On the pummel test and pummel-value evaluation of polyvinyl butyral laminated safety glass

Abstract

Laminated safety glass is popularly used as facades and structural elements in buildings. For safety concerns, the bonding between glass and interlayer needs to be ensured. Pummel test is one of the most commonly used approaches to evaluate the interfacial adhesion of laminated glass. This paper is concerned with the development of a software-based pummel-value evaluation method. First, a series of pummel tests were conducted to characterise the adhesion capacities of various types of Saflex® PVBs. Then, a software-based evaluation method was proposed using MATLAB. The basic idea is to quantitatively characterise the fracture patterns and texture features of digital images based on Gray-Level-Co-Occurrence-Matrices (GLCM) and the Haralick features. The pummel values were subsequently classified through comparing the Haralick features from the test samples with that from the reference samples. To enhance the reliability of the proposed evaluation method, image equalization was adopted to minimize the impact of various light conditions, and influences of the offset distance and image resolution were studied based on a parametric analysis to search optimal parameter combinations. The results from the software-based method were validated against visual evaluations, and good agreement can be observed if the glass surfaces are adequately pulverized.