Papers by Keyword: Clearance

Abstract: Path planning refers to designing a reliable, feasible, optimum, safe, and collision-free path with the shortest distance that takes a mobile robot from the start position to the goal point within an environment. To ensure the successful operation of a robot, an effective and efficient Path planning technique that guarantees obstacle avoidance and an optimal path must be adopted. This paper applies a novel path length reduction technique – the Kenneth, Nnanna, and Saleh (KNS) algorithm-to notable path planning algorithms (APF, A*, RRT, and RRT*) to shorten their path length by reducing the waypoints' bends and retaining the obstacle avoidance capability of the algorithms. We simulated applying the technique to different notable algorithms in an environment configured with varying obstacles. We compared the resultant paths with the original paths. The results show that the KNS algorithm is very effective and can significantly reduce the path length of the notable algorithms.

Abstract: The buckling-restrained brace must be able to provide the designed structural performance in actual use. In other words, the buckling-restrained brace must retain its initial quality in during the fabricating process. In this study, for the purpose of ensuring the initial quality of the buckling-restrained brace using steel mortar planks (BRBSM), quality control values at the time of fabrication are set and conduct verification testing on clearance and gap.

Abstract: The paper presents a complex quarter car model obtained with ADAMS software, View module, useful in the first stage of suspension dimensioning and optimization.The model is equipped with compression and rebound stopper buffer and suspension trim corrector.The proposed quarter car model with two degrees of freedom (wheel and body) performs all these goals allowing changing:Geometrical elementsPosition of equilibrium, depending on vehicle load;Trim correction;Elastic and dissipative characteristics of the suspension and tire;Suspension stroke;Road profile, assessed either by simple or summation of harmonic functions or reproducing real roadsBuffers (for stroke limitation) position and characteristics;The models developed provide information on:Vertical stability assessed by vertical movements of the body and the longitudinal and transversal stability evaluated based on adherence characterized by wheel ground contact force and frequency of soil detachment wheel.Comfort assessed on the basis of body vertical acceleration and collision forces to the stroke ends.The body-road clearanceThe trim corrector efficiencyAll above performances evaluated function the road unevenness, acceleration, deceleration, turning regime.The damping characteristic is defined by damping forces at different speed for each strokes respectively one for rebound and other for compression.The contact force road-wheel is defined based tire rigidity law.The stopper buffer forces on rebound and compression are defined based each specific rigidity characteristics.The road excitation is realized with a function generator.The software allow the model evolution visualisation in real time, also generating the diagrams of displacements, forces, accelerations, speeds, for each elements or for relative evolution between diverse elements.The simulation was realized for unloaded and fully loaded car using a road generated by a sum of harmonic functions presented in equation (8).The excitation covers the specific frequencies area, being under the body frequencies up to the wheel proper frequencies.The realized ¼ car model, have reached the goal to evaluate the suspension trim correction advantages.The simulations confirm the trim corrector increases the suspension performances, thus for the analyzed case the trim corrector increase simultaneous:Body-ground clearance (evaluated by body higher increasing) between 18.5÷55.1 %Body stability (evaluated by maximal body displacement) between 9.8÷11.4 %Body comfort (evaluated by maximal body acceleration) between 3.4÷35.5 %Adherence (evaluated by maximal and RMS wheel-groundcontact force variation) between 7.0÷12.1 %Body and axles protection (evaluated by buffer strike force) between 10.8÷38.2 %

Abstract: Fine blanking is a widely used process that permits the production of precise finished components which are cleanly sheared through the whole cutting surface. It can be eliminated secondary operations, such as milling, grinding, etc. Many studies on the weight reduction of automobile for fuel saving were underway. The clearance of the punch-die of a fine blanking tool is an important design factor that affects the sheared surface of a product. If the clearance is too big, a fractured surface would occur in the product while if it is too small, bulging would occur. The main objective of this paper is to provide an overview of the effect of clearance between punch and die in a fine blanking tool on quality of sheared surface. A well as to specify the effect of mechanical properties of sheared steel sheet on blanked edge quality given by ratio of h_v/a_0.

Abstract: Spherical hinge as a kinematic pair is widely used in mechanical engineering, but clearance inevitably exists in it and reduces the run precision of the mechanical system. In this paper, two-mode theory of nonlinear spring-damper contact force and modified Coulomb friction model are used for creating a virtual prototype model of a kinematic pair with clearance. Drive force is calculated in 4 kinds of working conditions, 3 different sizes of clearance. Influence of the clearance on accuracy of the transmission force is discussed.

Abstract: A vibro-impact dynamic model of a typical single-stage spur gear train has been proposed in this study. The lumped parameter dynamic model includes the constant meshing stiffnesses, the linear time-invariant viscous damping values and the gear clearance (backlash) non-linearity allowing teeth separations. With taking account of the effect on impact of gear tooth when meshing, the dynamic equations of motion are solved for the steady period response by use of analytical method under given periodic motion conditions. The feasibility of the given periodic motion conditions is demonstrated by comparing the analytical results with that of numeric simulation method. A Poincaré map of the system is established. The stability and bifurcation of the system are studied using analytical methods. Finally, the theoretical analyses are verified using numerical simulation.

Abstract: A non-linear torsional vibration model of harmonic gear drive is proposed in the current study. The model includes clearance, nonlinearity torsional stiffness and nonlinearity damping. The clearance model is developed by introducing the piecewise-linear displacement functions. The function of nonlinearity torsional stiffness is obtained by torsional stiffness experimental. The model of nonlinearity damping is used to describe the process of transmission. The non-linear differential equations are solved using Runge-Kutta method. The numerical simulation results show that the influence of nonlinear factors on dynamic behavior, which has chaotic characteristics, is remarkable.

Abstract: The mechanical property of woven liner spherical plain bearing in different clearance has been analyzed using the finite element software. It indicated that when the positive clearance of woven liner spherical plain bearing is 100um, the maximum stress of its inner ring is the lowest. The position of the maximum stress is in the middle of the inner ring. That makes the bearing has a bigger carry capacity. Based on above analysis, the thermal properties between the friction pair of woven liner spherical plain bearing which clearance is 100um is also analyzed. The node temperature variation trend of inner ring and liner along with the analysis process is obtained.

Abstract: By analyzing the shipboard missile vertical launching system (VLS), we simplified the assembly model and reconstructed it with mathematical methods, established the clearance parameter and deviation angle mathematical formulas. In considering of the assembly errors of guide rail in missile vertical launcher system, we studied assembly clearance parameters effects on the system at first. And then established dynamic simulation model, researched the relationship between assembly clearance parameters and missile launching status. At last, used the above relationship model and conclusions, developed a prototype simulation method, and provided the foundation and guidance for design of missile vertical launching system.

Abstract: It is necessary to ensure performance characteristics of vane pump using virtual analysis of scale and geometrical tolerances. As performance characteristics are chosen axial and radial clearance between the rotor and the other details ensuring normal operation of the pump. The virtual analysis may be made by creating of nominal 3D-CAD model in Solid Works medium using the modules for dimensional analysis by DimXpert and analysis of tolerances TolAnalyst. The dimensional chains related to determined characteristics are developed. The results obtained will be used for amelioration of manufacturability of this pumps. This approach allows to find the most suitable constructional decision on this stage and to shorten the time for design.