Ultrasonic Testing Machines with Robot Mechanics - A New Approach to CFRP Component Testing

For a long time, Ultrasonic Testing Machines for aircraft components have been built with almost 100% custom made mechanics (gantry or bridge design) to match customer needs. This design comes with several disadvantages like price, delivery time or lack of flexibility. This article illustrates an alternative approach to Testing Machine design for the Aerospace industry and describes in detail the advantages of robot based mechanics together with different types of coupling mechanics and shows the abilities of today’s state of the art machine design to face CFRP component testing challenges. Non destructive testing of large aircraft parts or engine components made of CFRP or sandwich materials by using the ultrasonic method is a challenge for every manufacturer of testing machines. These aircraft components, which can easily have a length of 20 meters and more, require leading edge technology to answer the requirements of the inspection task in terms of part handling, mechanics’ accuracy, ultrasonic capabilities and data processing. 1 General Layout of an Ultrasonic Testing Machine Basically, an ultrasonic testing machine consists of the mechanical part, ultrasonic hardware and computer peripherals. Mechanics can be divided into the part handling components to position and fix the part under test, coupling mechanics to provide proper and stable ultrasonic signals and scan mechanics like a bridge, robots or linear manipulators. The electronics comprise one or more ultrasonic transducers appropriate to the actual application and ultrasonic hardware for pulse generation, phased array beam forming, receiving and signal processing. Last but not least, powerful computer hardware is needed for scan path generation, data evaluation and storage. 2nd International Symposium on NDT in Aerospace 2010 Mo.4.A.3 Licence: http://creativecommons.org/licenses/by-nd/3.0 1 [1] Exemplary basic layout of an ultrasonic testing machine 2 Coupling Mechanics State of the art UT testing machines for the inspection of large CFRPand Sandwich components are mainly based in two types of coupling methods: "Squirter" and "Bubbler". Immersion Technique is of course also being used and provides most stable coupling conditions, but due to restrictions in water basin size, immersion technique is not applicable in many cases. Therefore, only first two mentioned systems will be described in detail in this article. 2.1 Squirter Systems A squirter system uses a water jet to guide the ultrasonic pulse into the part under test. The Squirter technique is always used together with through transmission. [2] Squirter nozzles for through transmission testing