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Go to Editorial ManagerThis paper deals with the elastic stability of a column bolted at its mid-height to a simply supported square plate and subjected to a concentrated load, using energy method. A uniform homogeneous column is assumed to be pinned at both ends. From symmetry considerations, half of the column is modeled by making the plate acting as a torsion spring on the column at its mid-height. The column length and cross-section, plate dimensions and thickness, and the material properties for the column and the plate catch the interest of the author. The problem is solved by using energy method and ultimately, the elastic buckling load is found. The analytical elastic buckling load is compared with a numerical solution obtained from finite element method using SAP2000. The numerical results agree with the analytical solution. The finite element model is refined to catch the actual effect of the bolted plate on the elastic buckling load. It has been found that the elastic buckling load is increased due to the increase in the rotational stiffness provided from the plate.
A theoretical and experimental investigation pertaining to the buckling behavior of slender fiber reinforced polymer columns subjected to axial loading under varying temperatures (from room temperature to 50?). Two groups of composite materials were used for manufacturing of test specimens, the first consist of perlon fiber as a reinforcement and acrylic resin as a bonding matrix, while the second consists of a combination of perlon and carbon fibers as reinforcement. The composite specimens were fabricated by vacuum molding technique and cut according to ASTM D-638 for conducting tensile test. The data from tensile test were used to calculate the effective slenderness ratio and defining the column as Euler buckling column. An experimental rig was designed, manufactured and calibrated to study the effect of thermal and buckling load subjected to columns.Numerical analyses pertaining the buckling behavior for both groups were conducted. The results show that the temperature has a considerable effect on properties of fiberreinforced polymer composites where the value ofcritical load and Young's Modules decrease withthe increase of temperature for both groups.Perlon & Carbon reinforcement composites gavebest mechanical properties, which make them thebest candidate to improve the buckling resistancecharacteristics of composite materials.
This research deals with the extent to which corrosion affects the behavior of buckling for 6061-T4 aluminum alloy under increasing compressive dynamic loads. Two types of columns, long, and intermediate were used.1% of the length column is the allowable lateral deflection. This is called the critical buckling of the columns. For the purpose of calculating the critical deflection, a digital dial gauge was used and set at a distance of 0.7 of column length from the fixed end condition for the column. The experimental analysis revealed that the corrosion time negatively affects the mechanical properties of materials such as the corroded specimens of 60 days (The least time to observe the corrosion of aluminum in the soil) which have approximately 2.7 % reduction in ultimate strength compared with the non-corroded specimen. Increasing the corrosion time reduces the critical load such as the maximum reduction will be 4.24% in critical buckling load for 60 days’ corrosion time. The results obtained were experimentally compared with the theoretical formulas of the Perry-Robertson and Euler-Johnson formula with the results of the ANSYS. It was found that the Perry-Robertson formula has a good agreement with the experimental results with a safety factor of 1.2, while the Euler-Johnson formula agreed with the experimental results taking a safety factor of 1.5. The ANSYS results showed a good agreement between the measured and calculated values by taking 1.1 factor of safety.
The intention of this study was to explore the efficiency and feasibility of adsorption of Reactive Blue dye (H3R) used in textile industries using Raw wheat straw (RWS) and Modified wheat straw (MWS) as a low-cost adsorbent. Wheat straw was modified using cationic surfactant (CTAB) to study the improvement of dye removal. The properties of Raw and Modified wheat straw are studied by means of Fourier transform infrared (FTIR) and scanning electron microscope (SEM) analyses to determine the functional groups and the nature of their surface. Continuous experiments were done by fixed-bed column to study the characteristics of the breakthrough curve using different bed heights and flow rates. Results showed that the breakthrough time increases with increasing bed height and decreasing flow rate, in turn results into higher removal capacity. Results also showed a higher flow rate lead a lower adsorption capacity due to insufficient residence time. Bed depth service time model (BDST), Adam-Bohart and Thomas models were used to predict the breakthrough curves and to determine the adsorption capacity of the column. The highest bed capacity of 12.95 and 32.2 mg/g for MWS was obtained using 10 mg/L, 10 cm bed height at 10 mL/min and 30 mL/min respectively.
The oil industry has a direct impact on the economic feasibility of other sectors and is considered to be the most important energy source used to turn the wheels of other industries. Therefore, it was necessary to pay attention and continuously develop this industry, to find the best modern techniques for designing, pre-commissioning and controlling process, to improve efficiency, preserve energy and achieve the highest production of costly components with the highest purity of the product. This study aims to provide a literary analysis of the stages of development and progress of the dynamics and control of the petroleum industry, in particular the distillation column, because it is multivariable with high interaction between control cycles, nonlinear behaviour and large gains. Control processes have undergone many developments and modernizations to achieve the best results. Various control methods have been used, ranging from simple proportional-integral-derivative controller (PID) to advanced control strategies such as model predictive control (MPC), multivariate model predictive control (MMPC), fuzzy logic control (FLC), quadratic dynamic matrix control (QDMC), artificial neural network control (ANN) and other advanced control techniques. The authors concluded from the review that the advanced control strategies superior than the conventional methods.
Eight RC circular hollow columns (external diameter = 220 mm, internal diameter = 100 mm, length = 1000 mm and the hollow part = 700mm) casted and strengthened with ferrocement fibers composites to illustrate the behavior of these columns under concentric and eccentric axial compression force. Two columns where used as reference columns, which were repaired after failure to be tested as retrofitted columns. Six specimens were strengthened with one and two WWM layers as required. The variables considered included number of the WWM layers (N), the loading configuration and the eccentricity value (e) of loading. The ferrocement thickness was constant at 20 mm in all retrofitted and strengthened specimens.The test results revealed that the maximum increase in the ultimate concentric loads were 67% by strengthening the reference column with two layers of WWM, and the maximum increase in the ultimate eccentric load of columns was 78% by increasing of the WWM from one to two layers. For a constant number of WWM layers, the change from concentric to eccentric force caused a decrease in the ultimate load value attaining 73.5% for one- layer WWM strengthened columns. The failure of columns occurred by yielding of steel reinforcement followed by concrete crushing (i.e. tension failure).
In this paper, the cross section behavior of reinforced concrete columns made of normal and hybrid reactive powder concrete (hybrid by steel and polypropylene fibers) under concentric and eccentric vertical load was study. The casted columns were cured in two different type tap water for 28 days and chloride water for six months. Chloride salts with concentration was 8341.6 mg/l. Three variables were adopted in the experimental program; concrete type, curing type and the eccentricity of vertical load. Twenty (120x120x1200) mm columns were casted and tested depending on these variables. The different eccentricities were (0, 50,100 and 150) mm and where (e/h) were (0, 0.42, 0.83 and 1.25) respectively from the center of column, the other types of loading are tested the specimens as beam._x000D_ The experimental results showed increasing in ultimate load capacity and higher chlorides resisting for hybrid reactive powder concrete in comparison with normal concrete in both types of curing (tap and chloride water). Through studying load deflection, test results for Normal Strength Concrete (NSC) and Hybrid Fiber Reactive Powder Concrete (HFRPC) columns that deflection for columns cured in chloride water more than tap water when compared at the same load that also by increase eccentricity leads to an increase in deflection for both cured and The neutral axis depth for HFRPC columns is more than NSC at the same load also when eccentricity increases, the compression zone decreases and neutral axis also decrease by increase eccentricity. These results occur when columns are cured in tap and chloride water._x000D_
The aim of this work is to investigate the effect of soil corrosion on the critical buckling load of circular columns made of 2014-T4 aluminum alloy. In this work, 24 specimens were used and buried in the soil for 120 days. The samples divided into two groups (12 columns with corrosion before shot penning (SP) and ultrasonic impact treatment (UIT), and 12 columns with corrosion after combined surface treatments (SP+UIT)). The experimental1results revealed1that the corrosion negatively1affects the mechanical properties1of the material, and the1reduction percentage (R%) for1ultimate tensile strength (UTS) and1yield strength (YS) was (1.95% and 4.57%) respectively. After combined surface treatments (SP+UIT) for the corroded columns, the ultimate1tensile strength (UTS) and yield1strength (YS) were improved with (2.42%, and 2.87%) respectively. Perry-Robertson, Rankine, and ANSYS were used to estimate the critical buckling load (Pcr) and compare it with the experimental results. Rankine and Perry's formulas have been achieved a good agreement with the experimental without and with (1.5) factor of safety respectively. While ANSYS gave satisfactory prediction with a safety factor of (2.2, and 2.7) and (1.9, and 2.7) for long and intermediate columns before and after (SP+UIP) respectively.
In this work, model fuel (Thiophene in hexane) was treated for sulfur removal by adsorptive desulfurization method using modified bentonite with sodium (Na-B) adsorbent. Batch and continuous mode were used in this study. Several operating parameters such as initial thiophene concentration of 250 to 2000 mg/L , adsorbent dose 0.1 to 0.8g/ml were studied for sulfur removal %. Also a comparison between raw and modified bentonite was performed in this study. In continuous mode, a packed bed of Na-B adsorbent column was used at constant initial thiophene concentration and liquid hourly space velocity (LHSV) to study the breakthrough curve of thiophene. The results showed that Na-B adsorbent was better than raw bentonite in removal of sulfur components. The removal percentages was 67,75,87,and 91% for 500 mg/L initial thiophene concentration using adsorbent dose o.1, 0.2, 0.4 and 0.8g/ml respectively , and 87, 75, 57, and 53% for adsorbent dose of 0.2 g/ml using initial thiophene concentration of 250, 500, 1000, and 2000 mg/L respectively. It was concluded that when increase the dose of adsorbent, the removal of sulfur increase , and when increase the initial concentration the removal decrease.
Kids carrying heavy loads as a part of everyday activity may be related to bend their trunks forward to maintain body posture and balance while walking. This study was to determine a correlation between the weight of a child's backpack, their body weight, and certain features of their body posture. The study group consisted of 6 children, in age of primary school. The anthropometry (age, length, weight) were taken for each volunteers. A school backpack was specially built for the present study. Walking gait was filmed in three cases: (zero kg, 3 kg and 6 kg) backpack.Posture was analyzed by using (Kenova and MATLAB) computer programs.The results show that the forward inclination of the trunk increases when the load and the walking distance are increased, this forward inclination segment may impose greater stress over the vertebral column (ligaments and intervertebral disks) and increase the risk of back problems.Spine and back health may be adversely affected by load carriage and it may be important to use spinal curvature as a measure of posture for load carriage. This study shows that the backpack load cause a lumbar asymmetry by 10 to 20 degree according to the load which has a significant amount of back pain in kids.