Initial attempts to compile an analytical model by analogy to thermal impulse welding (13) provided serviceable results for temperature progression in cases where the absorbing part had a high absorption constant.
An increase in the absorption constant and hence the introduction of the laser radiation into the layers close to the surface of the absorbing component (surface absorption) ultimately lead to uniformly deep melting in both parts being joined by laser transmission.
where K is the absorption constant describing the absorption properties of the material.
The absorption constant that describes the absorption properties of the colored part being joined is the sole degree of freedom in the simulation of temperature profiles with the aid of finite element analysis.
An effective absorption constant that remains constant over the entire temperature range was assumed here for polypropylene with 0.
In this publication, it was assumed that a clear increase results in the absorption constant in the melting range of the material, in particular.
1] for the effective absorption constant can be used to calculate the measured melt layer thicknesses, with just slight deviations that can be attributed to the measuring inaccuracy.
Useful results for temperature development were obtained in cases of high absorption constants by setting up an analytical model by analogy to single-sided heat impulse welding.