Gearbox housing geometry and oil guide plates strongly influence gearbox oil flow and interaction of oil with machine elements. Guided oil flow can increase gearbox efficiency and improve heat management. Recent research studies have demonstrated the potential of Computational Fluid Dynamics (CFD) simulations to predict the gearbox oil flow and no-load losses. Thereby, the influence of housing geometry and guide plates has rarely been addressed. This study focuses on a CFD analysis on the oil flow of a dip lubricated spur gear stage with a guide plate. Grid-based CFD models with different simulation setups were confronted and evaluated. Results show that the selection of the simulation setup with respect to the acceleration ramp and mesh size needs to address the considered object of investigation and the desired depth of information. An appropriate simulation setup shows great accordance with recordings of the oil distribution by a high-speed camera. A detailed analysis of the simulation results identified the contribution of different gear surface zones to the no-load gear loss torque. For the considered guide plate a strong interaction of oil flow and loss torque due to pressure forces on the tooth flank surface zones and due to shear forces on the front and tip circle surface zones of the gears was determined.

Bone grafts are widely used in skeletal reconstruction subsequent to tumor surgery, traumatic injuries, or in conjunction with a total joint procedure. As the graft site may be subjected to destabilizing mechanical forces, any motion at the interface between graft and the host tissue may impede or prevent healing. The application and the maintenance of the compression between screw threads and the bone is the most important factor in attaining rigid internal fixation by means of screws or screws & plates. This study is designed to assess various allograft fixation options with the intent of finding an option that is secure yet does minimal damage to the allograft. Utilizing computational modeling and analysis (SolidWorks), we compared the bending stiffness for diaphyseal bone constructs with a gap and stabilized with a dynamic compression plate, with screws placed in a unicortical or bicortical manner, with and without intramedullary PMMA. The model was validated by comparing the simulation results with the experimental results from literature for two unicortical screws application with PMMA in bending test. The study was then exteneded by looking at the stress distribution across the plates with the use of bicortical and unicortical screws with and without PMMA. For unicortical screws the use of PMMA reduces the displacement by 4:65% and reduces the stress by 5:69%. For bicortical screws, the use of PMMA reduces the displacement by 1:78% and reduces the stress by 9:45%. The bicortical screws with PMMA has a displacement which is 0:74% smaller but a stress which is 0:73% higher when compared to the unicortical screws with PMMA. From the results of total displacement and maximum stress on the plate, conclusion can be drawn that the two best arrangements are the use of unicortical screws with PMMA and bicortical screws with PMMA, thus allowing the use of fewer screws.

The circular layout and the kinematics of planetary gearboxes result in characteristic oil flow phenomena. The goal of this paper is to apply a new remeshing strategy, based on the finite volume method, on the numerical analysis of a planetary gearbox and its evaluation of results as well as its validation. The numerical results are compared with experimental data acquired on the underlying test rig with high-speed camera recordings. By use of a transparent housing cover, the optical access in the front region of the gearbox is enabled. Different speeds of the planet carrier and immersion depths are considered. A proper domain partitioning and a specifically suited mesh-handling strategy provide a highly efficient numerical model. The open-source software OpenFOAM® is used.

Power losses in gearboxes result in frictional heating. Sufficient heat transfer from the gearbox to the environment is required for reliable operation. The heat dissipation from gears is linked to their interaction with fluids in the gearbox. Recent research has demonstrated the use of Computational Fluid Dynamics (CFD) to predict the gearbox fluid flow and no-load losses in an isothermal manner. This study focuses on a numerical analysis of the heat dissipation within a dry-lubricated gearbox under atmospheric conditions. Spur gears and helical gears are investigated. The air flow in the gearbox as well as the heat dissipation over the gear surfaces are evaluated in detail. The results show that the gear geometry and the circumferential speed have a strong impact on the air flow. Especially, the axial inflow of air to the gears has a great influence on the heat dissipation. Conveying effects of helical gears lead to a multidirectional airflow, resulting in higher values of the heat transfer coefficient on the gear surface compared to spur gears.