How to design a pin bushed flexible coupling?

@yadavundertaker mohit • 05 Oct, 2009 step 4

From bearing consideration

pb=F/(l*d3)
find l from above expression.

shear stress in pin t= (F*4)/(3.14*d1*d1)





step 5

Bending moment M = F*(l/2 + e)

select e suitably e= 3-5mm


section modulus Z =(3.14*d1*d1*d1)/32

bending stress = M/Z

@yadavundertaker mohit • 05 Oct, 2009

@raj87verma88 • 05 Oct, 2009 Good job.
Try to add some little theory also. That would make it complete.

@yadavundertaker mohit • 14 Oct, 2009 the C program for the above pin bushed coupling...


#include<stdio.h>
#include<conio.h>
#include<math.h>
#include<string.h>
float arr[20];
float *am(float d1,int d,float T,float pb,float n,float ta)
{
int d2,t1,t2,d3,e;
float a,d0,q,D1,k,F,l,ti,D2,D3,tp,z,M,c,qp,qb,w,t,l1;


/* Enlarged dia of pin */

d2=d1+2*3;
arr[0]=d2;

t1=2;
t2=6;
d3=d2+2*t1+2*t2;
arr[1]=d3;


/* STEP 3*/
D1=1.75*d;
D1 = abs(D1)+1;


/* check suitability of hub*/

k=d/D1;
k=pow(k,4);
ti=(16*T)/(3.14*D1*D1*D1);
ti=ti/(1-k);

if(ti<ta)
printf("\n\n\t");
else
D1=2*d;

arr[2]=D1;

/* PIN CIRCLE DIA*/
D2=3*d;
arr[3]=D2;

/* FORCE PER PIN*/

F=2*T/(D2*n);
arr[4]=F;

/* STEP 4*/

l=F/(pb*d3);
l=abs(l)+1;
arr[5]=l;


/* SHEAR STRESS IN PIN*/

tp=(4*F)/(3.14*d1*d1);
arr[6]=tp;

/* BENDING MOMENT
*/
e=4;
M=F*((l/2)+e);
arr[7]=M;


z=(3.14*d1*d1*d1)/32;

arr[8]=z;
qb=M/z;
arr[9]=qb;
/* PRINCIPAL STRESS IN PIN*/

c=(qb*qb)+4*(tp*tp);
qp=.5*(qb+sqrt(c));


/* KEY DIMENSIONS*/

w=d/4;
w=abs(w)+1;
t=d/6;
t=abs(t)+1;
l1=1.5*d;
l1=abs(l1)+1;
printf("\n\n\t principle stress in pin =\t%fN/mm2",qp);
arr[10]=qp;
printf("\n\n\t n=%f",n);
printf("\n\n\t d1=\%fmm",d1);
printf("\n\n\t D1=\%fmm",D1);
printf("\n\n\t ti=\t%fN/mm2",ti);
printf("\n\n\t Hub is safe");
printf("\n\n\t d2=%dmm",d2);
printf("\n\n\t d3=\t%dmm",d3);
printf("\n\n\t D2=\t%f",D2);
printf("\n\n\t Force per pin =\%fN",F);
printf("\n\n\t l=\%fmm",l);
printf("\n\n\t shear stress in pin =\t%fN/mm2",tp);
printf("\n\n\t bending moment =\t%fN-mm",M);
printf("\n\n\t section modulus =\t%fmm3",z);
printf("\n\n\t STRESS =\t%fN/mm2",qb);
printf("\n\n\t width of key =%fmm",w);
printf("\n\n\t thickness of key =\t%fmm",t);
printf("\n\n\t length of key =\t%fmm",l1);
printf("\n\n\n");
return arr;

}
main()
{
clrscr();
float farr[20];
int d,p,N,b,d2,t1,t2,d3,e,i;
float T,n,d1,a,d0,pb,ta,q,D1,k,F,l,ti,D2,D3,tp,z,M,c,qp,qb;
printf("\n\n\t\t DESIGN OF PIN BUSHED FLEXIBLE COUPLING");
printf("\n\n\n\t enter the dia of pipe to be joined in mm=\t");
scanf("%d",&d);
printf("\n\n\t enter the power to be transmitted in kw=\t");
scanf("%d",&p);
printf("\n\n\t enter the rpm of the shaft =\t");
scanf("%d",&N);
printf("\n\n\t enter the bearing pressure in N/mm2=\t");
scanf("%f",&pb);
printf("\n\n\t enter the allowable shear stress in shaft,keys ,flange =\t");
scanf("%f",&ta);
printf("\n\n\t enter the allowable stress in pin =\t");
scanf("%f",&q);

/* To find the torque*/
T=(p*60000)/(2*3.14*N);
T=(T*1000);
printf("\n\n\t torque produced =\t%fN-mm",T);

/* Suitability of shaft dia*/
a=(16*T)/(3.14*ta);
d0=pow(a,.33333);

d0=fabs(d0)+1;
if (d0<d)
{
d0=d;
printf("\n\n\t d0=%fmm",d0);
}
else
printf("\n\n\t Dia is not secure");

/* No. of pins */
n=(0.02*d)+5;
if(abs(n)-n==0)
i=abs(n);
else
{
n=abs(n)+1;
i=abs(n)+1;
}
if(i%2==0)
n=n;
else
n=n+1;
printf("\n\n\t no. of pins =\t%f",n);

/* Pin dia*/
d1=(0.5*d)/sqrt(n);
b=abs(d1)+1;
d1=abs(d1)+1;
if(b<10)
printf("\n\n\t The value of d1 is =\t%fmm",d1);
else {
if(b%2==0)
printf("\n\n\t The value of d1 is =\t%fmm",d1);
else
{
d1=d1+1;
printf("\n\n\t The value of d1 is =\t%dmm",d1);

}
}
qp=0;

//farr[20] = am(d1,d,T,pb,n,ta);
memcpy(farr,am(d1,d,T,pb,n,ta),sizeof(am(d1,d,T,pb,n,ta)));
if (arr[10] > q)
{
for(int i=0;arr[10]>q;i++)
{
printf("\n\n*********************************************************");
printf("\n\n*********************************************************");
printf("\n\n\t ITERATION NO.%d",i+1);
d1=d1+2;
memcpy(farr,am(d1,d,T,pb,n,ta),sizeof(am(d1,d,T,pb,n,ta)));

}
}
getch();
return 0;
}