Comparative analysis of root bending strength calculation for spiral bevel gears based on HB,ISO standard and AGMA standard

WANG Qiuju; WEI Jing; CHEN Siyu; XING Bin; SONG Zhenhai; TAN Yuxin

doi:10.16578/j.issn.1004.2539.2026.03.002

Abstract：[Objective]Addressing the issue of difference in the evaluation of tooth root bending strength for spiral bevel gears based on the strength verification benchmarks in Aviation Industry Standard of China(HB for short),International Organization for Standardization(ISO)standard,and American Gear Manufacturers Association(AGMA)standard,a comparative analysis was conducted to derive the optimal strategy for the design of spiral bevel gear.[Methods]Firstly,based on the foundational mathematical models of each standard,the essential differences among the three standards were analyzed.Secondly,the influence parameters and their corresponding influence mechanisms of bending stress and strength safety factors obtained from the three standards were investigated from a theoretical perspective.Finally,through case analysis,the influence law of stress results and differences in strength calculation results obtained from the three standards were further explored.[Results]The results show that ISO standard and HB use the 30° tangent method to determine the dangerous section and select the load point at the top of the tooth for calculation,while AGMA standard uses the parabolic method to determine the dangerous section and select the load point at the dangerous points for calculation.Compared with the 30° tangent method,the chord tooth thickness and bending moment arm obtained by the parabola method are more accurate,so the tooth form coefficient and stress correction coefficient obtained by the two methods are slightly different.According to the correction coefficients and their corresponding calculation formula,because the geometric coefficient YJ in AGMA standard replaces multiple correction coefficients in HB and ISO standard,the AGMA standard has the most concise calculation process and introduces the least number of correction coefficients.According to the correction coefficients and stress calculation results,the stress results of ISO standard are larger than those of HB and much larger than those of AGMA standard.The values of the tooth form coefficient,load sharing coefficient and coincidence coefficient in ISO standard are similar to those of HB,while the values of dynamic load coefficient,stress correction coefficient and helix load distribution coefficient are significantly different from those of HB and AGMA standard.According to the variation law of bending stresses obtained from the three standards,the parameters such as tooth number,modulus,spiral angle,pressure angle,tooth width and design speed have great influence on the bending stress.