In this study, a transient, non-Newtonian, mixed elastohydrodynamic lubrication (EHL) model of involute spur gear tooth contacts is proposed. Unlike the contact between two cylindrical rollers, spur gear contacts experience a number of time-varying contact parameters including the normal load, radii of curvature, surface velocities, and slide-toroll ratio. The proposed EHL model is designed to ...

PURPOSE This study examined the factors that can be associated with the appearance of the interproximal papilla. METHODS One hundred and forty-seven healthy interproximal papillae between the maxillary central incisors were examined. For each subject, a digital photograph and periapical radiograph of the interdental embrasure were taken using a 1-mm grid metal piece. The following parameters ...

Study background: Bolton Index is one of the most commonly used analysis in order to evaluate tooth-size discrepancy. Even if this measure could represent an important tool in clinical practice, many Authors questioned its widespread applicability. The aim of this study was to compare the anterior and total tooth width ratios of an orthodontic population with the Bolton standards and analyse di...

Gearboxes sustain a variety of faults such as broken-shafts, eroded, broken, or missing teeth, and even broken-cases. Casing mounted accelerometers can detect fault patterns but the signals are complicated and difficult to interpret. This study considers the tooth loading of ideal gears and gears with defects. A large industrial gearbox used in a 12m electric mining shovel is modeled. The nonli...

This paper presents results of experimental research on the acoustic properties of gear wheels with high-profile teeth with differentiated tooth height. Those results showed that gear transmissions with high-profile teeth have the best acoustic properties, with the value of the transverse contact ratio εα ≈ 2.0. They also showed that a reduction in tooth height, and thereby in contact ratio, in...

This study demonstrates the early transient dynamic loading on teeth within a fixed-axis gear transmission arising from backlash and geometric manufacturing errors by utilizing a non-linear multi-body dynamics software model. Selection of the non-linear contact parameters such as the stiffness, force exponent, damping, and friction coefficients are presented for a practical transmission. Backla...

Adhesive forces are capable of deforming a soft elastic object when it comes in contact with a flat rigid substrate. The contact is in stable equilibrium if the total energy of the system arising from the elastic and surface forces exhibits a minimum at a zero or at a slightly negative load. However, as the system is continually unloaded, the energy barrier decreases and it eventually disappear...

PURPOSE With the increasing popularity and publication of loading implants at the time of placement, including at time of dental extraction and simultaneous with reconstructive procedures, the objective was to evaluate known variables identified for a traditional unloaded healing period and determine the applicability of these variables to immediate loading. MATERIALS A total of 124 published...

A new Dipterus−like lungfish, Harajicadipterus youngi, is described from the Givetian (Middle Devonian) Harajica Sand− stone Member of central Australia. The material is comprised of five specimens representing the skull roof, orbital bones, tooth plates, operculo−gular bones, a partial pectoral girdle, centra and scales. Harajicadipterus can be distinguished from other dipnoans by its long pos...