Mechanical Engineering Principles

108 MECHANICAL ENGINEERING PRINCIPLES

as shown in Figure 8.11, determine the

maximum stress in the beam. [34 MPa]

40 mm

Thickness = 5 mm

15 mm

Figure 8.11

Exercise 42 Short answer questions on

the bending of beams

1. Define neutral layer.


2. Define the neutral axis of a beam’s cross-
   section.


3. Give another name for the neutral axis.


4. Write down the relationship between
   stressσand bending momentM.


5. Write down the relationship between
   stressσand radius of curvatureR.

Exercise 43 Multi-choice questions on the

bending of beams (Answers

on page 284)

1. The maximum stress due to bending
   occurs:

(a) at the neutral axis

(b) at the outermost fibre

(c) between the neutral axis and the

outermost fibre

2. If the bending moment is increased in a
   beam, the radius of curvature will:

(a) increase

(b) decrease

(c) stay the same

3. If the Young’s modulus is increased in a
   beam in bending, due to a constant value
   ofM, the resulting bending stress will:

(a) increase

(b) decrease

(c) stay the same