Objective:This study aimed to determine the effect of hardening temperature on microstructure, wear and corrosion resistance of Fe-Al-Mn alloy grinding ball.Methods:Hardening process was carried out at 900oC, 950oC, 1000oC, 1050oC and 1100oC, held for 60 minutes and cooled using SAE 20 oil. Tests included chemical composition, SEM-EDS, wear and corrosion resistance test.Results:Chemical composition test results show that this alloy is high alloy steel because it contains 3.6% aluminum (Al), 13.6% manganese (Mn) and 1.1% carbon (C). Microstructures found are austenite, ferrite and kappa. EDS test results show that in the austenite phase, C decreased when hardening temperature increased. Ferrite phase contains Mn which increased when hardening temperature increased while C was the other way around. Mn is relatively stable in the kappa phase. The best wear and corrosion resistance (4.3 x 10-7mm2/kg and 0.00026 mm/yr) of hardened Fe-Al-Mn grinding ball occurred at 900oC. The corrosion rate is extraordinary.Conclusion:Microstructures of the Fe-Al-Mn alloy grinding ball after the hardening process are austenite, ferrite and kappa.
Background: During operation, cylindrical gearset experiences tangential, radial, and axial (helical gears only) force components that induce bending, compressive, and shear stresses at the root area of the gear tooth. Accurate estimation of the effective bending stress at the gear root is a challenge. Lewis was the first person who attempted estimating the root bending stress of spur gears with some reasonable accuracy. Various gear standards and codes in use today are modifications and improvements of the Lewis model. Objective: This research aims at revising the Lewis model by making adjustments for dynamic loads, shear stresses, axial bending stress for helical gears, and stress concentration factor that is independent on the moment arm of tangential or axial force component. Methods: An analytical approach is used in formulating a modified formula for the root bending stress in cylindrical gears starting with the original Lewis model. Intermediate expressions are developed in the process and works from many previous authors are reviewed and summarized. The new model developed is used to estimate the root bending stress in four example gearsets of 0o to 41.41o helix angle and the results are compared with those of AGMA (American Gear Manufacturers Association) formula. Results: Analysis from the examples shows that neglecting the radial compressive stress over-estimated the root bending stress by 5.27% on average. When shear stresses are ignored, the root bending stress is under-estimated by 7.49% on average. It is important, therefore, to account for both compressive and shear stresses in cylindrical gear root bending stress. When the root bending stress estimates from the revised Lewis model were compared with AGMA results, deviations in the range of -4.86% to 26.61% were observed. The stress estimates from the revised Lewis formulae were mostly higher than those of AGMA. Conclusion: The new root bending stress model uses stress concentration factors (normal and shear) that are independent of the point of load application on the gear tooth. This decoupling of stress concentration factor from the load moment arm distinguishes the new model from AGMA formula and brings bending stress analysis in gear design in line with classical bending stress analysis of straight and curved beams. The model can be used for both normal contact ratio and high contact ratio cylindrical gears.
Background: On the most elementary level, you and I (human beings) were created with five main mechanisms (or parts): • A body which is termed as the main structure of the human being. • A sensory system that takes certain information around the body and the immediate environment. • A muscle system to aid the body move easily. • A control base to trigger the muscles and sensors. • A brain system that develops sensory data and tells the muscles what to do in other words the way forward. Obviously, we likewise have some imperceptible qualities, for example, intellect and ethics, among others but on an absolute corporeal level. Robots, on the other hand, can be created with five main mechanisms or more. Objectives: This research aims at implementing robots in some tedious jobs that as supposed to be executed by human beings in various factories and industries. This study also presents the practical and tentative model for Extenics replications of the moveable mechanical device (robot) useful on VIPRO stage. Methods: Momentary antiquity and indication of the pertinent hypothetical ideas are provided. The intelligent boundary for drawn-out switch uses a novel element for synthetic intelligence which is drawn-out control (Extenics) to expand DHFPC switch rapid enactment of mobile robots. Result: Applying Extenics specific methods and application in vague interplanetary result in a novel, advanced application for the VIPRO stage which can be used to feign and device innovative switch approaches of moveable robots.
Aims:A procedure to optimise the stacking sequence of a composite fan blade-like structure is proposed in this article. The aim of the optimisation is to minimise weight when respecting deformation, frequency and strain constraints. The literature often deals with stacking sequence optimisation of airplane wings or wind turbine blades whilst less attention has been dedicated to aero-engines fan blades, the objective of the present paper. The manufacturing constraints are also implemented in the optimisation process in order to obtain a manufacturable structure.Background:Stacking sequence of composite laminates can be tailored to drive the deformation towards the desired shape (potentially exploiting unbalanced laminates and their anisotropy). When optimising the stacking sequence (including blending/tapering) of an aero-engine fan blade-like structure, manufacturing constraints must be included in order to apply the results of the optimisation procedure into a “Real World” design.Objectives:To define an engineering procedure able to provide a good design point to minimise the weight of a fan blade-like structure subjected to deformation (tip extension and untwist), frequency and strain constraints.Methods:A two-level optimisation procedure is proposed. At the first level, the stacking sequence is optimised in such a way to maximise stiffness (and therefore to minimise deformation). Less stringent limits are applied to the constraints of such a level 1 optimisation. In the second step of the optimisation, the blending/tapering of each ply of the stacking sequence is searched.Results:The fan blade-like structure is loaded only with a centrifugal load (the main load acting on this kind of components). The stacking sequence obtained to minimise the weight contains 42.3% of 0 degrees fibres, 19.25% of 45 degrees fibres, 19.25% of -45 degrees fibres and 19.2% of 90 degrees fibres. Blending in terms of width and length of each layer is given in the numerical results section.Conclusions:When the fan blade-like structure is loaded with a centrifugal force only, in order to minimise weight by respecting untwist, tip extension, frequency and integrity constraints, no unbalance in the laminate has been found necessary. An “Optimum” point has been found after a two steps optimisation. This design point is claimed as a good industrial design point rather than as “optimum” in the mathematical sense. Such a “Best Solution” design point has been verified by exploring the design space near it. All the performance of the neighbour points has been found worse. A comparison between a quasi-isotropic laminate and a zero degreed dominated laminate has been also performed.
There are many joint problems between applied mathematics and mechanical engineering.Such problems are very important for development of both experimental and theoretical studies.For example, Fluid flow problems such as boundary layer flow, bio-fluids and turbulent flow are important for various engineering applications.Such problems are studied by many ways such as analytical or numerical solutions of the Navier-Stokes equation.Dealing with the large data that obtained by the numerical simulations needs to be filtered and analyzed by different filtering techniques.Now, Filtering techniques that are used in image processing problems are considered as efficient techniques for several fluid flow problems.Many research efforts for extraction and filtering of the flow fields are carried out and the results show high ability to extract important characteristics of the flow fields.However, more efforts are required to achieve better understanding for the universal characteristics of the fluid flow problems.Also, analytical solutions to continuum mechanics and elasticity problems are very important as well as their numerical solutions.Investigation of those studies with their applications to real world life problem help in understanding and developing theoretical as well as empirical techniques.
Background: Turbulent flow is characterized by vortices with different scales. Extraction of various scales and filtering the turbulent field into coherent and incoherent parts are important processes that improve our understanding of turbulent characteristics. Objective: Joint probability distribution functions (JPDFs) for the filtered velocity gradient invariants are extensively studied for different scales as well as for the coherent and incoherent parts of each scale. Methods: The Fourier decomposition and the anisotropic diffusion model are used in the investigation. The extraction process is performed by employing the Fourier decomposition at different cutoff wavenumbers for the velocity field and three distinct scales (large, medium and fine scale) are identified. The velocity gradient invariants such as the second invariant Q and the third invariant R for the different scales are extracted. Then other important invariants such as the rate of rotation tensor Q W and the rate of deformation Q S are also identified for each scale. The anisotropic diffusion model is used to extract the coherent and incoherent parts of each invariant at each scale. Then the JPDFs of the coherent and incoherent invariants are compared. The scale decomposition and the filtering process are applied for turbulent flow fields that are simulated using the lattice Boltzmann method with resolution of 128 3 . Results: Results show that the ( R-Q ) space has a universal topological pear-like shape for the different scales as well as their coherent field. However, the ( R-Q )-space for the incoherent fields are found different and no general shape can be observed. The ( Q w -Q S )-space results show self-similar shapes for coherent fields and for the incoherent fields no specific shape can be observed since the noise distributed as separated points everywhere. Conclusion: Two different methods for extraction and filtering of forced isotropic turbulence and the JPDFs of the velocity gradient invariants are studied. Some universal characteristics for the coherent parts were found. However, for the incoherent parts, no universal JPDFs were found.
Objective: Magneto-active Polymers (MAP) are smart materials whose mechanical characteristics, such as elastic and shear moduli, may be controllable by means of an externally applied magnetic field. Methods: Various additives may be used to influence the characteristics of the polymer matrix whilst a suspension of soft and/or hard magnetic particles determine the magnetic properties of the composite. Both pre-cure and post-cure magnetization is possible. Results: A range of control strategies have been investigated for evaluation of the system using fluids of differing kinematic viscosity. Conclusion: Depending on the degree of magnetic field homogeneity, magneto-deformation and magnetostriction contribute to MAP actuation. This paper presents a novel application in the form of a peristaltic MAP tube system, applicable to flow control and pumping of hemorheological fluids in blood circulatory systems for biomedical research purposes.
Objective: Hard turning in dry condition using cubic boron nitride tools, as an alternative of traditional grinding operation, is an advanced machining operation in which hardened steel with the hardness greater than 46 HRc is machined without the use of any coolant. Method: In the hard turning process, due to its hard nature, usually the cutting depth is selected lower than or equal to the nose radius, and the cutting zone is mainly limited within the tool nose area. Thus, unlike the traditional turning, the effect of the nose radius on the surface finish and dimensional accuracy becomes more complicated. Therefore, in this paper, firstly, the effect of processing parameters such as nose radius on the surface roughness and dimensional accuracy is investigated. Then, the relationship between the surface finish and dimensional accuracy variations with vibration, cutting forces, and tool wear is studied experimentally. The results revealed that feed rate is the most important factor influencing the surface roughness, whereas spindle speed and cutting depth are insignificant factors. On the other hand, cutting depth and spindle speed have the greatest effect on the dimensional accuracy, while nose radius has no significant effect. The vibration and wear analysis revealed that compared with the vibration, the tool wear has no considerable effect on the dimensional accuracy. It was also observed that the spindle speed has a contradictory effect on the surface roughness and dimensional accuracy. The best dimensional accuracy is obtained at 500 rpm, while the best surface quality is achieved at 2000 rpm. Result: The obtained results also showed that increasing the feed rate from a particular value not only leads to no significant changes in the surface roughness value but in some cases can also decrease the surface roughness. Conclusion: According to the analysis results, the lowest cutting depth, the moderate feed rate, and the speed lower than 1100 rpm provide the best dimensional accuracy. Compared with carbides and ceramics, cubic boron nitride tools produce a better surface roughness at both higher cutting depth and speed. 0.202 µm is the best surface roughness that was obtained at rε = 1.2 mm, N = 2000 rpm, f = 0.08 mm/rev, d = 0.5 mm which is comparable with the surface quality obtained by the conventional grinding operation.
Aims:This article proposes an alternate view of dimensional homogeneity that greatly simplifies the solution of nonlinear engineering problems.Background:The conventional view of dimensional homogeneity is generally credited to Fourier (1822).Objectives:The objectives of this article are to describe the alternate view of dimensional homogeneity and to demonstrate its application to practical engineering problems.Methods:By presenting the solution of several nonlinear engineering problems, this article compares solutions based on the alternate view of dimensional homogeneity with solutions based on the conventional view.Results:Example problems demonstrate that nonlinear engineering problems are much easier to solve if the solutions are based on the alternate view of dimensional homogeneity rather than the conventional view. The relative simplicity results because the alternate view of dimensional homogeneity reduces the number of variables in nonlinear problems.Conclusion:The widely accepted view of dimensional homogeneity should be replaced by the alternate view because the solution of nonlinear engineering problems is greatly simplified.
Background:Composite materials are widely used in the aerospace, marine and automotive industries. One of their main advantages is that their stacking sequence can be tailored to maximise/minimise a specific structural performance. Efficient and non-computational-expensive algorithms are always needed to find the optimum stacking sequence of a composite laminate whose thickness is either to be minimised or may be kept constant (i.e.the thickness and the plies orientation percentages are pre-determined; the problem of the optimisation is therefore permutational).Objective:A modified branch and bound algorithm is proposed here and used to determine the stacking sequence for single and multi-objective optimisation problems. Laminate thickness and orientation percentages are either variables or determined a priori (the optimisation problem is therefore permutational). Computational time is drastically reduced when compared with other meta-heuristic techniques.Methods:The proposed method is a branch and bound algorithm, modified from the original work proposed by Kim and Hwang [10]. The main novelty is the starting point of the optimisation sequence: a laminate formed by “Ideal” layers, described in this paper.Results:The modified branch and bound has been first tested with a laminate having fixed thickness and a fixed percentage of layer orientation. Three different problems have been investigated: maximisation of natural frequencies, minimisation of tip deflection and maximisation of buckling critical load. The algorithm has been also tested, secondly, for a problem of weight minimisation subjected to buckling and strength constraints.Conclusion:The MBB has been shown to give good fidelity and significant computational advantages compared with a GA. Despite the simplicity of the structures in the numerical examples, it is anticipated that the MBB can be used to determine lay-ups in multi-part structures. The method was used to determine stacking sequences for several problems. The modified branch and bound method was shown to determine good laminate designs and offer significant efficiency savings.A “Good Design” is here defined as a solution producing “Near Global Optima” fitness values by minimising the computational effort. It was shown that for a single objective without ply competition, global optima were obtained.
Background:Auto rickshaws are compact, three-wheeled vehicles which are normally used altogether in numerous Asian nations (i.e.China, Japan, Bangladesh, India, Pakistan and so forth) for transportation of people and products. The vehicles are little and have simple transportability in occupied Asian cities. In Bangladesh, auto rickshaws/simple bicycles regularly offer their taxi services, as they are fantastically reasonable to work. Simultaneously, these three-wheelers running on fuel cause extreme air-pollution and create impressive measures of greenhouse gasses (i.e.Carbon dioxide).Objectives:This paper introduces a transportation system in view of auto rickshaws that work in an eco-accommodating way. Existing vehicles are to be substituted by a small scale-cross sort framework overhauled in a way which helps the productivity of the vehicle.Methods:A reviving foundation is suggested that will take into consideration the power-packs to be charged utilizing halfway energy, for example, solar energy. Necessary simulations had been done using MATLAB platform.Results:Results shows that the current vehicle and nature, in which it works, made a model of the vehicle and researched re-charging infrastructure prerequisites and plans. About 31% efficiency was observed.Conclusions:The objective of the research introduced in this paper is to build up a conservative, vigorous and feasible fuel utilization system and deplete auto-rickshaws. In this research, 23% of grid power savings has been found.
Background: In many applications, it is required to control a large output load using a relatively low control force. To satisfy such purposes, a device like mechanical power amplifier can be used which generally gives a very fast response. As per the requirement of the system, power can be instantaneously available from continuously rotating drums of the mechanical power amplifier. Objective: This paper focuses on the computation of amplification factor of the mechanical power amplifier for different rope materials like leather, woven cotton and steel rope. Method: In this study the experimental analysis is performed. A capstan is a simple mechanical amplifier-rope wound on a motor-driven drum. The drums rotate continuously but communicate torque only when the input shaft is rotated to constricts drum A as shown in Fig. (3). Results: From the experimental analysis, it endorses that when the optimal number of turns tend to two, power amplification factor is to be 2.23 for leather contact, 1.867 for woven cotton contact, 1.32 for steel contact of rope. Conclusion: From the experimental analysis, it is seen that power amplification is higher for leather as compared to woven cotton and steel. The results are remarkably consistent with experimental measurements including favorable calculation of amplification factor.
Background: This paper extends earlier research on the dynamics of two coupled Mathieu equations by introducing nonlinear terms and focusing on the effect of one-way coupling. The studied system of n equations models the motion of a train of n particle bunches in a circular particle accelerator. Objective: The goal is to determine (a) the system parameters which correspond to bounded motion, and (b) the resulting amplitudes of vibration for parameters in (a). Method: We start the investigation by examining two coupled equations and then generalize the results to any number of coupled equations. We use a perturbation method to obtain a slow flow and calculate its nontrivial fixed points to determine steady state oscillations. Results: The perturbation method reveals the existence of an upper bound on the amplitude of steady state oscillations. Conclusion: The model predicts how many bunches may be included in a train before instability occurs.
Background:Garlic is one of the main economic crops in China and the planting area is increasing quickly. But the harvest process of the garlic mainly relies on manual digging, resulting in low harvest efficiency and high cost.Objective:In order to improve the efficiency of garlic harvest, and achieve the mechanization of garlic harvest. The study presents a new design of a garlic harvesting machine that can perform automatic processing and deal with the issue of garlic harvesting.Methods:Firstly, the three-dimensional model of the whole machine and the key mechanism is established and the parameters of the system are calculated by theoretical calculation. Then, the simulation be made and the design be optimized. Finally, the design was processed into a product. It employs an isolation mechanism and positioned cutting mechanism to isolate garlic and crop stubbles and keep the length of the remaining garlic straw consistent.Results:The results of field harvest experiments show that the miss digging rate, miss cutting rate and injury rate of the harvester are as low as 1.23%, 3.13% and 0.68% respectively, and the harvest efficiency is 0.06km2/h.Conclusion:The advantages of the harvester such as high harvesting rate, low damage rate, strong adaptability and high versatility, effectively improve the working efficiency, reduce the labor intensity and the harvest cost.
A study on green vehicle was introduced and promoted to minimize the problem of air pollution caused by emissions of conventional vehicle. Green mobility are vehicles with low fuel/energy consumption and low/zero exhaust gas emission, these vehicles are like hybrid, battery powered, and fuel cell electric vehicle that can be enhanced to be more efficient than the conventional vehicles through a new design and development of power transmission system. Power transmission system for green and lightweight vehicles consists of different components like gear box, propeller shaft, differential and final drive. In this review more emphasis is given to gear box due to some reasons: firstly, it is one of the heaviest component of the power train system and as a result weight reduction is critically needed to increase the efficiency of the vehicle. Secondly, gearshift takes place therefore, torque interruption needs to minimize. The use of simulation software's i. e. Mat lab, AMEsim, cruise software and other similar programs can simulate high-efficiency power transmission system. The results from the simulation software will be validated by experimental tests on test rigs. One way of minimizing fuel consumption is to reduce the weight of the gearbox by 10% reduction in vehicle weight can improved fuel economy by about 5-7%. As different researchers confirm that to have high vehicle efficiency the type of the transmission they used matters. A vehicle using automated manual transmission (AMT) and dual clutch transmission is more efficient in terms of less energy loss and gearshift comfort.
Background:Beam models have been proven effective in the preliminary analysis and design of aerospace structures. Accurate cross sectional stiffness constants are however needed, especially when dealing with bending, torsion and bend-twist coupling deformations. Several models have been proposed in the literature, even recently, but a lack of precision may be found when dealing with a high level of anisotropy and different lay-ups.Objective:A simplified analytical model is proposed to evaluate bending and torsional stiffness of a prismatic, anisotropic, thin-walled box. The proposed model is an extension of the model proposed by Lemanski and Weaver for the evaluation of the bend-twist coupling constant.Methods:Bending and torsional stiffness are derived analytically by using physical reasoning and by applying bending and torsional stiffness mathematic definition. Unitary deformations have been applied when evaluation forces and moments arising on the cross section.Results:Good accuracy has been obtained for structures with different geometries and lay-ups. The model has been validated with respect to finite element analysis. Numerical results are commented upon and compared with other models presented in literature.Conclusion:For cross sections with a high level of anisotropy, the accuracy of the proposed formulation is within 2% for bending stiffness and 6% for torsional stiffness. The percentage of error is further reduced for more realistic geometries and lay-ups.The proposed formulation gives accurate results for different dimensions and length rations of horizontal and vertical walls.
Background: The velocity fluctuations grow dominantly by convective instability form 32 spiral vortices which are stationary with respect to the disk. However, recent researches suggest that the global instability plays a role in the boundary layer transition. Objective: The study looks into the relation between convective instability and global instability. Method: A finite difference method is used to carry out numerical simulation. The full Navier-Stokes perturbation equations and the continuity equation solved by simulation code. Results: A disturbance is continuatively introduced to excite the convectively unstable mode, which successfully generates a flow field with 32 spiral and stationary vortices. Next, a short-duration artificial disturbance with an azimuthal wavenumber of 64 is introduced at Reynolds number of 530 in order to introduce a velocity fluctuation of the traveling mode, which is globally unstable. It is shown that the source of vibration for the globally unstable mode exists between Reynolds number of 560 and 670. Finally, the global and traveling wavenumber 64 component is excited in a flow field which is dominated by the convective and stationary wavenumber 32 component. It is shown that the wavenumber 64 component grows by the global instability even when the excitation is very weak. Conclusion: The results suggest that the reason why the globally unstable mode has not been observed in experiments is because the boundary layer transition caused by the convective instability takes place before the globally unstable mode can start to grow by itself.
Background:Instabilities on a rotating disk flow can be classified into two distinct groups, convective instability and global instability. Contrary to the convective instability, many characteristics of the global instability are left unknown despite of a lot of researches.Objective:The study investigates the characteristics of the globally unstable mode.Method:Numerical simulation is carried out by a finite difference method. The simulation code solves the full Navier-Stokes perturbation equations and the continuity equation.Results:Four cases with azimuthal domain sizes of 2π/10, 2π/70, 2π/80 and 2π/90 are compared. In all cases, a short-duration wall-normal random suction and blowing is introduced from the wall at the beginning of the computation. In the computation for the wider size 2π/10 domain, wavenumber components of 70, 80 and 90 are all found to co-exist in the flow field, with the wavenumber 80 component being much stronger than the other two components. The strength of the wavenumber 80 component is equivalent to the narrower domain case. For the other two wavenumber components of 70 and 90, the strengths in the wider domain case are much lower compared to the corresponding narrower domain cases. When the same wavenumber components are compared between the wider and narrower domain computations, no difference can be found, indicating that each wavenumber component grows by the global instability.Conclusion:The results imply that the amplitude saturation levels of wavenumber components 70 and 90 are suppressed by the wavenumber 80 component through the nonlinear effect.
Background: In precision machining, thermal error is the main source of machine tool error. And thermal error compensation is an effective method to reduce thermal error. Objective: In order to improve the prediction accuracy and computational efficiency of thermal error model, a new optimization method used for the selection of temperature measurement point is proposed. Method: This method is based on stepwise regression. According to the results of partial-F statistic, new variable is selected one by one, unapparent variables are deleted, and optimization selection of temperature measurement point is fulfilled, thermal error model of the NC machine tool is presented. Result: The new modeling method was used on NC machine tool, which reduced the temperature point number from 24 to 5. Moreover, model residual was less than 5µm after compensation. Conclusion: The result shows that the new thermal error model has higher prediction accuracy and less temperature variables.
Background: Vibrations in cycling produced by road irregularities could cause health problems and affect the cyclist’s comfort and performance. Therefore researchers and manufacturers focus their efforts to reduce the vibrations. Objective: The agro materials appear to consume important properties which help in reducing the values of vibrations. This study offers a perspective on the agro materials’ contribution in the bicycle design. Methods: Three bicycle frames were compared in two situations: (i) real locomotion conditions at three speeds 15, 25, and 35 km/h on slightly grainy road with paved sector and bumps, and (ii) laboratory conditions on a vibrating platform with frequencies ranging between 20 and 80 Hz. The used frames’ materials were carbon, aluminum and agro materials (bamboo and flax). The first protocol measured the effective values in four points of the bicycle (fork, stay, stem, and saddle) in real locomotion condition. The transmissibility was calculated between the input points of vibration and the output points in contact with the rider. The second protocol defined dynamic behavior of the three frames on a vibrating platform at the range of 20-80 Hz. Results: It was noted that the Root Mean Square values (RMS) were significantly higher with the agro materials in 44.4% of the cases and the values were significantly lower in 1 case (Road with 15km/h). The agro materials absorbed a significant part of vibrations in comparison to other materials (19.1%, 14.7%, and 17.2% for agro materials, aluminum, and carbon, respectively). Conclusion: Vibration comfort for cyclists is related to the choice of the frame. The contribution of relevant biomaterials can be relevant. Indeed, agro materials have remarkable properties for the absorption of vibrations.
