Working group
Intensified use of existing materials and the employment of new materials requires enhanced operational control procedures for condition monitoring and diagnosis of safety systems and processes, e. g. in mechanical engineering, civil engineering and environmental technology. Due to reasons of safety and costs, these control procedures should be rapidly applied, contactless and in-situ or in-line. Consequently, there are high demands on sensor technology and signal and image processing. For infrared (IR) thermography, this implies new areas of application within both micro and macro scales for individual testing, periodic investigation and long-term monitoring.
Experimental set-up for the investigation of concrete structures using active thermography. The photo shows the infrared radiators for heating the surface, the infrared camera and the computer system for recording the thermograms in real time.
IR thermography encompasses the determination of the surface temperature of an object using an IR camera. This temperature distribution is visualised in false colour or grey scale in a thermogram. Therefore, IR thermography is an imaging technology which is contactless and completely non-destructive. Data recording can be performed using time resolution. The applications are classified into passive and active methods: By using passive thermography, differences in emissivity and, if a temperature gradient is present, differences in temperatures can be related to subsurface structures. If additional energy is induced into the structure by heating or cooling, the procedure is called active thermography.
One of the main objectives of IR thermography for non-destructive testing is the detection and quantitative analysis of flaws and heterogeneities inside the structure being tested. These can be distinguished from the sound material if the thermal properties are different. In addition to direct heat sources, energy sources, which generate heat directly at a flaw or heterogeneity through dissipative processes, are being increasingly used.
Dr. rer. nat.