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Gray cast irons are frequently used in machine tool beds due to low cost, high vibration damping capacity, and easiness of manufacturing. The guiding standards for production of these alloys determine their classes based on the range of tensile strength and shape of graphites. This research project aims at investigating the differences in machinability between two gray cast irons belonging to the...
This work aimed at the development of the requirements of project of a self-propelled aerosol generator, product that performs the control of mosquitoes through the space application of insecticides in the ambient. The demand of this work was based on low efficiency currently obtained in the process, especially in inside of residence, together with the super sizing of the systems available for this...
With the increasing interest in hypersonic propulsion, National University of Defense Technology in China sets up a large high-temperature wind tunnel. A pilot-operated pressure regulator is developed to supply gas with a given pressure to the wind tunnel. Although the regulator works normally and stably during the working stage, severe oscillations with maximum amplitude of 3 MPa occur during the...
Mechatronic design can be defined as the integrated design of mechanical systems and their embedded control system. Two main challenges in designing mechatronic systems are treated in this manuscript: challenges in modeling mechatronic systems and challenges in optimizing mechatronic systems. Modeling methodologies, model-reduction strategies, control system evaluation have been discussed in order...
This work presents a study on the effect of low pressure cryogenic liquid nitrogen on cutting forces, friction coefficient, surface roughness of the machined surface and tool wear under high speed machining of a relatively new titanium alloy, Ti-5Al-4V-0.6Mo-0.4Fe. The experiments were conducted in dry and cryogenic conditions. The experimental results show that liquid nitrogen can reduce the friction...
The paper aims to investigate the nonlinear geometrical behavior of a tensegrity structure subject to dynamic loading in the time domain. The geometric nonlinearity is considered here with the aid of a simple set of equations, based on the Finite Element Method, but using nodal positions rather than nodal displacements as variables. The finite element strains are evaluated directly from the proposed...
In dextrous robotic manipulation we are often confronted with the problem that the robot fingers need to be repositioned on the object surface, either because a finger reaches its workspace limits or because the manipulation planner decides to do so due to its manipulation strategy. In this paper we propose a trajectory type for the purpose of regrasping, named “Squeezed Screw”. It is smooth and has...
The effect of thermal shock on a cracked functionally graded material (FGM) layer is considered using the extended finite element method. Classical coupled thermoelastic equations are used in the calculations. The coupled dynamical system of equations obtained from the extended finite element discretization is solved by the Newmark method in the time domain. Micromechanical models for conventional...
Predictive modeling is essential to better understanding and optimization of machining processes. Modeling of cutting forces has always been one of the main problems in metal cutting theory. In this paper, artificial neural networks (ANNs) were used for modeling correlations between cutting parameters and cutting force components in turning AISI 1043 steel. Cutting force components were predicted...
By means of hot wire anemometry technique and flow visualizations, the presence of the phenomenon of the bistability around three cylinders in two triangular arrangements is investigated in an aerodynamic channel and in a water channel. Bistability occurs in flows over sets of bluff bodies forming a flip-flopping wake characterized by a biased flow switching at irregular intervals, which can represent...
The paper presents a simple and automatic procedure to estimate the intrinsic and extrinsic parameters of a camera, based on the image of a standard calibration box. Image processing techniques are used to determine the relevant image points to be used in the calibration procedure. A non-recursive solution scheme is proposed to estimate the intrinsic and extrinsic camera parameters. Simulated and...
The advanced high-strength steels (AHSS) have become an interesting alternative to the automotive industry that aims to reduce the thickness of the components without compromising the structural performance and absorption capacity of impact. However, their mass utilization is still limited due to computational problems to predict the occurrence of the phenomenon of springback. Nonlinear unloading...
The paper is concerned with downwash correction methods for aeroelastic stability analyses in the transonic regime. The effects of the formulation used in the calculation of nonlinear, unsteady reference pressures are addressed, together with the influence of the motion amplitude. A finite-difference Euler/Navier–Stokes code is used to calculate the unsteady aerodynamic loading due to dynamic angle...
In order to solve the aerostatic stability problem of long-span bridges more effectively, an upper limit of the external iteration number is set optimally to improve the incremental double iteration method, and an optimum iteration method is brought forward. For new suspension bridges with multiple main spans, the assumption of the spatial uniformity of wind speed is invalid due to their long decks...
This paper discusses the influence of asymmetrical anchors on guyed mast behavior under wind loads. Anchor asymmetry is due to variations on anchor levels in guyed mast placed at the top of hills. Six FEM models were developed with different guy anchor asymmetries. The mast was modeled as a three dimensional structure formed by pinned members (braced and horizontal members) and continuous members...
This research aims at proposing adaptations in the quality function deployment (QFD) methodology; analyzing its use to assist business development projects (BDP); and evaluating the results of a case study. In order to support the analysis of the use of QFD in the business development environment, a bibliographic review was performed and a case study of a BDP was set-up and executed in a small enterprise...
This paper presents an artificial intelligence approach for the development of predictive models for a CO2 laser cutting of mild steel by using artificial neural networks (ANNs) and real coded genetic algorithm (RCGA). Laser cutting experiment, conducted according to Taguchi’s experimental design using L25 orthogonal array, provided a set of data for the development of ANN models for the prediction...
This paper presents a strain analysis in transmission line cables caused by mechanical vibrations induced mainly by the wind action that can cause the fatigue rupture of the cable. The tests were performed on a test bench that consists of two spans of 9 and 12 m, respectively, and it was built using elements of transmission lines (suspension clamps, insulators, anchoring towers, etc.). The vibrations...
Free surface flows in inclined channels can develop periodic instabilities that are propagated downstream as shock waves with well-defined wavelengths and amplitudes. Such disturbances are called “roll waves” and are common in channels, torrential lava, landslides, and avalanches. The prediction and detection of such waves over certain types of structures and environments are useful for the prevention...
A detailed numerical simulation of ethanol turbulent spray combustion on a rounded jet flame is presented in this article. The focus is to propose a robust mathematical model with relatively low complexity submodels to reproduce the main characteristics of the coupling between both phases, such as the turbulence modulation, turbulent droplets dissipation, and evaporative cooling effect. A RANS turbulent...
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