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Go to Editorial ManagerThe welding process involves a very complex thermal cycle, resulting in irreversible elastic-plastic deformation, and residual stresses in and around fusion zone and heat-affected zone (HAZ). A residual stress due to welding arises from the differential heating of the pipes due to the weld heat source. However, the presence of residual stresses in and around the weld zone reduces the strength and life of the component. The objective of this work is to measure the welding residual stress in ASTM (A-106 Gr. b) steel pipes with 4" diameter and 6 mm thickness welded manually (SMAW) in a three-pass butt joint. The shielded metal arc welding process consists of heating, melting, and solidification of parent metals and a filler material in a localized fusion zone by a transient heat source to form a joint between the parent metals. The welding process was carried out without preheating and heat treatment. This measurement of residual stress occurs by using the hole-drilling strain gauge method according to (ASTM E-873), and the experimental results for residual stresses obtained from welded carbon steel pipes are used to provide validation for finite element simulations. The welding process and welding residual stress distribution is calculated by Ansys Finite Element techniques. Theoretical considerations can be assessed by a mechanical model. Overall, there is good agreement between the predicted and measured distributions of residual stress, but the magnitude of predicted stress tends to be greater in the welding region.
Modeling and simulation of non-linear quarter-car suspension system for two air spring models (traditional and dynamic new air spring) are contrasted in terms of (RMS) sprung mass acceleration, dynamic load coefficient, the vertical displacement, they are compared. Two and three (DOF) of the mathematical quarter models are implemented in MATLAB/Simulink platform. The Ride Comfort (RC), Dynamic Load Coefficient (DLC) and Road Handling (RH) responses are evaluated as objective functions respectively considering a vehicle speed at 72 km/h and road ISO Class B. The obtained results indicate that the vertical displacement, the (RMS) of the sprung mass acceleration, and dynamic load coefficient values with the new air model system decrease by 10.7 %, 30.6 %, and 13.49 % respectively, in comparison to a tradition suspension system, this one gives more comfort and effortless handling.
In this paper, the finite-element and the matlab procedures are used for the torsional analysis of large rotor system. A large rotor system of 13 discs are considered for the purpose of analysis. As a result, the finite-element and matlab procedures are good tools for the analysis of vibration analysis and design of large rotors and their results are accurate in comparison with other literatures. The normal elastic curve and T-ω diagram obtained in this study are an effective illustration for the vibration problems in large rotors, and the developed equation for drawing the normalized elastic curve reduce the need for tabulated calculation of this curve and its very essential for vibration analysts and designers.
This study presents a modified approach for analyzing torsional vibrations in rotor systems using an enhanced Holzer method integrated with MATLAB-based techniques through the development of a graphical user interface (GUI). The primary objective is to demonstrate the applicability and effectiveness of the proposed approach and GUI in evaluating torsional vibration behavior in well-known rotor configurations, including two-, three-, and five-rotor systems. Classic torsional vibration problems were examined using the developed tools, and the results verified the accuracy and practicality of the method. The findings indicate that the modified approach and MATLAB GUI provide efficient, reliable, and user-friendly solutions for engineers, designers, and vibration analysts in studying and addressing torsional vibration issues in rotor systems.
The functionally graded beam is a wide field of research, which attracts great interest today in the field of engineering, science, and medicine society. This type of beam is made from functionally graded material that is characterized by several properties one of them is the high strength to weight ratio. In the current years, this beam has witnessed great developments in the mechanism of its composition and the materials used in its manufacture. This research provides an overview of the properties, types, advantages and challenges, and applications of the functionally graded materials. In addition, this paper review provides a summary of the analysis of bending and buckling that occurs on the functionally graded beam with and without crack effect from (2008-2021) year. Through this review, the following was noted: Firstly, a small number of researchers have worked experimentally, and the properties of a beam in most of the research are gradual towards thickness using the mixing rule. Secondly, the crack has a very severe effect on the behavior of both bending and buckling for the graded beam. This critical review can be considered a milestone in future analyzes of the graded beam and is also beneficial to designers and researchers working in this field.
The dieless drawing process is an innovative method emanated and appeared in coincidence with development of the concept of metal superplasticity. It is utilized from the local heating of a wire or tube to a specified temperature and followed by a local cooling, so an additional deformation is inhibited. In this study, a special dieless drawing machine was designed to carry out an experimental program on SUS304-stainless steel wire having diameter of (1.6-2) mm to investigate the main process parameters such as speeds, heat quantity, heating coil width and heating-cooling separation distance. Also, a numerical model based on thermo-mechanical analysis was developed and validated with experimental program. Furthermore, an artificial neural network ANN model based on current experimental data was prepared to predict the dieless drawing behavior. A maximum area reduction of 40.7% was obtained in single pass. A 3.12mm/s feeding velocity and 4.97mm/s drawing velocity were realized through the experimental tests. The results showed that both drawing force and wire profile were effected by increasing of feeding speed, heating coil width and separation distance. Also, it is confirmed that strain rate was reduced by increasing the heating coil width and the reduction ratio was promoted. A maximum error of 21% was recorded between ANN model and experimental results. The results showed a good agreement among experimental, numerical and ANN models.
This paper presents the effect of fiber orientation angle on the stress intensity factor SIF for carbon epoxy composite plates with single-edge, center, and inclined cracks of varying lengths under tensile load. The stress intensity factor and shape factor were calculated individually for each case, with nine different fiber orientation angles computed using the extended finite element method XFEM concepts. It is found the stress intensity factor increases with increasing crack lengths while the shape factor decreases. In the case of single edge cracks, the SIF increases in the average value reached (173 %) for composite plates with different fiber orientation angles, while in the case of the center crack, the average value of SIF reaches (81 %). It was observed in this study that the increases in stress intensity factor and the decreases in the shape factor with different crack lengths were more stable in the composite plate with a fiber orientation angle of 75°. The higher values of SIF at an angle of 75° are because of the high probability of fiber slippage at 75° due to induced shear stresses in addition to the tensile stresses at the fiber-matrix interface. As a result, the crack tip has a high-stress intensity factor.
Adhesives have been around for millennia. Nevertheless, this technique for joining has only seen significant development within the past 70 years. Professional technical engineering applications primarily use adhesives derived from synthetic polymers, a development that dates back to the mid-1940s. Its characteristics facilitate their strong adhesion to most substrates, as well as their ability to transfer substantial loads. This paper presents an extensive assessment of the current knowledge in the field of adhesives and related technologies, with a focus on adhesion theories and their parameters, as well as designing, joint configuration, geometric aspects, and failure modes. The paper also explores the interplay between research and development efforts, industrial standards, and regulatory aspects, with the goal of fostering collaboration between academia and industry. Over the past years, the development of new materials, methods, and models has resolved many of the shortcomings. Nonetheless, it is still possible to evaluate and estimate the optimal combination of aspects that will give the greatest efficiency and performance for adhesive bond joints (ABJs).
The extended-finite element method (X-FEM) is used for crack analysis of orthotropic and isotropic functionally- graded composite material (FGCM) plate with slanted crack under thermal loadings. The enrichments functions of discontinuity are implemented. Mixed-mode SIFs are calculated in isotropic and orthotropic FGMs. Gaussian technique (Q4) has been applied in numerical calculation of interaction of solution. Thermal effects, fundamental equations, the interaction integral of non-homogeneous cases (M-integral), and proposal numerical integration rule are set to simulate and to debate the accuracy of the present work results in comparing with the results of the references that available in the literature. In addition, the effect of size of crack is studied to discuss the values of energy release rate and stress intensity factors with different crack angles. The present study is implemented by using MATLAB program to present steady state thermo XFEM fracture analysis of isotropic and an isotropic FG plate with inclined center crack.
In this paper, a new model of beam was built to study and simulate the buckling behavior of function graded beam. All equations of motion are derived using the principal of the minimum total potential energy and based on Euler-Bernoulli, first and high order shear deformation Timoshenko beam theory. The Navier solution is used for simply supported beam, and exact formulas found for buckling load. The properties of material of FG beam are assumed to change in thickness direction by using the power law formula. The dimensionless critical buckling load is calculated analytically by the FORTRAN program and numerically by ANSYS software. In the beginning, the analytical and numerical results are validated with results available in previous works and it is also has very good agreement in comparison with and some researchers. In the present study, the lower layer of the graded beam is made up of aluminum metal. As for the properties of the rest of the layers, they are calculated based on the modulus ratios studied. The effect of length to thickness ratio, modulus ratio, and power law index on the dimensionless critical buckling load of function graded beam calculating by FORTRAN and ANSYS programs are discussed. The numerical analysis of function graded beam offers accurate results and very close to the analytical solution using Timoshenko Beam theory.
Vehicles usually consist of several essential systems. The performance of the vehicle is evaluated through the efficiency of these systems to perform their duties. The suspension system is one of these systems dedicated to absorbing shocks arising from vehicles passing over road bumps, thus reducing vibrations and achieving passenger comfort while driving. This paper presents a study on enhancing ride comfort in a nonlinear half-car model using a modified Proportional-Integral-Derivative (PID) controller. In this study a half-car model is developed considering the nonlinearities in the suspension system components. A nonlinear half-car model was adopted to increase accuracy and make the overall system closer to reality. Instead of the feed-forward conventional PID controller gains, the proposed controller gains are formed by putting the proportional and derivative gains in the feedback path while keeping the integral gain in the feed-forward path to act as an I- PD controller. The proposed controller is integrated into the model to deal with these nonlinearities effectively and to achieve the optimal performance of the vehicle body. The overall system has been developed and simulated in the Matlab Simulink environment to show the dynamic response. Simulation results demonstrate the effectiveness of the I-PD controller in improving the ride comfort and handling stability of the nonlinear half-car model by reducing body acceleration and suspension deflection. A comparison with other study has been conducted to verify the effectiveness of the proposed controller.
In this study, a new approach for the torsional vibration analysis of rotor systems using Holzer and Matlab techniques, by developing a graphical user interface (GUI), has been introduced. The objective of the work is to show the usefulness and power of Matlab GUI in investigating and analyzing the effects of torsional vibration on rotor systems. Also to carry out an analysis using the developed GUI to simulate three different rotor configurations such as 2-Rotor, 3-Rotor, and 5-Rotor systems. Illustrated problems in the field of analysis of torsional vibration are carried out. The results show that the developed GUI is very useful for engineers, designers, and analysts of torsional vibration problems in rotor systems.
The purpose of this research is to control a quarter car suspension system and also to reduce the fluctuated movement caused by passing the vehicle over road bump using modified PID (Proportional Integral and Derivative) controller. The proposed controller deals with dual loop feedback signals instead of single feedback signal as in the conventional PID controller. The structure of the modified PID controller was created by moving the proportional and derivative actions in the feedback path while remaining the integral action in the forward path. Thus, high accuracy results were obtained. Firstly, modelling and simulation of linear passive suspension system for a quarter car system was performed using Matlab – Simulink software. Then the linear suspension system was activated and simulated by using an active hydraulic actuator to generate the necessary force which can be regulated and controlled by the proposed controller. The performance of whole system has been enhanced with a modified PID controller.
Fracture mechanics approach is important for all mechanical and civil projects that might involve cracks in metallic materials the purpose of this paper is to determine a crack tip opening displacement fracture toughness experimentally, also study the effect of thickness on CTOD fracture toughness of low carbon steel and study the effect of Wire Electrical Discharge Machine (WEDM) to have a pre-crack, instead of fatigue pre-crack by using a CT specimen of low carbon steel with a thickness of (8,10, and15 mm), a width of 30mm, crack length of 15mm, and pre-crack of 1.3mm for all samples, this dimension according to ASTM-E399-13, by pulling the specimen in a 100 KN universal testing machine at a slow speed rate of 0.5 mm/min, the load applied on the specimen is generally a tension load. The crack tip plastically deforms until a critical point P C at this moment a crack is initiated. The computer-controlled universal testing machine gives the value of the load and the displacement transducer gives a crack mouth opening displacement. Critical crack tip opening displacement CTOD is found with the plastic hinge model (PHM) method. The result showed the stress intensity factor K I increases with increased loading in the elastic region and t he thickness effect refers to the effect of the plastic zone at the crack tip on the stress intensity factor, In a thin specimen, a plastic zone is large at the fracture tip leads to a high-stress intensity factor at the fracture tip but in the thick specimen, on the other hand, has a small a plastic zone and a low-stress intensity factor around the crack tip. The fracture toughness is found to increase with an increase in the thickness of specimens.
The frequency analysis of bones is a new tool to assess bone quality or integrity to characterize osteoporosis. The modal analysis can also be used to determine failure characteristics of remodeled bone in the fractured model. This study describes the numerical characterization of the modal analysis of the standardized femur model. The objective of the numerical procedure is to identify the natural frequencies and mode shapes of an unconstrained femur. The vibration modes of the human femur are studied by digital modal analysis and finite element simulation using ANSYS version 10 programs, with respect to femur dimensions and mechanical properties. The changing of the values of free vibration natural frequencies and mode shapes of the femur due to changing of the femur densities are studied. The results are compared to those obtained experimentally. The comparison of the results shows a good agreement, which indicates that the used model can be utilized in vibration analysis of bones.
The purpose of this paper is to determine a stress intensity factor experimental and numerically in the linear region by using a CT specimen of ductile material with a thickness of 15 mm, a width of 30 mm, and pre-crack 1.3 mm this dimension according to ASTM-E399-12 [1], by pulling the specimen in a 600 kN universal testing machine at a very slow speed rate of 0.5 mm/min. The load is applied until the fracture is accrued, the computer-controlled universal testing machine gives the value of the load and the displacement transducer gives a crack mouth opening displacement. The result showed experimental K I is equal to 75.412 MPa √ m, and numerical K I is equal to74.576 MPa √ m, this test showed a very slight decrease in FEA stress intensity factor compared to that in an experimental result which means the stress intensity factor, K I remains very close between experimental and numerical with an error percentage of about (1.12 %). The finite element analysis provides the best approximation to true fracture toughness values, and it can be used to acquire close parameters if experimental testing is not possible.
New illustration for mixed mode fracture mechanics analysis of central cracked plates using crack extension technique and Matlab Environment is presented. The technique of crack extension is applied to the computation of mixed mode stress intensity factors in linear elastic fracture mechanics for these plates for different loads. The technique uses the Brown approximate solutions for stress intensity factors and the Westergaard analytical solutions for stress and displacement near a crack tip in finite plate to calculate crack extension during each load step using an proved to be a good tool for computation and results illustration for mixed mode stress intensity factors. The results were illustrated in a new form which is convenient for engineers and fracture mechanics analyst. The developed procedure reduced the need for sophisticated numerical analyses, which require more time and effort, to calculate the same parameters tackled in this research.