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Non-Destructive Testing of Carbon Fiber Reinforced Plastic
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Thermography as a method of quality assurance in the aerospace industry
Composites in general and carbon fibre reinforced polymers (CFRP) in particular, have long played a major role in the aerospace industry. They are lightweight, extremely strong and can withstand high mechanical stresses. Through their use, fuel consumption can be reduced and CO2 emissions often noticeably drop decreased. However, assembly errors of these materials can result in severe consequences. This makes examining the components and parts made of CFRP to test for strength through the rigorous demands of the aerospace industry that much more important.

Non-destructive testing (NDT) through active and passive thermography has set new standards in this field. Both methods can be used to visualize and analyse a lot of materials for different types of errors. These methods save money due to the fact that the examined pieces remain intact, and are also efficient because thermal imagers can capture large areas. Facts that are becoming more relevant for the industry, as quality and reliability must always be matched with profitability.

Depending on the process, users can make temperature differences visible for processes that are inherent or caused by externally induced heat flows. Depending on the structure and the thermal conductivity of the analysed material, errors in deeper layers can also be precisely identified. Things like impact damage, delamination, inserts, curing or adhesive failures in frames and stringers can be accurately assessed in terms of type, size and location.

For such demanding tests, InfraTec provides two powerful solutions with the high-end camera series ImageIR ® and the VarioCAM ® High Definition series. The thermal imagers enable precise, high-resolution temperature measurements of CFRP panels, which are required due to the large differences in the thermo-physical properties of the fibre-reinforced composites. A specially-developed precision calibration ensures high measurement accuracy.

Both thermal imaging system series are impressive in their stand-alone versions and as components of turnkey automation solutions. In combination with efficient control and analysis, as well as customised and appropriate continuous operation excitation sources and controllers, InfraTec offers the total package. The NDT user can flexibly adapt these systems to different test conditions.

Infrared camera systems minimize crap and waste from testing procedures
Material tests using thermography save time and costs as test objects will not be destroyed but they could be used for further testing or quality problems could be corrected. NDT test with infrared camera systems provide good solutions for more and more applications as they can be used for a wide range of different materials and for different types of faults. A big advantage thereby is that thermographic testing procedures can be applied to larger areas at once in comparison to ultrasonic or other methods being focus on smaller zones.

Passive thermography as well as active heat flow thermography find faults
A major difference in usage of thermography in material testing results from the source the measured temperature differences derive from. At one side they could stem directly from the heating the test object will gain during its production process. This case is referred to as passive thermography. The other possibility is called active heat flow thermography or just active thermography. This is when the test object will be thermally activated by an external energy input for instance by a halogen radiator or a flash lamp.

Lock-in thermography is integrated in IRBIS ® 3 software
Active thermography can detect faults even more precisely when the activation of the test object will be carried out in a pulsed mode. Thereby it will even be possible to detect faults which are placed in deeper subsurface layers. Such analysis algorithms like the one of lock-in thermography are already available as a module of the IRBIS ® 3 software family. The adaptation to the specific application can be done quite easily and flexibly. InfraTec can also provide customer specific and complete active thermography test solutions.

Founded in 1991, the Dresden-based company InfraTec GmbH that ever since has been managed by its owners, offers a wide range of high-quality, innovative products and services in the field of infrared technology. About 200 staff members are facing the market’s demands as a challenge that they meet with detailed expertise, daily commitment and a high degree of quality awareness. A best possible consultation, an exemplary service and tailored product design, all by in-house development and production capacities, are used in order to fulfil the customer’s demands at the highest possible level. Therewith, InfraTec contributes considerably to the sustained success of its customers.

The high product quality of all InfraTec products is based on both a sound and permanent development process as well as on an optimised production. The focus of all processes concentrates on the satisfaction of our customers. A process definition is made by ISO 9001, the certified quality management system.
Mistras Group