logging in or signing up UNIT 1 of I GSANJANA Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 4696 Category: Education License: All Rights Reserved Like it (18) Dislike it (0) Added: May 19, 2009 This Presentation is Public Favorites: 7 Presentation Description No description available. Comments Posting comment... By: dadda0522 (3 week(s) ago) hey xelent one ......plz aalow me to download or send it to jhansi990@yahoo.in thank you Saving..... Post Reply Close Saving..... Edit Comment Close By: leenamahesh (3 month(s) ago) sir wonder ppt can you send all ppt to mbd_gdg @yahoo.co.in thanking you Saving..... Post Reply Close Saving..... Edit Comment Close By: sachin1983 (4 month(s) ago) good presentation.please send me shindesms1983@gmail.com Saving..... Post Reply Close Saving..... Edit Comment Close By: HARRY111 (7 month(s) ago) nice.......please allow to download jatharlal16@gmail.com Saving..... Post Reply Close Saving..... Edit Comment Close By: poornibhavani (10 month(s) ago) nice ppt..............can u snd me on my id .........kkspoornimasundar@gmail.com Saving..... Post Reply Close Saving..... Edit Comment Close loading.... See all Premium member Presentation Transcript Slide 1: UNIT : I Definitions: Links, Pairs, chain, Mechanism, structure, degree of freedom, Inversion of machines & inversion of 4 bar chains. Velocity and acceleration: Velocity and acceleration of simple mechanism by relative velocity method. Klein’s construction for slider - crank chain. Analytical methods and solution for mechanisms. 1 UNIT I Slide 2: To move some heavy boxes into a moving truck B would be easier because a ramp is an inclined plane A B 2 UNIT I Slide 3: To move a heavy box a long distance A would be easier because the wagon has wheels and axels. A B 3 UNIT I Slide 4: To change a flat tire on the moving truck. A B B would be easier because a jack uses a screw. 4 UNIT I Simple Machines : Simple Machines 5 WEDGE PULLEY SCREW LEVER BY-CYCLE INCLINED PLANE UNIT I Slide 6: Inclined plane Wheel and axel Wedge Screw Pulley Inclined plane 6 UNIT I Slide 7: TERMINOLOGY STEAM ENGINE STEAM ENGINE – SPACE DIAGRAM FRAME 7 UNIT I Slide 8: A LINK is defined as a rigid body having two or more pairing elements which connect it to other bodies for the purpose of transmitting force or motion. Classification of Links: Binary Link 2. Ternary Link Quarternary Link Types of Links: Rigid Link - Eg.: Connecting rod and Crank Flexible Link –Eg.: Belts ,Ropes, Chains, Springs and bands etc. Fluid Link – Eg. Fluids in Hydraulics press, Lifts Floating Link – Not connected to the frame. – Eg.Pointer in a Clock 8 UNIT I Slide 9: Types of joints in a Chain Binary Joint 2. Ternary joint 3. Quaternary joint KINEMATIC PAIR is a joint between the surfaces of two rigid bodies that keeps them in contact and relatively movable. 9 UNIT I Slide 10: 10 Classification of Kinematic pairs: According to the type of contact(nature of contact between them) Lower pairs - Surface-contact , Eg. Nut and Bolt, Shaft in a bearing. higher pairs - Point-, line-, or curve-contact ,Eg. Belts,Ropes, Gears, Cam and follower. According to the nature of relative motion between them Sliding/Prismatic Pair (P) Turning /Pin /Revolute Pair (R) Cylindrical Pair (C) Screw /Helical Pair (S) Spherical /globular Pair (G) Flat/Planar Pair (F) According to nature of mechanical arrangement for constraining relative motion ( type of constraint) Closed /Self closed Pair – Eg. All lower pairs Open /Unclosed /Forced closed pair – Eg. Cam & follower, belt running on a pulley. UNIT I Slide 11: 11 UNIT I Slide 12: 12 UNIT I Slide 13: 13 UNIT I Higher Pairs Joints Slide 14: 14 UNIT I CONSTRAINED MOTION one element has got only one definite motion relative to the other (b) Successfully constrained motion (a) Completely constrained motion (c) Incompletely constrained motion Slide 15: MECHANISM: An assemblage of resistant bodies, connected by movable joints, to form a closed kinematic chain with one link fixed and having the purpose of transforming motion. – A/c to Reuleaux MACHINE: An assemblage of parts that transmit forces, motion and energy in a predetermined manner OR A combination of rigid or resistant bodies, so arranged that by their means the mechanical forces of nature can be compelled to do work accompanied by certain determinate motions. – A/c to Reuleaux The similarity between machines and mechanisms is that they are both combinations of rigid bodies the relative motion among the rigid bodies are definite. The difference between machine and mechanism is that machines transform energy to do work, while mechanisms so not necessarily perform this function. The term machinery generally means machines and mechanisms 15 UNIT I Slide 16: TYPES OF MECHANISMS Simple - 4 links Compound – more than 4 links Complex – ternary or higher order floating links Planar – all links lie in the same plane Spatial – links of a mechanism lie in different planes Equivalent – Turning pairs of plane mechanisms may be replaced by other types of pairs such as sliding pairs or cam pairs. The new mechanism thus obtained having the same no. of DOF as the original mechanism is known as equivalent mechanism. Ex. A turning pair can be replaced by a sliding pair. A spring can be replaced by two binary links 16 UNIT I Slide 17: TYPES OF MECHANISMS - diagrams 17 UNIT I Planar Mechanism Simple Mechanism Compound Mechanism Complex Mechanism Slide 18: 18 UNIT I Parallel robot Spatial Mechanism Slide 19: KINEMATIC CHAIN : An assembly of links in which the relative motion of links is possible and the motion of each link relative to the others is definite. The last link of the kinematic chain is attached to the first link. Relationships holds for a kinematic chain having lower pairs only: l = 2 p – 4 ---- (1) and j = (3/2) l – 2 ------(2) Where l = no. of links p = no. of pairs j = no. of joint If LHS > RHS, then the chain is locked / rigid / redundant structure. LHS = RHS, then the chain is constrained . LHS < RHS, then the chain is unconstrained. For a kinematic chain having higher pairs, each higher pair is taken as equivalent to two lower pairs and an additional link. 19 UNIT I Slide 20: A.W.Klein’s Criterion : A.W.Klein given a relationship beween no. of linka and no. of binary joints, in oredr to dtemine the nature of chain as follows: j + h / 2 = (3/2) l – 2 -------------(3) Where l = no. of links h = no. of higher pairs j = no. of binary joint If LHS > RHS, then the chain is locked / rigid / redundant structure. LHS = RHS, then the chain is constrained . LHS < RHS, then the chain is unconstrained. 20 UNIT I Slide 21: 21 UNIT I DEGREES OF FREEDOM (DOF): It is the number of independent coordinates required to describe the position of a body. Slide 22: DEGREE OF FREEDOM An unconstrained rigid body moving in space can have 3 translations and 3 rotational motions about three mutually perpendicular axes. The no.of degrees of freedom of a kinematic pair is defined as the no. of independent relative motions, both translational and rotational that a kinematic chain can have. DOF = 6 – number of restraints. DOF for Planar Mechanism: MOBILITY OF A MECHANISM : The mobility of a mechanism is defined as the number of degrees of freedom it possesses, or the minimum number of independent parameters required to specify the location of every link within a mechanism. The German literature distinguishes between movability and mobility. Movability includes the 6 dof of the device as a whole, as though the ground link were not fixed, and thus applies to a kinematic chain. Mobility neglects these and considers only the internal relative motions , thus applying to a mechanism. 22 UNIT I Slide 23: Kutzbach Criterion For Planar Mechanism: n = 3 ( l -1) – 2 j – h ------------------(1) For Spatial Mechanism: n = 6 (l -1) – 5p1 – 4p2 – 3p3 – 2p4 – 1p5 -------(2) Where n = no. degree of freedom l = no. of links j = no. of joints h = no. of higher pairs p1 = no. of pairs having one dof. p2 = no. of pairs having two dof. p3 = no. of pairs having three dof. and so on. 23 UNIT I Slide 24: Grubler’s Criterion For Planar Mechanism is obtained by substituting n=1 and h = 0 in the Kutzbach’s criterion. We get 3l – 2 j – 4 = 0 ------------------(3) So, it applies to mechanisms with only single dof joints and the overall mobility of the mechanism is unity. For Spatial Mechanism: If mechanism has all single dof pairs and overall mobility is of unity, then Kutzbach’s equation for spatial mechanism becomes i.e. n=1, p2=p3= - - - - p5 = 0 6l – 5p1 – 7 = 0 --------------------------(4) If n = 1 : the device is a mechanism with n dof n = 1 : the device is a statically determinate structure n < -1 : the device is a statically indeterminate structure 24 UNIT I Slide 25: INVERSION OF MACHANISMS 25 UNIT I Kinematic Inversion Process of fixing different links of a chain to create different mechanisms Relative motion between links does not change in different inversions Overall motion may change Changing frame (ground) changes same mechanism to different configurations of 4 Grashof mechanisms Slide 26: 26 UNIT I Grashof Law: Sum of shortest and longest links of a planar 4-bar linkage cannot be greater than the sum of the remaining 2 links if there is to be continuous relative motion between 2 links. i.e., at least one link can make a full revolution with respect to the ground plane Let l = longest link s = shortest link p, q = other two links Then the linkage is Grashof if The linkage is non-Grashof if the inequality is not true.No link can make a complete revolution relative to any other link. Slide 27: 27 UNIT I 4 possible mechanisms exist if Crank-rocker Shortest link is crank Double-crank (drag-link) Shortest link is frame Rocker-crank Shortest link is follower Double-rocker Shortest link is opposite the frame FOUR BAR MECHANISM Slide 28: 28 UNIT I 4 - BAR MECHANISM INVERSION - APPLICATIONS 1.Crank-rocker (or) 3.Rocker-Crank 2.Double-crank (drag-link) 4.Double-rocker(lever) Slide 29: 29 UNIT I Inversions of slider crank chain (a) crank fixed (b) connecting rod fixed (c) slider fixed Slide 30: 30 UNIT I Single Slider Crank Chain Inversion - Applications Rotary engine / Gnome Engine – I (crank fixed) Oscillating cylinder engine–II (connecting rod fixed) Slide 31: 31 UNIT I Pendulum pump or bull engine–III (slider fixed) Slide 32: 32 UNIT I Whitworth quick return motion mechanism Slide 33: 33 UNIT I Crank and slotted lever quick return motion mechanism Slide 34: 34 UNIT I DOUBLE SLIDER CRANK CHAIN It is a kinematic chain consisting of two turning pairs and two sliding pairs. SCOTCH –YOKE MECHANISM Turning pairs –1&2, 2&3; Sliding pairs – 3&4, 4&1 Slide 35: 35 UNIT I Inversions of double slider crank mechanism Elliptical trammel AC = p and BC = q, then, x = q.cos? and y = p.sin?. Rearranging, Slide 36: 36 UNIT I OLDHAM COUPLING Slide 37: 37 UNIT I THANK YOU You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
UNIT 1 of I GSANJANA Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 4696 Category: Education License: All Rights Reserved Like it (18) Dislike it (0) Added: May 19, 2009 This Presentation is Public Favorites: 7 Presentation Description No description available. Comments Posting comment... By: dadda0522 (3 week(s) ago) hey xelent one ......plz aalow me to download or send it to jhansi990@yahoo.in thank you Saving..... Post Reply Close Saving..... Edit Comment Close By: leenamahesh (3 month(s) ago) sir wonder ppt can you send all ppt to mbd_gdg @yahoo.co.in thanking you Saving..... Post Reply Close Saving..... Edit Comment Close By: sachin1983 (4 month(s) ago) good presentation.please send me shindesms1983@gmail.com Saving..... Post Reply Close Saving..... Edit Comment Close By: HARRY111 (7 month(s) ago) nice.......please allow to download jatharlal16@gmail.com Saving..... Post Reply Close Saving..... Edit Comment Close By: poornibhavani (10 month(s) ago) nice ppt..............can u snd me on my id .........kkspoornimasundar@gmail.com Saving..... Post Reply Close Saving..... Edit Comment Close loading.... See all Premium member Presentation Transcript Slide 1: UNIT : I Definitions: Links, Pairs, chain, Mechanism, structure, degree of freedom, Inversion of machines & inversion of 4 bar chains. Velocity and acceleration: Velocity and acceleration of simple mechanism by relative velocity method. Klein’s construction for slider - crank chain. Analytical methods and solution for mechanisms. 1 UNIT I Slide 2: To move some heavy boxes into a moving truck B would be easier because a ramp is an inclined plane A B 2 UNIT I Slide 3: To move a heavy box a long distance A would be easier because the wagon has wheels and axels. A B 3 UNIT I Slide 4: To change a flat tire on the moving truck. A B B would be easier because a jack uses a screw. 4 UNIT I Simple Machines : Simple Machines 5 WEDGE PULLEY SCREW LEVER BY-CYCLE INCLINED PLANE UNIT I Slide 6: Inclined plane Wheel and axel Wedge Screw Pulley Inclined plane 6 UNIT I Slide 7: TERMINOLOGY STEAM ENGINE STEAM ENGINE – SPACE DIAGRAM FRAME 7 UNIT I Slide 8: A LINK is defined as a rigid body having two or more pairing elements which connect it to other bodies for the purpose of transmitting force or motion. Classification of Links: Binary Link 2. Ternary Link Quarternary Link Types of Links: Rigid Link - Eg.: Connecting rod and Crank Flexible Link –Eg.: Belts ,Ropes, Chains, Springs and bands etc. Fluid Link – Eg. Fluids in Hydraulics press, Lifts Floating Link – Not connected to the frame. – Eg.Pointer in a Clock 8 UNIT I Slide 9: Types of joints in a Chain Binary Joint 2. Ternary joint 3. Quaternary joint KINEMATIC PAIR is a joint between the surfaces of two rigid bodies that keeps them in contact and relatively movable. 9 UNIT I Slide 10: 10 Classification of Kinematic pairs: According to the type of contact(nature of contact between them) Lower pairs - Surface-contact , Eg. Nut and Bolt, Shaft in a bearing. higher pairs - Point-, line-, or curve-contact ,Eg. Belts,Ropes, Gears, Cam and follower. According to the nature of relative motion between them Sliding/Prismatic Pair (P) Turning /Pin /Revolute Pair (R) Cylindrical Pair (C) Screw /Helical Pair (S) Spherical /globular Pair (G) Flat/Planar Pair (F) According to nature of mechanical arrangement for constraining relative motion ( type of constraint) Closed /Self closed Pair – Eg. All lower pairs Open /Unclosed /Forced closed pair – Eg. Cam & follower, belt running on a pulley. UNIT I Slide 11: 11 UNIT I Slide 12: 12 UNIT I Slide 13: 13 UNIT I Higher Pairs Joints Slide 14: 14 UNIT I CONSTRAINED MOTION one element has got only one definite motion relative to the other (b) Successfully constrained motion (a) Completely constrained motion (c) Incompletely constrained motion Slide 15: MECHANISM: An assemblage of resistant bodies, connected by movable joints, to form a closed kinematic chain with one link fixed and having the purpose of transforming motion. – A/c to Reuleaux MACHINE: An assemblage of parts that transmit forces, motion and energy in a predetermined manner OR A combination of rigid or resistant bodies, so arranged that by their means the mechanical forces of nature can be compelled to do work accompanied by certain determinate motions. – A/c to Reuleaux The similarity between machines and mechanisms is that they are both combinations of rigid bodies the relative motion among the rigid bodies are definite. The difference between machine and mechanism is that machines transform energy to do work, while mechanisms so not necessarily perform this function. The term machinery generally means machines and mechanisms 15 UNIT I Slide 16: TYPES OF MECHANISMS Simple - 4 links Compound – more than 4 links Complex – ternary or higher order floating links Planar – all links lie in the same plane Spatial – links of a mechanism lie in different planes Equivalent – Turning pairs of plane mechanisms may be replaced by other types of pairs such as sliding pairs or cam pairs. The new mechanism thus obtained having the same no. of DOF as the original mechanism is known as equivalent mechanism. Ex. A turning pair can be replaced by a sliding pair. A spring can be replaced by two binary links 16 UNIT I Slide 17: TYPES OF MECHANISMS - diagrams 17 UNIT I Planar Mechanism Simple Mechanism Compound Mechanism Complex Mechanism Slide 18: 18 UNIT I Parallel robot Spatial Mechanism Slide 19: KINEMATIC CHAIN : An assembly of links in which the relative motion of links is possible and the motion of each link relative to the others is definite. The last link of the kinematic chain is attached to the first link. Relationships holds for a kinematic chain having lower pairs only: l = 2 p – 4 ---- (1) and j = (3/2) l – 2 ------(2) Where l = no. of links p = no. of pairs j = no. of joint If LHS > RHS, then the chain is locked / rigid / redundant structure. LHS = RHS, then the chain is constrained . LHS < RHS, then the chain is unconstrained. For a kinematic chain having higher pairs, each higher pair is taken as equivalent to two lower pairs and an additional link. 19 UNIT I Slide 20: A.W.Klein’s Criterion : A.W.Klein given a relationship beween no. of linka and no. of binary joints, in oredr to dtemine the nature of chain as follows: j + h / 2 = (3/2) l – 2 -------------(3) Where l = no. of links h = no. of higher pairs j = no. of binary joint If LHS > RHS, then the chain is locked / rigid / redundant structure. LHS = RHS, then the chain is constrained . LHS < RHS, then the chain is unconstrained. 20 UNIT I Slide 21: 21 UNIT I DEGREES OF FREEDOM (DOF): It is the number of independent coordinates required to describe the position of a body. Slide 22: DEGREE OF FREEDOM An unconstrained rigid body moving in space can have 3 translations and 3 rotational motions about three mutually perpendicular axes. The no.of degrees of freedom of a kinematic pair is defined as the no. of independent relative motions, both translational and rotational that a kinematic chain can have. DOF = 6 – number of restraints. DOF for Planar Mechanism: MOBILITY OF A MECHANISM : The mobility of a mechanism is defined as the number of degrees of freedom it possesses, or the minimum number of independent parameters required to specify the location of every link within a mechanism. The German literature distinguishes between movability and mobility. Movability includes the 6 dof of the device as a whole, as though the ground link were not fixed, and thus applies to a kinematic chain. Mobility neglects these and considers only the internal relative motions , thus applying to a mechanism. 22 UNIT I Slide 23: Kutzbach Criterion For Planar Mechanism: n = 3 ( l -1) – 2 j – h ------------------(1) For Spatial Mechanism: n = 6 (l -1) – 5p1 – 4p2 – 3p3 – 2p4 – 1p5 -------(2) Where n = no. degree of freedom l = no. of links j = no. of joints h = no. of higher pairs p1 = no. of pairs having one dof. p2 = no. of pairs having two dof. p3 = no. of pairs having three dof. and so on. 23 UNIT I Slide 24: Grubler’s Criterion For Planar Mechanism is obtained by substituting n=1 and h = 0 in the Kutzbach’s criterion. We get 3l – 2 j – 4 = 0 ------------------(3) So, it applies to mechanisms with only single dof joints and the overall mobility of the mechanism is unity. For Spatial Mechanism: If mechanism has all single dof pairs and overall mobility is of unity, then Kutzbach’s equation for spatial mechanism becomes i.e. n=1, p2=p3= - - - - p5 = 0 6l – 5p1 – 7 = 0 --------------------------(4) If n = 1 : the device is a mechanism with n dof n = 1 : the device is a statically determinate structure n < -1 : the device is a statically indeterminate structure 24 UNIT I Slide 25: INVERSION OF MACHANISMS 25 UNIT I Kinematic Inversion Process of fixing different links of a chain to create different mechanisms Relative motion between links does not change in different inversions Overall motion may change Changing frame (ground) changes same mechanism to different configurations of 4 Grashof mechanisms Slide 26: 26 UNIT I Grashof Law: Sum of shortest and longest links of a planar 4-bar linkage cannot be greater than the sum of the remaining 2 links if there is to be continuous relative motion between 2 links. i.e., at least one link can make a full revolution with respect to the ground plane Let l = longest link s = shortest link p, q = other two links Then the linkage is Grashof if The linkage is non-Grashof if the inequality is not true.No link can make a complete revolution relative to any other link. Slide 27: 27 UNIT I 4 possible mechanisms exist if Crank-rocker Shortest link is crank Double-crank (drag-link) Shortest link is frame Rocker-crank Shortest link is follower Double-rocker Shortest link is opposite the frame FOUR BAR MECHANISM Slide 28: 28 UNIT I 4 - BAR MECHANISM INVERSION - APPLICATIONS 1.Crank-rocker (or) 3.Rocker-Crank 2.Double-crank (drag-link) 4.Double-rocker(lever) Slide 29: 29 UNIT I Inversions of slider crank chain (a) crank fixed (b) connecting rod fixed (c) slider fixed Slide 30: 30 UNIT I Single Slider Crank Chain Inversion - Applications Rotary engine / Gnome Engine – I (crank fixed) Oscillating cylinder engine–II (connecting rod fixed) Slide 31: 31 UNIT I Pendulum pump or bull engine–III (slider fixed) Slide 32: 32 UNIT I Whitworth quick return motion mechanism Slide 33: 33 UNIT I Crank and slotted lever quick return motion mechanism Slide 34: 34 UNIT I DOUBLE SLIDER CRANK CHAIN It is a kinematic chain consisting of two turning pairs and two sliding pairs. SCOTCH –YOKE MECHANISM Turning pairs –1&2, 2&3; Sliding pairs – 3&4, 4&1 Slide 35: 35 UNIT I Inversions of double slider crank mechanism Elliptical trammel AC = p and BC = q, then, x = q.cos? and y = p.sin?. Rearranging, Slide 36: 36 UNIT I OLDHAM COUPLING Slide 37: 37 UNIT I THANK YOU