What are the differences in impact resistance between tempered laminated glass layers and interlayers with different thickness combinations?
Publish Time: 2025-03-25
In the field of construction and security protection, tempered laminated glass is like a silent guardian, and its ability to resist impact is often hidden under a seemingly ordinary transparent plane. This ability is not accidental, but the result of a careful ratio of the thickness of the glass layer and the interlayer. Every millimeter of change may rewrite the fate of glass when facing impact and create a completely different protection story.The thickness selection of the tempered glass layer constitutes the first line of defense against impact performance. Thicker tempered glass layers (such as more than 6mm) have higher initial rigidity and can effectively disperse the area of impact force. When a flying stone or blunt object hits, the surface compressive stress layer of the thick glass layer is like a solid shield that can withstand greater initial impact energy. However, simply increasing the thickness of the glass is not a panacea. Although overly thick glass can resist the initial impact, once it breaks through the critical point, the entire piece of glass will instantly disintegrate into fine particles and completely lose its residual bearing capacity. This "all or nothing" characteristic makes the solution that relies solely on the thickness of the glass have obvious defects in security protection.The thickness and type of the interlayer play a key role in the second act. The thickness of traditional PVB film between 0.38mm and 1.52mm is essentially to find a balance between flexibility and strength. Thicker interlayers (such as above 1.14mm) can absorb more impact energy and convert point impact into surface load through plastic deformation of polymer materials. When the impact penetrates the outer glass, the thick interlayer is like a high-strength net, firmly grasping the glass fragments to prevent them from flying and hurting people. The emergence of SGP ionic interlayer has rewritten this rule. The thickness of only 0.89mm can achieve the penetration resistance of traditional PVB 1.52mm, thanks to its higher shear modulus and elongation at break.The most subtle thing is the art of combining the thickness of the glass layer and the interlayer. The combination of 2.5mm tempered glass and 1.52mm PVB may show excellent wind pressure resistance, but it is not as good as the combination of 3mm glass and 0.76mm PVB in resisting baseball impact. This is because the thinner but harder glass layer can transfer the impact energy to the interlayer faster, while the thicker interlayer provides a longer energy absorption stroke. In the design of bulletproof glass, this ratio is more sophisticated, usually using multiple layers of thinner glass and interlayers alternately stacked to ensure that each glass layer can contribute its strength and provide progressive energy absorption through multiple layers of interlayers.Temperature factors add another layer of complexity to thickness selection. In low temperature environments, PVB interlayers will become harder and more brittle. At this time, the returns of increasing the thickness of the interlayer are diminishing. Instead, the thickness of the glass layer should be appropriately increased to compensate. In high temperature areas, thicker interlayers can better maintain their viscoelasticity and prevent the glass from self-exploding due to thermal stress. This environmentally adaptable thickness adjustment reflects the material engineers' careful consideration of regional differences.Modern simulation technology provides a new perspective for thickness optimization. Finite element analysis can simulate the stress propagation path of different thickness combinations under impact loads, revealing weak links that are difficult to find in traditional tests. These digital insights lead to asymmetric thickness design - for example, the front windshield of a car adopts a configuration with a thinner outer layer and a thicker inner layer, which not only meets the requirements of pedestrian protection, but also ensures the safety of passengers in the car. This fine-tuning of thickness with an accuracy of 0.1mm is the subtlety of contemporary material engineering.From the curtain wall of a skyscraper to the bulletproof counter of a bank, the thickness combination of tempered laminated glass is like a tailor-made armor, writing a poem belonging to material science between transparency and safety. Behind each set of numbers is a deep understanding of impact mechanics, a precise calculation of the safety boundary, and a silent commitment to human protection. When we enjoy the sunshine and view in a glass building, we may not think that this sense of security comes from those invisible thickness codes.
