Optimal design of a spherical parallel manipulator based on kinetostatic performance using evolutionary techniques

Morteza Daneshmand,Mohammad Hossein Saadatzi,Mohammad Hadi Farzaneh Kaloorazi,Mehdi Tale Masouleh,Gholamreza Anbarjafari 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3

This study aims to provide an optimal design for a Spherical parallel manipulator (SPM), namely, the Agile Eye. This aim is approached by investigating kinetostatic performance and workspace and searching for the most promising design. Previously recommended designs are examined to determine whether they provide acceptable kinetostatic performance and workspace. Optimal designs are provided according to different kinetostatic performance indices, especially kinematic sensitivity. The optimization process is launched based on the concept of the genetic algorithm. A single-objective process is implemented in accordance with the guidelines of an evolutionary algorithm called differential evolution. A multi-objective procedure is then provided following the reasoning of the nondominated sorting genetic algorithm-II. This process results in several sets of Pareto points for reconciliation between kinetostatic performance indices and workspace. The concept of numerous kinetostatic performance indices and the results of optimization algorithms are elaborated. The conclusions provide hints on the provided set of designs and their credibility to provide a well-conditioned workspace and acceptable kinetostatic performance for the SPM under study, which can be well extended to other types of SPMs.

A modified particle swarm approach for multi-objective optimization of laminated composite structures

Sepehri, A.,Daneshmand, F.,Jafarpur, K. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.42 No.3

Particle Swarm Optimization (PSO) is a stochastic population based optimization algorithm which has attracted attentions of many researchers. This method has great potentials to be applied to many optimization problems. Despite its robustness the standard version of PSO has some drawbacks that may reduce its performance in optimization of complex structures such as laminated composites. In this paper by suggesting a new variation scheme for acceleration parameters and inertial weight factors of PSO a novel optimization algorithm is developed to enhance the basic version's performance in optimization of laminated composite structures. To verify the performance of the new proposed method, it is applied in two multi-objective design optimization problems of laminated cylindrical. The numerical results from the proposed method are compared with those from two other conventional versions of PSO-based algorithms. The convergancy of the new algorithms is also compared with the other two versions. The results reveal that the new modifications inthe basic forms of particle swarm optimization method can increase its convergence speed and evade it from local optima traps. It is shown that the parameter variation scheme as presented in this paper is successful and can evenfind more preferable optimum results in design of laminated composite structures.

Efficacy of corticosteroids for postoperative endodontic pain: A systematic review and meta-analysis

Nath, Ranjivendra,Daneshmand, Ali,Sizemore, Dan,Guo, Jing,Enciso, Reyes The Korean Dental Society of Anesthsiology 2018 Journal of Dental Anesthesia and Pain Medicine Vol.18 No.4

This systematic review aimed to analyze the efficacy of corticosteroid premedication compared to placebo or no treatment to reduce postoperative pain in endodontic patients. Randomized controlled trials (RCTs) assessing corticosteroids via oral, intramuscular, subperiosteal, intraligamentary or intracanal route compared to passive or active placebo, or no treatment were included. Four databases were searched: PubMed, Web of Science, Cochrane Library and Embase up to 2/21/2018. Risk of bias was assessed with Cochrane Risk of bias tool. Fourteen RCTs with 1,462 generally healthy adults in need of endodontic treatment were included. 50% of the studies were at unclear risk and 50% at high risk of bias. Meta-analysis showed Visual Analog Scale (VAS) pain at 4-6 hours after Inferior Alveolar Nerve Block (IANB) was significantly lower by 21 points (0-100 scale) in the corticosteroid group compared to the control group (95% CI -35 to -7; P = 0.003), however this difference was not statistically significant after 24 hours (P = 0.116). The route of administration was oral and intraligament injection. Patients who received corticosteroids prior to IANB were 70.7% more likely to have none or mild pain 4-8 hours after treatment (P = 0.001) and 13.5% more likely 24 hours after IANB (P = 0.013) than patients in the control group. In conclusion, corticosteroid administration (oral or intraligamental) may clinically reduce the level of postoperative pain at 4-8 hours after IANB, however the quality of the evidence was low/moderate due to risk of bias and heterogeneity. Further studies are recommended.

Analysis of the Influence of Electrical Discharge Machining Parameters on Surface Roughness of CK45

Abedi, Esmail,Daneshmand, Saeed,Karimi, Iman,Neyestanak, A. A. Lotfi The Korean Electrochemical Society 2015 Journal of electrochemical science and technology Vol.6 No.4

Electrical discharge machining is an unconventional machining process in which successive sparks applied to machine the electrically conductive materials. Any changes in electrical discharge machining parameters lead to the pieces with distinct surface roughness. The electrical discharge machining process is well applied for high hardness materials or when it is difficult to use traditional techniques to do material removing. Furthermore, this method is widely applied in industries such as aerospace, automobile, molding, and tool making. CK45 is one of the important steels in industrial and electrical discharge machining can be considered as a proper way for its machining because of high hardness of CK45 after thermal operation of the electrical discharge machining process. Optimization of surface roughness as an output parameters as well as electrical discharge machining parameters including current, voltage and frequency for electrical discharge machining of CK45 has been studied using copper tools and kerosene as the dielectric. For such a purpose and to achieve the precise statistical analysis of the experiment results design of experiment was applied while non linear regression method was chosen to assess the response of surface roughness. Then, the results were analyzed by means of ANOVA method and machining parameters with more effects on the desired outputs were determined. Finally, mathematical model obtained for surface roughness.

Dynamic behavior of a functionally graded plate resting on Winkler elastic foundation and in contact with fluid

Ali A. Shafiee,Farhang Daneshmand,Ehsan Askari,Mojtaba Mahzoon 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.1

A semi-analytical method is developed to consider free vibrations of a functionally graded elastic plate resting on Winkler elastic foundation and in contact with a quiescent fluid. Material properties are assumed to be graded distribution along the thickness direction according to a power-law in terms of the volume fractions of the constituents. The fluid is considered to be incompressible and inviscid. In the analysis, the effect of an in-plane force in the plate due to the weight of the fluid is taken into account. By satisfying the compatibility conditions along the interface of fluid and plate, the fluid-structure interaction is taken into account and natural frequencies and mode shapes of the coupled system are acquired by employing energy methods. The results obtained from the present approach are verified by those from a finite element analysis. Besides, the effects of volume fractions of functionally graded materials, Winkler foundation stiffness and in-plane forces on the dynamic of plate are elucidated.

Closed loop control of the planar flexible manipulator via Youla-Kucera parameterization

Habib Esfandiar,Saeed Daneshmand 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.11

This work treats the problem of controlling a flexible robotic manipulator. The case study is a planar manipulator with a single flexible arm together with a clamped-free end and a tip lumped mass. To control the angular position of the flexible arm using an actuator, a controller method is developed which is based on Youla-Kucera parameterization. The main challenge in this approach is to obtain a Youla parameter with infinity dimensions. This parameter is approximated by a subspace with finite dimensions which makes the problem tractable. The developed approach exhibit advanced theoretical properties and good numerical convergence. In this paper, two sets of orthogonal bases such as FIR and Laguerre bases are used for system identification. The results of the present case study indicate that the proposed method is very efficient and robust for the time-continuous instances. The characteristics of an optimization problem are finally formulated for larger systems with hundreds of variables and solved with the interior point method.

Effect of Tio₂ particles on the mechanical, bonding properties and microstructural evolution of AA1060/TiO₂ composites fabricated by WARB

Vini, Mohamad Heydari,Daneshmand, Saeed Techno-Press 2020 Advances in materials research Vol.9 No.2

Reinforced aluminum alloy base composites have become increasingly popular for engineering applications, since they usually possess several desirable properties. Recently, Warm Accumulative Roll Bonding (WARB) process has been used as a new novel process to fabricate particle reinforced metal matrix composites. In the present study, TiO₂ particles are used as reinforcement in aluminum metal matrix composites fabricated through warm accumulative roll bonding process. Firstly, the raw aluminum alloy 1060 strips with TiO₂ as reinforcement particle were roll bonded to four accumulative rolling cycles by preheating for 5 min at 300℃before each cycle. The mechanical and bonding properties of composites have been studied versus different volume contents of TiO₂ particles by tensile test, peeling test and vickers micro-hardness test. Moreover, the fracture surface and peeling surface of samples after the tensile test and peeling test have been studied versus different amount of TiO₂ volume contents by scanning electron microscopy. The results indicated that the strength and the average vickers micro-hardness of composites improved by increasing the volume content of TiO₂ particles and the amount of their elongation and bonding strength decreased significantly.

Bonding evolution of bimetallic Al/Cu laminates fabricated by asymmetric roll bonding

Vini, Mohamad Heydari,Daneshmand, Saeed Techno-Press 2019 Advances in materials research Vol.8 No.1

Roll bonding (RB) process of bi-metal laminates as a new noble method of bonding has been widely used in the production of bimetal laminates. In the present study, asymmetric roll bonding process as a new noble method has been presented to produce Al/Cu bimetallic laminates with the thickness reduction ratios 10%, 20% and 30% together with mismatch rolling diameter ($\frac{R_2}{R_1}$) ratio 1:1, 1:1.1 and 1:1.2. ABAQUS as a finite element simulation software was used to model the deformation of samples. The main attention in this study focuses on the bonding properties of Al/Cu samples. The effect of the $\frac{R_2}{R_1}$ ratios was investigated to improve the bond strength. During the simulation, for samples produced with $\frac{R_2}{R_1}=1:1.2$, the vertical plastic strain of samples was reach the maximum value with a high quality bond. Moreover, the peeling surface of samples after the peeling test was investigated by the scanning electron microscopy (SEM).

OPTIMIZATION AND DESIGN OF DISK-TYPE MR BRAKES

B. ASSADSANGABI,F. DANESHMAND,N. VAHDATI,M. EGHTESAD,Y. BAZARGAN-LARI4 한국자동차공학회 2011 International journal of automotive technology Vol.12 No.6

In this paper, first a new design for a disk-type magneto-rheological (MR) brake for automotive applications is proposed and then, a finite element analysis is performed to analyze the resulting magnetic field intensity distribution within the MR brake configuration. This finite element model of the brake is then utilized in a optimization process which incorporates Genetic Algorithm (GA) to obtain optimal design parameters. The optimization process goal is to increase the braking torque capacity of the brake while keeping the weight of the brake as low as possible. Although, the braking torque of the present design is larger compared to the previous designs, the braking toque capacity of the present design is still smaller than the required braking torque for automobiles.

Mechanical and wear properties evaluation of Al/Al₂O₃ composites fabricated by combined compo-casting and WARB process

Vini, Mohamad Heydari,Daneshmand, Saeed Techno-Press 2022 Advances in computational design Vol.7 No.2

Compo-casting method is one of the popular technique to produce metal based matrix composites. But, one of the main challenges in this process is un-uniform spreading of reinforced subdivisions (particles) inside the metallic matrix and the lack of desirable mechanical properties of the final produced composites due to the low bonding strength among the metal matrix and reinforcement particles. To remove these difficulties and to promote the mechanical properties of these kind of composites, the WARM ARB technique was utilized as supplementary technique to heighten the mechanical and microstructural evolution of the casted Al/Al₂O₃ composite strips. The microstructure evolution and mechanical properties of these composites have been considered versus different WARM ARB cycles by tensile test, average Vickers micro hardness test, wear test and scanning electron microscopy (SEM). The SEM results revealed that during the higher warm- ARB cycles, big alumina clusters are broken and make a uniform distribution of alumina particles. It was shown that cumulating the forming cycles improved the mechanical properties of composites. In general, combined compo-casting and ARB process would consent making Al/Al₂O₃ composites with high consistency, good microstructural and mechanical properties.