• Structural Engineering and Mechanics
• /
• v.2 no.1
• /
• pp.63-80
• /
• 1994

A cable is considered as a system of helical wires and a core with distributed dry friction forces at their interfaces. Deformations of the cable subjected to a uniform bending are analyzed. It is shown that there is a critical bending curvature when a slip at the wire-core interface occurs. It originates at the neutral axis of the cross section of the cable and then spreads symmetrically over the cross section with the increase of bending. The effect of slippage on the cable stiffness is investigated. This model is also used to analyze a cable under the quasi-static cyclic bending. Explicit expression for the hysteretic losses per cycle of bending is derived. Numerical examples are given to show the influence of dry friction and helix angle on the bending stiffness and hysteretic losses in the cable.

• Structural Engineering and Mechanics
• /
• v.21 no.1
• /
• pp.1-18
• /
• 2005

Foschi's connector model is used as a basic component in the development of nonlinear analysis programs for timber structures. This paper presents the extension of the model to include the effect of shaft frictional forces. The wood medium is modeled using the Foschi embedment model, while shaft friction is modeled using an elastic Coulomb-type friction model. The initial confining pressure for the case of driven fasteners is accounted for by a lateral shift of the load-embedment curve. The model is used to compute the cyclic response of both driven and inserted fasteners. The results obtained from the cases studied indicate that initial confining pressure and friction do not have a significant effect on the computed hysteretic response, however, they significantly affect the computed amount of fastener withdrawal. This model is particularly well-suited for modeling the hysteretic response of shear walls with moderate fastener withdrawal under lateral cyclic or earthquake loading.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.517-522
• /
• 2000

When a body including a crack inside is subjected to the compressive forces, the crack is closed and sliding occurs on the crack surfaces. In this work, a subsurface crack subjected to a static or moving compressive load is analyzed with the finite element method considering friction on the crack surface. The friction on the crack surface is assumed to follow the Coulomb friction law. A numerical method based on the finite element method and iterative method is applied in this work. And the result is compared with the frictional contact of crack by ANSYS using contact 12 element. The numerical results of two methods are compared with the wellknown analytical solutions, and the accuracy of iterative method is checked..

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.939-942
• /
• 1997

In chemical mechanical polishing(CMP) there are many factors affecting the results. Temperature is one of the factors and it affects the removal rate. That is, the higher it arise, the more the material is removed. But the detailed temperature behavior is not discovered. In this study, we discover the distribution of temperature across the pad where the wafer has just been polished. And then we reveal the cause of the result in connection with the mechanical structure. In addition, we also discover the relationship of the friction force and normal force. With the result of two forces, we get the friction coefficient and obtain the contact model of the wafer and pad.

• Journal of the Korean Society for Railway
• /
• v.9 no.6 s.37
• /
• pp.677-681
• /
• 2006

In general, the braking system of high speed train has an important role for the safety of the train. To stop the train safely at its pre-decided position, it is necessary to combine the various brakes properly. The Korean high speed train (HSR-350x) has adopted a combined electrical and mechanical (friction) braking system. In this study, the measuring method that can obtain the disc braking forces and friction coefficient between disc and pad during on-line test of HSR-350x has been suggested and verified through the comparison of the results obtained from this method and those of the results of the dynamo-tests.

• KSTLE International Journal
• /
• v.3 no.1
• /
• pp.49-53
• /
• 2002

Inconel 690 for nuclear steam generator tube has more chromium than the conventionally used Inconel 600 in order to increase the corrosion resistance. TD evaluate the tribological characteristics under fretting condition the fretting tests as well as sliding tests were carried out in elevated temperature water environment. Fretting tests of the cross-cylinder type were done under various vibrating amplitudes and applied normal loads in order to measure the friction forces and wear volumes. Also, the conventional sliding tests of pin-en-disk type were carried out to compare the test results. In fretting, the friction was very sensitive to the load and the amplitude. The friction coefficient decreased with increasing load and decreasing amplitude. Also, the wear of Inconel 690 can be predictable using the work rate model. Depending on normal loads and vibrating amplitudes, distinctively different wear mechanisms and of ten drastically different wear rates can occur. It was fecund that the fretting wear coefficients in water were increased as increasing the temperature of water.

• Proceedings of the KSME Conference
• /
• 2000.11a
• /
• pp.665-670
• /
• 2000

The paper presents the dynamic instability of a disc brake pad subjected to distributed friction forces. A brake pad can be modeled as a beam with two translational springs. The study of this prototypical model is intended to provide a fundamental understanding of disc brake pad instabilities. Governing equations of motion are derived form energy expressions and their corresponding solutions are obtained by employing the finite element method. The critical distributed friction force and the instability regions are demonstrated by changing two translational spring constants. Finally, the changes of eigen-frequencies of a beam determining instability types are investigated for various combinations of two spring constants.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.8 no.3
• /
• pp.21-26
• /
• 2011

Nonlinear seal friction in pneumatic cylinders can impede the performance of pneumatic systems designed for high precision positioning with favorable high speed actuation. The behaviour of an elastomeric piston seals in high speed pneumatic cylinders is analyzed by nonlinear finite element analysis using ABAQUS. The contact pressures, stress and strain distributions and frictional forces of the squeeze type piston seal are simulated with variation of the seal radial installed interference, the operating pressures, friction coefficients and piston rod velocities. The nonlinear finite element model of the squeeze type piston seal is used to predict deformation of a seal, friction force and contact pressure distributions.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.6
• /
• pp.190-196
• /
• 1999

In this study, a procedure for analyzing chip-tool friction and shear processes in 3-D cutting with a single point tool has been established. The edge of a single point tool including circular nose is modified to the equivalent straight edge, then 3-D cutting with a single point tool is reduced to equivalent oblique cutting. Transforming the conventional coordinate systems and using the measured three component of cutting forces, force components on the rake face and the shear plane of the equivalent oblique cutting system can be obtained. And it can be possible to assess the chip-tool friction and shear characteristics in 3-D cutting with a single point tool.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.2
• /
• pp.112-119
• /
• 2004

This paper discussed on the effect of an internal damping on the stability of an elastic material subjected to dry friction force. Dry friction forces act tangentially at the contact surface between a moving belt and elastic material. The elastic material on a belt moving is modeled for simplicity into a cantilevered beam subjected to distributed follower force. In the analysis, the discretized equations derived according to finite element method are used. The impulse response of the beam are studied by the mode superposition method to observe the growth rate of the motion. It is found that the internal damping in cantilevered beam subjected to distributed follower force may act destabilizing.