Design and Optimization

This paper provides an optimum design for regular thin-walled box section beams on their cross-sectional profiles. The thin-walled box beams with optimized cross-sectional dimensions perform ideally during the crashworthiness analysis. In this paper, the response surface method (RSM) is utilized to formulate the complex design problem. During the optimum design, the specific energy absorption (SEA) is set as the design objective, and it is constrained by the maximum crushing force (P m ) and the cross-sectional dimensions. Detailed finite element (FE) models are created for such thin-walled box beams which are used for the design optimization. Finally, simplified FE models for these beams are also created for the same design process. Optimal design obtained with the simplified models is compared to the design achieved from the detailed models to verify the accuracy and efficiency of the simplified models. ᭧

This paper proposes the incorporation of engineering knowledge through both (a) advanced state-of-the-art preference handling decision-making tools integrated in multiobjective evolutionary algorithms and (b) engineering knowledge-based variancereduction simulation as enhancing tools for the robust optimum design of structural frames taking uncertainties into consideration in the design variables. The simultaneous minimization of the constrained weight (adding structural weight and average distribution of constraint violations) on the one hand and the standard deviation of the distribution of constraint violation on the other are handled with multiobjective optimization-based evolutionary computation in two different multiobjective algorithms. The optimum design values of the deterministic structural problem in question are proposed as a reference point (the aspiration level) in reference-point-based evolutionary multiobjective algorithms (here g-dominance is used). Results including -metric statistics in a structural frame test case with uncertain loads show considerable reductions in computational costs without harming the nondominated front quality, obtaining a design set that makes it possible to select minimum weight and maximum robustness optimum designs.

Electric Overhead Travelling (EOT) Crane is one of the essential industrial equipment for material handling job. In recent years little attention has been paid to the optimal design of Heavy Electric Overhead Travelling Crane Bridges. The motive might be, but not limited to the availability of prevailing FEM, DIN, ISO, CMAA, BS, Chinese and now CEN standards for the design of cranes. Most of the crane manufacturers have standardized the single dimensioned box section for multiple spans and duties of Crane Bridges for manufacturing simplicity. Owing to the recent upward trend in the price of structural materials not to mention the demanding dimensions of heavy duty crane box girders, utilization of modern design optimization tools is inevitable. This paper demonstrates design optimization of EOT crane thin walled welded box girder subjected to rolling loads. A simple and innovative procedure has been introduced to use Generalized Reduced Gradient (GRG2) nonlinear optimization code for optimization of various parameters of the welded box section bridge and then comparing the results with the FE simulation. Local buckling of web and compression flange has also been taken in account while performing GRG2 optimization. Later vigorous random and 1st order Design Optimization is performed to establish design space and convergent solutions utilizing commercially available FEA software. Maximum allowable bending stress, allowable shear stress and deflection are constrained to recommended limits of design norms, keeping the volume of the bridge as objective function. The size and thicknesses of plates, stiffeners and reinforcement are included as design parameters (DV's). Optimal girder so designed is efficient in respect of design technique and verified as cost-effective.

— This paper investigates the effect of various rotor structures on the torque production capability of DC excited flux-switching motors. In these machines two set of windings, excited with DC and three-phase AC currents, are placed within the stator and the rotor structure should ensure that the applicable magnetic circuit is present to achieve both a high and smooth torque. As such, the rotor structure is an important factor that affects the performance of DC excited flux-switching motors. Results show that it is possible to increase the mean torque by varying the rotor tooth width or decreasing the torque ripple value by shaping the rotor tooth tip.

Purpose -This paper aims to develop a simulating model of a journal porous metal bearing under elastohydrodynamic conditions and combined (radial, friction and thermal) load distribution and to carry out structural optimization. Design/methodology/approach -The structure analysis is carried out for each kind of load separately and for the combined load distribution of the bearing, where a dynamically loaded porous metal bearing is simulated. This simulating model is developed by finite elements method using the structure analysis module of the CATIA V5 software. Further, a parameter optimization of a porous metal bearing is presented considering the elastic deformations of the bearing shell. Findings -It is revealed that the bearing, even at points with maximum displacements, could not reach the mounting clearance value during its operational life. Relatively small bearing dimensions produce very high values of eigenfrequency response (over 150 kHz) and common dynamic loads met in all sorts of sliding bearing are not dangerous for bearing damage compared with static loads. In the stage of structural optimization based on the correlation between stress and geometric bearing parameters like wall thickness and outer diameter, the influence of finite element dimension on calculated results can be also analyzed and a proper choice of the latter is achieved.

although hypoid gears provide smooth operation and high reduction ratios where compactness of design and maximum pinion strength are important, their efficiency is less than that of a similar set of spiral bevel gears. However, hypoid gears generally have greater tolerance to shock loading and can frequently be used at higher single stage ratios than spiral bevel gears. The objective of the present work is to develop a computer aided design (CAD) package for optimizing the design of hypoid gears. The CAD program calculates the gear set geometrical and strength performance variables such as the bending and contact safety factors. Strength calculations are based on ANSI/AGMA 2003-B97 standards. The CAD package allows the designer to select and change the design variables to satisfy any applied constraints. A genetic based optimization module manipulates the CAD package in a manner similar to the way that can be done by the designer but in an iterative and systematic way. The optimization module changes the design variables and compares the results to minimize the objective function subject to specified constraints. A minimum pinion volume objective function has been chosen in the present work. The main constraints are to equate the working bending and contact stresses to their respective allowable stresses. This would further make the best utilization of material and indirectly minimizes the volume. A numerical example is given to demonstrate the analysis procedure and the effectiveness of the optimization module. The results showed that the optimization procedure reduced the volume of a gear designed according to ANSI/AGMA 2003-B97 to 54% of its original volume. Further analysis was performed to study the effect of the design variables and the input parameters on the objective function.

Mechanical systems will almost inevitably fail at some point during operation. This can either be due to a preexisting design flaw or some unexpected damage during usage. No matter how much planning and fault analysis is performed it is impossible to create a perfectly reliable machine. Existing approaches to improving reliability normally involve advances in modeling and detection to include specific mechanisms to overcome a particular failure or mitigate its effect. Whilst this has gone a long way to increasing the operational life of a machine, the overall complexity of systems has improved sharply and it is becoming more and more difficult to predict and account for all possible failure modes. Rather than focusing on mitigating or reducing the probability of failure, a new design philosophy is proposed that allows systems to reconfigure themselves to overcome failure -thus yielding a self-healing design. This approach is demonstrated in the design of a selfrectifying 4-bar linkage mechanism.

Generative Design coupled with associative parametric modelling is proving to be a successful tool for many designers particularly in the early phases of design. The wealth of design solutions which can be rapidly generated certainly help in expanding ideas and exploring possibilities. But simply having the capability to generate different solutions is only half of the process. The designer must make decisions as to which solutions are better. ParaGen, as described in this paper, offers a way to direct the generative process toward more desirable results, and to explore better solutions.

The Roadway vehicles like cars, buses, trucks and land movers having many mechanical parts in common like Engine parts, Propeller shafts, Gearbox, Brakes, Clutches, Wheels, etc., To make the vehicle fuel efficient which in result make the transportation economical, the weight of that vehicle should be reduced. Since the composite materials are light weight with more strength & stiffness, inclusion of composite materials to conventional steel materials used in auto parts will reduce the weight and improve the mechanical properties of those components. This paper deals with propeller shaft of heavy vehicle to design the shaft for its minimum dimensions to satisfy current problem specification and then replace conventional steel material with composite material. The design of the propeller shaft is first theoretically designed for steel, Carbon/Epoxy and Glass/Epoxy composite material for its safe dimensions. Then they can be created as a part model for respective dimensions in CREO software. After modeling, Torsional buckling analysis can be carried out in the propeller shafts using ABAQUS software to check whether theoretical calculations and analytical results are similar. Then obtained results are compared among those three materials and Carbon/Epoxy composite material is selected as suitable replacement material for conventional steel material in terms of several mechanical properties.

Traditional urban design methods, still relying on the static and sectoral approaches, reach their limits to adapt themselves to the growing complexities and dynamics of modern cities. With the flourishing of artificial intelligence, a new approach called " cognitive design computing " has been proposed to utilize both the human creativity and computing power for the development of next generation urban design supporting tools, where Evolutionary Multi-objective Optimization (EMO) is employed for urban synthesis. However, a unified data structure is missing for the genotype representation of different urban features, such as streets, blocks, plots and buildings, so that they can be optimized together. This paper aims to address this problem and is focused on i) the introduction and description of the genotype data structure, and ii) the application of the prototype of the proposed design tool in practice. (1) PhD student,

Genetic algorithm (GA) is a Non-Traditional method is useful and applicable for optimization of mechanical component design. The GA is an efficient search method which is inspired from a natural genetic selection process to explore a given search space. In this work, GA is applied to minimize the volume of hypoid gear with respect to a specified set of constraints. Module, face width and number of teeth of hypoid are used as design variables and the bending stress, contact stress and a geometric limit on the face width are set as constraints. The results showed that the optimal procedure reduced the volume of a gear designed according to ANSI/AGMA 2003-B97 to 54% of its original volume. Further analysis was performed to study the effect of the design variables and the input parameters of the objective function.

Tujuan penelitian ini adalah melakukan analisis kekuatan mekanis knuckle, dibuat dari material FCD 50, dengan menggunakan analisis statis pada pembebanan maksimal. Beban maksimal ini diperoleh dari perhitungan pembebanan pada poros depan kendaraan dalam kondisi operasi kendaraan yang direm pada saat berbelok di jalan menurun. Pada analisis pembebanan poros kendaraan sebelumnya diperoleh beberapa nilai pembebanan pada beberapa nilai kecepatan dan deselerasi. Akhirnya, diperoleh nilai deselerasi dan nilai kecepatan maksimum kendaraan dimana kendaraan aman dioperasikan pada saat direm di jalan menurun dan berbelok. Sebagai perbandingan juga dilakukan perhitungan pembebanan poros depan kendaraan pada kondisi operasi kendaraan yang direm pada saat berbelok di jalan mendatar, karena deselerasi yang berbeda untuk masing-masing kondisi operasi, yaitu 0,5g untuk kondisi operasi di jalan mendatar dan 0,2g untuk kondisi operasi di jalan menurun. Hasil perhitungan tetap menunjukkan pembebanan maksimum pada kondisi operasi di jalan menurun. Studi statika diarahkan pada deskripsi kuantitatif dari gaya-gaya yang bekerja pada struktur teknik dalam kesetimbangan.

This work is on the aerodynamics design of the body and frame of a motor tricycle using SolidWorks 2011 modeling system. Its Computational Fluid Dynamics (CFD) feature was used to run simulation tests at a target speed of 150 km/h to evaluate the aerodynamic performance of the tricycle. Simulation results presented shows that lift and drag forces are diminished considerably and that 170 km/h is the maximum speed to be traveled by the tricycle for a smooth and stable ride. Also, the design reduced drastically the effects of lift and drag forces, increased the tricycle’s stability, traction and performance as well as minimized the weight of the tricycle as a result of the use of high performance to mass ratio materials such as carbon fiber for the body and alloy steel for the frame and rims.

Recent years have witnessed the use of wind as renewable energy source. This rapid growth has tremendously developed since the growing concern of the environmental pollution and also oil crisis. The size of the blades is a major factor in the power output of a wind turbine and as a result, blade length has tremendously increased in line with the growth of the wind turbine industry. However, the rapid expansion in use and size of wind turbines contribute its problems. Among the problem is maintaining the shape control at high load especially which substantially affect the aerodynamic efficiency of the airfoil of the wind blade. The structure of the wind blade is made of glass fibre reinforced plastic (GFRP) which is not only has high strength -to-weight ratio and also good rigidity. Nevertheless, it can't resist the shape upon operational air loading such as deflection from root to tip. The higher stress levels acting on the blade root will also contributes to the accumulation of fatigue damages and consequently catastrophic failures. This study intends to experimentally investigate the application of smart materials in composite wind turbine blades like structures. Nickel-Titanium (NiTi) wire which is classified as Shape Memory Alloy (SMA) has been embedded in the core of a graded beam to alleviate the load at the fixed. This corrective action relieves the high stress concentration at blade root and as a consequence minimizes fatigue damages to the blade. The study closely look at the heat load needs to be applied, the transformation temperatures, the recovery stress of NiTi. The recovery stress is very important in structural application for SMA as the recovered stress could be purposely for actuation and damping control in composite blades. A mathematical model has been developed on commercial finite element software ABAQUS for comparison.