Laminated Vehicle Glazing With Stiff Interlayer for Torque Resistance
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Solution Overview
Problem
Existing laminated vehicle glazings, particularly windshields, face challenges in maintaining mechanical robustness and strength while reducing weight, especially in out-of-plane torque tests, due to the use of thinner glass sheets without chemical strengthening, which can lead to interfacial peeling and breakage at attachments.
Innovation Solution
A laminated vehicle glazing design with a polymer interlayer featuring a major part and a stiff part adjacent to the major part, where the stiff part has a higher Young's modulus than the major part, providing enhanced adhesion and stiffness to support attachments like rear-view mirrors, thereby improving mechanical robustness and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If thinner glass sheets are used to reduce weight, then weight is reduced, but mechanical robustness and strength deteriorate
Solution Approach 1:
The interlayer is designed with different stiffness in different regions: a first region with lower stiffness and a second region with higher stiffness. This local differentiation allows the glazing to be lightweight overall while providing localized strength where attachments are mounted, resolving the contradiction between weight reduction and mechanical robustness.
Solution Approach 2:
The interlayer comprises a composite structure with a first interlayer material (softer) and a second interlayer material (stiffer). This composite approach enables the glazing to achieve both weight reduction through thinner glass and maintained strength through the stiff second region that prevents interfacial peeling at attachments.
2Strength
If chemical strengthening is applied to thinner glass sheets, then mechanical robustness is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the strengthening function from the glass itself and relocates it to the interlayer's second region. Instead of chemically strengthening the glass (which adds manufacturing complexity), the stiffer second interlayer material provides the necessary strength support, simplifying the manufacturing process while maintaining mechanical robustness.
Solution Approach 2:
The second region of the interlayer acts as an intermediary that provides mechanical support to thinner glass sheets without requiring chemical strengthening of the glass. This intermediary layer transfers and distributes stresses, enabling the use of simpler, non-chemically strengthened glass while maintaining overall structural strength.
3Ease of manufacture
If uniform interlayer material is used, then manufacturing is simplified, but local strength at attachments is insufficient
Solution Approach 1:
The interlayer transitions from a uniform structure to a non-uniform structure with a first region and a second region having different stiffness characteristics. This local quality differentiation provides enhanced strength at attachment areas (second region) while maintaining overall manufacturing feasibility through established lamination processes.
Solution Approach 2:
The interlayer is segmented into functionally distinct regions: a first region for general bonding and a second region for localized strength support at attachments. This segmentation allows each region to be optimized for its specific function while maintaining compatibility with standard manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively distributes torque forces across a larger area, enhancing the glazing's ability to withstand out-of-plane torque without breakage, while maintaining adhesion to the glass sheets, thus meeting regulatory standards and daily application requirements.
Implementation Method 1
the stiff part comprises at least one layer of a second interlayer material, wherein the stiff part is adhered to the first and second glass sheets and to the major part, and the second interlayer material has a higher Young's modulus than the first interlayer material
Implementation Method 2
the stiff part is adhered to the first and second glass sheets and to the major part
Data Source
Figure 1(a)
Figure 1(b)
Figure 1(c)
AI summary
Disclosed generally herein is a laminated vehicle glazing including first and second glass sheets and a polymer interlayer interposed therebetween. The interlayer includes a major part and a stiff part adjacent to the major part. The stiff part does not surround the major part, such that the major part is along at least one edge of the laminated vehicle glazing. The stiff part includes at least one layer made of a material that has a higher Young's modulus than that of the material used in the major part. Young's modulus in the thickness direction of the stiff part is higher than that of the major part.