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.

Carbon Fiber in the Chevrolet Silverado ZR2 Concept

At the 2009 Las Vegas SEMA show, Chevrolet introduced their ZR2 Concept pickup truck.  This truck is tricked out for off-road capability with all wheel drive and a tricked out suspension.  Weight savings improves performance and the designers turned to carbon fiber composites.

Exterior body panels were improved by saving weight by using carbon fiber.  These panels include the hood, fenders, tailgate, grille, fascias, fender flares, and rocker panels.  The hood and tailgate have used clear-coated carbon fiber to show the weave and give an interesting two-tone look to the vehicle.

The interior is also reported to use carbon fiber in the dash and the door panels.

It is unknown whether this concept vehicle goes into production, but certain elements are certainly becoming mainstream.  Aftermarket carbon fiber parts have been popular for years especially on tuner cars.  This may catch on for mainstream OEM production.  Carbon fiber parts save weight, do not corrode, do not dent, and do not require pigmented paint.

Boeing’s 787

Boeing’s 787 will be the first composites-intensive commercial airliner.  Traditionally made from aluminum, carbon fiber composites will work to create a plane that is stronger and lighter with fewer manufactured parts.  Carbon Fiber reinforcement with Epoxy resin will be the main construction of these composites, which will make use of an autoclave during processing to control the molding conditions and ensure the quality and durability of the laminate.

Composites will reduce the number of parts for the airplane, and Boeing predicts that the front section alone would normally require using 1,500 sheets of aluminum, which also means drilling between 40,000 and 50,000 holes for the nuts and bolts to attach these sheets together and to the underlying framework.  Carbon Fiber composites will allow for the skin and underlying supports to be molded as one large piece.  Boeing predicts that assembly line time will be reduced from about three weeks to attach all of this aluminum together to about 3 days to attach the large composites sections together for the entire plane fuselage.

Switching materials has its’ own set of problems to overcome.  The customers’ mechanics will need to be trained to repair damage on these composite planes.  Damage detection will be important as well.  Some will be visible to the naked eye, and other damage will not.  Several forms of Non Destructive Testing will be employed to test for damage and wear on the composites body to ensure a safe aircraft.

Composites have been used in aircraft before, but not as extensively in commercial airplane bodies.  Existing commercial airplanes have made use of composites in other areas to help make the planes stronger and lighter.  Military jets have used carbon fiber composites for many years in their technologies for strength and weight advantages.  Private business jets have utilized fiberglass composites for many years in their construction.  Homemade kit planes have also made extensive use of fiberglass to make inexpensive craft in personal shops.

The profile of carbon fiber composites will definitely be elevated if Boeing’s 787 becomes as successful as promised.

Energy Conservation

Composites are such a great material for energy conservation. Their superior stiffness to weight ratio allows for them to replace other materials in sectors like transportation in order to gain weight savings. These weight savings of course require less energy to move and stop the vehicles.

This of course comes back to the horsepower to weight ratios which are no secret formula. They were discovered decades ago by racers of all kinds who made their vehicles as light as possible to gain advantage, many times using fiberglass. The sailboat guys know it too; the lightweight carbonfiber masts reduce weight versus aluminum to gain a weight advantage. Drag car bodies made of lightweight fiberglass instead of sheetmetal or aluminum. Circle track cars with fiberglass hoods, noses, and bumpers.

Examples of conserving energy with composites, and the racers got it right a long time ago!