In this paper, an analytical investigation is made of the frictional damping properties of axially loaded metallic cables made from one layer of wires helically wrapped around a central wire. Our efforts are focused on the quantity of energy dissipated through friction due to the motions between wires when a cable is loaded. Although the local interwire pivoting drives the response of the cables studied, a first linear model is built where pivoting is allowed, but friction is not taken into account. Then, a law of friction is established and linearized to extend the linear model into a tractable piecewise linear hysteretic one. Through a variety of examples, it appears that the energy dissipated in friction over a load cycle is very small compared to other sources of dissipation, because axially loaded simple straight strands do not experience fretting-induced failures, except close to terminations. It is also shown that modifying the design of such cables is not expected to significantly improve their damping properties.
Purpose: The aim of this study was to determine stress levels on supporting structures of implant-retained overdentures as a function of varying degrees of palatal coverage using finite element analysis modeling at different loading angles. Materials and Methods: ABAQUS®-software was used to perform finite element analysis on eight overdenture models with three and four implants and with and without palatal coverage designs. Loads were applied perpendicular and 45º to the implants. Von Mises stress was measured to determine bone stress. A one-way ANOVA determined which model caused the most stress to the maxillary bone. Results: Palatal coverage increased stress to anterior implant in three implant (p = 0.08) models but decreased stress to all implants in four implant models (p = 0.43). Distal implants received more stress than anterior implants for all models. There was no significant difference between a full palate and no palate coverage overdenture prosthesis when a bar was added under axial loading (p = 0.954). Under non-axial loading, a decrease in stress was noted with the bar in all areas except the anterior implant site. Conclusions: Palatal coverage may not be necessary when applying a pure axial load. The addition of a bar decreased stress at loading.
The frictional damping properties of axially loaded simple straight wire rope strands are studied using an analytical model for cables of current design. Since the cable axial response is driven by the interwire local pivoting, a first linear model is built in which pivoting occurs without friction. A hysteretic model is then built after a specific law of friction is established. Using comparisons with experimental results described in the literature, the frictional energy dissipated over a load cycle is shown to be very small compared to the elastic strain energy and other dissipations. This result is in agreement with the experimental fact that axially loaded simple straight strands do not experience fretting-induced failures, except when they are close to the terminations.
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