Glass Container Stress Features for Crack Redirection
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Solution Overview
Problem
Glass containers used for storing pharmaceutical compositions face challenges in maintaining sterility due to potential cracks that can form during handling and transport, which may not be immediately noticeable, especially when adhesive labels are used.
Innovation Solution
The method involves forming a glass container with specific stress regions: a compressively stressed layer on the surface, a region under central tension that allows crack propagation, and a crack re-direction region with higher tensile stress to redirect cracks in a predetermined direction, thereby making them more noticeable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass containers are made with standard uniform thickness, then manufacturing is simple and cost-effective, but cracks can propagate unnoticed through the container wall compromising sterility
Solution Approach 1:
The patent applies local quality by creating a crack re-direction region with non-uniform thickness (reduced thickness) and different stress characteristics (higher central tension) in a specific location, while the rest of the container maintains standard uniform thickness. This localized modification redirects cracks to a visible location without complicating the overall manufacturing process
Solution Approach 2:
The patent implements preliminary action by pre-forming the crack re-direction region with specific stress characteristics during manufacturing. The compressively stressed layer and central tension region are established beforehand to guide crack propagation paths, so that when cracks occur during use, they automatically redirect to the predetermined visible location
2Ease of manufacture
If adhesive labels are applied to glass containers, then appearance and information display are improved, but cracks become less noticeable and sterility compromise is not detected
Solution Approach 1:
The patent uses the crack re-direction region as an intermediary mechanism. Instead of trying to make cracks visible through the label itself, the invention creates a structural feature that redirects cracks to a specific location where they become visible despite the presence of adhesive labels covering most of the container surface
3Strength
If glass containers have higher strength to prevent cracks, then durability is improved, but crack propagation control becomes more difficult
Solution Approach 1:
The patent applies parameter changes by modifying the stress distribution parameters within the glass container wall. A compressively stressed layer is created near the outer surface, and a central tension region is established in the crack re-direction region. These parameter changes enhance overall strength while controlling crack propagation paths through the stress field configuration
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
This approach enhances the durability of glass containers by preventing cracks from propagating unnoticed, maintaining the sterility of contents, and allowing for the identification of defective containers.
Implementation Method 1
forming a first region under a compressive stress on the first surface of the glass container, wherein the first region extends from the first surface to a depth of compression in the glass container
Implementation Method 2
forming a second region under a central tension, the second region extending from the depth of compression into the thickness
Implementation Method 3
forming a crack re-direction region in the first surface, wherein the crack re-direction region extends in a predetermined propagation direction for the crack and comprises a higher central tension than a remainder of the glass article in a direction substantially perpendicular to the predetermined propagation direction such that, upon the crack propagating and reaching the crack re-direction region, the crack is redirected along the predetermined propagation direction
Data Source
AI summary
A glass container comprises a glass body comprising a first region under a compressive stress extending from a surface of the glass body to a depth of compression and a second region extending from the depth of compression into a thickness of the glass body, the second region being under a tensile stress. The glass container also includes a localized compressive stress region having a localized compressive stress extending from the surface to a localized depth of compression within the body. The localized depth of compression is greater than the depth of compression of the first region. The glass container also includes a crack re-direction region extending in a predetermined propagation direction, wherein the crack re-direction region possesses a higher tensile stress than the tensile stress in the second region in a sub-region of the crack re-direction region, the sub-region extending substantially perpendicular to the predetermined propagation direction.