lämpöimpulssimenetelmälle

The thermal impulse method, known in Finnish as lämpöimpulssimenetelmä, is a non-destructive testing technique used to determine the thermal conductivity of materials. It is particularly useful for characterizing insulating materials and composites where traditional methods might be difficult to apply. The fundamental principle involves applying a short, controlled burst of heat to a sample and then measuring the temperature rise over time at specific points on the material's surface.

The heat source is typically a thin electrical resistance wire or a thin film heater embedded in or placed on the surface of the material. The electrical power supplied to the heater is precisely controlled and measured, providing a known energy input. Temperature sensors, such as thermocouples or resistance temperature detectors, are strategically positioned at known distances from the heat source to record the transient temperature response.

By analyzing the rate at which the heat dissipates through the material, engineers and scientists can calculate its thermal diffusivity and, consequently, its thermal conductivity. The duration of the heat pulse is kept short enough to ensure that heat transfer is primarily one-dimensional and that heat losses to the surroundings are minimized. This method offers advantages in terms of speed and the ability to test samples in situ or in complex geometries. It finds applications in fields such as building insulation assessment, aerospace materials, and the characterization of polymers and ceramics.