Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"Coulomb friction"”.
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Single- and Dual-Plane Automatic Balancing of an Elastically-Mounted Cylindrical Rotor with Considerations of Coulomb Friction and Gravity
… which contains up to two sliding particles. The friction model for the particles includes both viscous and Coulomb friction forces. Of considerable complexity is the logic path for the individual particles being either in motion or stationary relative to the rotor. The exact equations of motion …
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Dahl friction modeling
The drive behind improved friction models has been better prediction and control of dynamic systems. The earliest model was of classical Coulomb friction; however, the discontinuity during force reversal of the Coulomb friction model has long been a point of contention since such a discontinuity …
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A New Node-to-Node Approach to Contact/impact Problems for Two Dimensional Elastic Solids Subject to Finite Deformation
… used to apply contact constraints. Non-classical Coulomb friction laws are used where friction is present. Several quasi-static and impact examples are given to demonstrate the performance and validity of the new approach.
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Uma estratégia adaptativa para problemas de contato em elasticidade
… scheme in used to solve contact problems with Coulomb friction. An existing 2D mesh generator based on a frontal technique is used for the construction of the initial mesh of triangular elements. The contact problem is then solved using a sequence of sub-problems P1,P2,P1,P2,... where P1 is the …
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A thermo-mechanical finite element simulation of hot rolling for the prediction of roll forces
… plane strain elements. The model used a basic Coulomb Friction model with a specified maximum value of friction before shearing of the billet material took place. The roller was modelled as a rigid body.
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Practical Challenges in the Method of Controlled Lagrangians
… cart damping is best modeled using static and Coulomb friction. Experiments show that static and Coulomb friction degrades the closed-loop performance and induces limit cycles. A Lyapunov-based switching controller is proposed and successfully implemented to suppress the limit cycle …
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Analytical and experimental investigation of a 1/5 scale rail vehicle simulator
… force saturation, and it includes the effects of Coulomb friction in the truck bearings. The linear model predicts the truck's natural Frequency versus speed within 5% of the experimental values. lt also predicts the damping ratio decrease that occurs with increasing truck speed. The nonlinear …
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Horizontal Shear Transfer for Full-Depth Precast Concrete Bridge Deck Panels
… performed changes to the principles of the shear friction theory as presented in the AASHTO LRFD specifications are proposed. The proposal is to break the current equation into two equation that separate coulomb friction and cohesion. Along with these changes, values for the coefficient of …
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Semi-active control of elastic and inelastic building structures with piezoelectric friction dampers
… devices.</p> <p>In this study, a piezoelectric friction damper (PFD) was first introduced with its clamping force regulated by piezoelectric stack actuators. A new semi-active control algorithm, which consists of Coulomb friction, viscous and non-linear Reid damping mechanisms, was proposed to …
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An anisotropic damage model for rock
… equation. Damage initiation is defined by a Coulomb friction law, which excludes damage at low deviatoric stress levels. The formulation of the directional damage extends the arguments of continuum damage models for tension cracking to general, tension and compression, stress states. This is …
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Efficient Control of DC Servomotor Systems Using Backpropagation Neural Networks
… dynamic factors, such as backlash, dead zone and Coulomb friction that make the systems hard to control using conventional control methods such as PID controllers. Also, the dynamics of the servomotor and outside factors add more complexity to the analysis of the system, for example when the load …
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Seismic response of structures with Coulomb damping
The usefulness of Coulomb (friction) damping in earthquake-resistant design of structures is examined by studying the seismic response characteristics of structures with various arrangements of sliding interfaces. First, three basic arrangements are studied for their effectiveness in reducing …
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Numerical modeling of mixed mode multiple crack propagation and its application to the simulation of nonlinear rock deformation and borehole breakout
… calculation of stress intensity factors, adding Coulomb friction for closed portions of cracks, adding a crack generator, and adding an algorithm for crack coalescence. The numerical model is used to simulate the non-linear deformation and the progression of breakout in Westerly granite, and the …
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A study of chatter-induced loss of mechanical contact
… body mechanics called reverse chatter, in which friction can cause the problem of two rigid bodies in sustained contact to admit multiple solutions. In particular, when the point of contact between the two bodies comes to rest, under certain conditions the rigid body model-coupled with …
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Determination of thermo-mechanical variables during plain strain compression testing
… because of an increased coef6cient of friction as the test temperature is increased. Lubrication breakdown has been characterised using a Coulomb friction model for PSC testing temperatures between 25 and 440 °C, which when incorporated into a FEM model for a specific deformation …
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Assessing the effect of friction on compression split Hopkinson pressure bar tests
… the accuracy of the results, such as interface friction and specimen inertia, still required further clarification. This report details a thorough experimental and numerical investigation into the effect of friction on SHPB test data. The objectives are to assess the magnitude of the effect of …
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Finite Element Analysis of a Shaft-Rotor System
… stack comprised of two rotor lamina, with a Coulomb friction surface interaction, and held together by a compressive axial force. These models represent a first step towards understanding the behavior of the entire rotor stack.
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Numerical modeling of submarine landslides and surface water waves which they generate
… a viscous fluid, a Bingham-plastic fluid, and a Coulomb frictional material. Formulations of the dynamics are presented for the slides on a gentle uniform slope reactively coupled with the surface waves which they generate. The governing equations are solved by a finite-difference method. In the …
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Response of a nonlinear two-degree-of-freedom system subjected to an impact loading
… to have velocity-squared hydraulic damping and coulomb friction forces on the strut bearings. The nonlinear spring characteristic of the tire is represented by a sectionally linear spring. In the first part of this paper the equations of motion for this nonlinear system are derived making use of …
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Numerical Modelling of Seismic Activity at Tabular Orebody Mines in South Africa using the Boundary Element Method
… evaluated using the Limit Equilibrium Method and Coulomb-friction, Hoek-Brown and Mohr-Coulomb strength criteria. Unlike other methodologies that only accommodate fault-slip seismic events on geological features, the proposed methodology also accommodates crush and shear seismic events ahead of …
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