Showing papers in "Mechanics Based Design of Structures and Machines in 2013"
SIDI1
TL;DR: In this paper, an efficient shear deformation beam theory based on neutral surface position is developed for bending and frees vibration analysis of functionally graded beams, which accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors.
Abstract: In this article, an efficient shear deformation beam theory based on neutral surface position is developed for bending and frees vibration analysis of functionally graded beams. The theory accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. The neutral surface position for a functionally graded beam in which its material properties vary in the thickness direction is determined. Based on the present higher order shear deformation beam theory and the neutral surface concept, the equations of motion are derived from Hamilton's principle. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions. It can be concluded that the present theory is not only accurate but also simple in predicting the bending and vibration behavior of functionally graded beams.
166 citations
TL;DR: In this paper, a bi-criterion optimization problem is formulated for finding an optimal acceleration transition and an associated shift control in a double-clutch transmission, and a theoretically optimal solution is shown.
Abstract: In general, gearshift is related to change of acceleration due to the changing gear ratio. Modern double-clutch transmissions allow for shaping the acceleration transition by controlling the torques transmitted by the clutches. Thus, the question arises about an optimal transition law for the acceleration. The paper demonstrates that jerk and change of jerk may be considered as major sources of discomfort. Thus, a bi-criterion optimization problem is formulated for finding an optimal acceleration transition and an associated shift control. The problem is solved by analytical and polynomial approaches, and a theoretically optimal solution is shown. The latter is applied to a simple simulation model of a double-clutch transmission to demonstrate its applicability.
31 citations
TL;DR: In this article, the geometrically large translations and/or rotations and the excess thermal deformation of the curved panel based on higher order shear deformation theory (HSDT) using nonlinear finite element is reported.
Abstract: Postbuckling behavior of laminated shell panel in thermal environment is reported in this article. The geometric nonlinearity is introduced in Green–Lagrange sense and the model is developed for the geometrically large translations and/or rotations and the excess thermal deformation of the curved panel based on higher order shear deformation theory (HSDT) using nonlinear finite element. The governing equation of shell panel is derived by minimizing the energy expression. The postbuckling strength in terms of temperature ratio (postbuckling to buckling temperature) of the panel by obtained by a direct iterative method. The results are obtained using the developed model and compared with those of the available published literature. Some of the new results are computed for different parameters such as layup sequences, thickness ratios, amplitude ratios, boundary conditions, aspect ratios, and various curvature ratios and presented.
30 citations
TL;DR: In this article, the authors modeled the web as a thin elastic plate of brittle material, traveling between a system of supports at a constant velocity, and subjected to bending, in-plane tension and small initial cracks.
Abstract: We study systems of traveling continuum modeling the web as a thin elastic plate of brittle material, traveling between a system of supports at a constant velocity, and subjected to bending, in-plane tension and small initial cracks. We study crack growth under cyclic in-plane tension and transverse buckling of the web analytically. We seek optimal in-plane tension that maximizes a performance vector function consisting of the number of cycles before fracture, the critical velocity and process effectiveness. The present way of applying optimization in the studies of fracture and stability is new and affords an analytical tool for process analysis.
25 citations
TL;DR: In this article, a finite element method is presented to solve static and free vibration problems of axially and/or transversally functionally graded (FG) beams with variable cross-section profile.
Abstract: A novel finite element method is presented to solve static and free vibration problems of axially and/or transversally functionally graded (FG) beams with variable cross-section profile. The presented method overcomes the inaccuracy of the conventional finite beam elements for analysis of the FG beams by introduction of exact displacement interpolation functions. The introduced exact displacement interpolation functions have a unified expression for individual case of axially FG beams, transversally FG beams, varied cross-section beams, as well as their coupled cases. Hence, such cases can be modeled with a unified method and by only one beam element, leading to the presented method easy for modeling the FG beams. The element stiffness matrix is derived according to the internal force equilibrium relationship of the beam element. The element mass matrix and element equivalent nodal loads are derived based on the exact displacement interpolation functions. The method has high accuracy and fast convergence,...
25 citations
TL;DR: In this paper, a finite element (FE) analysis of frictional contacts of elastic members is presented with functionally graded material (FGM) coatings and the contact of cylinders with positive-positive and positive-negative curvatures is investigated in details.
Abstract: Finite element (FE) analysis of frictional contacts of elastic members is presented with functionally graded material (FGM) coatings. The contact of cylinders with positive-positive and positive-negative curvatures and the contact of rectangular parts are investigated in details. The percent error in energy norm in the FE models are minimized and mesh convergence rates are compared with analytical results. Various analytical solutions are compared with FE solutions for different radii of curvatures. The slip and stick regions and contact stresses are investigated in all cases for different stiffness ratios.
25 citations
TL;DR: A Distributed Parallel Motion Control system merged with distributed control and field bus technology for multi-thruster AUV and results show the proposed system and controller can work effectively and efficiently.
Abstract: Based on the study of decoupled dynamics characteristics of the autonomous underwater vehicles (AUVs), A Distributed Parallel Motion Control system (DPMC) merged with distributed control and field bus technology for multi-thruster AUV was presented in this paper. It acts based on the distributed parallel hardware architecture and decoupled control algorithm for easy implementation, and then the sliding-mode control (SMC) had been presented for system control due to its robustness. Simulation experiments were conducted to verify the proposed control algorithms. Compared with the PID controllers, the system performances, including the stability and robustness, had been improved obviously by the SMC. It's suitable for such high nonlinear, dynamics and disturbed systems as AUVs. In order to illustrate the effectiveness of the whole control system, sea tests had been carried out also; both simulation and experimental results show the proposed system and controller can work effectively and efficiently.
23 citations
TL;DR: In this article, a nonlinear three-dimensional tire-soil interaction model with the analytical and finite element method (FEM) is proposed to model the interaction between a bias tire and soft soil.
Abstract: This article is devoted to the modeling of tire–soil interaction with the analytical and finite element method (FEM). Different from the traditional tire–soil interaction models in which the contact between tires and soils is described by nonlinear springs in the normal direction, the new analytical model added dampers accounting for the soil damping effects. A nonlinear three-dimensional tire–soil interaction model with the FEM, which takes into consideration the tire treads and belt/carcass layers, was validated by measuring tire vertical stiffness and contact stress. The conversion of the Modified Drucker-Prager/Cap soil model to the analytical soil model was demonstrated as well. The simulations for investigating the dynamic behavior of a bias tire running on the soft soil were performed. Good agreement was observed based on the simulation results obtained from these two tire–soil interaction models. However, experimental validation is necessary before the models can be further applied in the predicti...
23 citations
TL;DR: In this article, the transverse vibration response, stability, and bifurcations of an axially moving viscoelastic beam with time-dependent axial speed are investigated.
Abstract: The subject of this article is the investigation of the transverse vibration response, stability, and bifurcations of an axially moving viscoelastic beam with time-dependent axial speed. The force and moment balances as well as constitutive relations are employed to derive the equation of motion. Due to the presence of the time-dependent axial speed and steady dissipation terms, time-dependent coefficients and nonlinear dissipation terms are generated, respectively. The equation of motion is reduced into a set of coupled nonlinear ordinary differential equations with time-dependent coefficients. The subcritical resonant response of the system is obtained using the pseudo-arclength continuation technique, while the bifurcation diagrams of Poincare maps are obtained via direct time integration of the discretized equations of motion.
20 citations
TL;DR: In this paper, the authors established a framework for predictive modeling of shot velocities and found a relationship between Almen intensity and shot velocity, which is not used as a controlled parameter by the shot peening industry.
Abstract: Shot peening is a mechanical surface treatment that is used to improve material performance. The velocity of the shots is a significant parameter of the shot peening process, but it is not used as a controlled parameter by the shot peening industry. The present article establishes a framework for predictive modeling of shot velocity. The predicted shot velocities were in good agreement with published experimental results. The present results clearly show that once the shot material and its size are known, the velocity shot depends directly on Almen intensity. For a given combination of shot size, material, and peening angle, an increase in Almen intensity involves an increase in shot velocity. As a further demonstration of the capabilities of the proposed approach, we have found a relationship between Almen intensity and shot velocity.
19 citations
TL;DR: In this paper, the exact elastic buckling of annular plates with elastically restrained edges against rotation and translation at inner and outer periphery was analyzed and the critical buckling load parameters for axisymmetric and asymmetric buckling modes were presented.
Abstract: This article presents the exact elastic buckling of annular plates with elastically restrained edges against rotation and translation at inner and outer periphery. The classical plate theory is used to derive the governing differential equation for annular plate with elastically restrained edge support system. The buckling mode may not be axisymmetric as previously assumed. In certain cases, an asymmetric mode would yield a lower (critical) buckling load. This is due to switching of mode. This work presents the critical buckling load parameters for axisymmetric and asymmetric buckling modes. Extensive data is tabulated so that pertinent conclusions can be arrived at on the influence of rotational and translational restraints, Poisson's ratio and other boundary conditions on the buckling of uniform isotropic annular plates. The numerical results obtained are in good agreement with the previously published data. In this article, the characteristic equations are exact; therefore, the results can be calculate...
TL;DR: In this article, the symmetric flexure hinge with circular longitudinal axis and midpoint radial symmetry was obtained from one half flexure using rotation and mirroring, and the six planar bending compliances of the full hinge were determined analytically for small deformations by combining only three compliances.
Abstract: The new class of flexure hinges with circular longitudinal axis and midpoint radial symmetry is introduced. Using rotation and mirroring, the symmetric flexure hinge is obtained from one half flexure. The six planar-bending compliances of the full hinge are determined analytically for small deformations by combining only three compliances of the half flexure. To illustrate the general flexure hinge category, the novel circular-axis, right circularly corner-filleted design is introduced. Experimental and finite element results correlate well with the analytical model predictions. The new flexure hinge design is compared to the circular-axis, constant-thickness flexure and the straight-axis, right circularly corner-filleted hinge.
TL;DR: In this article, the radial basis functions-QR (RBFQR) algorithm is used for the static and vibration analysis of plates, which can be applied to any geometry and node sets embedded in the 2D unitary disk.
Abstract: An application of a meshless technique for the static and vibration analysis of plates is presented in this paper. The method is based on the radial basis functions-QR (RBF-QR) algorithm. Static deformations and free vibration analysis of plates are obtained by Gaussian RBF-QR technique, previously proposed by Fornberg and Piret (2007) for interpolation problems. Circular and square plates are analyzed considering free-edge, simply-supported, and fully-clamped boundary conditions. The presented technique can be applied to any geometry and node sets embedded in the 2D unitary disk. The RBF-QR approach is stable for decreasing values of the shape parameter, corresponding to flat RBFs and the conversion to polar coordinates brings an extra improvement in precision. The method produces highly accurate displacements, natural frequencies, and modes of vibrations.
TL;DR: Using the isogeometric approach, the variational formulation of both response and sensitivity analyses for geometrically nonlinear structures is derived using the total Lagrangian formulation in this article.
Abstract: Using the isogeometric approach, the variational formulation of both response and sensitivity analyses for geometrically nonlinear structures is derived using the total Lagrangian formulation The geometric properties of design are embedded in the nonuniform rational B-splines basis functions and control points whose perturbation naturally results in shape changes Thus, exact geometric models can be utilized in both response and sensitivity analyses The normal vector and curvature are continuous in the whole design space so that enhanced shape sensitivity can be expected Refinements and design changes during the shape optimization are easily implemented within the isogeometric framework, which maintains exact geometry without subsequent communication with computer-aided design description Through numerical examples, the developed isogeometric sensitivity is verified to demonstrate excellent agreement with finite difference sensitivity Also, the proposed method works very well in various shape optimiz
TL;DR: In this article, a three-wheeled mobile robot with a two-degree-of-freedom suspension mechanism is designed to traverse uneven terrains with very little slip and experiments with the prototype on a representative uneven terrain confirm that the slip is significantly reduced.
Abstract: A wheeled mobile robot (WMR) can move on uneven terrains without slip if the wheels are allowed to tilt laterally This paper deals with the analysis, design and experimentations with a WMR where the wheels can tilt laterally The wheels of such a WMR must be equipped with two degrees of freedom suspension mechanism A prototype three-wheeled mobile robot is fabricated with a two degree-of-freedom suspension mechanism Simulations show that the three-wheeled mobile robot can traverse uneven terrains with very little slip and experiments with the prototype on a representative uneven terrain confirm that the slip is significantly reduced
TL;DR: In this paper, the static and dynamic analysis of the shear deformable laminated composite beams with channel-sections based on an orthogonal Cartesian coordinate system is studied.
Abstract: In this study, the theoretical and numerical models are developed for the fully coupled static and dynamic analyses of the shear deformable laminated composite beams with channel-sections based on an orthogonal Cartesian coordinate system. The current composite beams take into account the transverse shear and the restrained warping induced shear deformation by using the first-order shear deformation beam theory. An analytical technique is used to derive the strain energy, the geometric potential energy, and the kinetic energy of the beam in a systematic manner considering all the deformation effects and their mutual couplings. To solve the static and dynamic problems, three different types of finite beam elements, namely, linear, quadratic and cubic elements are used. In order to demonstrate the validity of this study, the numerical solutions for the static and dynamics problems of channel-section beams are presented and compared with the experimental test results and the results obtained from other resea...
TL;DR: In this paper, some relevant kinematic properties of a spherical parallel manipulator with orientational actuators and without intersecting revolute axes are investigated mainly by means of the theory of screws.
Abstract: In this article, some relevant kinematic properties of a spherical parallel manipulator with orientational actuators and without intersecting revolute axes are investigated mainly by means of the theory of screws. The analyses considered in this contribution cover displacement analysis, velocity, and acceleration analyses as well as a brief explanation of the performance of the parallel wrist by studying its workspace, isotropy, and singular configurations. A case study is included in order to exemplify the application of the method.
TL;DR: In this paper, a numerical procedure is proposed to study the response of an inclined beam subjected to a sprung mass and a first-order shear deformation theory including rotary inertia is assumed for the beam element.
Abstract: A numerical procedure is proposed in this paper to study the response of an inclined beam subjected to sprung mass The first-order shear deformation theory (FSDT) including rotary inertia is assumed for the beam element The effects of inertial force as well as Coriolis and centrifugal forces induced by the moving sprung mass are considered in governing equations The Newmark time integration method is adopted in solving equations In this paper, the horizontal and vertical deformations of the beam, along with the Coriolis force and the inclined angle are investigated The moving system is considered as a one degree of freedom system including two masses located at the ends of the moving load system, one spring and viscous damping The effects of spring constant and damper ratio on the dynamic magnification factor (DMF) of the inclined beam are also studied The results obtained from the present study show that the Coriolis force in lower speed has significant influence on the dynamic response of the beam
TL;DR: In this article, the problem of layered plate multiobjective optimization against penetration of strikers having supersonic entry velocities is addressed, where the number of considered materials is supposed to be finite and consequently the admissible design set consists of separate discrete values.
Abstract: The study deals with the problem of layered plate multiobjective optimization against penetration of strikers having supersonic entry velocities. The plate is monolithic piece-wise homogeneous and composed from several plate-like layers produced from various given materials. The number of considered materials is supposed to be finite and consequently the admissible design set consists of separate discrete values. The impactor is modeled as an axisymmetric rigid body with blunted nose. The ballistic limit velocity and the mass of the plate are taken as components of the vector-functional that is optimized in Pareto sense. Best distribution of given materials is found with the help of genetic algorithm.
TL;DR: In this paper, the performance of a cross-feed servo system of a heavy-duty lathe with closed loop control subjected to friction is studied in a field test, where the critical stick slip feed velocity at different feed position is measured by the Renishaw XL laser inter...
Abstract: The performance of feed servo system has an important effect on the path tracking and positioning accuracy of computer numerical control (CNC) machine tools. The nonlinearity of friction can lead to the occurrences of unstable behavior of the feed servo system, such as stick-slip motion and oscillation. The crossfeed servo system of a heavy-duty lathe with closed loop control subjected to friction is studied in this article. The multi-degree of freedom (MDOF) mechanical and mathematical models of the crossfeed servo system are established. In the models, the torsional stiffness of shaft, meshing stiffness of gears, ballscrew-nut pair contacting stiffness, axial stiffness of the bearing, and the ballscrew and the kinematical friction force between up and down guideways are considered. The weakest link of the mechanical transmission system of the feed system is found by simulations. In the field test, the critical stick slip feed velocity at different feed position is measured by the Renishaw XL laser inter...
TL;DR: In this paper, four systematic approaches are developed in the context of the indirect methods for analyzing the nonlinear prebuckling behavior, and an appropriate test function to monitor bypassing of the critical points is utilized.
Abstract: Four systematic approaches are developed in the context of the indirect methods for analyzing the nonlinear prebuckling behavior. In this study, an appropriate test function to monitor bypassing of the critical points is utilized. The main idea of the article is to find the critical loads by using the perturbation of the eigenvalue. Both linear and quadratic variations of the eigenvalue and also parabolic changes of the structural stiffness are considered. Moreover, other available techniques to find the critical points are briefly reviewed. Finally, the accuracy and robustness of the presented procedures are investigated by solving some well-known benchmark problems.
TL;DR: In this paper, the material and/or geometrical uncertainties were embodied into calculations by using interval analysis in symmetrical structural systems that display elasto-plastic material behavior when exposed to the pure bending moment effect, and the moment bearing capacities of the systems under these uncertainties were determined.
Abstract: In this study, material and/or geometrical uncertainties were embodied into calculations by using interval analysis in symmetrical structural systems that display elasto-plastic material behavior when exposed to the pure bending moment effect, and the moment bearing capacities of the systems under these uncertainties were determined. The parameters used in the formulas, which are considered to be affected by the uncertainties, are defined under two sections: certain and uncertain. The uncertain section is expressed with interval numbers and then added to the actual value as a multiplying factor. By using interval analysis in the applications that require maximum sensitivity, the content of correct result is guaranteed, by enabling the use of a solution interval that includes the actual value, without considering the source of the uncertainty.
TL;DR: In this paper, a new analytic technique for locating the secondary instantaneous poles of single-degree-of-freedom spherical mechanisms is presented, which does not rely on any velocity information or graphical techniques.
Abstract: In spherical mechanisms, the instantaneous poles have the same function as the instant centers in planar mechanisms. So they can be used for kinematic analysis of spherical mechanisms, as the instant centers are for planar ones. The first step to make the instantaneous poles applicable for this analysis is the determination of the position of these poles. This paper presents a new analytic technique for locating the secondary instantaneous poles of single-degree-of-freedom spherical mechanisms. The proposed method does not rely on any velocity information or graphical techniques. Therefore, it can be applied systematically to all types of indeterminate single-degree-of-freedom spherical mechanisms.
TL;DR: In this article, the integral for a 2D stationary circular arc crack in a homogeneous and isotropic material subjected to multiple loads has been implemented into a finite element postprocessing program for examining the path-independence behavior under elastic deformation while employing rapidly varying mechanical load.
Abstract: In the present work, the integral , originally developed for a 2D stationary circular arc crack in a homogeneous and isotropic material subjected to multiple loads, has been implemented into a finite element postprocessing program for examining the path-independence behavior under elastic deformation while employing rapidly varying mechanical load. Under different loading rates, the integral has been computed on several contours in order to describe the invariant property of the integral . Numerical results reveal that, within the limits of computational accuracy, the path-invariant property is well preserved over the integration contours for the present loading rates. The variation of the integral with respect to time has also been studied for both plane strain and plane stress conditions. The numerical investigations confirm that the performance of the integral is sufficiently impressive and therefore suggest applicability in fracture-related studies.
TL;DR: In this article, an analytical model to calculate the wrinkling load of sandwich plates with nonorthogonal plain woven composite facesheets is established, and the effects of various parameters are demonstrated.
Abstract: Fabric is often attached on lightweight core to form a sandwich plate. When complex sandwich structure is manufactured, the fabric facesheets are in a state of in-plane tension or shear deformation, and the angle between the warp and weft yarns is altered. An analytical model to calculate the wrinkling load of sandwich plates with nonorthogonal plain woven composite facesheets is established, and the effects of various parameters are demonstrated. Analysis results indicate that the core modulus and thickness, fiber modulus, and yarn orientation of facesheets can influence the facesheets’ wrinkling behavior of sandwich plate on different levels.
TL;DR: In this paper, the effects of hard damper setting on ABS braking performance have been experimentally investigated by taking brake pressure changes as a reference by using medium-hard and hard dampers.
Abstract: In this study, the effects of hard damper setting on ABS braking performance have been experimentally investigated by taking brake pressure changes as a reference. For this aim, ABS tests have been conducted under wet and slippery rough road conditions by using medium-hard and hard dampers. In order to assess the test results, three braking maneuvers are considered. Test results show that hard damper setting improves ABS-braking performance under slippery road condition, while it deteriorates with wet road condition because of brake pressure oscillations occurring in vehicle body, axle and brake pressure pumping resonances. For this reason, the hard setting causes the bad braking performance during transition from slippery to wet road conditions.
TL;DR: In this article, a combination of floating frame of reference formulation with modal superposition and a sub-modeling approach is proposed to obtain the relevant fatigue assessment stress history for a structural detail during or after dynamic simulation.
Abstract: Modern machine structures are often fabricated by welding tens or even hundreds of plate elements. From a fatigue point of view, the structural details, and especially the welded details, are normally most sensitive to fatigue damage and failure. Obtaining the stress history of a structural detail during dynamic simulation is a challenging task, especially when the detail has a complex geometry. In particular, analyzing the stress history of every structural detail within a single finite element model can be overwhelming since the amount of nodal degrees of freedom needed in the model may require an impractical amount of computational effort. This study proposes that the problem can be greatly simplified by using a combination of Floating Frame of Reference Formulation with modal superposition and a sub-modeling approach. In practice, the proposed approach can be used to efficiently generate the relevant fatigue assessment stress history for a structural detail during or after dynamic simulation. In this ...