Experimental and numerical analysis of laser reflection for optical-thermal process modeling of tape winding

Temperature measurement in laser assisted tape winding (LATW) has been a source of great interest since the laser winding process becomes a popular way for producing new thermoplastic products. The accurate temperature of tape surfaces in this process is highly dependent on the optical behavior of materials. Changing the texture of materials is expected during the process which consequently causes changing in reflectance from the surfaces. The reflectance measurement is considered in the category of the optical measurement. In this research, the reflectance measurement is studied to characterize the optical response of material surface in a high temperature up to the melting point of the materials by using a heating plate. To do so, different thermoplastic materials were employed for capturing reflection patterns. It was found that different shapes and intensities can be attained for a specific material. Furthermore, during increasing the temperature, some shrinking in width of the tape has been observed probably due to relaxation of the residual stresses which also has an influence on texture architecture of the tape by moving fibers on the surface and changing the distance between them. The current observations suggest new modifications for the already developed BRDF function [1] to simulate the anisotropic reflection behavior as a function of temperature and surface texture. A three-dimensional (3D) optical model is used to simulate the laser intensity distribution on the tape surface. The predicted heat flux distribution is used in a 2D steady-state fully implicit thermal model considering advection term in the heat transfer equation to calculate the temperature distribution. Moreover, this gives us a better understanding of the phenomenological interaction on the surface of different samples at different temperatures to predict the surface temperature of the tape and substrate more accurately based on the proposed process models.