This report presents a new way to model and identify single-link flexible arms when Coulomb friction is present in the joint. In order to isolate the effects of this nonlinearity, the arm model is divided into two submodels: motor and beam. The two anm coupled through the torque at the base of the beam. A systematic method is developed to obtain the dynamics of a lumped-mass flexible beam, and ...

In general, joints are assumed without clearance in the dynamic analysis of multi-body echanical systems. When joint clearance is considered, the mechanism obtains two uncontrollable degrees of freedom and hence the dynamic response considerably changes. The joints’ clearances are the main sources of vibrations and noise due to the impact of the coupling parts in the joints. Therefore, the syst...

Introduction: Press-fit acetabular components are susceptible to deformation following implantation in an under-reamed socket, with excessive deformation of metal-on-metal (MOM) components potentially leading to increased torsional friction, component micromotion and implant loosening. The purpose of this study was to evaluate the effect of design and material considerations on induced deformat...

The framed structure infilled with a mortarless brick (MB) panel exhibits considerable in-plane energy dissipation because of the relative sliding between bricks and good out-of-plane stability resulting from the use of interlocking mechanisms. The cyclic behaviors of MB are investigated experimentally in this study. Two different types of bricks, namely non-interlocking mortarless brick (N-IMB...

Using molecular dynamics (MD), we investigate the importance of liquid-vapor interface topography in designing low-friction nanoengineered superhydrophobic surfaces. Shear flow is simulated on patterned surfaces. The relationship between the effective slip length and bubble meniscus curvature is attained by generating entrapped bubbles with large protrusion angles on patterned surfaces with nan...

In this paper experimentally, the friction-stir welding of the polypropylene sheets with 40% glass fiber has been investigated. Comparison to other welding methods, the strength of the joint is the most important feature in this process. Many parameters such as tool geometry, rotational speed, linear velocity, and tilt angle are very important as input parameters in this type of welding. Theref...

Surface modification techniques have been developed significantly in the last couple of decades for enhanced tribological performance of artificial hip implants. Surface modification techniques improve biological, chemical and mechanical properties of implant surfaces. Some of the most effective techniques, namely surface texturing, surface coating, and surface grafting, are applied to reduce t...

An aerostatic spherical bearing has been developed for parallel kinematic machines. The design is based on a ball and socket configuration and is preloaded by permanent magnets arranged about the socket. High pressure air is injected through three orifices into the cavity between the ball and socket to produce a low friction, high accuracy interface. Joint accuracy is measured using a coordinat...

The current paper presents a robust optimum design of friction stir welding (FSW) lap joint AA1100 aluminum alloy sheets using Monte Carlo simulation, NSGA-II and neural network. First, to find the relation between the inputs and outputs a perceptron neural network model was obtained. In this way, results of thirty friction stir welding tests are used for training and testing the neural network...