This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Characterization and Quantification of In-Service Windshield Fracture Mechanisms and Evaluation of Laminate Sharp Impact Resistance as a Function of Construction
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 14, 2020 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
Examination of field-fractured windshields was conducted for purposes of determining the principle fracture mechanisms experienced in-use. Samples for the study were gathered both in the United States (New York) and in Europe (France) to explore whether the primary causes of failure were similar for the different geographic regions. In total, over two hundred individual field-fractures were obtained and examined for the study. Detailed fracture analysis of the parts was performed, and multiple fracture mechanisms were identified and quantified. It was found that the two most frequently observed failure modes were common for both regions with the most frequent cause (~70%) of fractures being due to sharp contact of the exterior ply, while Hertzian cone cracking of the outer ply was the second leading cause (~20%). Several other modes were also identified.
Given that sharp impact fracture was the dominant observed failure mode, a high-speed, sharp impact test method was developed. The method consisted of using compressed gas to accelerate a ~2g diamond tipped dart into test samples and the method was thus named “Blow Dart”. The test method created fractures that closely replicated the sharp impact fracture mechanisms observed in field parts.
Blow Dart impact testing of numerous laminate constructions was performed, and results showed that sharp impact resistance of laminates was directly related to the square of the outer ply thickness of the laminate. Inner ply thickness also played a role, with impact resistance improving with reduced inner ply thickness. It was therefore concluded that highly asymmetric constructions utilizing a thick outer ply and a thin inner ply are preferred to improve durability against the most prevalent field failure mode for windshields. Furthermore, it was found that substantial light-weighting vs. today’s conventional windshields could be achieved while concurrently improving sharp impact resistance.
CitationCleary, T., Tremper, T., Huten, T., Strong, D. et al., "Characterization and Quantification of In-Service Windshield Fracture Mechanisms and Evaluation of Laminate Sharp Impact Resistance as a Function of Construction," SAE Technical Paper 2020-01-0607, 2020, https://doi.org/10.4271/2020-01-0607.
Data Sets - Support Documents
|[Unnamed Dataset 1]|
|[Unnamed Dataset 2]|
|[Unnamed Dataset 3]|
|[Unnamed Dataset 4]|
- Campfield, R. , “Facts and Findings about Windshields,” May 1, 2003, www.insurancejournal.com/services/newswire/2003/05/01/41550.htm.
- Quain, J.R. , “When the Windshield Helps Drive the Car, a Repair Isn’t So Simple,” Feb. 7, 2019, https://www.nytimes.com/2019/02/07/business/windshield-repairs.html.
- Cleary, T., Huten, T., Strong, D., and Walawender, C. , “Reliability Evaluation of Thin, Lightweight Laminates for Windshield Applications,” SAE Int. J. Passeng. Cars - Mech. Syst. 9(1):353-359, 2016, https://doi.org/10.4271/2016-01-1401.
- Gulati, S.T., Hagy, H.E., and Bayne, J.F. , “Delayed Cracking in Automotive Windshields,” presented at in the 7th International Symposium on Nondestructive Characterization of Materials, Prague, Czech. Republic, June 19-23, 1995.
- Hertz, H. , On Elastic Contact of Solids, in Miscellaneous papers by H. Hertz edited by Jones and Schott (London, Macmillan, 1896).
- Lawn, B.R. , Fracture of Brittle Solids Second Edition (Cambridge, UK: Cambridge University Press, 1993).
- Argon, A.S., Hori, Y., and Orowan, E. , “Indentation Strength of Glass,” J. Am. Ceram. Soc. 43(2):86-96, 1960.
- Knight, C.G., Swain, M.V. , and. Chaudri, M.M., “Impact of Small Steel Spheres on Glass Surfaces,” J. Mater. Sci., 12  1573-1586 (1977).
- Chaudri, M.M. and Walley, S.M. , “Damage to Glass Surfaces by the Impact of Small Glass and Steel Spheres,” Philos. Mag. A 37(2):153-165, 1978.
- Cleary, T.M., and Varner, J.R. , “Crack Initiation During Hertzian Indentation of Normal and Anomalous Glasses - A Study Using Fractography and Acoustic Emission,” in Fractography of Glasses and Ceramics III, Ceramic Transactions, vol. 64 (Westerville, OH, The Am. Ceram. Soc., 1993).
- Frechette, V.D. , “Failure Analysis of Brittle Materials,” Advances in Ceramics, vol. 28 (Westerville, OH, The Am. Ceram. Soc., 1990).
- Cleary, T.M. and Nichols, R.T. , “Adhesive Induced Fracture of Automotive Glass,” in Fractography of Glasses and Ceramics V, Ceramic Transactions, vol. 199 (Westerville, OH, The Am. Ceram. Soc., 2006).
- Trate, D.J., Griffin, J.A., and Zickel, M. , “Windshield Investigation - Manufacturing and Installation Stresses,” SAE Technical Paper 1999-01-3160, 1999, https://doi.org/10.4271/1999-01-3160.
- Gulati, S.T., Helfinstine, J.D., and Roe, T.A. , “Strength Degradation of Automotive Windshield from Manufacturing to On-Road Service,” presented at in International Congress on Glass, Edinburgh, Scotland, July 1-6, 2001.
- Grant, P.V., Cantell, W.J., McKenzie, H., and Corkhill, P. , “The Damage Threshold of Laminated Glass Structures,” Int. J. Impact Eng. 21:737-746, 1998.
- Durkop, D. and Weibman, R. , “Investigation of the Mechanism of Stone Impact on Laminated Glass Windscreens,” in XV, International Congress on Glass, 1989, vol. 3a.
- Cleary, T.M., Huten, T., Bhatia, V., Qarosh, Y. et al. , “Lighter, Tougher, and Optically Advantaged: How an Innovative Combination of Materials Can Enable Better Car Windows Today,” American Society Bulletin 96(4), May 2017.
- Linnhofer, D., and Durkop, D. , “Resistance of Glazings to Stone Impact,” in Proceedings AUTOTEST 96 Conference, IDIADA, Spain, 1996.