Long-term Bendable Glass Proof-test for Edge Stability
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Solution Overview
Problem
Thin glass materials with thicknesses less than 500 μm are prone to breaking due to edge damage and stress during winding and storage, leading to interruptions in processing and short-term stabilization issues, with existing methods failing to ensure long-term bendability and stability.
Innovation Solution
A long-term bendable glass material is developed with a proof-test that measures crack depth to classify its stability, using the formula ac = (K1c·R)/(E·d)^2, where ac is the critical crack depth, K1c is fracture toughness, R is bending radius, E is elasticity modulus, and d is thickness, to determine if the glass is suitable for long-term storage and use with a low probability of breaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thin glass is wound into a roll for handling and storage, then ease of operation is improved, but reliability deteriorates due to bending stresses causing breakages
Solution Approach 1:
The patent applies preliminary action by conducting a proof-test before the glass is put into service. The glass is bent to a specified radius and stored for a minimum period (e.g., 168 hours) to allow subcritical cracks to propagate. This preliminary stress application identifies and eliminates weak glass pieces before they cause problems during actual use, resolving the contradiction between handling convenience and breakage resistance.
Solution Approach 2:
The patent converts the harmful effect of bending stresses (which cause breakages) into a beneficial proof-test mechanism. By intentionally applying bending stresses during a controlled proof-test period, subcritical cracks are allowed to grow to detectable levels or cause breakages before service. This transforms the harmful stress effect into a useful quality control mechanism that ensures long-term reliability.
2Ease of operation
If glass is subjected to bending stresses during winding, then ease of operation is improved, but manufacturing precision deteriorates due to edge damage and crack progression
Solution Approach 1:
The proof-test performs preliminary action by subjecting the glass to bending stresses before final processing. Edge damage and crack progression that would occur during normal handling are pre-applied and identified during the proof-test period. This allows defective pieces to be removed before they affect manufacturing precision in subsequent processing steps.
Solution Approach 2:
The patent converts the harmful edge damage and crack progression into a beneficial quality filter. By allowing these defects to manifest during the controlled proof-test period, the system identifies and eliminates compromised glass pieces before they reach production lines. This transforms potential manufacturing precision problems into a pre-screening mechanism.
3Duration of action of stationary object
If glass is stored for long-term use, then duration of action is improved, but reliability deteriorates due to delayed breakages from subcritical crack growth
Solution Approach 1:
The patent applies preliminary action by implementing a mandatory proof-test storage period (minimum 168 hours, preferably up to several weeks or months) before the glass is put into service. During this period, subcritical cracks are allowed to propagate under controlled conditions. This preliminary aging process ensures that any glass pieces with hidden defects break or show signs of degradation before they are installed in long-term applications, thereby ensuring reliability for the intended service duration.
Solution Approach 2:
The patent converts the harmful effect of subcritical crack growth (which causes delayed breakages) into a beneficial proof-test mechanism. By intentionally allowing cracks to grow during the proof-test storage period, the system identifies and eliminates weak pieces before service. This transforms the harmful long-term crack propagation into a useful screening process that ensures long-term reliability.
4Reliability
If a proof-test is implemented to classify glass stability, then reliability is improved, but loss of time increases due to extended storage and testing requirements
Solution Approach 1:
The patent applies parameter changes by establishing specific proof-test parameters: minimum storage time (168 hours), bending radius (0.5mm to 500mm), and temperature conditions (e.g., 20°C ± 5°C). These standardized parameters create a controlled test environment that balances reliability assessment with time efficiency. By optimizing these parameters, the proof-test achieves reliable classification without unnecessarily extending the testing duration.
Solution Approach 2:
The patent applies local quality by differentiating proof-test requirements based on glass thickness and intended application. Different glass thicknesses (e.g., 3μm to 500μm) may have different minimum proof-test durations and bending radii. This localized approach ensures that each glass type undergoes appropriate testing without subjecting all glass to unnecessarily long test periods, thereby balancing reliability with time loss.
Data Source
AI summary
A method for producing long-term bendable glass material includes: bending a glass material in a bending radius in a range of 1 mm to 107 mm; storing the bent glass material for a time period of at least 1 day; inspecting at least a portion of the bent glass material for damage after the storing; and classifying the inspected bent glass material as a reject if damage is detected or as a long-term bendable glass material if no damage is detected.