POWER TRANSMISSION ELEMENTS AND MECHANISMS 



167 



STRESS IN A ROTATING DISK 



o\ 



\^ 



13 4 



l l lllll I I I 



10 15 20 



Maximum +angen+ial stress I'n a thin rotating 

 disk IS given by the relation 



S= 71wN^x lO'^ [C3+m)R^+(l-m)r^] 



Rand r are radii in in. 



N= angular velocity in 1,000 r.p.m. 



m= Poisson's ratio for the moten'al 



w= density in lb. per cu.in. 



S= maximum tangential stress in 100,000 lb. per sq.in. 



(if R exceeds 10 use light face scales for R^randN) 



(L i i I I 1 1 II 1 1 I I II I II II I II I I I I I I I I II I I I II I I I I I I I 1 1 1 1 



N 

 50—1—10 



45 



40 

 10 



R -- 



215 

 I 



50 35 



Outside Radius^ R 



40 



45 



50 

 35 



,5" 1 



Q. 



o 

 o 

 o 



2 — 



tn 



c 







I— 



3 — 



■1^ 



Dotted lines show that for R=5, r = l and m= 0.35, 

 v\/ith w=0.4, a disk rotating 30,000 r.p.m. will be 

 subject too maximum tangential stress of 

 214,000 lb. persq.in. 



■ir 



Density w in Lb. per Cu. In. -<,^ 



0.15 0.2 0.>^ 0.4 0.5 0.60? 



■ ■ ■ lLlU 



"Copper 



-Steel 



~ Cast iron 



Q. 



ai 



o 



o 



.c 



-1-7 g 



•4- L 



D 



01 



=6^ 



inside Radius, r 



