NHTSA’s Evaluation of Glazing Performance Testing

FMVSS No. 205, “Glazing Materials,” uses impact test methods specified in ANSI/SAE Z26.1-1996. NHTSA’s Vehicle Research and Test Center initiated research to evaluate a subset of test methods from ANSI Z26.1-1996 including the 227 gram ball and shot bag impact tests, and the fracture test. Additional research was completed to learn about potential changes to tempered glass strength due to the ceramic paint area (CPA), and to compare the performance of twelve by twelve inch flat samples and full-size production parts. Glass evaluated included tempered rear quarter, sunroof, and backlight glazing. Samples with a paint edge were compared to samples without paint, and to production parts with and without paint in equivalent impact tests. A modified shot bag with stiffened sidewalls was compared to the ANSI standard shot bag. The fracture test comparison included evaluating the ANSI Z26.1 impact location and ECE R43 impact location. Over 900 tests covering the various test conditions outlined above were completed. High-speed video was recorded for each test to capture break initiation and propagation. Overall trends showed a decrease in glazing strength due to the CPA when impacted with the 227 gm ball. The modified shot bag concentrated the impact force, resulting in more glass breakages than with the ANSI bag. ECE R43 fracture test location produced larger pieces than the ANSI fracture location. Results of this study may be used to help determine if the tests in ECE R43 and ANSI/SAE Z26.1-1996 can be harmonized to reduce testing burden, and also if the effect of the ceramic paint on glazing performance could be considered in evaluating glazing performance.