic energy to the soil surface. The study was conducted in the rainfall simulation laboratory, Department of Hydraulic, Faculty of Civil and Environmental Engineering, Tarbiat ModaresUniversity, Iran. For this study, four events with different temporal profiles of rainfall intensity, each with the same kinetic energy, were chosen; (a) constant intensity, (b) increasing intensity, (c) decreasing intensity and (d) increasing - decreasing intensity. The soil samples used in the experiments were a sandy soil (soil A) and a sandy loam soil (soil B). Disturbed soil samples were collected, air dried, crushed to pass a 4.75-mm sieve, and thoroughly mixed. For each experiment soil was packed into a drainable detachment tray to a specific bulk density. The test area of this tray was 15cmwide by 30cmlong and 15cmdeep.Eliminating the effects of soil moisture on results, soil was saturated from the bottom using drainage outlet tube connected to a water reservoir 24hr before each experiment. The tray was setup at a slope of 0.5% and exposed to simulated rainfall events. For each simulation, runoff and sediment were sampled at regular intervals. Our results showed that while the peak runoff was affected by event profile for the two soil types, there was no significant difference in total runoff among rainfall events examined for both soil types. However, our experiments showed that soil type significantly affected the soil loss. In addition our results showed that models that derive interrill soil erosion directly from rainfall intensity can, therefore, be expected to perform poorly in predicting soil erosion from varying intensity rainfall events. It may imply that various and complicated mechanisms might be activated for runoff and erosion under natural rainfall conditions. Our results may indicate that negligence of event profile may lead to inaccurate understanding of mechanisms involved in runoff and soil erosion.

Volume 17, Issue 4 (1-2015)
Abstract

Objectives: CtxB (Cholera toxin B subunit) contributes to a vaccine's efficacy by stimulating production of the anti-CtxB antibody. Various attempts have been made to increase production of this antibody. Chitosan is a mucoadhesive polysaccharide that has tremendous potential for oral vaccine delivery in terms of its exclusive features that include biocompatibility, biodegradability, high charge density and non-toxicity. We investigated the potential for chitosan nano­fibers and nanocapsules as novel carrier systems for the oral delivery of CtxB. Methods: Antigen-containing chitosan nanofibers were prepared by electrospinning a chitosan/AcOH solution. Encapsulation of the antigen inside the chitosan nanofibers was confirmed through infrared spectroscopy analysis (FTIR). Guinea pigs were immunized with free antigen and CtxB antigen or antigen alone by direct administration of antigen-containing chitosan nanofibers into the buccal cavity. Serum immunoglobulin G (IgG) and intestinal immunoglobulin A (IgA) antibody responses were determined Results: The results indicated that antigen in the chitosan nanofibers or nanocapsules elicited very high IgA and IgG responses. No detectable IgA and IgG responses were obtained after oral immuniza­tion with CtxB. The results of the antibody titer were analyzed using the ANOVA and LSD tests. Conclusion: CtxB inside the nanofiber increased antibody production when administered orally. This system might be used for delivery of other antigens.

Volume 17, Issue 4 (7-2015)
Abstract

In this study, micromorphological properties of some samples collected from pedons polluted with petroleum refinery wastes and some adjacent unpolluted pedons were studied. After description of the studied pedons, disturbed and undisturbed samples were collected for physicochemical and micromorphological analyses. The results showed that the physicochemical properties (i.e. structure, bulk density, pH, EC and organic matter) of the soils polluted with petroleum wastes were strongly changed. Prolonged exposure of soils to the petroleum wastes resulted in the formation of specific and distinctive micromorphological features. Strongly developed granular microstructure and infillings of solid petroleum wastes alone or mixed with soil aggregates were some of the most important pedofeatures which were observed in deeper horizons. The existence of excrement belonging to different soil micro and macro fauna, coatings, hypocoatings, quasicoatings, and zones depleted from petroleum dissolvable materials at different depths were the other features throughout the pedons. The type of developed pedofeatures was correlated with the state of petroleum wastes and their fluidity in penetration, deposition, or dissolving and removal of soil compounds. This study demonstrated that micromorphology can be used as a powerful technique in characterization of petroleum polluted soils.

Volume 17, Issue 5 (7-2017)
Abstract

One of the most important machining processes in the field of orthopedic surgeries and biomedical engineering is the drilling process. Applying excessive forces on the bone tissue, it can be caused cracking and damage bone tissue during the drilling process. In this paper, it is produced an improved analytical model based on early work done by Bono and Ni, Chandrasekharan, and Lee to predict the thrust force in the bone drilling process. In this model, the cutting action at the drill point is divided into three regions: the primary cutting lips, outer portion of the chisel edge (the secondary cutting edges), and inner portion of the chisel edge (the indentation zone). All three regions have been investigated for the cutting process by the analytical model. In order validating the model, some experiments performed on the fresh bovine bone. Feed rate and rotational speed are adapted as the effective parameter in the drilling process, The statistical model to obtain the mathematical model and provide interaction diagrams of input variables experiments, to response surface methodology and experimental investigation of bone drilling have been offered. Comparing the analytical model and experimental results show good agreement. From both analytical model and experiments, it is can conclude that with decreasing feed rate and increasing rotational speed, thrust force on the bone tissue decreases.

Volume 17, Issue 5 (7-2017)
Abstract

Guidance of an underwater vehicle in the wake of target due to the complexity of guidance in water and also sensor limitations, is still the most important homing guidance method. Disadvantages of wake guidance can be mentioned as zigzag motion for rediscovering the wake in its path which according to the decreasing linear speed of approaching the target, sometime it doesn't reach the target and collision fails. Therefore various ideas, with both positive and negative aspects, have been introduced to improve movement in the wake path. According to complexity of the wake model and also its instability in order to extract its parameters, makes it a very nonlinear phenomenon and guidance in it is a problematic in underwater vehicle. Since the wake detection area by the sensor is not enough widespread, wake is just discovered in the near of itself. Hence the real wake path is not detectable and therefore advanced guidance method is not available. For this reason, it is suggested to use a method of unknown path tracking for the wake guidance. This guidance law consists of two parts of path estimation and nonlinear guidance. The estimation method is performed using particle filter that has the ability to estimate nonlinear paths. The stability proof of nonlinear guidance method is done by Lyapunov.

Volume 17, Issue 6 (11-2015)
Abstract

Sustainable coastal fishing management includes different components and factors. One of the practical initiatives to achieve sustainability is to evaluate or measure different criteria of sustainability and measuring sustainability of each system needs its own indicators. This study aimed to investigate different criteria of sustainable coastal fishing management in Beach Seine Cooperatives (BSC) in Guilan Province of Iran and to analyze different aspects of sustainable coastal fishing management in the cooperatives. The statistical populations of the research were 58 active BSC’s of Guilan Province, 36 of which were determined through formula of Cochran and were selected randomly. Sampling was done from September 2011 to April 2012.The method used in this research was descriptive-survey research and data was gathered through questionnaires. Reliability of the questionnaire was confirmed with Cronbach's Alpha that was calculated for each of the seven criteria of the questionnaire (Cronbach's α coefficients ranging from 0.78 to 0.93). The construct validity was analyzed with a factorial analysis of the main components whose applicability was verified by means of Bartlett’s test of sphericity and the KMO test (acceptable with values above 0.6). Technique used in this study was Multi-Criteria Analysis (MCA), a general approach that can analyze complex problems involving multiple criteria used in sophisticated systems such as fishing. MCA is a decision-making tool to analyze and evaluate multiple indicators under a participatory group decision-making environment. Seven variable criteria of sustainability indicators including ecological, economic, social, institutional, coastal management, restocking the reserves, and resource conservation indicators were investigated. According to the results, social sustainability in BSC cooperatives had the best situation among different criteria of sustainable coastal fishing management, while the economic coastal management and resource conservation criteria had unfavorable status of sustainability.

Volume 17, Issue 10 (1-2018)
Abstract

Partial differential equations are needed in most of the engineering fields. Analytical solutions to these equations cannot be derived except in some very special cases, making numerical methods more important. Alongside advances in science and technology, new methods have been proposed for solution of partial differential equations, such as meshless methods. Recently, the generalized exponential basis function (GEBF) meshless method has been introduced. In this method the unknown function is approximated as a linear combination of exponential basis functions. In linear problems, the unknown coefficients are calculated such that the homogenous form of main differential equation is satisfied in all points of the grid. In order to solve nonlinear equations, Newton-Kantorovich scheme is first used to linearize them. The linearized equations are then solved iteratively to obtain the result. In this paper, time dependent problems in solid mechanics have been investigated. In order to examine performance of the proposed method, linear and non-linear problems in solid mechanics are considered and the results are compared with analytical solutions. The results show good accuracy (less than 1 percentage error) of the presented method.

Volume 17, Issue 101 (july 2020)
Abstract

Essential oils (EOs) are highly aromatic and volatile compounds obtained from plant material, which are also known as secondary plant metabolites. The plant active ingredients are produced under the control of genetic processes; however, its production in the plant varies under the influence of some environmental factors. Therefore, in the present study, the chemical analysis and identifies dominant essential oils compositions from Sage) Salvia officinalis L.) are investigated in Ardabil province, Iran. Sage plant (Salvia officinalis L.) were collected and After drying at room temperature, samples extracted by method of water, essential oils yield 0.5% was obtained. Chemical analysis of the collected Salvia officinalis species was performed using a gas chromatograph (GC) coupled to a mass spectrometer (MS). Chemical analysis results showed that the plant contains 114 secondary chemical components, among which Camphor Bicyclo [2.2.1] heptan, compound was identified as the predominant essential oil (14.47%). Comparing the study results with other samples collected from different parts of Iran and world reveals some significant similarities and differences in chemical structure and dominant composition of the medicinal plant. In addition, the geographical features and environmental conditions influence the change of secondary metabolites in various plants, Therefore, the researchers need to pay attention to this issue while identifying the plant essential oils.
 

Volume 17, Issue 102 (August 2020)
Abstract

Chicken nugget is one of the most popular convenience food in the world. Because of high-fat content in preparation of nuggets with regular methods that causes obesity and other related diseases, other techniques like pretreatment using gum and drying came into attention. In this study, chicken nuggets coated with batter containing Balangu gum (0.25 and 0.5%) were cooked by infrared-frying method in three heat fluxes of 18.5, 21.6, 24.7 kW/m2 for 12 minutes. The effects of the process and gum concentration on moisture content, fat, total weight loss, color parameters (a*, b* and L*) and texture properties of this product were investigated. The sample containing 0.5% gum had the highest moisture content (51.80%) and by increasing the power of the infrared radiation, moisture content decreased. The lowest fat content was related to the sample with a heat flux of 24.7kW/m2 containing 0.5% Balangu gum. By decreasing gum concentration and decreasing the power of the infrared radiation, fat content of samples increased. Also, Color attribute L* which shows lightness had the lowest amount in the control sample because of higher heat during the cooking process. The hardness of chicken nugget in various treatments did not change significantly, which can be important in consumer acceptance, but cohesiveness of samples treated using infrared-gum treatment showed significant difference compared to the control sample (P<0.05).

Volume 17, Issue 102 (August 2020)
Abstract

In recent years there has been extensive research into the use of edible coatings in food packaging. Today, the use of edible coatings has increased due to consumers' desire to purchase products that maintain their freshness. In this research, edible coating based on different percentages of Spirulina platensis (0.5-1.5%) with constant percentages of gelatin powder (2%), chitosan powder (1%), and glycerol as lubricants was used. Physicochemical properties such as moisture content, pH, Acidity, color, total phenol, nutritional properties such as protein content, iron content and ascorbic acid content, sensory evaluation and microbial characteristics of control and other treatments were evaluated at days 0, 7 and 14 after production. The results of chemical tests showed the moisture content, acidity, phenol level were increased with increasing of Spriulina platencis in different treatments. The results of colorimetric analysis also showed that by increasing the percentage of spirulina the transparency of treatments decreased. The results of nutritional evaluation showed that there was a significant difference in protein, iron and ascorbic acid levels with increasing of Spirulina platensis (p <0.05). Increasing the amount of spirulina platensis was effective on the microbial growth as well as the taste and color of the treatments, which was diagnosed by sensory evaluation.

 
Fazel Asadi Amjad,
Volume 18, Issue 1 (2-2011)
Abstract

Time and perception are two major concerns of Woolf in many of her novels and short stories. Woolf as a modernist writer often tries in her fiction to find an epistemological solution to the problems of mortality and immortality, appearance and reality and diversity and unity and she succeeds, I think, by taking on a kind of perception that is intuitive and temporal. For her, true perception is time-bound, but like Bergson she divides time into mechanical and organic one. In her writing, she often associates symbolically the former with death and aridity and the latter with life and fertility, presenting them in the images, to name but a few of keyboard of a piano or alphabetical letters and tree or green shawl and dress, respectively. Evidently, in her views and the solution, she finds to the problems of time and perception Woolf is influenced by Bergson whose theory of time has also influenced so many other modernists. This paper elaborates on the relationship between time and perception in the works of Woolf, especially in her two major novels To the Lighthouse (1927) and Mrs Dalloway (1924) and her short story “An Unwritten Novel” (1921).

Volume 18, Issue 1 (may 2018)
Abstract

The experience of Northridge and Kobe earthquakes have demonstrated poor behavior of welded beam-column connections due to deficiency of welds. After numerous studies, proper method for welding of connection has been proposed. Yet, the proper procedure and detailing of welding usually do not follow due to insufficient supervision of welding process, therefore deficiency in the connection of a real steel structures is expected. One of the most common moment resisting connections in the steel structures is connection with top and bottom plates which is the subject of study in this paper. Among the possible deficiency in the welds, lack of penetration (LOP) and the lack of fusion (LOF) are two main deficiencies in these connections. In this study, the cyclic behavior of three steel moment resistant connection with LOP deficiency in the weld have been studied by analytical method. The deficiency was considered on the top, bottom and both top and bottom plates and results are compared with the original connection. The connections are selected from three different size (small, medium and large) to evaluate the size effect on the results. The connections are modeled by ABAQUS finite element software. The molding of the initiation and growing of cracks in the connections was conducted by the extended finite element technique (XFEM). In the beginning, to examine the efficiency and accuracy of modeling, an experimental study was used for verification. The hysteretic behavior of specimens was studied under the typical loading protocol of SAC and based on that, the constitutional behavior of connections was developed. The backbone curve of each connection was obtained and the curve of each deficiency was compared with each other and the original connection. Results show that in LOP deficiency, the crack is formed and grow in the welds which ultimately lead to rupture in the welds. In general, the deficiency reduces energy absorption, moment and ductility capacity of connections. The result in different beams size are very close which suggest that the size of the beam has not effect on the reduction of the capacity. To estimate the reduced capacity of connections with deficiency in the real cases, reduction coefficient is introduced and presented for yield and ultimate moment and yield and ultimate rotation. In general, it can be concluded that LOP cause 30% reduction in the yielding and ultimate moment capacity of connections and 20% reduction in the yielding and ultimate rotation of connection. In addition, to study the effect of different deficiencies on the reduction of absorbed energy, the area under the hysteresis curve are calculated and compared. The results indicated that the connection with LOP in both plate have the highest reduction in observed energy which follows by the LOP in top and then bottom plate. This results in addition to the value of reduction in capacity and ductility of connections indicated that LOP in the top plate cause the connection to fail in shorter cycles compare to other cases. Therefore, it is better to have not the LOP in top plate which needs special attention in welding of that plate which usually conducted in the workshop with the least possible of supervision.

Volume 18, Issue 1 (may 2018)
Abstract

Reduction of social and financial losses and rehabilitation in important buildings as a result of terrorist attacks and accidental blast is vital. In this regards, using concrete slabs as a protective shield is one of the main methods of protection. Currently, many methods have been used for improve the behavior of this element such as FRP sheets, fibers, high strength concrete and composite concretes. Using these methods is not favorable due to several reasons such as: increase the dead load of structure, increase the cost of project, employ high-tech methodology and needed high skilled worker for implementation. Therefore, for ordinary projects and households, these methods may not cost effective and a simple and more cost effective method needed to be implemented. In this paper, the behavior of RC slabs reinforced with steel wire mesh which is easy to implement and cheap was studied analytically under blast loads. To this goal, effect of different parameters such as number of wire meshes, slab thickness and concrete strength on maximum slab displacement, damage areas and performance of slabs were studied numerically. First the model was built in general FEM software and calibrated to existing experimental and analytical studies. Then numerous slabs with different thickness (40, 60 and 80 mm), concrete strength (30, 40 and 50 MP), different layers of wire mesh (0, 1, 2, 3) where considered and analyzed with a general FEM software. The results have shown that increasing of slab thickness, concrete strength and adding different layers of wire mesh reduces the slab displacement and the damage area. Due to higher damage in thin slabs (4 Cm) and low concrete strength (30 MP), the effect of adding wire were higher. Generally, the slab thickness is the most important parameter in controlling the damage in the salbs under blast load, but increasing the concerete strength and adding different layer of wire mesh, reduced this damages. From the viewpoint of slab performance, which is defined by the amount of displacement and plastic rotation of hinges, it is observed that the performance of thicker slabs (60 and 80 mm) were in the life safety or immediate occupancy state which is quite good for ordinary purposes. Using wire improved the performance of these slabs. In the thinner slab (40 mm) the performance of slab with concerete strength of 30 MP, was not satisfy the life-safety requirement, therefore it is needed to improve this performance. The result of analysis were shown that adding different layer of wire mesh improve the performance of the slab and limits that. Although different layer of wire mesh did not have significant effect on improvement of the slab performance, it limits the performance of slabs to the code’s value in several occations. Generally, it can be concluded that adding the wire mesh could reduce the amount of damage to the slabs under blast loads, which was expected results, but this reduction, is not that much significant for many occations. This method is more effective in thin slabs with lower concerete strnght.

Volume 18, Issue 3 (5-2018)
Abstract

In this paper, the single point incremental forming (SPIF) of friction stir welded (FSWed) 5083 aluminum alloy sheets are investigated experimentally and numerically. The aluminum sheets with 2mm thickness are friction stir welded with the same FSW parameters. In order to obtain the effect of FSW on the formability of SPIF, the base sheets and FSWed sheets are formed to conical shapes with different forming angles and then the limiting wall angles are determined for each condition. The experimental results indicate that the limiting forming angle of FSWed sheet is not so much different than the base sheet and FSW does not have a negative effect on the sheet metal formability in SPIF. To study the effect of SPIF and FSW in mechanical and microstructural properties of the formed parts, the effects of these process on the grain size and micro-hardness is investigated. Furthermore, the incremental forming is numerically simulated using the ABAQUS software and the sheet thickness distribution, obtained from the simulation, is compared with the experimental results. After verification of the numerical simulation model, the effect of FSW on the thickness distribution and strain distribution in SPIF is studied. The results indicate that in weld region and base metal region, the distributions of thickness and major strain are uniform while the distribution of minor strain is non-uniform.

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