On the Strength Calculation of Shaft Bracket

Abstract

Mr. A. W. Johns states in the T. I. N. A. of 1907 that stress induced by centrifugal force T originating in unbalance of propeller is greatest and gives the value of the maximum bending moment at that time, but in this paper, the value of the bending moment is scrutinized a little further, and farthermore, the value of the twisting moment, shearing force, and normal force is examind. If the various dimensions are taken as given in the annexed figures. In ordinary ships l2 is severa times or more than l1 or 1, and L is several times or more larger than a. Furthermore, granting that conditions is between about 50 degrees and 90 degrees are generally substantiated, at such times, the stress due to twisting moment, shearing force, and normal force are negligibly small in comparnson to the stress due to bending moment. When T indicates certain direction the bending moment enlarges at the barrel part, but when the direction a changes it enlarges at the root. However its maximum value is induced in the barrel edge of the bracket, and its value, MI, is determined by the following formula;MI=-Tlc1cosα/(1+Kc2c)sinθwhereK=E0I0L/EI1lc1=3ll12+6ll22+12ll1l2+4l12l2+3l1l22/2ll2(4l1+3l2)c2=6l(l1+2l2)/l2(4l1+3l2)c=1/8sin2θ{5cos2(0-α)-6cosα×cos(θ-α)+5cos2α}E0 & I0…Young's modulus of shaft &moment of inertia of the section.E & I1… … shaft bracket & _??_.L, l, l1, l2, α, θ & α…the values givenin the annexed figures.Value of α in the aforementioned formula is determined by the following formula;Ncos2α/sinα=1/sin(θ-α)whereN=2(3-5cosθ)/(8/Kc2+5sin2θ