Faculty Of Engineering 3 r d Y ear Time : 3 hours Mechanical Engineering Department 5/2/2016 2 nd Term Design of Machine Elements I FINAL EXAM Questions: Answer only tree !uestions Poin ts Q F igure P! sho "s a port ion of a hi gh#pressure $oil er accumula tor ha%ing &a t he ad ' Th e en d plates are a()ed us in g a num$ er of $ol ts of M 16 × 2−UNC ! grade *'+! "ith rolled threads' ,i%en: S e =100 Mpa ! e)ternal load P varie s ¿ 0 ¿ 12 kips bolts -and k p =5 k b "here the connection is permanent' Determine: I' The factor of safety n of the $olt against fati gue failure "ith and "ithout preload' II ' The lo ad factor ns against .oint separation' /0 Q/ a1 2 ri% et ed .oint is under an incli ned eccentric lo ad P! as indic ated in Fig'P/#a' alculate the ma)imum shear stress in the #in diameter ri%ets' 0 $1 2 steel side plate is to $e "elded to a %ertical steel column according to th e speci4cations in F ig'P/#$' 5egl ecting stress concentrat ions e6ects! calcula te the magnitude and cl ear ly indicate the direction of the resultant shearing stress at the critical point' In selecting the critical point is sure to consider e6ects of $oth torsion#li7e shear and direct shear' 0 Q3 2 helica l#coil spr ing "ith plain en ds a nd grou nd i s to $e used as a return spring on the cam#dri%en %al%e mechanism sho"n in Fig'P3' The '*0#in diameter rod must pass freely t hrough the s pring' The cam eccentricity is 0'8* inch 9the total str o7e is '*0 inches1' The height of the compressed spring "hen the cam is at the head#end#dead#center 9ED1 position is ;'8* in as sho"n' The spring must e) ert a force of 300 l$ "hen at the ED position sho"n in the s7etch! and must e)ert a force of *0 l$ "hen the cran7#end#dead#center 9ED1 at the $ottom of the stro 7e' That is! the spring is preloaded into the machine' The spring is to $e made of a patented spring steel "ire that has a /00!000#psi ultimate tensile strength! <0!000#psi tension yield strength! and <0!000#psi f atigue endurance limit' =ased on in4nite life design a safety factor of '/* and Spri ng inde x, C =8 are desired' Determine the follo"ing: ' Mean coil r adius ! > ! /' ?ir e d iameter! d! /0 Of / " Page