QA, QC & Testing

Stress Testing

How does a product behave when it is pushed to its limits?

Does it get damaged or can it still be used?

Stress testing is used to determine whether a product can be still used after it has been taken to its limit.

These limits then can be used to improve the product to overcome failure or mechanisms put in place to stop failure points being reached.

Consider two fast cars which undergo a stress test to determine whether their main marketing assets, their ability to reach speeds in excess of 150 mph can be justified.

During the stress tests, it is found that when the first vehicle reaches 141mph, it's tyres explode, causing the vehicle to crash. The second vehicle when reaching 163mph, causes the engine to explode.

These are stresses at which the vehicles fail and from where it is not possible to use these vehicles again as they get damaged.

The manufacturer of these vehicles may decide that it would be far too expensive to develop new tyres and engines to overcome these limitations. Therefore devices that limit speed could be put onto the engines, reducing the maximum speed that could be reached.

The vehicle whose tyres explode past 141mph may be limited to a maximum speed of just 130mph by the devices that limit speed. Whilst the other vehicle whose engine explodes at 163mph, will have a speed limiting device added that inhibits the engine from producing the power that is required to take the vehicle over 150mph.

Stress testing determines the recoverable limits of a product.

In fact many cars today have speed limiting devices fitted, to protect the car from being damaged. Ultimately saving the organisation from accruing losses from litigation and compensation claims.

Another example for the benefits of stress testing could be a chocolate manufacturer, who accepts a very large order for specialist chocolates. After an hour of the production lines starting, two hundred chocolate pieces a minute is reached, things suddenly start to go wrong.

The electric motor on the chocolate mixer machine burns out and smoke starts appearing over the conveyor belt as the excessive heat caused from the belt moving even more quickly over the rollers builds up.

The chocolate manufacturer has exceeded the maximum capacity of what the production lines can produce. If adequate stress testing had been done prior, then the manufacturer would have been able to set limits on the size of the orders that they could accept. Instead of taking on orders which damaged their production facilities.