The dynamic behavior in a recumbent tricycle can be affected by several factors. The great variety of existent configurations does not guarantee a good acting but until they are built. The main factor involved in the handling behavior of a recumbent tricycle is the steering system; a good design of the steering system can guarantee an acceptable handling. This project analyzes the handling characteristics, directional stability and the dynamic behavior of a tricycle recumbent by means of the use of simulation software, with the advantage of not having to build a prototype to know its performance. A model of the system tricycle-cyclist is designed and simulated. Movement equations are developed to compare the results of the simulation. The analysis has as objective to establish the critical speeds and operation range by means of the simulation in different handling tests.

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Magnetorheological fluids are materials that exhibit a change in its rheological properties (like elasticity, plasticity, or viscosity) with the application of a magnetic field. The purpose of this study is to introduce the theoretical and practical applications of magnetorheological (MR) fluids for controllable MR devices such as shock absorbers, vibration insulators, prosthesis, brakes and clutches; and the primary objective of this research is to analyze the behavior of semiactive suspension systems subjected to a harmonic excitacion. A base excited system, representing a quarter-car suspension system, is used to compare the vibration isolation of the output responses due to a conventional passive damper, an optimal (skyhook) passive damper, and semiactive dampers controled by different control polices. This control polices include on-off control models and continuously variable control models, besides four continuosly variable control models are proposed, compared and simulated using MATLAB® and ADAMS® software.

It is a challenging job for manufacturers to build robust and sturdy portable electronic products in today's competitive market. It is not uncommon that these electronic products accidentally drop to the ground. This shock or impact load on these products leads to breakage of circuitry inside Printed Circuit Board (PCB) and results in malfunction or total failure of the product. Manufacturers usually determine the fragility of such products by conducting experimental drop tests, which is time consuming and expensive. Alternatively, research can be done by analytical analysis and numerical simulation. In this paper, drop impact response of the mobile phone is investigated. The mobile phone is simplified as a discrete two degree of freedom system. The simulation is carried out in two step analysis. First, finite elemental analysis is used to determine the stiffness for the housing and the Printed Circuit Board. Second, the mobile phone is simplified as a discrete two degree of freedom system. A predictive vibration analysis is established to investigate the drop impact response of the system. A guideline for the material selections of the product are developed, so that dynamic stability is maintained. Transient analysis has been performed to study the peak acceleration, maximum displacement, and determining dynamic stresses/strains induced in the package. Finally, the developed model is applied to evaluate dynamic response of commercially used mobile phone.

Moisture plays an important role in the integrity and reliability of plastic electronic packaging. The presence of moisture in the plastic packaging alters thermal stress through alteration of thermo-mechanical properties; induces hygroscopic stress through differential swelling; induces vapor pressure that is responsible for the eventual popcorn cracking; reduces interfacial adhesion strength; induces corrosion; and finally alters dielectric properties of materials. Despite this pivotal role, moisture properties of packaging materials are rarely reported, even though moisture has been known to be at least as damaging as temperature to plastic packaging. This is in part due to the lack of characterization knowledge for such properties. In this paper, two methods are proposed to analyze the experimental data based on the total weight loss and dimensional change using two identical specimens. 3-dimentional moisture diffusion solution is introduced to consider the non-uniform moisture distribution. The corresponding upper- and lower-bound solutions in determining the coefficient of hygroscopic swelling are obtained analytically. The analytical predication shows a remarkable agreement with the experiment results.

Premixed gas turbine combustors are susceptible to combustion instabilities, which can yield in hardware damage. Sound waves produce oscillations in the unsteady heat release by perturbing the instantaneous equivalence ratio. Furthermore, many land based power generation units currently operate on natural gas and many of them would need to tackle the challenges due to a fuel switch towards syngas in the near future. Operating conditions of a pre-mixed gas turbine combustor is very sensitive to the changes in the fuel composition. G-equation is coupled with combustor acoustics in order to track the flame-front, which provides an understanding of dynamic flame holding and flashback behavior. Non-linear relation between acoustic velocity perturbations and equivalence ratio fluctuations is responsible for limit cycle behavior. Assuming a choked fuel injector these equivalence ratio perturbations are traced by seeding the axial airflow with massless particles. It is observed that these particles can cross both the injector and the flame a number of times due to flow reversal within the instability cycle. Behavior of a premixed confined conical hydrogen enriched methane flame is studied with regard to thermo-acoustic instability induced flame flashback and RMS pressure levels over a range of operating conditions.

Full encirclement split tees are used in the petroleum industry with plugging machines to temporarily plug lines for maintenance or repair, or with hot tapping machines to add branch connections without shutdown or process interruptions. A split tee is an extruded style, carbon steel fitting, fabricated and tested to ASME regulations. ASME regulations request that any branch connections which are inserted in an opening in the run shall be attached by fully penetrated groove welds. To use fillet welds as primary welds, regulations expect calculations shall be substantiated by testing and simulation. This project presents the results of tension test, burst test, finite element analysis and, metallographic tests performed to cover ASME requirements for the particular case of an actual in-service welded branch connection. Analytical results will show what has been proved in the field for years, benefiting an industry where process interruptions create considerable losses every year.

The paper deals with the modeling of complex microstructure at multivariant martensitic phase transitions (PT) in elastic materials at nanoscale. A phase field approach including a new Ginzburg-Landau equation and equations of motion is used. The corresponding numerical technique based on the finite element method has been first developed in our papers [6, 8]. The new approach is applied to the modeling of martensitic PT in 2-D and 3-D specimens from NiAl. A random distribution of initial martensitic nuclei is prescribed. The results of microstructure simulation show a large difference in the evolution of microstructure for static (without inertial forces) and new dynamic (with inertial forces) formulations.

Thin films of chromium oxide (Cr2O3) were deposited on glass, silicon and steel substrates by A.C. inverted magnetron sputtering technique. The influence of the O2/Ar gas ratio and power dependence on the structure and adhesion was investigated. The X-ray diffraction data showed that Cr2O3 deposited at different O2/Ar gas ratios showed different orientation of the grains. With the increase in sputtering power, the grains showed (110) preferred orientation. SEM was used for calculating the grain size. The Cr:O ratio in the samples was evaluated using EDAX. All the films showed good adhesion. Results of detailed film characterization will be presented.

This paper describes the first steps taken as part of a project initiated by the Arkansas Energy Office and the Arkansas Department of Education to reduce the overall energy and water usage of Arkansas K-12 school buildings, thereby reducing operating costs. Utility data for each academic building within eight school districts were collected and entered into an online database. The initial set of benchmark values for electricity, natural gas, and water usage was computed by normalizing consumption by building floor area and student occupancy and defining high, low, and average values. In the future, the relative efficiency of other buildings can be evaluated by comparison to these benchmark numbers. Buildings having the highest potential for improvement will be recommended for implementing energy and water saving projects. Future work will include further refinement of the benchmark data such that it will be applicable outside the immediate geographical region.

H13 is widely used in hot work and cold work tooling applications primarily because of its ability to resist thermal fatigue cracking. Results of the CO2 laser assisted processing of H13 tool steel are presented. SEM, Optical observations and cooling rate calculations indicated that martensitic formation was dominant post welding. Solidification cracking has also been observed and an alternate heat treatment cycle has been proposed.

The need for improved tool life in machining has led to better and more improved coatings. Transition-metal nitrides - such as TiN, CrN, ZrN which are commonly used in these applications - are deposited by various physical vapor deposition (PVD) methods such as sputtering, e-beam and cathodic arc evaporation. In this study CrN and CrAlN films are deposited using an inverted cylindrical magnetron sputtering system (ICM-10) with chromium and aluminum targets on various substrates. The deposition parameters, such as the N2/Ar ratio and the target power, will be varied to study the properties of the coatings obtained. The microstructures and properties of these coatings will be investigated by various analytical techniques such as XRD, SEM, and EDS. This paper presents initial results of deposition conditions and the oxidation behavior of CrAlN and CrN coatings in both air and oxygen.

To carry out manual geometric changes in a machine element during the early design stage, a new graphically driven interactive stress reanalysis finite element technique has been developed. The interface allows an engineer to model a machine element in the commercial finite element code ANSYS® and then modify part geometry graphically to see instantaneous graphical changes in the stress and displacement contour plots. A combined approximation (CA) reanalysis technique is used to enhance the computational performance for solving the modified problem; with the aim of obtaining results of acceptable accuracy in as short a period of time in order to emphasize the interactive nature of the design process. A case study is considered to demonstrate the effectiveness of the prototype graphically driven reanalysis finite element technique. The finite element type considered is a plane stress four-node quadrilateral based on a homogenous, isotropic, linear elastic material. A combined approximation reanalysis method is used to solve each redesigned problem. The problem considered in the case study is a design and redesign of a support bracket. The goal is to design the cantilever portion of the bracket to have uniform strength and to minimize the stress concentration at the fillet. The presentation will also cover two more design problems to illustrate the technique.

High strength, chemical reactivity and poor conduction of heat pose difficulties in machining titanium alloys. Drilling, being a constrictive metal removal process is particularly problematic. Large cutting forces are therefore encountered. In case of micro-drilling, the buckling tendencies of the tools compound the problem. Thrust Force and torque are important design considerations in micro-drilling. This paper investigates the effect of cutting conditions on Thrust force and torque when drilling Ti6Al4V using HSS and carbide tools. Using ANOVA analysis, the two parameters have been modeled based on cutting conditions for both the tool materials. Regression equations are arrived at and compared with the results from previous research on other materials.

Multiple e-Learning platforms have been designed, implemented and evaluated over the past decade for effective implementation of teaching and learning in engineering education. This study deals with the development of an interactive prototype interface for the finite element method e-Lecture using life-like animated pedagogical agents, computer mediated communications and multimedia technologies. The use of animated pedagogical agents in engineering education tries to overcome the challenges of current e-Learning techniques with a new effective and efficient intellectual human computer interface. These agents with gaze, gesture and voice capabilities are used to actively/interactively communicate with the students. A prototype e-Lecture interface using animated pedagogical agent called Mr. FEMur (Finite Element Method universal resource) demonstrates the concepts of "Degree of Freedom" in this paper. These e-Lectures will be integrated into the finite element method learning environment that is a part of bigger effort to develop the FEMur web site.