Accelerated Life Timing Determines Product Lifetime

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When a new product is made, or a new part is added to an existing system, it is necessary to understand how reliable this new part will be and what its estimated lifetime is.

E.A. Elsayed, distinguished professor of industrial and systems engineering at Rutgers University, spoke about the process of testing such products Tuesday in the Memorial Union’s Hidatsa Room as a part of North Dakota State’s College of Engineering Distinguished Lecture Series.

The process is called Accelerated Life Testing (ALT) and is currently the most common form of product and prototype testing, according to Elsayed.

The goal of the testing is to build a statistical model that can be compared with the physics of the actual product to determine where the product’s failure threshold is.

This is done by putting the product through accelerated conditions, or constant cycles of stress until the product shows signs of deterioration.

The product is put through three levels of accelerated conditions: low, medium and high. The most number of units are tested at low conditions because it is more cost effective and a more realistic setting of the wear and tear the product will see.

For every four products tested at the lowest condition, two are tested at medium and one at the highest condition.

Naturally, the fewest number of units are tested on the highest condition, which cannot exceed the stress a user of the product can put on it because the most failures are expected here and the prototypes that are tested can be expensive to produce.

An example of where this process could have prevented organizational economic loss and increase user safety is the Toyota recall in 2010 where 2.3 million vehicles in the U.S. and 1.8 million in China and Europe were recalled due to faulty accelerator pedals.

According to a 2010 CBS report, the faulty accelerators have “been involved in the deaths of 89 people.”

Previously, failure predications used to be based off field data. If it were for a car part, for instance, data would be collected from dealership repair shops about which parts were malfunctioning and when, in terms of the car’s mileage.

This process was too lengthy and can lower the reputation of a company because mass recalls can occur if the malfunction is caught too late.

Other products Elsayed has been involved in the degradation testing of include Tomahawk Missiles used by the U.S. Navy, transpacific and transatlantic cables that connect the U.S. to other countries and the human spine.

Working with a medical school, Elsayed and his team created a computer-generated model of the spine. They used computer programs to test different sections of the spine to determine how quickly the bone degrades.

Unfortunately, with some products you can’t possibly know the reliability of it until you use it, but by then it would be too late. These types of products include parachutes and airbags, Elsayed said.

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