Contemporary philippine arts from the regions_PPT_Module_12 [Autosaved] (1).pptx
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Instantaneous Centre of Rotation (ICR) Analysis and Velocity Calculation of a 6-Bar Mechanism
1. Theory of Machines-I
Velocity and Acceleration Analysis of Mechanisms
Numerical:- Instantaneous Centre of Rotation (ICR)
Prof. K N Wakchaure
Department of Mechanical Engineering
Sanjivani College of Engineering, Kopargaon
2. Problem Statement
β’ A 6bar mechanism, as shown in Fig. 6, has the following dimensions: OA = 200
mm; AB = 1.5 m; BC = 600 mm; CD = 500 mm and BE = 400 mm, OE=1.35m.
Locate all the instantaneous centres. If crank OA rotates uniformly at 120 r.p.m.
clockwise, find 1. the velocity of B, C and D, 2. the angular velocity of the links
AB, BC and CD.
3. Procedure to Solve Numericals
Step-1:-Read the problem statement Carefully.
Step-2:-Draw the given Mechanism with Suitable Scale.
SCALE 1:8Given:ππ=120 rpm
π π =
2 β π β ππ
60
= ππ. ππ πππ/π
4. Basics of ICR
Scale 1:8
Step-3:-Give the numbers to the link in the mechanism starting with fixed LINK.
5. Step-5:-Draw the table of Instantaneous centres.
1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
Step-6:-Locate Fixed and Permanent ICR.
I16@κ
Step-4:-Find No. of ICR using Formula: N=
πβ(πβπ)
π
n=6
N=15 (no. of ICR)
Step-7:-Circle/ highlight the known ICR in the table..
6. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
I16@κ
Step-8:-Draw one circle (Kennedyβs Circle) of Arbitrary diameter, divide it βnβ
number of Parts.
n= No of Links in the Mechanism here n=6
7. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
I16@κ
Step-9:- Join the points in Kennedyβs circle for known ICR
8. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
I12 Iππ
Iππ I34
I24
Join ICR I14 and I12 and extend line
Join ICR I23 and I34 and extend line
I16@κ
Step-10:- Use Kennedyβs theorem to locate Remaining ICR
Consider Quad. 1-2-3-4
At the intersection locate I24
9. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
I12 Iππ
Iππ I34
I13
Join ICR I12 at I23 and extend line
Join ICR I14 and I34 and extend line
I16@κ
Step-10:- Use Kennedyβs theorem to locate Remaining ICR
Consider Quad. 1-2-3-4
At the intersection locate I13
10. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
I1π Iππ
Iππ Iππ
I15
Join ICR I14 and I45 and extend line
Join ICR I16 and I56 and extend line
Step-10:- Use Kennedyβs theorem to locate Remaining ICR
Consider Quad. 1-4-5-6
At the intersection locate I15
11. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
I1π Iππ
Iππ Iππ
I46
Move ICR I16 at I14 and extend line
Join ICR I45 and I56 and extend line
Step-10:- Use Kennedyβs theorem to locate Remaining ICR
Consider Quad. 1-4-5-6
At the intersection locate I46
12. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
I1π Iππ
Iππ Iππ
I26
Move ICR I16 at I12 and extend line
Join ICR I24 and I46 and extend line
Step-10:- Use Kennedyβs theorem to locate Remaining ICR
Consider Quad. 1-2-4-6
At the intersection locate I26
13. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
I1π Iππ
Iππ Iππ
I25
Join ICR I12 at I15 and extend line
Join ICR I24 and I45 and extend line
Step-10:- Use Kennedyβs theorem to locate Remaining ICR
Consider Quad. 1-2-4-5
At the intersection locate I25
14. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
I1π Iππ
Iππ Iππ
I36
Move ICR I16 at I13 and extend line
Join ICR I34 and I46 and extend line
Step-10:- Use Kennedyβs theorem to locate Remaining ICR
Consider Quad. 1-3-4-6
At the intersection locate I36
15. 1 2 3 4 5 6
I12 I23 I34 I45 I56
I13 I24 I35 I46
I14 I25 I36
I15 I26
I16
Iππ Iππ
Iππ Iππ
I35
Join ICR I36 at I65 and extend line
Join ICR I34 and I45 and extend line
Step-10:- Use Kennedyβs theorem to locate Remaining ICR
Consider Quad. 1-3-5-6
At the intersection locate I35
16. Procedure to Solve Numericals
Step-11:- Find Velocity and Angular Velocity
Use Angular Velocity Ratio
Find the angular velocity of link y when angular velocity of link x
is known to us
π π
π π
=
π°ππ β π°ππ
π°ππ β π°ππ
angular velocity of link 3 when angular
velocity of link 2 is known
π3
π2
=
πΌ12 β πΌ23
πΌ13 β πΌ23
π2
18. Procedure to Solve Numericals
Step-12:- Find Velocity and Angular Velocity
Velocity of any point the mechanism
Velocity of any point P which is on link Q
Then ππ = (πΌ1π β π)Xπ π*S.F
Velocity of any point B which is on link 3
Then ππ΅ = (πΌ13. π΅)Xπ3*S.F
Velocity of any point B which is on link 4
Then ππ΅ = (πΌ14. π΅)Xπ4*S.F
Velocity of any point C which is on link 4
Then ππΆ = (πΌ14. πΆ)Xπ4*S.F
Velocity of any point D which is on link 5
Then ππ· = (πΌ15. π·)Xπ5*S.F
S.F=8
19. Procedure to Solve Numericals
Step-12:- Find Velocity and Angular Velocity
Velocity of slider in the mechanism
π2
In this case velocity of slider(link 6) is the velocity of point
D(Point at the joint of link 5 and link 6).
By considering point D is on link 5
Then π6 = ππ· = (πΌ15. π·)Xπ5*S.F
ππ΅ =3.444m/sec
ππΆ = 1.67m/sec
π6 = ππ·= 1.11m/sec