Papers by Keyword: Contact Force

Abstract: Columns are prone to sinusoidal buckling and repeated instability on the effect of drilling pressure and fluid pressure during drilling operation. The resulted large area of random contact to borehole wall would affect the drilling efficiency. It made the backreaming and loading hard and the drilling pressure low. Using energy method, taking flexural deformation energy and external potential energy of strings, hole section (slant hole, bending hole, level hole) and annular clearance etc. into consideration, derived the counting function of force that sinusoidal buckling occurred on coiled tubing when it contact with the wellbore, establishing the mechanical analysis method of calculating for sinusoidal buckling of slim lined construction roof bolt and string borehole. It proves an effective method for the applying of coiled tubing drilling pressure and the optimization of process parameters.

Abstract: This paper discussed some properties of ovoid gear. The gear is a kind of special gear that transformed from the non-circular gear, hence just like the non-circular gear it also has some unique properties itself. In the paper we did some research start from the transmission of non-circular gear and point out the variable working pressure angle property. Then toke the ovoid gear as an example to deduce the working pressure angle expression, and discusse the force between two separate tooth during the meshing process. After all those things has been done, a 3D model of ovoid gear was established under the help of Pro/E, and then imported it to the Adams to do some meshing simulation in order to find the contact force under the impact of variable working pressure angle.

Abstract: A multibody formulation is used to accurately describe the relation between the different components in chain drive systems and their full dynamics [1]. All components, including sprockets, are represented by rigid bodies connected to each other by revolute clearance joints [2]. The complete formulation is implemented in a computational simulation tool integrating all relevant dynamic characteristics inherent to chain drives and incorporated in the general-purpose multibody program [3]. Penalty contact force models are considered for modelling the revolute clearance joints, particularly those proposed by Lankarani and Nikravesh to quantify the normal contact force [4]. The friction force is accounted for based on the modified Coulombs friction law [2]. This work draws on the influence of dry contact parameters such as friction coefficient, restitution coefficient and clearance value on the dynamics of chain drives. The effect of a pretension level is also analyzed.

Abstract: Dynamic response and damage mechanism of two-core sandwich panels with foam and honeycomb cores and glass fiber/epoxy composite sheets under low-velocity transverse impact are investigated. The emphasis is focused on the contact force response and crash mechanism of the two-core sandwich panels. Effects of configurations, impact energy levels and types of the cores on the dynamic response are investigated. A modified drop-test experiment is carried out to obtain contact force history of the two-core sandwich structures under different impact energies. The experimental results show that the 10:10 configurations for both honeycomb and foam core sandwich structures under lower impact energy absorb more impact energy than the other two structures. However, under higher impact energy, the honeycomb core sandwich structures of 15:5 configuration absorbs a little more impact energy than the other two, while for the foam core sandwich structures the 5:15 configuration shows a little better impact resistance. Results also show that when impact energy is low foam core sandwich structures do better in absorbing impact energy than the honeycomb ones.

Abstract: Due to the high flow pulsation，the ordinary gear pump has large vibration, noise. A new structure named multi-gear pump was proposed. The model of the pump was established. The motion simulation was given to compare with common gear pump. The simulation analysis show that the pump tooth contact force pulse value is 0.296, which is about 25% lower than the common gear pump. Findings from the paper are supposed to provide a theoretical basis for the following experiments and to improve the life of gear.

Abstract: Besides the material properties and operating environment, the strain and strain state of the wires in multi-stage twisted rope with large frictional contact force, as applied in traction hoister of suspended access platform, strongly influence their service life. For an accurate quantitative prediction of the performance and a proper understanding of the underlying phenomena, a detailed analysis of the stress-strain distribution along all individual wires is required. For this, a numerical model for a wore rope in traction hoister was describe to be considering the complex strand pattern, mutual interaction by contacts form surrounding strands and contact deformation, in this paper. The model well understood response of wire rope under an axial tensile load and twisting moment, and concise described the effects of rope deformation on the rotate ratio and slip behavior of the hoister. The results of this model were compared with the experiment analyzed, which showed that the inclusion of interfacial forces at the contact locations and their associated effects of internal force of helical wires is importance.

Abstract: The existence of clearance in joints of manipulator system is inevitable and the movements of the real manipulator are deflection from the ideal manipulator for the clearances. In this study, the effects of clearance on dynamic responses of real manipulator system with multiple clearance joints are investigated using a computational methodology. By applying the nonlinear continuous contact force model, the contact dynamics model in joint clearance is established and the friction effect is considered with the help of Coulomb friction model. Then the dynamics simulation is carried out and the dynamic characteristics of manipulator system with multiple clearance joints are investigated. The results show that the clearance leads to degradation of dynamic performance of the real manipulator system.

Abstract: The dynamic behavior of a reciprocating compressor transmission mechanism with joint clearance is studied in this paper. A transmission mechanism virtual prototype model is built under software ADAMS. Revolute joint between connecting rod and crosshead pin is modeled with clearance by contact model based on the so called Impact-function, and four processes of cylinder pressure load is simulated by the IF function. Cylinder pressure load, amplitude of joint clearance, crank speed and flexibility of connecting rod is taken as influence factors. Four different cases were simulated. Joint contact forces, accelerations of compressor block and journal centre path are used to analyze the dynamic behavior. The presented results show that these factors play a significant role of dynamic behavior of mechanisms.

Abstract: Computer simulations, such as PC-CRASH, were used in this paper to develop simulation model of car-bicycle/bicyclist crash. The change law of throw ditance which belongs to the first falling point and final falling point of bicyclist were studied on. Through researching the parameters obtained in the process of computer simulation, we concluded the stress size on the important part such as head, chest and knee of bicyclist in different accident modality. This research result provides a good idea in car-bicycle/bicyclist crash reconstruction.

Abstract: Influence of the support stiffness and contact force on friction and wear behaviors of stainless steel rubbing against copper-impregnated metalized carbon under electric current was researched on an improved friction and wear test machine. The result indicates that the support stiffness and the contact force significantly affect the friction coefficient of contact pairs, wear and surface roughness of pin samples. The appropriated support stiffness and contact force can effectively reduce friction material wear of contact couple.