Machine Elements Design

Exam 1

Student Name:

St. No.

1- What are the differences and/or the relations between the following:

A-    Stress (s), Strain (ε):

B-    Moment (M), Torque (T):

C-    Normal stress (σ), Shear stress (τ):

D-   Second moment of area (I), Polar moment of area (J):

2- A structure suspended by EN3 tie-bars is equivalent to a load of F = 120,000 N. The tie-bars each have a diameter of d = 24 mm. If the SF is 9, calculate the minimum number of tie-bars (n).

Description: http://www.thecartech.com/subjects/machine_elements_design/Exam_1_files/image006.jpg

 

 

 

 

3- Find the stress at point A due to the Forces shown in the figure.

Where: Fx = 100 N, Fy = 150 N, Fz = 200 N, L= 40 mm, H= 20 mm, d= 4 mm

 

 

 

A = ..

I =

J = ..

 

F

AT

A

Normal force

Shear
Force

Moment

Torque

Fx

Load

 

 

 

 

Stress

 

 

 

 

Fy

Load

 

 

 

 

Stress

 

 

 

 

Fz

Load

X

 

Fz = 200 N

 

M = Fz L

= 200 x 40

= 8000 N mm

X

 

Stress

X

 

τz = Fz/A

= 200/

=

σb = M y /I =

- 8000 x 2/

=

X