Non-Destructive Testing with Ultrasound
Composite materials can become damaged in many different ways. There can also be flaws in the original manufacturing process. Many times it is necessary to identify any damaged areas within the composites layers that cannot be detected with the eye.
Inspection of composites fiberglass and carbon fiber structures may be required for advanced critical applications of composites materials. Identifying any potential problems with the composites structure is extremely important.
Of course problems can be identified through destructive testing-drilling holes, making cuts, etc. It also may be necessary to do testing in a non-destructive manner, i.e. not cutting into the laminate that is being tested.
One method of accomplishing non-destructive testing of composites laminates is using ultrasound. This Youtube video demonstrates the use of this method.
As you can see, the damage is found in this carbon fiber laminate. This information is a flag that can be used to decide whether to make a repair or replace the structure.
Delamination within the fiberglass or carbon fiber part will result in a much weaker structure than the design intended. Other areas of the composites part will be further strained by weaknesses in other areas and may also fail.
This ultrasonic test can help to identify otherwise invisible problems with either the original manufacturing process or damage during the life cycle of the composite part.
Cirrus Composite Airframes
I found a very interesting Youtube peek inside of the Cirrus airplane assembly factory in Minnesota. While it would be cool to learn more about the actual composites fabrication of the individual parts, there is some great information about part bonding, inspection, and final assembly of the Cirrus aircraft. They use fiberglass and carbon fiber reinforcements to create a very strong and durable fuselage, and it is great to see in action.
Personal jets made of composite materials offer many advantages and unique properties. Design of complex shapes and anti corrosion of aluminum are two advantages. Disadvantages include repeatability and upgrading/modification.
Composites that are properly designed and fabricated can be used in many applications where safety is a big concern. Proper design and inspection during production can create an airplane that can be easily maintained and have a very long life.
Great factory tour courtesy of Aero-TV:
Composites Application: Utility Trucks
A composites materials application I recently looked at was a man-lift bucket made from composites. These man-lift buckets are mounted on a lifting arm atop a work truck to lift workmen up to perform utilities repairs and service. This is an application that has been around for a long time, and is a great fit for composites materials.
Utility bucket lays sideways for travel
These buckets are designed to hold one or two people and allow them to perform jobs such as hanging electrical wires, television cable, and telephone lines. The workers also need to work on the utility poles and trim the trees and vegetation growing near the lines.
This is a great composites application for serveral reasons.
*The composites allow the manlift bucket to be non-conductive for safety reasons. Many other considerations are made to prevent electricution, and this adds to those safety considerations.
*The bucket is also lightweight due to composites, which allow for greater lifting capacity of the workers and their tools because weight is not used inthe lifting device itself.
*These trucks spend the majority of their lives outdoors, and the anti-corrosive nature of composites helps give these manlift buckets long lives.
Fiberglass composites are normally non-conductive, and this is a very important consideration for applications such as these involved with utilities. Composites are found in many applications where electrocution is possible.
Not all composites materials are non-conductive, however. The use of conductive fillers and reinforcements can allow for electricity to travel in these applications. Carbon fiber and carbon black are a couple of ingredients that can cause this. Testing finished composites for conductivitiy can be conducted to determine their insulative properties.
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