Characterization of Composite Structure Surface Uniformity using Interval Based Gradient Field Histogram Analysis of Thermographic Images (IGF-HA)

This paper presents a new approach to composite surface characterization using Image Histogram Analysis as a function of Gradient Field. Image sequences are weighed and combined in order to present a pattern change in the thermal response of a tested composite structure. Reaction Injection Molding samples used and subjected to thermal energy to characterize their surface uniformity and any existing damage. A threshold value is used for the purpose of segmenting and separating damaged from undamaged areas in the tested composite structure. Gradient field analysis established the critical time at which the surface started to show damage and segmented the tested images into areas of concern. The resulting histograms cover four main regions of interest according to the gradient intensities as a function of time. Each region is divided into eight subsections according to the corresponding limit value, resulting in thirty two subsections. Correlation between region gradient field and its histogram resulted in uncovering of surface deformities as a function of surface area thermal storage. The process is modeled mathematically.