This thesis presents a detailed analysis of the plane rake faced drill design, its grinding method and grinding wheel geometry. A fundamental geometrical analysis has then been carried out on the major cutting edges of the modified drills according to the national and international standards. It has been shown that this new drill design results in a significant increase in the normal rake angle at lips as well as point relieving at the chisel edge region. Geometrical models for the various drill point features have been established which uniquely define the drill point features of the modified drill design. A comprehensive experimental investigation has been carried out to study the drilling performance of the modified drills, when drilling a high tensile steel, ASSAB 4340, with TiN coated high speed steel drills over a wide range of drilling conditions. Comparing to the drilling performance with conventional twist drills under the corresponding conditions, it has been found that the modified drills can reduce the thrust force by as much as 46.9% with the average of 23.8%; the reduction of drilling torque is also significant at an average of 13.2% and the maximum of 24.9%. Similarly, the new drill design shows great superiorities over the conventional drills in terms of drill-life. In the drill-life tests, a few conventional drills were broken, but all plane rake faced drills performed very well. In order to estimate the cutting performance in process planning on a mathematical and quantitative basis when drilling with the modified drills, predictive cutting force models have been developed based on the unified-generalized mechanics of cutting approach. The models have been assessed qualitatively and quantitatively and showed good agreements with the experimental thrust, torque and power. Empirical-type force equations have also been developed to provide simple alternatives for practical applications.

This thesis presents a detailed analysis of the plane rake faced drill design, its grinding method and grinding wheel geometry. A fundamental geometrical analysis has then been carried out on the major cutting edges of the modified drills according to the national and international standards. It has been shown that this new drill design results in a significant increase in the normal rake angle at lips as well as point relieving at the chisel edge region. Geometrical models for the various drill point features have been established which uniquely define the drill point features of the modified drill design. A comprehensive experimental investigation has been carried out to study the drilling performance of the modified drills, when drilling a high tensile steel, ASSAB 4340, with TiN coated high speed steel drills over a wide range of drilling conditions. Comparing to the drilling performance with conventional twist drills under the corresponding conditions, it has been found that the modified drills can reduce the thrust force by as much as 46.9% with the average of 23.8%; the reduction of drilling torque is also significant at an average of 13.2% and the maximum of 24.9%. Similarly, the new drill design shows great superiorities over the conventional drills in terms of drill-life. In the drill-life tests, a few conventional drills were broken, but all plane rake faced drills performed very well. In order to estimate the cutting performance in process planning on a mathematical and quantitative basis when drilling with the modified drills, predictive cutting force models have been developed based on the unified-generalized mechanics of cutting approach. The models have been assessed qualitatively and quantitatively and showed good agreements with the experimental thrust, torque and power. Empirical-type force equations have also been developed to provide simple alternatives for practical applications.

Orientador: Siome Klein Goldenstein / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-16T21:25:11Z (GMT). No. of bitstreams: 1 Saboia_PriscilaCorrea_M.pdf: 2582894 bytes, checksum: 1645aa6b8b779ee7180adbbb04d23981 (MD5) Previous issue date: 2010 / Resumo: Atualmente, estima-se que a população mundial seja de cerca de seis bilhões e oitocentos milhões de habitantes (6.800.000.000), dos quais metade mora em aglomerados urbanos. Nestes centros, é corriqueiro o fen¿omeno da movimentação de multidões. Tecnicamente, entende-se multidão como um grande grupo de indivíduos em um mesmo ambiente físico, compartilhando um objetivo comum e podendo agir diferentemente do que quando estão sozinhos. Compreender a movimentação destas multidões é de vital import¿ancia para o planejamento e a melhoria dos locais públicos, não só no sentido de facilitar e agilizar o deslocamento dos cidadãos, mas também garantir-lhes segurança, especialmente em condições de perigo iminente, onde pode haver a necessidade de evacuação de tais locais. Além disso, existem várias áreas do conhecimento que têm potencial para se beneficiar do estudo do comportamento de multidões. Na indústria de entretenimento, por exemplo, simulações de multidões podem ser utilizadas na produção de animações e jogos de computador. No treinamento policial e militar, simulações podem ser usadas para demonstração e controle de rebeliões. Na área de engenharia de segurança, simulações podem ser utilizadas para estudo de desocupação emergencial de construções, navios e aviões. Em todas as áreas citadas, observa-se que a necessidade por simulações de multidões advém de duas situações que podem ocorrer no mundo real. Primeiramente, pode ser perigoso para os indivíduos realizar as ações objetivadas (como cair de um prédio em um filme, ou evacuar uma sala de cinema em chamas, por exemplo), bem como é antiético submetê-los a tais condições. Segundo, é muito complexo e oneroso lidar com um grande número de indivíduos no mundo real. Ambas as situações podem ser evitadas pela simulação computacional da situação real. Nestes termos, o objetivo desta dissertação é modelar a movimentação de multidões, tendo em vista a simulação em computador. Para tanto, sistemas multiagentes brownianos são introduzidos como uma alternativa tecnológica 'a implementação dos modelos encontrados na literatura, bem como 'a implementação de um novo modelo de movimentação de multidões, híbrido por reunir conceitos de modelos que lançam mão das chamadas forças sociais, com conceitos de modelos baseados na estratégia Lattice-Gas. Como resultado prático, um novo simulador de sistemas multiagentes construído para a tarefa de simulação de movimentação de multidões é apresentado / Abstract: Currently, it is estimated that world population is about six billion and eight hundred million inhabitants (6.8 billion), of whom half live in urban areas. In these centers, it is common the phenomenon of moving crowds. Technically, a crowd can be seen as a large group of individuals put in the same physical environment, sharing a common goal and acting differently than when they are alone. Understanding the movement of these crowds is very important for planning and improving public places, not only in order to facilitate and expedite the movement of citizens, but also in order to guarantee their safety, especially in conditions of imminent danger, where it can be necessary the evacuation of such sites. Furthermore, there are several areas of knowledge that can gain benefits from the study of crowd behavior. In the entertainment industry, for example, crowd simulations can be used to produce animations and computer games. In Police and military training, simulations can be used for demonstration and control of riots. In the area of safety engineering, simulations can be used to study the urgent evacuation of buildings, ships and aircrafts. In all mentioned areas, it is observed that the need for crowd simulations comes from two situations, taking into consideration the real world. First, it can be dangerous for individuals to perform the desired actions (like falling from a building in a movie, or evacuating the room on fire of a failing movie session). It is also unethical to expose them to such conditions. Second, it is very complex and expensive to handle a large number of individuals in the real world. Both situations can be dealt by simulating the real world into a computer. Thus, this dissertation aims to model the movement of crowds, always having in mind the computer simulation. For this, Brownian multi-agent systems are introduced as a technological alternative to implement the models found in literature, as well as to implement a new hybrid movement model, that gathers together concepts from solutions based on social forces, and solutions based on Lattice- Gas. As a practical result, a new simulator for multi-agent systems is presented, built for the task of simulating moving crowds / Mestrado / Sistemas de Informação / Mestre em Ciência da Computação

<p>Soft pneumatic actuators allow compliant force application and movement for a variety of tasks. While most soft actuators have compliance in directions perpendicular to their direction of force application, they are most often analyzed only in their direction of actuation. In this work, we show a characterization of a soft 3D printed bellows actuator that considers shear and axial deformations, modeling both active and passive degrees of freedom. We build a model based on actuator geometry and a parallel linear and torsional spring system which we fit to experimental data in order to obtain the model constants. We demonstrate this model on two complex parallel networks, a delta mechanism and a floating actuator mechanism, and show how this single actuator model can be used to better predict movements in parallel structures of actuators. These results verify that the presented model and modeling approach can be used to speed up the design and simulation of more complex soft robot models by characterizing both active and passive forces of their one degree-of-freedom soft actuators.<br> </p>