Effect of the load location along the involute curve of spur gears on the applied stress at the fillet radius

Abstract

In this study, attempts are carried out to determine the amount of stress at the fillet radius region of spur gears when the applied load location changes, along the involute curve, from the top surface to the bottom. For this purpose the photoelastic method and numerical MSC/NASTRAN software are used. The gears with pressure angle (f) 20 o , and 25 o were prepared from photoelastic material type PLM-4B in this study. Practical calibration is used to determine the fringe order value of this material. Four different modules (m); 6, 10, 14, and 20 mm were prepared for two different numbers of teeth (N); 18 and 26, with different face widths (B 1 , B 2 , B 3 ); 10, 17, 25.4 mm respectively. Four load values were applied on each tooth at five to six different load locations along the involutes curve profile. In order to accomplish the comparison between the results for different methods, the same sample dimensions and parameters were prepared again for the MSC/NASTRAN software.The results showed that the maximum applied stress at the fillet radius occur when the applied load location is on the top land of a tooth, and then that amount is decreased when the applied load positions change toward the bottom land. The results of the NAS-TRAN method showed that the applied stress at the fillet radius would be minimum when the loading point locates between the pitch circle and dedendum circle, in particular around 1.5 times module (1.5 m) of the total tooth height which equals 2.25 module, and then the applied stresses are increased again. However, in the photoelastic method the applied stresses were decreased continuously to the bottom land. The reasons behind such results can be attributed to the type of failure theories that can be used in NAS-TRAN software for characterization the applied stresses, i.e. considering types of applied stresses into account, such as bending, direct compressive, and shear stresses. Moreover, in order to compare the applied stress values at fillet regions, obtained by theoretical and practical approaches, four different standard mathematical equations are used for stress calculation at fillet radius of spur gears to show the difference of the parameters and variables that can affect the applied stress results.

Generalised non-dimensional multi-parametric involute spur gear design model considering manufacturability and geometrical compatibility

“…for the influence of module [7,13], addendum [14][15][16][17][18][19][20][21][22], profile modification [23][24][25][26][27][28][29] tooth thickness [30][31][32][33][34][35][36], dedendum [37][38][39][40][41][42], cutter tip radius [43][44][45][46], pressure angle [47][48][49][50][51][52][53][54], etc, but without considering the simultaneous manipulation of other design parameters as well, typically assigning standard values to the latter. Additionally, many researchers have investigated the influences of each design parameter for different applications such as contact analysis [55][56][57][58][59]…”

The pressure angle effects of spur gears on stress concentration factor

“…Previously published works (Khoshnaw and Ahmed, 2006, 2008) discussed the effect of gear specifications, such as m , B and N , for pressure angle φ = 20, on K t values. In this study, the effect of other parameters such as φ and critical geometric ( h and t ) on K t is investigated.…”

“…For each φ, four different modules; m 1 = 6, m 2 = 10, m 3 = 14, and m 4 = 20 mm, three different face widths B 1 = 10, B 2 = 17 and B 3 = 25.4 mm, and one number of teeth N = 18 were prepared. According to AGMA standard, the angle of actions θ for each θ has been calculated as below (Khoshnaw and Ahmed, 2006, 2008).…”

“…Since gears do not have uniform shape like beams and shafts, determination of their stress concentration factor ( K t ) is a difficult task. Moreover, since there are many parameters, such as φ, m, face width ( B ), number of teeth ( N ), etc, that affect K t values, there is no commonly known equation or diagram that can be used to calculate K t (Khoshnaw and Ahmed, 2006, 2008; Senthilvelan and Gnanamoorthy, 2006; Litvin et al , 2002; Pedrero et al , 2000).…”

Determination of the ISO face load factor in spur gear drives by the finite element modeling of gears and shafts

“…Atanasovska [10] proposed a finite element model to calculate the face load factor, and studied several causes that produce variations in the load capacity of a gear, like mesh stiffness [11], the addendum coefficient [12], or the nominal transmitted load [13]. Others have contributed investigating how the load is distributed over the gear face width [14,15], and have studied numerically, analytically, or empirically, the elastic deformations of the gear teeth [16,17] and the effect of manufacturing and assembly deviations [18,19]. There are fewer authors that have studied the elastic deformations of the shafts that support the gears [20,21], and how their mechanical behavior affects to the gear load capacity.…”