Papers by Keyword: Load Distribution

Abstract: In order to verify the bearing performance of Mg-Li alloy thread connections, the tightening performance and axial pull-out performance of the Mg-Li alloy thread structure with wire thread insert were tested, and the failure load and mode were obtained. The finite element 2D axisymmetric model was used to numerically analyze the bearing properties of Mg-Li alloy threads. The reliability of the analysis model was verified by comparison with the experimental results and theoretical basis. The load distribution and stress distribution characteristics of the thread connection were studied, and the influence of boundary constraints on the axial pull-out performance was studied. The results show that the M5 Mg-Li alloy embeded wire threat insert with 8 rounds has sufficient connection strength under the action of tightening torque and axial pull-out load, and the failure mode is mainly bolts fracture. Boundary constraints will have an influence on the load distribution and performance of the Mg-Li alloy thread connection structure. The load-bearing ratio of each round thread changes obviously with the downward movement of the top of the boundary. As the top of the boundary moves downward, the location where the maximum load-bearing ratio will be transformed from the first thread to the last thread. The load-bearing ratio of the last thread gradually increases from 11.3% when the outer circumference fully restrained to 23.1% when the boundary area below 4 mm from the last thread. For the M5 Mg-Li alloy embeded wire threat insert with 8 rounds, the axial pull-out bearing capacity of M5 inserts is between 9.5 kN and 12 kN under different boundary conditions.

Abstract: Extensive concerns on environmental protection have provoked low-carbon buildings to be the mainstream of building construction worldwide, and wooden structures in this sense outperform other structural forms. Wooden-concrete hybrid structures featuring distinct wooden and concrete stories typically exhibit uneven stiffness distribution along the structure height; in particular, abrupt stiffness changes occur at the wood-concrete transition stories. Therefore, structural designing of such hybrid structures must consider a stiffness amplification effect in the static structural calculation as well as complicated procedures in the dynamic analysis. To determine an appropriate amplification factor for design purpose, this study employed a dynamic numerical approach to determine the displacement response of wooden-concrete hybrid buildings and compared the results with the displacement response obtained from static analyses. According to the results, it is found that the appropriate amplification factor should beα= f (x) = 0.47x + 1.00.αcan be valued 1.94 at 2nd floor, 2.41 at 3rd floor and 2.88 at 4th floor. The results may serve as a reference for seismic designing of wooden-concrete hybrid structures.

Abstract: One of the advanced ways of provision of functional properties of interference fit joints is to control contact interaction between mating parts, particularly by assembling with application of anaerobic materials polymerizing in contact area. The main advantage of using anaerobic materials is that this technology allows us to harden different parts of the joints selectively. The purpose of the work is to study the possibility of rational provision of functional properties of interference fit joints by selective hardening in case of assembling with the use of anaerobic materials. Modelling of bearing strength of interference fit joint is carried out according to finite element method, with theory of contact interaction between mating surfaces being used. The results of experimental research are given. Anaerobic material is used as a material for hardening of joints. It was discovered that exploitation load in form of torque or axial force is distributed along the length of interference fit joint rather nonuniformly. To decrease expenses, it is necessary to harden those areas of joint which are located by the side of load application. The way of assembling of interference fit joints by pressing with selective use of hardening material is proposed. The technique of reliable identification of the necessity and the moment to apply anaerobic material while assembling parts was developed. As a result, functional properties of pressure joints are reached the most rational way.

Abstract: Currently available foot prosthesis model are more than 50 in number. In order to perform some extraordinary errands, for example, strolling, moving, cycling, golfing, swimming, snow skiing or running they are employed. Many are waterproof and made of lightweight materials, for example, plastic, metal combinations and carbon-fiber composites. Prosthetic feet can be essential (unmoving), explained (moving in at least one bearings), or element reaction (putting away and returning vitality when strolling, giving a feeling of "pushing off," much like the human foot). However there are certain problems which are not completely tackled by the currently available prosthesis for which the walking pattern remains strongly disturbed. Today's prosthetic feet may have toe and heel springs to permit more lower leg development and movable heel statures, and to assimilate stun but the load distribution is not proper which leads to fatigue. In this paper, a powered ankle-foot prosthesis mechanism that aims at the equal distribution of the load using a hydraulic system in order to store the energy in the spring over the movement of prosthetic ankle was presented. Although the prosthetic foot presented in this paper is driven by an electric-motor it is made lighter and robust than the currently available ones. Some primary experiments were conducted by taking the forces acting to account. A 3-D model of the proposed design was made using piston cylinder arrangement in order to get a real ankle like movement, thereafter the stress analysis of the same was done and results were discussed.

Abstract: Cantilever is the most important structure of the jack-up rig. Jack-up usually has three working conditions: drilling condition, storm condition, preloading condition. The fulcrums of the cantilever in the drilling condition are less than the other two. So the distribution of the cantilever force in the storm and preloading conditions becomes extremely complicated with the increase of fulcrums. In order to facilitate the evaluation of jack-up rig strength, a simplified analytical method and a finite element method (FEM) are presented to distribute the cantilever force on a jack-up rig during the storm and preloading conditions. For the simplified analytical method, the fulcrum force is obtained from the distance between the fulcrum and the position of the cantilever resultant force. For the FEM, the cantilever is assumed to be perfect rigid body without any strain. The fulcrum force is calculated according to the balance of the fulcrum forces. Both results of fulcrum force are analyzed and compared. It is shown that they are in good agreement. Thus both methods can be applied in distributing the cantilever force to evaluate the strength of jack-up rig.

Abstract: The central heating units of buildings are typically replaced every 20 to 30 years. There exists a variety of solutions for fuel-and gas-based units, but it would be advantageous to be able to use renewable energies. This would become possible by the combination of planar carbon-fiber-based infrared (IR) radiant heating foils with a heat pump providing hot water. The main goal of our proposed overall control strategy is to increase the energy efficiency while maintaining the thermal comfort for the residents. We examined the electromagnetic compatibility of the heating foils and simulated the relative contributions of the amount of energy provided by the heat pump and by the heating foils to obtain a maximum coefficient of performance for the combined heating system.

Abstract: An method was proposed to derive the formula of the overlap coefficient and the influence of main parameters on overlap coefficient were also discussed; The load distribution is deduced and the rule of contact load varying with overlap coefficient was revealed; The results indicate that the increasing overlap coefficient can extend the time of rollers engaging, reducing the contact load of globoidal indexing cam mechanism and altering the load distribution.

Abstract: The paper presents an analysis of displacements and the load distribution between elements in the planetary roller screw for assumed computational model. Based on the analysis of stresses and threads deformations the load distribution on threads for the case of consistent and opposite load of the screw and nut is obtained. By applying finite element analysis the stiffness of the contact regions on threads was estimated for various dimensions of the screw, roller and nut.

Abstract: A procedure for obtaining the load distribution in a four point contact wind turbine yaw bearing considering the effect of the structure’s elasticity is presented. The inhomogeneous stiffness of the supporting structures creates a variation in the results obtained with a rigid model. A finite element model substituting the rolling elements with nonlinear compression springs has been built to evaluate the effect of the supporting structure elasticity on the contact forces between the rolling elements and the raceways.

Abstract: The paper presents a model for quasi-static analysis of angular contact ball bearings. This model allows the computation of the load distribution on ball and races contacts as a function of radial and axial inner ring displacements, including the effect of the misalignment between the inner and outer rings. The results show the influence of the misalignment on ball and races load distribution.