Topic 5 Notes - How Structures Fail

Question 1

What is the main purpose of engineers in designing structures?

Answer 1

To design safe and stable structures

Engineers choose the best materials and strongest shapes to ensure longevity.

Question 2

What can cause a material to bend and buckle?

Answer 2

Compression

An example is a pop can that is stepped on.

Question 3

Can buckling ever be useful? Give an example.

Answer 3

Yes, in car crumple zones

Crumple zones are designed to absorb energy during a collision.

Question 4

What is shear in the context of material failure?

Answer 4

Small cracks and weaknesses in materials can cause complete failure due to shear stress

Examples include landslides and concrete beam failure.

Question 5

How can shear force be beneficial?

Answer 5

Boat motors use shear pins to prevent damage

If the motor tangles in weeds, the pin breaks, separating the motor from the propeller.

Question 6

What does torsion refer to in material failure?

Answer 6

Twisting that can cause material failure

Even if not broken, the material may lose shape and develop cracks.

Question 7

What is metal fatigue?

Answer 7

When metal gets bent back and forth, particles end up farther apart

This results in less attractive forces holding them together, as seen in bending a nail.

Question 8

How can you increase a force?

Answer 8

Using mechanical advantage

Levers, pulleys, and other simple machines can be employed to increase forces.