1984-04-01

Failure Modes During Static and Impact Loading of Light-Weight Rectangular Glass Headlamps 840745

An approximate analytical solution for stress distribution in the rectangular lens of a glass headlamp due to static and impact loading is presented. Both low mass/high velocity and high mass/low velocity impact data and the resulting failure modes are discussed. Generally, glass headlamp lenses break either due to Hertz stress (front surface under high localized tension), or due to flexural stress (back surface under tension due to bending), or the combination of two. Failure due to flexural stress is illustrated by a star-crack, while that due to Hertz stress is illustrated by a Hertzian cone or “bullet hole” in the lens.
The failure mode during low mass/high velocity impact is predominantly Hertzian while that during high mass/low velocity impact is flexural for lenses 0.120″ to 0.150′ thick. No significant differences are observed in the impact resistance of standard and light-weight lenses in this thickness range.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 43% off list price.
Login to see discount.
Special Offer: With TechSelect, you decide what SAE Technical Papers you need, when you need them, and how much you want to pay.
X