WORLD FOR CIVIL

opic 6.9: Torsion, Rivets & Welds - Topic Examination

Torsion - Topic Exam

Modulus of Rigidity for several materials:
Steel = 12 x 10⁶ lb/in².; Brass = 6 x 10⁶ lb/in².; Aluminum = 4 x 10⁶ lb/in².

1. A compound shaft is attached to a fixed wall as shown in Diagram 1. Section AB brass, section BC is steel, and section CD is brass. If the allowable shear stress for steel is 18,000 lb/in², and for brass is 16,000 lb/in².

A. Determine the maximum torque which could be applied at points D, C, & B (T_D,T_C, & T_B) without exceeding the allowable shear stress in any section of the shaft.
B. Using the torque found in part A, determine the resultant angle of twist of end D with respect to end A.
(For Solution Select: Torsion - Solution Problem 1)

2. A 2 foot long hollow steel shaft with an outer diameter of 2 inches and an inner diameter of 1.5 inches is to transmit power while being driven a 3000 rpm.

A.) If the allowable shear stress in the shaft is 15,000 lb/in²., what is the maximum horsepower which can be transmitted down the shaft ?
B.) If we were not given the outer diameter of the shaft, but were told that the inner diameter was to be four-tenths of the outer diameter, what would be the minimum outer diameter of the shaft which could safely transmit the horse power found in part A? (The allowable shear stress in the shaft is 15,000 lb/in² )
(For Solution Select: Torsion - Solution Problem 2)

Rivets & Welds - Topic Exam

1. A riveted lap joint is shown in Diagram 1. The diameter of the rivets is 1 inch. The width of the plates is 12 inches, and the thickness of the plates is 5/8 inch. The allowable stresses are as follows:

Rivets: = 20, 000 lb/in², _t = 26, 000 lb/in², _c = 28, 000 lb/in²
Plate: = 17,000 lb/in², _t = 22, 000 lb/in², _c = 24, 000 lb/in²
Determine the Strength of the Joint, and the Efficiency of the Joint.
(For Solution Select: Rivets & Welds - Solution Problem 1)

2. A double cover plate butt joint (Diagram 2) is to connect two steel plates both with a width of 9 inches and a thickness of 7/8 inch. The rivets to be used have a diameter of 3/4 inch.

The maximum allowable stresses for the rivet and plate materials are as follows:
Rivets: = 17, 000 lb/in², _t = 22, 000 lb/in², _c = 23, 000 lb/in²
Plate: = 18,000 lb/in², _t = 24, 000 lb/in², _c = 26, 000 lb/in²
A. Determine the number of rivets for the most efficient joint.
B. Select the best pattern from the patterns in Diagram 3 .
C. Calculate the strength and efficiency of the joint.
(For Solution Select: Rivets & Welds - Solution Problem 2)

3. Two metal plates are shown below. The top plate is 3/4 inch thick and 9 inches wide, and is to be welded to the bottom plate with a 45^o fillet weld. The top plate is to be weld completely across end AG and partially along sides AB and FG.

A.) Determine the minimum inches of weld need to carry the 100,000 lb. load and specify how many inches of weld should be placed along each side AB and FG.

B.) Determine the number of inches of weld needed to make the weld strength as great as the plate strength.

The allowable stresses are as follows;
Weld Material: = 12,000 lb/in² ; t = 24, 000 lb/in²
Plate Material: = 13,000 lb/in² ; t = 22,000 lb/in²
Dimensions: AB = GF = 20 inches; CD = 3 inches; DE = 6 inches
(For Solution Select: Rivets & Welds - Solution Problem 3)