Experimental and numerical characterization of displacement field on biological tissues

"The need to understand the behavior of biological tissues, especially human tissue, has stimulated the development of experimental and" "numerical techniques that allow the characterization of such materials. Nowadays the use of experimental tests has been frequently replaced by the numerical simulation using finite element method, with important advantages from the standpoint of saving financial costs and time consumption." "The Digital Image Correlation (DIC) is a measurement technique which uses a mathematical correlation method to calculate the displacement on the plane surfaces of components or structures subjected to thermal or mechanical charges In this work were done two different experimental tests using the DIC to characterize hard and soft materials behavior and the respectively numerical comparison with a commercial finite elements" "code, Ansys®.

Reduction of surface roughness by taguchi design: an approach for milling parameters

The quality performance of a machined product is measured by its geometric dimensioning and tolerancing as well as its surface roughness. The surface roughness should be as smooth as possible for the same price. This geometrical property depends on the combination of the machining parameters. The most important parameters are: feed rate, spindle speed, cutting axial and radial depths.info:eu-repo/semantics/publishedVersio

A wireless acquisition system for monitoring the influence of loads on vertebral column behaviour

This paper presents a wireless acquisition module (WAM). This allows the monitoring of heavy loads influence on vertebral column’s behaviour. Each module makes the electromyography (EMG), to measure the electric potentials on the iliocostalis and longissimus thoracis muscles, and use a dual-axis accelerometer to get the movements of the body, in order to obtain the complete behaviour of the vertebral column. The solution chosen to transmit the body’s measured signals for further processing, is a wireless link working in the 433 MHz ISM band. The acquired information is transmitted with a maximum rate of 40 kbps, a resolution of 9.8 V, and accommodates two analog channels. An analog channel with differential input connected to the electrodes, is used to measure the EMG signal, while the remained channel is used in the patient’s movements measurements. The dimensions of the proposed acquisition system are about 7×5×2 cm, and will help to understand the influence of heavy loads as a risk factors in the vertebral column, such as the scoliosis and lordosis

Recoupling matrix elements and decay

Recoupling matrix elements are evaluated, in the harmonic oscillator approximation, for all possible angular and radial excitations in processes where quarks recombine. A diagrammatic representation is given. Their use is demonstrated in calculating the transition potential for rho to two pions in a pair creation model.Comment: 15 pages, 10 figure

Medição de campos de tensões recorrendo à técnica de Moiré

Neste trabalho é apresentada uma aplicação da técnica de Moiré para a medição de campos de tensões. O caso em estudo consiste na medição do campo de deslocamentos na superfície de um provete sob tracção, possuindo um furo passante no seu centro. As redes são obtidas por impressão laser num papel especial. A replicação da rede na superfície do provete é feita por um processo térmico com pressão controlada. Foram ensaiados provetes de alumínio. A rede registada na superfície do provete foi fotografada em diferentes fases do ensaio, estas fotografias são tratadas num programa de processamento de imagem. Os valores obtidos experimentalmente são comparados com os valores calculados com o código de elementos finitos ANSYS

Medição de campos de tensões residuais: estudo preliminar

Este trabalho tem em vista o desenvolvimento de uma técnica experimental para medição de tensões residuais que possa ser uma alternativa ao clássico método do furo. Para caracterizar os campos de deformação nas proximidades do furo prevê-se a utilização do método de Moiré. Trata-se de uma técnica de campo que permite medir sem contacto, deslocamentos no plano, com uma resolução que é condicionada pela frequência espacial das redes. As técnicas para a gravação das redes nas superfícies dos objectos são descritas e caracterizadas. É também apresentada a montagem de interferometria laser utilizada para gerar, de forma controlada, a rede necessária à interrogação. Técnicas experimentais e numéricas são utilizadas para determinar as constantes de calibração ( A e B ) usadas no método do furo. Para isso é analisado, com detalhe, o campo de tensões na vizinhança de um furo cilíndrico resultante da tracção uniaxial no plano, aplicada a uma placa fina

The influence of manufacturing factors in the short-fiber non-woven chestnut hedgehog spine-reinforced polyester composite performance

One of the most important agricultural products in the northeast of Portugal is sweet chestnuts. In this region only, several tons of this product are produced every year. Sweet chestnuts are enclosed in a hedgehog covered with a large number of short and fine spines and containing more than one nut. This hedgehog, with long spines, does not have any commercial value, and they are considered an agricultural waste that is left in the fields to be incorporated into the soil. In this work, the authors propose to study the influence of some factors in the short-fiber non-woven chestnut hedgehog spine-reinforced polyester composite performance. For this purpose, the tensile properties of chestnut spines were determined by implementing a design of experiments (DOE) approach developed by Taguchi. Thus, the factors that will be controlled are the fiber dispersion which is defined by fiber/matrix mass ratio or weight fraction, the interfacial strength that could be improved using an alkali–silane treatment and, finally, the moisture level in the fibers. For each factor, three levels were used, an L9 orthogonal array of experiments was implemented to evaluate tensile and flexural properties. These properties were determined based on results of 54 tests, and the maximum mean values for tensile and flexural strength were 23.5 MPa and 33.6 MPa, respectively. The most influential factor for maximizing the tensile strength was the volume fraction of fiber with a contribution of 30%, and most influential factor for maximizing the flexural strength was the moisture level with a contribution of 65%. The determined mean value of tensile strength of the spines was 148 MPa.info:eu-repo/semantics/publishedVersio

Welding process automation of aluminum alloys for the transport industry: an industrial robotics approach

The materials used in the transport industry have been changing in the last decades. The traditional and heavy steel have been switching by the light alloys like aluminum alloys. However, despite their advantages as low density and high corrosion resistance, the manufacturing process, especially fusion welding, is very demanding and challenging. In the transport industry, most of the hyperstatic components made in aluminum alloys are welded manually with the associate financial costs as well as the lack of quality and repeatability. For these reasons, it is urgent to develop new methodologies to automate this process. The present work intends to show a scientific method to automate the welding process of hyperstatic frames, very common in bicycles, made in aluminum alloy. This methodology involves two steps, the first one in which is performed numerical simulations to determine the optimal welding parameters to minimize the distortion and residual stresses. The second step is experimental one, and it is created an automated welding cell with a robot to weld the frames. It has been proved that it is possible to obtain welding aluminum frames with acceptable quality in agreement with the ASME IX standard.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020).info:eu-repo/semantics/publishedVersio

New advances in vehicular technology and automotive engineering

An automobile was seen as a simple accessory of luxury in the early years of the past century. Therefore, it was an expensive asset which none of the common citizen could afford. It was necessary to pass a long period and waiting for Henry Ford to establish the first plants with the series fabrication. This new industrial paradigm makes easy to the common American to acquire an automobile, either for running away or for working purposes. Since that date, the automotive research grown exponentially to the levels observed in the actuality. Now, the automobiles are indispensable goods; saying with other words, the automobile is a first necessity article in a wide number of aspects of living: for workers to allow them to move from their homes into their workplaces, for transportation of students, for allowing the domestic women in their home tasks, for ambulances to carry people with decease to the hospitals, for transportation of materials, and so on, the list don’t ends. The new goal pursued by the automotive industry is to provide electric vehicles at low cost and with high reliability. This commitment is justified by the oil’s peak extraction on 50s of this century and also by the necessity to reduce the emissions of CO2 to the atmosphere, as well as to reduce the needs of this even more valuable natural resource. In order to achieve this task and to improve the regular cars based on oil, the automotive industry is even more concerned on doing applied research on technology and on fundamental research of new materials. The most important idea to retain from the previous introduction is to clarify the minds of the potential readers for the direct and indirect penetration of the vehicles and the vehicular industry in the today’s life. In this sequence of ideas, this book tries not only to fill a gap by presenting fresh subjects related to the vehicular technology and to the automotive engineering but to provide guidelines for future research. This book account with valuable contributions from worldwide experts of automotive’s field. The amount and type of contributions were judiciously selected to cover a broad range of research. The reader can found the most recent and cutting-edge sources of information divided in four major groups: electronics (power, communications, optics, batteries, alternators and sensors), mechanics (suspension control, torque converters, deformation analysis, structural monitoring), materials (nanotechnology, nanocomposites, lubrificants, biodegradable, composites, structural monitoring) and manufacturing (supply chains). We are sure that you will enjoy this book and will profit with the technical and scientific contents. To finish, we are thankful to all of those who contributed to this book and who made it possible.info:eu-repo/semantics/publishedVersio

Thermal evaluation of MAG/TIG welding using numerical extension tool

The manufacturing processes involving thermal transitions have been more used in industries nowadays, being the welding one of the most widely used. The requirement to design and predict adverse conditions are fundamental to the development of any mechanical project. As a result, the market needs have motivated the companies to find faster and more effective solutions, being one of a recent tools an ACT (Ansys Customization Toolkit) called “Moving Heat Source”, in which is executed the Gaussian heat source to model welding and laser processes. Based on this, the present work proposes to evaluate the accuracy of that extension implementing a finite element model for the MAG/TIG welding processes in DINCK20 steel and Al6082-T6 aluminium alloy, comparing with one of the first mathematical model proposed by the literature (Rosenthal) and with a recent analytical method of high precision already validated experimentally. The results showed a smaller global error for MAG process (3~10%) when compared to TIG (15~18%) and, the temperatures measured on the surface of the plate presented errors lower than the bottom in both alloys.This research would like to thank the support of the double degree program by the Polytechnic Institute of Bragança and the Federal Center Celso Suckow da Fonseca (CEFET/RJ) as part of the master’s project entitled “Estudo Numérico do Shot-Peening no Alívio de Tensões Residuais em Soldaduras de topo MAG e TIG”. This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: CIMO (UIDB/00690/2020).info:eu-repo/semantics/publishedVersio