DRAFT: This module has unpublished changes.
DRAFT: This module has unpublished changes.

1. Describe an example of a material-related cause of failure in the real-world.

 

On December 31st 2011, Erin Langworthy, a 22 year old from Australia was bungee jumping off a 111 meter bridge near the Victoria Falls. Unfortunately for her, she did not spring back as planned, instead her cord snapped and sent her plummeting 111 meters into the river below. Even though Erin survived, she not only suffered immense physical damage by breaking her collarbone and fracturing other parts of her body, she went through a lot of mental trauma as well. Erin slapped right into the river and had to swin across the crocodile infested water with her feet still tied together with the harness.

 

The failure was caused as the cord couldn't take the stress and strained beyond the fracture point. The factor of safety for these cords should be typically more than 3 since it could lead to fatal accidents.

 

2. How was this cause of failure related to other causes of failure (human/design/poor maintenance/extreme conditions) in this case?


The primary cause of failure was the poor design and estimation in this case. The engineers designing the cord should have estimated all kinds of loads and stresses that the cord could go through.

 

Bungee jumping cords are primarily made of natural rubber and a lot of testing is done before putting them to use considering the amount of risk there is in the fall. Another factor that could've influenced this disaster is poor maintenance of the cord. The cords are made to last a certain period of time under regular conditions, if put through extreme conditions like temperature, load or improper storage, the lifetime of these rubber cords can shorten significantly.

 

Another factor that can be taken into consideration is the human factor. Maybe the cord was made perfectly by the engineers for use over a certain period of time, but the company providing the service didn't want to replace these cords in order to save some money and used them beyond the advised period. Every material that experiences load goes through something known as fatigue, what that means is everytime something is used, even if it make come back to the exact shape, it loses a minimal amount of its stress bearing capabilities.

 

3. How are materials engineers trying to design better materials to improve relaibility and create safer engineered systems and structures? Give an example.


As talked about in class on 3/25, Engineers are increasingly using composite materials these days. From tennis racquets and golf clubs to industrial and automotive uses, as the production of composite materials is becoming cheaper, more and more industries are trying to incorporate it.

 

What's so special about composites? The biggest advantage that composite materials have is that they not only are extremely light weight, but are also very tough, which means they're hard to tear apart.

 

Composite materials are a big hit in the aircrat industry, being lighter and tougher than aluminum, composite mterials are being used to build most of the parts of the modern day aircrafts.

 

DRAFT: This module has unpublished changes.