Design and testing of a novel multipath-actuation compliant manipulator

In this paper, a novel multipath-actuation compliant manipulator (MCM) driven by piezoelectric actuators is proposed. Specifically, the monolithic MCM employs two vertically arranged compliant limbs with multipath motion transmission to actuate a symmetrically constrained planar mechanism, realizing x- and y-directional motion. For each limb, the multiple branched chains are configured in different paths but all contribute to the output motion, which results in a large displacement amplification ratio as well as a high working bandwidth. The ideal motion transmission of the proposed MCM is revealed by a specially established rigid-body kinematics model. Finite element analysis is carried out to predict the realistic static and dynamic performance of designed MCM. Moreover, a monolithic MCM prototype is fabricated, which is demonstrated to have a large displacement amplification ratio of 11.05, a high resonance frequency of 969 Hz, and a fine motion resolution of 25.48 nm. With promising static and dynamic characteristics, the proposed MCM can be widely used in practical applications.

Design of a Dislocation Well Pattern and Drilling of Shallow 3D Cluster Horizontal Wells for Development of Ultra Heavy Oil

The Junin block in Venezuela was known as an ultra heavy oil belt reserved in extra shallow layers (950ft-1,380ft) with unconsolidated formations. A cluster wells platform drilling was required for the Field Development Program (FDP). Optimisation of the well pattern and drilling of shallow 3D cluster horizontal wells for development of ultra heavy oil are presented in this paper. A well pattern of hand-shape dislocation was forwarded to enhance effective recovery of heavy oil in diamond blind area. Optimisation of the casing programs and control of the well trajectories as well as other key performance drilling were designed. A strict anti-collision barrier design and operation steps were worked out to assure the drilling safety. The loss-resistance, anti-collapse, stick-stuck proof, lubrication and reservoir protection were put into considerations for the drilling fluid design. Recovery of heavy oil was enhanced by means of electrical heating system. Drilling challenges such as shallow target zones, big build-up rate, long horizontal sections, great friction drag and torques, and well trajectories control were experienced and settled. Especially the puzzles of well trajectories control in unconsolidated formations, great friction drag and torques of strings in large displacement long horizontal sections for subsequent operations, and the unstable wellbore were tackled. A typical well data revealed that the horizontal displacement vs. TVD ratio was as high as up to 4.5. The setting depth of surface casing and the determination of KOP were critical to the horizontal wells with large displacement in shallow layers. Pressurized combined drilling and casing-running by means of top drive overcame the drag and torque and achieved planned TD and casing setting depth. The use of electrical wireline heating rod increased the temperatures in and close to the wellbore, and compensated the radius heat loss and avoided viscosity increase of heavy oil so that the output was maintained and improved. It was the first time for successful drilling of shallow 3D cluster horizontal wells with ratio of horizontal displacement vs. TVD over 3.5 in heavy oil belt of Venezuela. The innovative palm-shape dislocation of the well pattern design satisfied the demand of reservoir development and contributed to good production gain of heavy oil.

DE ONDE EU VINHA:

O texto apresenta um panorama das nomeações de docentes de Geografia para o magistério municipal no estado do Rio Grande do Sul. Como recorte temporal, têm-se os editais de concursos públicos municipais publicizados no triênio de 2016-2019 e as nomeações ocorridas até agosto de 2020. A pesquisa desenvolveu-se a partir de um desenho misto de caráter explanatório-sequencial, iniciando com uma etapa quantitativa e, posteriormente, uma etapa qualitativa, a partir das quais foi possível inferir, em números absolutos, a distribuição das nomeações. Organizadas por regiões intermediárias do estado estudado, relacionou-se o local de formação com o de nomeação, permitindo depreender o deslocamento espacial dos/das docentes. Como principais resultados a pesquisa realizada apresenta o elevado número de nomeações de docentes para o período, totalizando, até o momento, 152 nomeações e o grande deslocamento de mão de obra de regiões formadoras para municípios localizados em outras regiões. Palavras-chave Docente de Geografia, Nomeações, Concursos, Magistério Municipal. WHERE I CAME FROM: appointed teachers for teaching in the municipal education of Rio Grande do Sul - spatiality of Geography teachers Abstract The text presents an overview of the appointments of Geography teachers for the municipal education of the state of Rio Grande do Sul. As a time frame, there are the notices that took place in the 2016-2019 triennium and the appointments that occurred until August 2020. The research was developed from a mixed design of explanatory-sequential character, starting with a quantitative stage and, later, a qualitative stage, from which it was possible to infer, in absolute numbers, the distribution of nominations. Organized by intermediate regions of the studied state, the place of formation was related to the place of appointment, allowing the understanding of the spatial displacement of the teachers. As main results the article presents the high number of teachers’ appointments for the period, a total of 152 appointments, and the large displacement of labor from training regions to municipalities located in other regions. Keywords Geography teachers, Appointments, Contests, Municipal Education.

Multi-material topology optimization of large-displacement compliant mechanisms considering material-dependent boundary condition

Multi-material compliant mechanisms design enables potential design possibilities by exploiting the advantages of different materials. To satisfy mechanical/thermal impedance matching requirements, a method for multi-material topology optimization of large-displacement compliant mechanisms considering material-dependent boundary condition is presented in this study. In the optimization model, the element stacking method is employed to describe the material distribution and handle material-dependent boundary condition. The maximization of the output displacement of the compliant mechanism is developed as the objective function and the structural volume of each material is the constraint. Fictitious domain approach is applied to circumvent the numerical instabilities in topology optimization problem with geometrical nonlinearities. The method of moving asymptotes is applied to solve the optimization problem. Several numerical examples are presented to demonstrate the validity of the proposed method. The optimal topologies of the compliant mechanisms obtained by the proposed method can satisfy the specified material-dependent boundary condition.

Generation of Shakedown Boundaries of Thin-Walled 90-Degree Scheduled Pipe Bends Determined via Large and Small Displacement Finite Element Models

The present research investigates the effect of employing large displacement in finite element modelling on the generated shakedown (SD) boundaries of thin-walled 90-degree scheduled pipe bends. A recently developed methodology termed: Shakedown Limit - Plastic Work Dissipation (SDLimit-PWD) method generates the SD boundaries via employing the large displacement in the FE simulations. Additionally, a well-established direct non-cyclic technique termed: Shakedown Direct Noncyclic Technique (SD_DNT) generates the SD boundaries via employing the small displacement formulation in the FE simulations. Comparing the SD boundaries generated via both methods illustrated marked increase in the generated SD domains due to employing large displacement.

Modelling of Low-velocity Impacts on Composite Beams in Large Displacement

The paper provides an evaluation of the nonlinear dynamic response of a cantilever beam made of composite material subjected to low-velocity impacts. The structure is assumed to respond in a quasi-static manner and modelled by a continuous beam in large displacement with a lumped mass attached. First, an analytical model was developed to study the free vibrations of a beam, taking into account the nonlinearities due to large displacements and inertia. Then, the analytical findings were compared with experimental test data. The vibration of a real composite beam has been acquired through high-speed imaging technique. The displacements of the beam were extracted by digital image analysis; then, the nonlinear parameters of the analytical model were determined by the Fitting Time History technique. The results obtained by the analytical model and the experimental test are compared with numerical analysis. The validated analytical model was adapted to study a low-velocity impact; the lumped mass was associated with a rigid projectile, whose initial speed represents the impact velocity.