1. If it is known that the center pin A supports one-half of the vertical loading shown, determine the force in member BF.

Transcription

1 1. If it is known that the center pin A supports one-half of the vertical loading shown, determine the force in member B.

2 Joint A AB A I. Cut D D B A 26 kn A I. Cut H 13 kn D B D A H 13 kn

3 2. Determine the forces acting in members D, DI, JK,AJ. 4 m 4 m 4 m B C D M I G 3 m 3 m L K J H 37 o 20 kn 6 m A

4 3. Determine the force acting in member JI. 20 kn 3 kn 4 kn L D G H K J I 3 kn C 5 kn 3 m 3 m A B 3 m 5 kn 4 m M 4 m N P 10 kn 4 m 4 m

5 4. Determine the forces in members D, I, I and HI.

6 II. Cut I. Cut G A G

7 5. Compute the force in link AB of the lifting tongs which cross without touching.

8 6. The design of a hoisting mechanism for the dump truck is shown in the enlarged view. Determine the compression P in the hdraulic clinder B and the magnitude of the force supported b the pin at A for the particular position shown, where BA is perpendicular to OA and link DC is perpendicular to AC. The dump and its load together have a mass of 9 Mg with center of gravit at G. All dimensions for the indicated geometr are given on the figure.

9 7. The pruning mechanism of a pole saw is shown as it cuts a branch S. or the particular position drawn, the actuating cord is parallel to the pole and carries a tension of 120 N. Determine the shearing force P applied to the branch b the cutter and the total force supported b the pin at. The force eerted b the light return spring at C is small and ma be neglected.

10 Two-force member: CD BD of member D

11 8. A pneumatic clinder pivoted at operates the lever AB of the quick-acting toggle clamp, which holds the workpiece in position while it is machined. or an air pressure of 400 kpa against the 50 mm diameter piston, determine the clamping force at G for the position α10 o. or this position the piston rod is perpendicular to AB.

12 9. A small trailer-mounted dumper is shown. All connections are pinned and member is horizontal. The hdraulic clinder simultaneousl tilts the dumper and opens the gate G. The pin at D can slide freel in the slot at the dumper and point does not contact the dumper. Determine the force supported b hdraulic clinder A. State whether it works in Tension / Compression.

13 10. The mechanism in the figure is used to raise the bucket of a bulldozer. The bucket and its contents weigh 10 kn and have a center of gravit at H. Arm ABCD has a weight of 2 kn and a center of gravit at B, arm DG has a weight of 1 kn and a center of gravit at. The weights of the hdraulic clinders can be neglected. Determine the forces in the hdraulic clinders CJ, B and I and also determine all the forces acting at arm DG.

14 Two-force members: CJ, B, I. BD of bucket I G G 10 kn M G G G ( 0. 3) ( 1. 2cos30) I I G G I kn kn 10 kn BD of hdraulic clinder I I I I

15 BD of DG D D D 30 o 1 kn D I B α 19 o 30 o 30 o β B G G G B sinα sin β sin 60 (. 8)( 1. 2) cos 60 α 41 o, β 79 o B m M D I ( 0. 6cos30 ) + 1 ( 0. 6 sin30 ) + B sin 711 (. 2cos30 ) + B cos 711 (. 2 sin30 ) + G ( 1. 8cos30 ) + G ( 1. 8 sin30 ) B kn G G + D + D B 1 cos19 B I sin19 D D kn kn

16 BD of entire sstem P CJ A 2 kn 1 kn 10 kn A M CJ A ( 1. 8sin 60) + 10( sin sin30) + 1( 0. 6 sin sin30) + 2( 0. 9 sin30) CJ 18 kn 0 A CJ + A A A kn kn

17 20 kn 15 kn 11. The figure shows a special rig designed to erect vertical sections of a construction tower. The assembl A has a weight of 15 kn and is elevated b the platform B, which itself has a weight of 20 kn. The platform is guided up the fied vertical column b rollers and is activated b the hdraulic clinder CD and links D and H. or the particular position shown, calculate the force eerted b the hdraulic clinder at D and the magnitude of the force supported b the pin at.

18 Two-force members: CD, H. 15 kn ( H ) BD of H 20 kn H ( H ) 35 kn α 3 m 1.25 m α o 35 H H kn

19 BD of D o. H α , kn 0.75 m 1 m D 3 m β CD β H α C 1 sin β β o M CD cos β ( 1) sin β ( 0. 75) + cosα( 3) sinα( 2. 25) CD H H 0 CD kn + H H sinα + cosα + CD CD sin β cos β kn kn

20 12. The lever AB is welded to the bent rod BCD which is supported b bearing and cable DG. Assuming that the bearing can eert an aial thrust and couples about aes parallel to the and z aes, determine the tension in cable DG and the reaction at under the action of the 220 N force. The mass of ABCD is neglected. 60 mm 240 mm B 250 mm 220 N A C 225 mm 120 mm z 160 mm D G

21 13. The bent rod is supported b a ball-and-socket joint at O, a cable at B, and a radial bearing at D. Neglecting the weight of the rod, calculate the tension in the cable B and the reactions at D and O. Assume that the radial bearing does not support an moments.