Tham khảo tài liệu 'simulating fatigue cracks growth in spiral bevel gears part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | represented by a single point the crack tip. At a crack tip there are only two modes of displacement in three dimensional models however there is a distribution of three modes of displacement along the crack front. Propagating a crack in two dimensions is completely defined by a single angle and extension length. On the other hand along the crack front there is a distribution of angles and lengths. Codes developed by the Cornell Fracture Group at Cornell University such as Object Solid Modeler OSM and FRacture ANalysis Code - 3D FRANC3D have been developed to handle three dimensional fracture problems. FRANC3D explicitly models cracks and predicts crack trajectories under static loads. The crack growth models are based on accepted fatigue crack growth and linear elastic fracture mechanics LEFM mixed mode theories. Because gears operate at high loading frequencies the actual time from crack initiation to failure is limited. As a result crack trajectories and preventing catastrophic failure modes are the primary concern in gear design. Crack growth rates are not as important. The goal of this research is to investigate issues related to predicting three dimensional fatigue crack growth in spiral bevel gears. A simulation that allows for arbitrarily shaped curved crack fronts and crack trajectories will be most accurate. In addition the loading on a tooth as a function of time position and magnitude should be considered. Numerical Analyses of Gears Computational fracture mechanics applied to gear design is a relatively novel research area. As a result the majority of work has been limited to two dimensional analyses. In three dimensions very little work has predicted crack trajectories in gears. This section summarizes some pertinent developments in applying numerical methods and fracture mechanics to gear design. The complexity of two dimensional gear analyses has evolved. Albrecht 1988 used the FEM to investigate gear tooth stresses gear resonance and .
