A finite element method for free vibration analysis of generally laminated composite plateswith central crack and clamped edges have been studied using ANSYS 5.4 program. The fiber-reinforced composite materials are ideal for structural applications where highstrength-to-weight and stiffness-to-weight ratios are required, where structures must safelywork during its service life. But damages initiate a breakdown period on the structures.Cracks are among the most encountered damage types in the structures. The non-dimensionalfundamental frequency of vibration decreases with presence of cracks because, therigidity of cracked plate decreases. The natural frequency of plates depends on size andshape of the cracks, the effect of number of layers is found to be insignificant beyond fourlayers and the change of fiber orientation increasing the fundamental frequency of vibration.The results obtained have been compared with the available published literature with goodagreement results
Free vibration analysis of a cracked cantilever beam with two types of additional substructure attachment is investigated using ANSYS program. The cantilever beam is used as a master structure with single substructure attachment in various locations (as 1-DOF mass attachment and 1-DOF mass-spring attachment) with influence of crack in different location and depths. The results for the changes of the natural frequencies of a cracked beam are compared with the results produced by Vahit et al [1]. So the same geometrical properties have been studied. In additional work a cracked beam carrying two types of substructure attachment are compared with the results of the beam without a crack and with multi crack depth. In all calculations the beam has a uniform cross-section and the crack was modeled by reduction in the modulus of the beam. The reducing effects of the cracked beam on the natural frequencies had been more apparent with the substructure attached to the beam in different situations. The effect of mass-spring substructure is larger than the effect of the attachment when modeled as mass substructure for the same mass, with 17% for the first natural frequency and 2% for the second and third natural frequencies. The results can be used to identify cracks in simple beam structure; cracks have a clearer decreasing impact on the natural frequencies.
Enhancing heat transfer, particularly through convection, is crucial in various industrial applications, driving ongoing interest in methods to improve heat transfer rates and the efficiency of heat transfer equipment. Ultrasound has emerged as an effective and reliable method for boosting convective heat transfer, primarily due to the unique phenomena it creates within irradiated fluids, such as sound cavitation and streaming. In heat exchanges, where forced heat convection is typically the primary technique, ultrasound has shown notable effectiveness by improving convective heat transfer and reducing fouling. This paper summarizes recent research on the application of ultrasound in both forced and free convection heat transfer systems, emphasizing studies published in the past decade. Previous research has demonstrated that the influence of ultrasound on heat transfer varies significantly between laminar and turbulent flows, necessitating thoughtful consideration in system design. While progress has been made, gaps remain in understanding the influence of flow rates across systems and the thermal enhancement provided by ultrasound in gaseous systems. Furthermore, most research is conducted in experimental settings, highlighting the need for increased studies to support industrial applications.
This research presented a strategy for designing a particular set of surfaces, obtained by the technique of cross-sectional design. The surfaces considered were formed by sliding a Bezier curve (profile curve), and also this research describes an automatic procedure for selective identification of sampling points in reverse engineering applications using Coordinate Measurement Machine. In addition, Matlab program have been used in the present work so as to plot the curve sections of the surfaces using transformation matrices. UGS program have been also used to connect the sections that designed in Matlab program to get the final shape of the proposed surface. It can be concluded that the whole steps task which built in the present research can be programmed in a single block of the part program that’s from it can be create any curve or surface at minimum designing time.
The research deals with a study carried out on the influence of iron oxide (Fe2O3) on the characteristics of kaolin clay and the possibility of reducing iron oxide percentage in kaolin clay in the location of Ghamij in Anbar Governorate, prior to using it in industry. The raw material used in the research contained about 5.72% of iron oxide. When such a percentage of iron oxide is contained in kaolin clay, it makes it harmful in numerous industries such as paper, plastic, drugs etc….. In this research the hydro metallurgy method was used where oxalic acid was diluted with distilled water, and with the help of heat and mixing ( as assisting factor) to cause iron oxide to melt and thereafter subjected to filtration and thus the ‘Bakkag’, i.e. white kaolin which was almost free from iron oxide was obtained. The sample of kaolin raw material weighted about 25 grammas and the acid diluted in the distilled water used along periods of (2, 3) hours weighted (4,5,6,7,8,10) grammas. The findings showed that this method is very practical in ridding the kaolin samples from iron oxide; in the sample where the concentration of the acid amounted to 6 along a 3- hour period, the percentage of iron oxid reduced to 3.2% In this way much of iron oxide melted and even its red color of the raw material changed to white. The same result was obtained by using a No. 10 concentration acid was used for two hours, the percentage of iron oxid reduced to 3.18%.The construction of iron oxide reach to 45%,the loss in weight of raw material used in this research is about 14%.
In this research a simply supported beam is used as a master structure with unknown number of attachments (fuzzy substructure) which is modeled as a system of 1-DOF attachments. Two types of attachments models were studied, namely 1-DOF mass attachment model and 1-DOF mass-spring attachment model. It is shown that the effect of attachments on the master structure natural frequencies when modeled as (mass-spring substructure) is larger than that when modeled as (mass substructure) for the same attachment mass. Engineering Statistics and normal distribution were used to find the values of the attachments to be added to the simply supported beam to improve the dynamical properties of the master structure and to find the best distribution of the attachment. The results also show that the distribution of the additional substructure can produce a great change in the natural frequencies so that the proposed statistical approach can be used to find the best distribution of attachments and number, value and location of the additional substructure .
Management of water resources become one of the most important subjects in the human's life. The water sustains life on earth, therefore; more care for water management is necessary. In the last years, studies show water use will be more in the world as result of rapid increase in population, industrialization, and urbanization etc. The evaporation losses from dam's reservoirs and lagoon form very huge losses in water resources. The annual evaporation depth losses in Iraqi Western Desert is about (2.25 -3) meter, this depth store the highest percentage of the small dams. Sub-surface storage reduces evaporation losses and maintains water quality by minimizing salt concentration. In present study, three tanks are used to simulate the subsurface reservoirs to study the effectiveness of underground storage on reducing the evaporation loss. Each tank have squares cross section tanks of (80) cm length and (40) cm depth and filled up to (34) cm with different graded soil (labeled as A, B with coarse soil, and D with fine soil) to simulate the storage below the ground. While the forth tank filled with water (labeled as C) to represent the reservoir of direct evaporation for comparison study. The present study considers three parameters that can controlled the evaporation from subsurface reservoirs: (a) temperature variation, (b) water table variation, and (c) material properties such as porosity. The field study continues for four months, it was started at Jun.11, 2016 and ended at Dec. 15, 2016 in the Erbil city at north of Iraq. The results showed evaporation losses are reduced by using subsurface storage reservoir with gravel in comparison with free surface evaporation. The evaporation losses are reduced about 46 % , 39% , 64% when the water table below gravel surface range from 5 to 10 cm , while at 20 cm depth of the water table the evaporation reduction is about (85 % to 86% 95%) from A, B and D tanks with porosity 0.65 ,0.67 and o.35 for A ,B and D tanks, respectively..
Rising energy prices and growing environmental concerns are making solar electric systems more attractive to homeowners. A solar electric system reduces high energy costs and keeps your home up and running during power out-ages. The advantages to buying a solar electric system include: Saving a significant amount on your electric bill. Increasing your home’s appraisal value. Enjoying reliable, clean, free power for 25 to 30 years. Helping and assist to boost our economy by creating jobs and new solar companies. A solar electric system is typically made up of solar panels, an inverter, battery, charge controller, wiring, and support structure. The three most common types of solar electric systems are grid-connected, grid-connected with battery backup, and off-grid (stand-alone). This work presents design and analysis of high performance of home solar energy, that include: the orientation and pitch of the southernmost facing roof to maximize solar gain, the roof vents, chimneys, gables or other obstructions in order to sit to the north side of the planned array. Ensure that the roof structure is strong enough. Structural support into the roof to handle the weight of a rack-mounted system. The space for inverters and disconnects near the main service panel. Finally comparison between these systems with other sources of energy.
The Cooper-Harper rating of aircraft handling qualities has been adopted as a standard for measuring the performance of aircraft. In the present work, the tail plane design for satisfying longitudinal handling qualities has been investigated with different tail design for two flight conditions based on the Shomber and Gertsen method. Tail plane design is considered as the tail/wing area ratio. Parameters most affecting on the aircraft stability derivative is the tail/wing area ratio. The longitudinal handling qualities criteria were introduced in the mathematical contributions of stability derivative. This design technique has been applied to the Paris Jet; MS 760 Morane-Sualnier aircraft. The results show that when the tail/wing area ratio increases the aircraft stability derivative increases, the damping ratio and the natural frequency increases and the aircraft stability is improved. Three regions of flight conditions had been presented which are satisfactory, acceptable and unacceptable. The optimum tail/wing area ratio satisfying the longitudinal handling qualities and stability is (0.025KeywordsLongitudinal Handling---Stability---Tail Design
In most cases, the concrete wall panels are subjected to axial eccentric distributed loading; due to this type of loading, concrete wall panels behave and fail somehow. There are many parameters that affect the structural behavior of the concrete wall panels. This study presents experimental investigation the structural behavior of concrete wall panels subjected to axial eccentric distributed loading; also evaluates the effect of the parameters, slenderness ratio (H/t), aspect ratio (H/L) and concrete strength on the behavior of concrete wall panels. The experimental program includes testing fifteen concrete wall panels hinged at top and bottom with free sides, by applying the load axially with eccentricity equal to (t/6); these panels are divided into five groups, each group consists of three panels with slenderness ratio (H/t) equals to (20 , 25 , 30) for each panel, three groups of normal concrete strength with aspect ratio (H/L) equal to (1.0 , 1.5 . 2.0) for each group and the other two groups are of high strength concrete with aspect ratio (H/L) equal to 2.0 for both two groups. The deflections of concrete wall panels depend on the slenderness ratio (H/t), aspect ratio (H/L) and concrete strength. The failure mode of the concrete wall panels is greatly affected by the aspect ratio (H/L); the panels with low aspect ratio tend to fail by crushing, while panels with high aspect ratio tends to fail by buckling.
Recently, the investigations studies of simulating flow over spillways have increased using numerical models. Due to its important structure in the dams to pass flood wave to the downstream safely. Researches finding have shown that CFD (Computational fluid dynamics) models as the numerical method are a perfect alternative for laboratory tests. Performance analysis of the CFD platforms Ansys Fluent-2D and Flow-3D are presented, focus on finding the variations between the numerical results of the two programs to simulate the flow over ogee spillway. The present study treats the turbulence using RNG k-ε of RANS approach, and also use the Volume of Fluid (VOF) algorithm to track the water-air interaction. The Fluent-2D and Flow-3D accuracy are assessed by comparing representative flows variables (velocity; free surface profiles; pressure; and the turbulent kinetic energy). The results of both codes have been also compared with experimental data. The results of the analysis show an excellent agreement between the two platforms data, which could assist in the future by using both programs to calibrate each other, rather than traditionally relying on laboratory calibration models.
Better understanding the innovative process of renewable energy technologies is important for tackling climate change. Concentrated solar power (CSP) is a method of electric generation fueled by the heat of the sun, an endless source of clean, free energy. Commercially viable and quickly expanding, this type of solar technology requires strong, direct solar radiation and is primarily used as a large, centralized source of power for utilities. This study has focused on the feasibility of improving concentrating solar power (CSP) plant efficiency, by manufacturing a diminished prototype. Three states were studied, coloring the central target with a selective black color, fixing a reflector with arc form behind the target, and using these two changes together. The results showed an improvement in the thermal storage varied form month to month. The maximum stored energy was gained at August with increments about 56.1%, 58.63%, 62.23 and 64.69% for ordinary target, black painting, using reflector alone and black target with reflector together, respectively compared with stored energy for March.
Since FGM orthotropic structures have such striking qualities as high strength, exceptional stiffness, stiffness-to-weight ratio, reduced cost, and high strength-to-weight ratio, they are employed extensively in the mechanical, aerospace, and civil engineering sectors. Thick plates and shells have more noticeable shear deformation effects. Therefore, in recent years, there has been a lot of interest in the vibration and buckling investigation of FGMs orthotropic plates and shells. Moreover, researchers have developed a variety of approaches and procedures for the examination of orthotropic FGM plates and shells. The majority of the literature review in this publication is focused on orthotropic FGMs plate and shell buckling and linear and nonlinear free vibration. In engineering practices, it is customary to use material-oriented or orthotropic materials in several domains to optimize the structures and maximize material properties, which is especially crucial for FG constructions. Solutions for the orthotropic FGM structure are studied analytically and numerically with different plate and shell theories.
Solar cells play a vital role in renewable energy systems, and ongoing research is dedicated to enhancing their power efficiency and longevity. Advancements in perovskite solar cells, particularly in power conversion efficiency (PCE), have shown significant progress, confirming its viability as a technology. Perovskite solar cells have achieved power conversion efficiency (PCE) levels of up to 25.5%, comparable to conventional photovoltaic technologies like silicon, gallium arsenide, and cadmium telluride. The substantial enhancement in power conversion efficiency figures over the last decade has shown a remarkable advancement in the efficiency of perovskite solar cells. This study examines the trajectory of perovskite solar cells in becoming economically feasible and generally embraced as a critical renewable energy technology. The advancement of flexible and wearable solar cells, together with miniature solar-powered sensors, has increased the efficiency of solar cell power production. Perovskite solar cells have shown a specific power of 23 W/g, much higher than traditional silicon or gallium arsenide solar cells. Further research is needed to address the challenges related to perovskite solar cells' stability and power conversion efficiency. Perovskite solar cells integrated with energy storage units have the potential to enhance the overall efficiency of the system. This study discusses an approach to improve the efficiency of novel solar cells, specifically focusing on lead-free tin-based perovskite solar cells and tandem solar cells. The advancement of technology in thin films, such as hybrid nanocomposite thin films and quantum dot-sensitive solar cells, has the potential to improve the efficiency of solar cells. The primary outcome of this study is derived from the following inference: incorporating plasmatic nanostructures into thermal energy systems will enhance their efficiency and sustainability by integrating solar energy.
Recently, the use of sandwich panels has become increasingly important. This is due to its good mechanical properties and high strength-to-weight ratio. It is used in many fields, especially in aviation, construction and aerospace. It is necessary to know the behavior of the materials used, especially the free vibrations, to know the effect of external factors on the sandwich panels. The honeycomb core sandwich panel was studied. A model for analysis and modeling is proposed. A previous model was chosen for analysis and comparison. Hoff theory was applied to convert honeycomb sandwich panel into equivalent sandwich panel to facilitate the solution and save time. The limits were considered fixed on the one hand and moving on the other hand, and the ANSYS program was used to analyze and extract the results, and the results were compared and were promising and accurate, which proves to us the validity and accuracy of the proposed theoretical results