International Journal of Advanced Design and Manufacturing Technology: 1 (1)

Open Access Article

1 - Application of Different Hill’s Yield Criteria to Predict Limit Strains for Aerospace Titanium and Aluminum Sheet Alloys
Milad Janbakhsh S. M. R. Loghmanian Faramarz Djavanroodi

More recently, Titanium and aluminum alloys are gaining more interests to be implemented in hydro-forming applications. It is necessary to predict forming limits for these sheet alloys. Forming limits play an important role in metal forming processes. Forming limit diag More

More recently, Titanium and aluminum alloys are gaining more interests to be implemented in hydro-forming applications. It is necessary to predict forming limits for these sheet alloys. Forming limits play an important role in metal forming processes. Forming limit diagrams, present the limit strains for various linear strain paths. In other hand, forming limit curve (FLC), illustrates localized formability for sheet metals under proportional loadings and are known as a powerful tool for trouble-shooting in sheet metal forming processes. In this study, mechanical properties of Ti-6Al-4V titanium sheets, AA7075-T6 and AA2024-T3 aluminum sheets are investigated through the uni-axial tensile test. Anisotropy coefficients as well as work-hardening exponent resulted from tensile test were used to theoretically prediction and numerical simulations of limit strains. For the theoretical prediction of the forming limit curves, several constitutive models were implemented. Several Hill’s yield criteria combined with Swift equation and empirical equation proposed by NADDRG were accomplished to predict the FLDs. Results showed that calculated numerical results are in good agreement with the predicted theoretical data when Hill93-Swift is the instability criteria used. Manuscript profile

Open Access Article

2 - Optimal control with adaptive weighting coefficients for integrated vehicle dynamics control
naser esmaeili S. Hamed Tabatabaei Oreh Reza Kazemi

Abstract: In this work, an optimal control scheme with adaptive weighting coefficients is presented which coordinates different vehicle dynamics control objectives, thus ruling out possible conflicts among them. In a new approach, the weighting coefficients in optimal c More

Abstract: In this work, an optimal control scheme with adaptive weighting coefficients is presented which coordinates different vehicle dynamics control objectives, thus ruling out possible conflicts among them. In a new approach, the weighting coefficients in optimal control are adjusted according to the vehicle state in the phase plane in such a way that a priority is given to each objective of handling and stability in each region. The optimal control acts as a high-level control for the vehicle body, which determines the body lateral force and yaw moment for stable vehicle motion. The body lateral force and yaw moment provide the inputs to the mid-level force (control) distribution module, which works out the desired lateral and longitudinal forces at each wheel. Therefore, the high-level control objectives are allocated to individual tire forces in an optimal manner with the assumption of a 4-wheel-independent car. A low-level control uses the desired individual tire forces to compute the steering angle and applied torque at each wheel. Simulation tests with a nonlinear vehicle model are conducted and comparison with the well-recognized work in the literature is made to show the efficiency of the proposed method. Manuscript profile

Open Access Article

3 - Path Following of a High Speed Planing Boat Based on Gauss Pseudospectral Method
M. T. Ghorbani

In this paper, the problem of optimal path following for a high speed planing boat is addressed. First, a nonlinear mathematical model of the boat’s dynamics is derived and then the Serret-Frenet frame is presented to facilitate the path following control design. To sat More

In this paper, the problem of optimal path following for a high speed planing boat is addressed. First, a nonlinear mathematical model of the boat’s dynamics is derived and then the Serret-Frenet frame is presented to facilitate the path following control design. To satisfy the constraints on the states and the input controls of the boat's nonlinear dynamics and minimize both the cross tracking and heading error, a nonlinear optimal controller is formed. To solve the resulted nonlinear constrained optimal control problem, the Gauss pseudospectral method (GPM) is used to transcribe the optimal control problem into a nonlinear programming problem (NLP) by discretization of states and controls. The resulted NLP is then solved by a well-developed algorithm known as SNOPT. The results illustrate the effectiveness of the proposed approach to tackle the boat path following problem. Manuscript profile

Open Access Article

4 - Design and performance evaluation of Tuned Vibration Absorber for the vibration control of a centrifugal pump
Anant Sheth

With the prolonged use of domestic centrifugal pump, due to erosion, corrosion and an unbalance the sever vibration of the pump are resulted. An erratic sound coming out of pump makes the user uncomfortable. Here, Tuned Vibration Absorber (TVA) is used as a vibration co More

With the prolonged use of domestic centrifugal pump, due to erosion, corrosion and an unbalance the sever vibration of the pump are resulted. An erratic sound coming out of pump makes the user uncomfortable. Here, Tuned Vibration Absorber (TVA) is used as a vibration controlling device. It is designed to reduce the RMS velocity below 20% of the circumferential speed, at which the impeller is balanced. Natural frequency were found both by analytical and the numerical methods. A fan cover is considered as a TVA, tuned to the operating frequency and the dominating higher frequencies have been tackled by designing new TVA. Here with TVA, the vibration has been reduced to the permissible limit and the amplification factor is within the allowable limit. Manuscript profile

Open Access Article

5 - Simulation of Air Pad Shape on Pressure Distribution in Air Gap of Air Table in Ultra Precision Machine Tools
Mohammad Akhondzadeh Mehrdad Vahdati

Air pads are applicable in ultra precision machines very much. Two main components of these machines, spindle and table, use the advantages of such systems. The performance and efficiency of air pads have big influence on the whole machine quality. Parameters affecting More

Air pads are applicable in ultra precision machines very much. Two main components of these machines, spindle and table, use the advantages of such systems. The performance and efficiency of air pads have big influence on the whole machine quality. Parameters affecting pressure distribution of air tables may be considered as, 1) air compressing method, 2) air nozzle diameter, shape, and size, 3) number of air pads, 4) air gap thickness, etc. In this study, effects of air pad shape on pressure distribution in air gap have been investigated using ANSYS. In this simulation, FOTRAN environment have been employed. Investigated shapes for air pads are triangle, rectangle, pentagon, hexagon, ellipse and circle. Pressure distribution-distance from orifice has been plotted for each air pad shape. The results indicate that the rectangle air pad has best pressure distribution. Manuscript profile

Open Access Article

6 - Heat transfer of Nano-fluids as working fluids of swimming pool heat exchangers
Nariman Ashrafi Yashar Bashirzadeh

The present experimental study reports on enhancement of heat transfer by addition of nanoparticles to the working fluid of commercial swimming pool heat exchangers under laminar flow condition. Three different concentrations of Titanium dioxide nanoparticles were added More

The present experimental study reports on enhancement of heat transfer by addition of nanoparticles to the working fluid of commercial swimming pool heat exchangers under laminar flow condition. Three different concentrations of Titanium dioxide nanoparticles were added to the water as working fluid of a typical forced convective heat exchanger used to transfer heat to public swimming pools. The experimental setup is capable of measuring velocity, heat transfer rate, and temperature at different points. TiO2 nanoparticles with mean diameter of 20 nm were used. The effects of concentration of suspended nanoparticles and that of Reynolds number on forced convective heat transfer were investigated. It is observed that at 0.1%, 0.5% and 1% weight concentration of suspended TiO2 nanoparticles, the average convective heat transfer coefficient improved by 1.1%, 15.9% and 31.6% respectively. The coefficient is further increased at higher Reynolds numbers. The efficiency of heat exchanger is evaluated for different scenarios. Manuscript profile

Open Access Article

7 - Trajectory Optimization of Spherical Parallel Robots Using Artificial Neural Network
Reza Alibakhshi

This article addresses an efficient and novel method for singularity-free path planning and obstacle avoidance of parallel manipulator based on neural networks. A modified 4-5-6-7 interpolating polynomial is used to plan a trajectory for a spherical parallel manipulator More

This article addresses an efficient and novel method for singularity-free path planning and obstacle avoidance of parallel manipulator based on neural networks. A modified 4-5-6-7 interpolating polynomial is used to plan a trajectory for a spherical parallel manipulator. The polynomial function which is smooth and continuous in displacement, velocity, acceleration and jerk is used to find a path avoiding obstacles and singularities. The polynomial is further modified to plan a trajectory with minimum passing length through the obstacle and singularity, and the best kinematics conditioning index, as well. An artificial neural network is implemented to solve forward kinematics of the manipulator to estimate the distance between gripper and singularity or obstacle in Euler coordinate. Moreover, the simulation results prove the efficiency of the proposed algorithm. Manuscript profile

Open Access Article

8 - Design Enhancement of EGR System for Improved Vibration Performance on Truck Diesel Engine
Karthikeyan Subramanian

In the diesel engine Exhaust Gas Recirculation (EGR) components, valve and connecting pipes are the critical components and fails often during new engine development. These components are important for meeting NOx emissions norms. Therefore design of these components sh More

In the diesel engine Exhaust Gas Recirculation (EGR) components, valve and connecting pipes are the critical components and fails often during new engine development. These components are important for meeting NOx emissions norms. Therefore design of these components should remain robust. But the challenge in design is compact packaging of complete EGR components on the engine consequently vibration related failure plays a major role. Normally in pneumatic EGR valve, shaft spring stiffness plays a major role for shaft opening and closing. But in this layout during emission testing, shaft is self-opened without feedback signal from sensor this is due to resonance and this problem is solved by increasing the spring stiffness. The next key components is the EGR pipes, the flexible bellows on these pipes are useful for thermal expansion during hot conditions. In this case the bellow crack failure is observed due to vibration. Therefore design improvements were made by proper design of bellow geometry and bracket support for these pipes facilitated prevention of EGR pipe failure. Overall this paper describes the methodology to conduct proper failure investigation to identify the root cause for vibration related failures of EGR system during new product development. Manuscript profile

Open Access Article

9 - Multi-objective Suspension Optimization of a 5-DOF Vehicle Vibration Model Excited by Random Road Profile
Mohammad Hasan Shojaeefard Abolfazl Khalkhali Pedram Safarpour Erfani

The vehicle driving comfort has become one of the important factors of vehicle quality and receives increasing attention. In this paper, optimal points of vehicle suspension parameters are generated using modified non-dominated sorting genetic algorithm (NSGA-II) for Pa More

The vehicle driving comfort has become one of the important factors of vehicle quality and receives increasing attention. In this paper, optimal points of vehicle suspension parameters are generated using modified non-dominated sorting genetic algorithm (NSGA-II) for Pareto optimization of 5-degree of freedom vehicle vibration model considering three conflicting functions simultaneously. In this way random profile is considered for the road excitation. Objective functions are vertical acceleration of seat, relative displacement between sprung mass and forward tire and relative displacement between sprung mass and rear tire. Results are compared with the previous works. Such comparison shows good behaviour of the optimum design points proposed in this work. Manuscript profile

Open Access Article

10 - Nonlinear vibration and instability of embedded viscose-fluid-conveying pipes using DQM
Mohammad Mehdi Ghaitani Ali Ghorbanpour Arani Hasan Khademizadeh

In this paper, nonlinear vibration and instability response of an embedded pipe conveying viscose fluid is investigated. The pipe is considered as a Timoshenko beam embedded on an elastic foundation which is simulated by spring constant of the Winkler-model and the shea More

In this paper, nonlinear vibration and instability response of an embedded pipe conveying viscose fluid is investigated. The pipe is considered as a Timoshenko beam embedded on an elastic foundation which is simulated by spring constant of the Winkler-model and the shear constant of the Pasternak-model. The external flow force, acting on the beam in the direction of the flexural displacement is described by the well-known Navier-Stokes equation. The corresponding governing equations are obtained using Hamilton's principle considering nonlinear strains and first shear deformation theory. In order to obtain the nonlinear frequency and critical fluid velocity for clamped supported mechanical boundary condition at two ends of the pipe, Differential quadrature method (DQM) is used in conjunction with a program being written in MATLAB. The effect of dimensionless parameters such as aspect ratios of length to radius of the pipe, Winkler and Pasternak modules, fluid velocity and viscosity as well as the material type of the pipe on the frequencies and instability of pipe are investigated. Results indicate that the internal moving fluid plays an important role in the instability of the pipe. Furthermore, the nonlinear frequency and instability increases as the values of the elastic medium constants and viscosity of fluid increases. Manuscript profile

Open Access Article

11 - Process Parameters Optimization to Improve Dimensional Accuracy of Stereolithography Parts
sadegh Rahmati Farid Ghadami

Stereolithography process limits wider applications due to low dimensional accuracy comparing with CNC. To improve accuracy and reduce part distortion, understanding the physics involved in the relationship between the setup input parameters and the part dimensional acc More

Stereolithography process limits wider applications due to low dimensional accuracy comparing with CNC. To improve accuracy and reduce part distortion, understanding the physics involved in the relationship between the setup input parameters and the part dimensional accuracy is prerequisite. In this paper, a model is proposed to find and optimize important parameters to achieve a high accuracy and also, to prediction dimensional accuracy with various values of parameters. For this purpose, the result of a previous study is used. It is found in Stereolithography these factors, respectively, have a most impact on dimensional accuracy in parts built SLA: layer thickness, hatch style, hatch spacing, hatch fill cure depth and hatch overcure. The proposed neural network model in this paper is able to predict dimensional accuracy with about 6 percents error. Manuscript profile

Open Access Article

12 - Application of Pulsed eddy current technique to stress and residual stress measurement
Abbas Habibalahi M. S. Safizadeh

Stress and residual stress are the main problems in the operating performance of materials. They are the principal causes of material failure and can affect life time of component. However measurement or predictions of them are typically difficult. Two common non-destru More

Stress and residual stress are the main problems in the operating performance of materials. They are the principal causes of material failure and can affect life time of component. However measurement or predictions of them are typically difficult. Two common non-destructive methods, X-ray diffraction and ultrasound are not reliable methods for subsurface residual stress measurements and destructive hole-drilling method is not absolutely precise and safe. In this study, the PEC method was applied to the qualitative and quantitative measurements of stress in aluminum alloy specimens. PEC is a high performance non-destructive testing technique but its application in stress and residual measurement is unknown. In this study a qualitative and quantitative approach for measuring residual stress by PEC technique was developed. Results indicated that pulsed eddy current responses are sensitive to stress and showed PEC method is capable of residual stress measurements. Manuscript profile

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