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Go to Editorial ManagerIn this research, we investigate the nonlinear vibration of functionally graded carbon nanotubes (FG-CNTs) for simply supported sandwich cylindrical panels. The sandwich consisting of three layers formed of (FG-CNTs) and isotropic material as (CNT, ALMINUME, CNT). Mechanical properties of the sandwich media are acquired according to a re?ned rule of blend approach. The governing equations were derived using a first-order deformation theory (FOSDT). Four kinds of carbon nanotubes of sandwich cylindrical panels were analyzed. The volume fraction of CNTs is varied. The properties of nonlinear responses and free vibration are studied. The numerical approach employs the fourth-order Runge-Kutta and Galerkine procedure. Which conducted for the dynamic analysis of the panels to present the natural frequencies and non-linear dynamic response expression. The results show that; the natural frequencies and the nonlinear vibration amplitude decrease with the volume fraction and thickness ratio increase. The nonlinear vibration amplitude response increases when increasing the excitation force. The initial imperfection and the elastic foundation have a minor impact on the nonlinear vibration response of the panel. The Pasternak Foundation has a larger impact than the Winkler foundation. The structure formed of FG-CNT present an excellent choice for high-performance of engineering applications.
This study aims to review flow-induced vibration one of the repercussions of vibrations is caused by fluid movement. In general, the investigation of the structure of the systems affects the efficiency of the components that construct those systems. This review examined the influence of generated vibrations and internal pressure on fluid transport pipes using theoretical calculations, practical tests, and numerical analysis to identify and test the dynamic behavior of static fluid transport pipes. The experimental study considered the natural frequencies caused by the fluid pressure effect under various stability situations. The flow of all liquids, such as oil, water, gas, air, and vapors, through the pipes, was tested, and the mathematical models were correctly adjusted. All empirical, theoretical, numerical, and analytical research agrees that several approaches exist to develop, modify, and improve these metrics. However, one factor affecting rheological measurements is vibration, which was addressed as needed in the middle of the 20th century due to major discoveries that damage could be rooted in vibration. Established on the determinations, they provided mathematical models paired with pressure and velocity measurements of moving fluids and the influence of produced or uninduced vibration. This study demonstrates that additional empirical investigations, particularly more detailed analytical methodologies, are urgently required to produce better findings.
Forced vibration has been experimentally investigated on a model consists of circular pipe with1.6m length. The pipe built in tank (1.2m length, 0.6m height and 0.6m width) horizontally at 0.4m height with two different diameters d=15mm and d=35mm. The pipe conveying laminar flow in the fully developed region, of Reynolds number equals 2000. The experimental results of span pipe conveying water at five stations of forced excitation vibration were studied. The harmonic forced vibration with two different excitation frequencies (10 Hz and 15 Hz) are imposed at all of the five locations. The distance between two stations is (0.2m). Two conditions of pipe environment have been applied, the first in air and the other was immersed in water. It is concluded that the effect of flow induced vibration due to the pipe conveying fluid increases the maximum deflection when the fluid speed increases. The water surrounds the pipes reduce the effect of excitation vibration about (33 – 46%). The effect difference between the excitation frequencies was about (4 – 7%).
In the field of engineering, 3D printers are indispensable due to their high precision. This study focuses on the construction and optimization of a 3D printer using aluminum T-slotted bars for the frame, Raspberry Pi 4 for control, and Lightburn software for image printing and machine control. After assembling the main components and programming with Marlin firmware, the machine was tested for vibration and noise reduction. The research compared the vibration of a diode laser and spindle during printing, revealing significantly lower vibration with the laser compared to the spindle. These findings demonstrate the effectiveness of the constructed 3D printer in reducing vibration and noise during operation.
In the present work, theoretical and experimental Study of vibration of a drum type of Horizontal Washing Machine. The effect of the Isolators stiffness, damping coefficient and the drum mass for specific laundry capacity also has been studied. The work in this research has been carried out analytically by using MATLAB, and Study experimentally the effect of different speed and unbalance force during the spinning cycle of the washing machine at four sides of it. This analysis aims to reducing the excited vibration. This was achieved theoretically by investigate the effect of various parameters in order to assign property values to increase the isolation efficiency to reach optimum design. The results is show that drum vibration amplitude reduced to 42 % at spinning speed 1000 rpm and 41% at 1200, 1400 rpm when the applied selected parameters.
In this work a general dynamic response of two-story building due to earthquake is investigated .A spatial case of two degree mass-spring–damper random vibration model is employed .The base excitation acceleration is represented according to the well- known_x000D_ regression model by Kanai –Tajimi in term of the power specturm density (PSD). The transfer function between the ground an the roofs are evaluated assuming transverse modes of vibration._x000D_ A case study of typical two symitrical story building manufactored from reinforced concret and steel is investigated.The vibration parameters such as effective mass and stiffiness and damping are calculated according to the ACI 318-11 code.The natural frequncies , mode shape and transfer functions are calculated and plotted.The PSD acceleration at the roofs are evaluated from which the mean and standared diviation of the random accelration are found .The drift at the walls is calculated and compared with the allowable limits recommended by IBC 2015 .It is found that the probability of the bulding to be safe is between (13.74 -7.35)% for the first story and (8.7 - 1.67) % for the second.
An investigation of performance response of two types of bearings such as Cylindrical Roller Bearing and bush bearing on evaporative cooler driven by DC motor of 1500 r.p.m, through studying many parameters like vibration response, temperature raise, humidity, sound level and total performance. high quality 3D positions X, Y and Z, vibration sensors type (ADXL335 accelerometers) with Arduino mega 2560 that interfaced with Lab-View program were used to measure changes in vibration amplitude and frequency. Two temperature sensors of type (LM35) were used to investigate the temperature raise in the bearings also with Arduino mega 2560 that interfaced with Lab-View program. For humidity a sensor of type DHT22 was used, also, a portable device was used to measure electricity consumption, rotary speed and sound level in the bearings of evaporative cooler. By replacing bearings all the parameters above wear measured then a comparison between them were made to find the best performance and operation of these bearings. The obtained results from the experimental work have clarified and explained by tables and figures. It has been found that the vibration of evaporative cooler in X, Y and Z-directions increased by using two cylindrical roller bearings than using two of bush bearings. The temperature of cylindrical roller bearings increased When running the evaporative cooler more than bush bearings. the noise of Evaporative Cooler by using both types of Bearings was almost same but with a little Reduce by using cylindrical roller Bearings. Which means the Evaporative Cooler has better Performance by using bush bearings than using cylindrical roller bearings.
In this work, the vibrations in the rotor-bearing system are studied experimentally and theoretically using ANSYS Workbench 2020 R1 software to compute the natural frequencies and mode shapes. In the experimental part, the LABVIEW software was used to examine the signal of the frequency domain values obtained from the accelerometer sensors, based on Fast Fourier Transform (FFT) technology and dynamic response spectrum. in the theoretical part, the natural frequencies are determined based on the finite element method for analyzing the system and knowing its behavior and vibration response level. The results showed that the level of vibration becomes higher at high rotational speeds, and it becomes large when the distances between the bearings are large, according to the bearing position and type used in the system. in this work can be concluded, the system is usually affected by the dynamic response around it and is difficult to separate from it, and the vibrations in the system can be controlled by adding an external damping source, which gives the system more stable. A system operating at high speeds can give a large vibration and an unbalanced response.
Active vibration controlling loop with proportional - Integral (PI) controller was tested numerically and experimentally for delta wing with three different manufacturing materials; aluminum, [0/90] composite and aluminum foam, both P and PI loop were tested separately. Numerical work was performed in ANSYS v.15 where controller with piezoelectric transducers was totally integrated in program macro. Experimental wings where fabricated to be tested under simulated excitation. Labview 2015 program with high speed Data acquisition were used besides actuators to perform controlling circuit experimentally. Good suppression in wing oscillation was performed where 72% of wing's time of vibration was eliminated for aluminum foam wing. Noticeable agreement was achieved between experimental and numerical responses.
Fourier series and finite element analysis are utilized to obtain the solution of simply supported beams resting on elastic foundations with different loadings in order to arrive at a free vibration. The equation of the free vibration of beam on elastic foundation is derived and solved. Good agreement has been obtained between the results of the present study Fourier and finite element analysis and other previous solutions. The effect of modulus of subgrade reaction, axial tension force (foundation modulus) and beam depth on the behavior is studied.
Driven piles have often been used in many civil structures to provide structural loading support. However, the unavoidable vibrations induced by pile driving processes may cause varying degrees of damage to adjacent structures. This research presents experimental studies to investigate the transmitted vibrations induced by impact of pile driving on vicinity piles. In the experimental work, a small scale model was tested in a sand box (steel container 1 × 1.5 × 0.8 m) with pile driving hammer device to install the impact pile in sand soil by dropping weights (1, 2, 3, 4 and 5 kg) for different heights of falling (4, 8, 12, 16 and 20 cm). The peak particle velocity was measured at a head of the vicinity piles by vibration meter device. In this study, several piles on different distances away from the vibration source were studied. The experimental results indicate that the peak particle velocity for vibrations emitted with impact pile driving is increased with increasing the energy and the penetration depth of pile driving for all vicinity piles and it can be decreased without change in the driving energy by decreasing the weight of hammer and increasing the height of falling hammer. Vibration intensities are attenuated with increasing surface distance from the pile driving and the peak particle velocity decreased uniformly with surface distance from the pile driving for piles. Also, through laboratory model representation and evaluation of the results obtained in the laboratory, the empirical relations which were determined based on the scaled-distance concept, are appropriate and give results very close and can be relied upon to represent the transmission of vibration resulting from the impact of pile driving to nearby piles.
The effect of defect on structures and machines has negative consequences on them and it always takes researchers concern and attention in order to find feasible solutions to trace and detect the location of the defect accurately.In this research, the effect of a hole with different diameters on a square composite plate is studied as well as the effects of both the boundary condition and the plate thickness, furthermore, Vibration analysis of composite plate has been studied numerically and experimentally. The Numerical analysis has been carried out by using FEM by building MATLAB program as well as (ANSYS 15). The experimental part of this research is done by using vibration measuring instruments. The rate of error among the experimental tests and the numerical solution is less than 15%. These results have been used an inputs to the Genetic Algorithm model that the defect is located by, with a high percentage of success.
There are many patients who face a lot of things that hurt the knee joint. Knee replacement is the best solution to these problems. This research was based on reducing the vibrations of daily activities as measured by the frequency of foot and knee for the patient for three cases when the bare foot, sports shoes with ground air and sports shoes with ground air with silicon damping. Patient information for this work was of age, weight, height and leg length 48 years, 90 kg, 160 cm, 84 cm, respectively. The results was shown that the decline in acceleration results was in the case of sport shoes with ground air with silicon damping with 22.57%, while the decline in vibration results was in the case of sports shoes with ground air with -54.9%.
Pressure vessels are the heart of plants and oil refineries stations. In many engineering applications such vessels can be subjected to periodic loading either internally due to the charging and discharging process or externally due to the excitation from other nearby components such as pumps, compressors or from seismic. So that in spite of a good design according static assumption it may be critical in dynamics. In this work a horizontal pressure vessel with accessories subjected to liquefied petroleum gas pressure LPG is considered. Three models of different head types are investigated herein namely; Deep torispherical, Elliptical 2:1 and Hemispherical. The design and material selections are chosen as per ASME. For practical service many accessories are attached to the vessel such as manhole, supports, inlet and outlet opining. Finite Element method via ANSYS R18.2 is introduced for the numerical analysis. The fatigue life in case of fully reversed cyclic loading are estimated and located. Vibration characteristics such as mode shapes and natural frequencies for the lowest five modes are evaluated and compared. It is found that the fatigue life can be increased as higher as 180% for hemi- spherical head as compared with deep torispherical head pressure vessel and the lowest four natural frequencies are nearly identical for all models, however significant change observed in the fifth natural frequency.
This paper aims to assess the structures' seismic response with a system of Single-degree-of-freedom exposed to near-fault earthquakes, taking into account the effect of pulse period, shear wave velocity (VS30), and fault mechanism. Strong ground motion data were taken for different events in different places around the world and the prism software program is used for the analysis of seismic response for structures recognized as single-degree-of-freedom systems. Results show that the ground motion with a higher value of (VS30) provides an acceleration response higher than that of the lower value of (VS30). However, the findings revealed that the peak displacement requirements are observed in a nearby of the pulse period limits. In addition, it is noticed that there is an obvious increase in spectrum demand with longer pulse periods. Finally, results show at short vibration periods (T? 0.6sec) for both types (strike slip and dip slip) comparable results while an increment is observed in the results of the strike-slip for vibration periods more than (0.6sec) of the acceleration response spectrum. Nonetheless, for the velocity response spectrum dip-slip continuous in flocculating with a significant increase.
The free vibration analysis of rotating multi-layered cylindrical shell is investigated based on the first order shear deformation theory (FSDT) of shell. Cylindrical shell consists of three layers; outer and inner layers are isotropic material and the middle layer is a functionally graded material (FGM). The material properties for middle layer are assumed to be graded in the thickness direction. Based on Hamilton’s principle, the equilibrium equations and the equations of motion are derived and then solved by using the differential quadrature method (DQM) as a numerical tool. MATLAB software was adopted for programming the equations and the related boundary condition. The effect of (FGM) layer thickness, angular speed, index power law, circumferential wave number on the natural frequency of the clamped-clamped rotating cylindrical shell were examined. The numerical results showed that a reasonable agreement between the present study and analytical data available in the literature.
The axial capacity and pile transference of loads under static loading have both been well reported, but further research is needed to understand the dynamic lateral responses. The pile load imposed during an earthquake may increase, but the soil’s ability to support it may fall as a side effect of the vibration leading to more settlement. The key objective of this work is to identify what led to the substantial lateral destruction of the piles during the seismic event due to the kinematic effects. These failures were related to discontinuities in the subsoil as a result of sudden changes in soil strength due to shaking. The kinematic stresses exerted in a single pipe pile constructed in two sand layers under two different situations (dry and saturated states) are investigated in this study using numerical modeling. The bending moments were higher in the saturated sand soil than in the dry one which may be attributed to liquefaction. Generally, the acceleration increased through the loose layer (from bottom to top), and then significantly settled within the dense layer. It could be shown that using this modeling, one can estimate how a pile foundation will behave under "kinematic" loading driven by earthquakes. Therefore, the design and installation of drilled aluminum or steel piles in sand soil could make use of these present observations.
Corrosion in turbine blades may be considered the most crucial problems in power plants. Corrosion may lead to unbalance masses in turbine blades and therefor serious vibration problems. In this study coating nanomaterials namely Al2O3 and TiO2 are used to resist the corrosion. Coatings consist of Al2O3 with 13 wt% TiO2 are generally used to improve the corrosion, erosion and wear resistance. Tests specimens were taken from the portion of turbine blades in Al-Doura station which located in the south of Baghdad. The specimens are divided into two groups, the first group without coating and the second group with nanoparticale coating including alumina (Al2O3) and (Al2O3-13 % wt TiO2), the coating applying by airbrush device using atomization technique with the aid of nitrogen 2 bar pressure . The properties of coated specimens have been investigated by SEM. The SEM showed that the deposition of nanoparticles on the surface of the samples was uniform and homogeneous. The thickness of coated layers was obtained using gravimetric method. Nano alumina with 13% wt of Titanum oxide coating gave the highest thickness 7.1 µm because of agglomeration of these particles comparing with other particales. Electrochemical properties was achieved by corrosion test at 90 ° for 20 min, the properties indicated that the corrosion resistance increased for coated specimens and these properties showed that the nano alumina with 13% wt of nano Titanium oxide was better than other coating and get a protection efficiency equal to 85.56%.
In this paper, a dynamic analysis has been carried out on zoned earthdam subjected to earthquake excitation in which pore water pressure, effective stresses and displacements are calculated. The finite element method is used and the computer program Geo-Studio is adopted in the analysis through its sub-programs SEEP/W and QUAKE/W. A case study is considered to be Khassa Chai dam which is located on Khassa Chai river north of Iraq and consists of zoned embankment with a total length of 3.34 km. The selected earthquake for the analysis is El-Centro earthquake with a period of 10 sec and different amplitudes of acceleration. The time of the analysis is taken as 600 sec. with a time step (?t = 0.05 sec.) to investigate the behavior of the soil for a period of time after the earthquake has stopped, a free vibration period is included in the analysis. It was concluded that the value of pore water pressure generated at the base of the core is greater than that in the upper parts of dam. The horizontal and vertical effective stresses continue to decrease during the period of analysis 600 sec. which indicates that the soil continues to weaken during this period, the horizontal displacement increases with depth of the point from the crest and the largest horizontal displacement will be at the base of the dam at time 60 sec and There is attenuation of the acceleration to some degree depending on the amplitude of the input horizontal acceleration. The maximum horizontal displacement decreases by about 37%, 45% and 49% when using a horizontal drain 2 m thick at the downstream under a peak acceleration of 0.05g, 0.1g and 0.2g, respectively.
The effects of the ultrasonic peening treatment (UPT) on the rotating bending fatigue behavior and the behavior of the vibrations of alloy steel DIN 41Cr4 were studied. Hardness test, Tensile test, Constant amplitude fatigue tests, and the vibrations measurements have been carried out on the specimens. Also, the fracture surface was examined and analyzed by a Scanning Electron Microscope (SEM). The results of the investigations, e.g. stress to number of cycles to failure (S-N) curves, fatigue strength improvement factor was 7%. The decreasing percentage of maximum Fast Fourier Transform (FFT) acceleration of the ultrasonic peened condition compared to the untreated conditions was 45%.
Openings in reinforced concrete (RC) slabs are usually created as a result of variations in construction function, architectural or mechanical necessities. Heavy equipment loads resulting from mechanical system of any building are often carried by RC slabs. Even the static analysis and design of RC slabs with opening is not clearly stated in the available international Codes, dynamic analytical solution for such structure is complex._x000D_ In this paper, numerical analysis based on finite element approach is utilized to implement the modal analysis of RC slabs. Opening size and position was parametrically studied. Slab natural frequency or periods in addition to, the mode shape were registered. The results showed that the opening size and position involved in RC slab had a significant change in the value of natural frequency and period for the high level modes. The material nonlinearity affect on free vibration analysis of RC opening slab with different levels of stiffness modifiers was taken into account. The dynamic characteristics of RC opening slab as a function of stiffness modifier degree was numerically measured for six mode shapes. The paper found that a reduction in stiffness modifier value greatly reduce the .natural frequency of RC opening slab.
Field compaction equipment used for fine grained soil usually applies a kneading action or vibration that produces shear forces which also reshape soil particles arrangement. A state that might not be completely simulated by laboratory Proctor tests. This study aims at investigating the significance of using the newer modified Texas superpave gyratory compactor (SGC) to simulate field compaction of fine grained soil due to itsability to apply loads in different anglesgenerating shear forces on the compacted soilspecimens. Two types of soil (A-4) and (A-7-6)were compacted using standard Proctor,modified Proctor and (SGC). The results werecompared to dry field densities of the same soilin order to evaluate the most representative test.It was found that maximum dry densities of soiltype (A-4) obtained using (SGC) under (200kPa) and (600 kPa) were lower by (2.07%) andhigher by (1.35%) than the maximum drydensities obtained using standard and modifiedProctor tests respectively. It was also found thatmaximum dry densities of soil type (A-7-6)obtained using (SGC) under (300 kPa) and (600kPa) were lower by (1.02%) and higher by(1.23%) than the maximum dry densitiesobtained using standard and modified Proctortests respectively. The aforementionedconfinement pressure values were applied inorder to achieve dry densities similar to thatobtained by Proctor tests. When comparinglaboratory results to dry filed densities, it wasfound that (SGC) test results were slightly closerto them than Proctor tests results. Nevertheless,the difference between (SGC) and Proctor testsresults seems to be insignificant for these typesof soil compared to the higher effort needed toperform (SGC) tests.
Noise effects on the students include both auditory and non-auditory effects and cause ?the lack of concentration and disability of learning? ?and communication. The Faculty of ?Engineering was chosen to conduct the questionnaire ?because the students have both ?theoretical and practical courses and they ?spend one-third of their day in the ?laboratories, so it is expected they exposure to noise more than other faculties’ students ?A questionnaire was conducted to understand the effect of noise on student behavior ?and whether they could classify the sounds that they heard as noise and determine the ?noise sources (indoor, outdoor) and the noisiest places (classroom, laboratory, and ?campus). 438 students participated in this questionnaire from all stages, and they ?covered eight engineering departments in the Faculty of Engineering, Mustansiriyah ?University. A statistical analysis of the questionnaire found that 39.5%, 46%, 32% and ??49% of students suffered from noise in classrooms, laboratories, open spaces and closed ?spaces (campus), respectively. In the actual situation, the effects that students ?experience can be arranged in the following descending order: feeling discomfort, ?hearing difficulty, raising the voice when speaking, lack of concentration, headache, ?tinnitus and nausea. Using a sound and vibration meter with the analyzer, the noise ?levels in dBA were measured in the noisiest places that the students mentioned. The ?noise levels exceed the standard limitation that organizations and agencies such as the ?WHO determined. ??
Pick and place system is one of the significant employments of modern robots utilized in industrial environments. The objective of this research is to make a comparison of time sequences by combining multiple axes of sequences. A pick-place system implemented with pneumatic linear double-acting cylinders to applicator in automated systems processes for manufacturing. The challenge of 3-axes movement control was achieved using the PLC (Programmable Logic Controller) controller such that the merging between two or three axes was achieved according to the selected sequence of the program. The outcomes show the contrasted sequences and the reference in a constant velocity. The main variable parameter is the number of steps for each sequence. The combination of two axes has developed the sequence and reduced in number of sequences for a path. At last, one of the important factors in moving products industry is the smooth product’s movement, because any high speed might cause a vibration in the system and lead to a decreased positioning accuracy.
Platinum, copper, and nickel were founded the best metals used in resistance temperature detectors RTDs. They commonly used in laboratory and industrial applications because they provide accurate and reliable measurements in a wide temperature range from (- 200 to 850 °C). They have high conductivity, sensitivity, and hardness to resist strain shock, pressure, and vibration. The accuracy level of them depends on reliability, stability, repeatability, linearity, and response to time. This study aims to determine and compare the accuracy of these three metals in regarding to their features which include stability, repeatability, and response time. The study has gathered and analyzed the data of these suitable and precise metals and compared with each other. The results showed that platinum is widely needed for RTDs due to its precision, stability, higher accuracy, and linearity output, while copper and nickel are not stable or repeatable as platinum. It was indicated that temperature coefficient of resistance TCR for nickel is bigger and for copper is medium, but for platinum is lower.
Numerical analysis of the performance of reinforced concrete (RC) deep beam subjected to static and fixed-point pulsating loading at the midpoint has been investigated. Three-dimensional nonlinear finite element model using the Strut and Tie approach was adopted. The damage level under the influence of the applied fixed pulsating loading is higher than the static applied loading, hence early crack was observed because of the stepwise loading in the form of vibration. Although the Strut and Tie approach gave a good estimation of the resistance capacity of the beam, the beam undergo high shear damage when subjected to these two types of loading. Material strength properties, applied loadings and cross-sections adopted are some of the factors that affect the performance of the deep beam.
This paper studies the effect of different design spectral response acceleration parameters as suggested by the uniform building code (UBC), unified facilities criteria (UFC), and Iraqi seismic code(1997) (ISC 97) on the seismic response of reinforced concrete multi-story framed building located in Baghdad city, Iraq. These parameters are: (a) spectral response accelerations Ss, at short periods, and S1 at a 1-second period in accordance with international building code (IBC), (b) seismic zone factor (Z) according to UBC, (c) Seismic hazard zoning coefficient (Z) according to ISC 97. In this paper, first, the elastic seismic responses for significant modes of vibration for chosen building under design response spectrum that obtained from the above mentioned codes are calculated, and then a comparison was made among different design spectral response acceleration parameters. The intent of this study is to review the seismic provisions of the current edition of Iraqi seismic code (1997) to determine whether it provides an equivalent level of safety to that contained in other international codes. Design base shears, lateral seismic forces, inter story drifts, response spectrum modal, effective seismic modification, floors acceleration and story shears are comparatively presented.