Finite Element Analysis Of Tooth Root Bending Stress Based On Real Rough Surface

The finite element analysis of the gear transmission is based on the two gears mesh direct contact. It has some differences with the actual working condition of the gear transmission. First of all, most of the gear drive are working under a lubrication condition, besides the gear tooth surface is absolutely uneven. And that is to say, the lubricating oil film will share the contact loading with the direct impact of tooth surface. And it is should be comprehensive considered that the lubricating oil film and tooth surface roughness make a great contribution to the influence of the gear bending fatigue strength.In the first place,in this paper the roughness contourgraph compaction is used to test pieces of the surface roughness, and then using the Fourier transform method to obtain the roughness function,which will be overlay into a film thickness equation. On the other hand, gear parametric modeling is established with the Pro/E which is imported into the ANSYS through the data interface, and then established the gear finite element model by putting the rough tooth surface oil film pressure as an add-in to calculate3examples of middle loading geared condition. So the tooth root biggest bending stress is obtained by5special meshing points along the meshing line. On this basis, putting hertz pressure as an add-in to calculate3examples of the tooth root bending stress, and comparing the two calculations with the theoretical calculation of tooth root bending stress value. Summarize the research results in this paper, the research conclusions are as follows:1. Established the gear finite element model by putting the rough tooth surface oil film pressure as an add-in. By practical calculation we will know that tooth root bending stress along the meshing line show we a trend of decrease after the first increase; in addition to the meshes into point, tooth root stress of the other special meshing points is greater than the pressure side by side; The maximum tooth root bending stress is being in the critical point of single tooth meshing change into the double. So this special mesh point should be regard as a dangerous point to check calculation when setting about the gear design.2. The maximum tooth root bending stress significantly is less than the load of oil film pressure analysis results, which is calculated by the means of the Hertz stress loading gear finite element model set up as a comparison.3. It is the maximum when according to the involute cylindrical gear bearing capacity calculation of the national standard (GB3840-1997) as a benchmark calculation of numerical value. That is to say, the traditional theory calculation is running with larger room. And it is much more safe to design and check with the traditional theory. 4. The finite element model is more in line with the actual working condition, and the calculation results are more accurate, also the analysis of gear bending fatigue strength calculation has certain model function, for that regarding real rough tooth surface oil film pressure as an add-in to establish finite element model considers the effects of roughness and the gear lubrication effect in the process of transmission of gear comprehensive effectThe innovation in this paper is that the lubricating oil film and tooth surface roughness make a great contribution to the influence of the gear bending fatigue strength by the finite element method.The shortcoming laying in this paper is that the differences is still existence, which is between the loading of the finite element model and the gear mesh of the pressure distributions of the actual contact area.