Lock-In Thermography Phase Analysis
Lock-in thermography phase analysis is a modulated thermographic technique that uses the phase shift between excitation and response to detect depth-resolved defects. It allows precise measurement of thermal diffusivity and heat capacity of materials.
Physikalisch-chemischer Wirkmechanismus
Lock-in thermography phase analysis uses a modulated excitation source, e.g., pulsed laser light or periodic temperature variation. The material's thermal response is recorded and compared with the excitation. The phase shift between excitation and response provides information about the material's thermal conductivity and heat capacity.
Metallurgical Relevance & Welding Risks
This method is particularly useful for detecting deep defects, such as cracks or inhomogeneities, in materials. It can also be used for monitoring welding processes and quality control. A major drawback, however, is the complexity of the equipment and the specialized knowledge required for its operation.
Werkstattpraxis & Handlungsanweisungen
To successfully apply lock-in thermography phase analysis in the workshop, follow these steps:
1. Use a high-quality lock-in thermography device.
2. Ensure the material is homogeneous and free of surface contaminants.
3. Select the correct excitation frequency and amplitude based on the material's properties.
4. Carefully analyze the phase shift between excitation and response to identify defects.