Shoulder Rib Geometry for PET Bottle Top Load Resistance
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Solution Overview
Problem
Current polymeric containers, particularly PET bottles, face issues with buckling and ovalization under top load due to the flexibility of existing stiffening ribs, which fail to effectively transfer top load forces to the body ribs, compromising their structural integrity and resistance to compressive forces.
Innovation Solution
The introduction of a shoulder rib with a maximum height that is about 5 times greater than its maximum depth, allowing for efficient transfer of top load forces to the body ribs without compression or excessive rigidity, thereby enhancing the container's ability to absorb and distribute forces uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing stiffening ribs are used in the container shoulder, then the container can resist ovalization from internal vacuum forces, but the ribs buckle and ovalize under top load
Solution Approach 1:
The patent applies different rib configurations to different locations on the container. The shoulder ribs have a specific geometry with optimized curvature and thickness designed specifically for top load resistance, while other ribs may have different characteristics for vacuum resistance. This localized optimization allows each rib to perform its specific function effectively without compromising the other.
Solution Approach 2:
The shoulder ribs extend vertically along the container shoulder, adding a vertical dimension to the rib structure. This vertical orientation and extended length provide additional structural support against top load forces while maintaining the horizontal rigidity needed for vacuum resistance. The three-dimensional configuration of the ribs creates a more comprehensive load-bearing structure.
2Strength
If vacuum absorbing ribs are used in the shoulder location, then internal vacuum forces are absorbed, but the ribs are too flexible and ovalize under top load
Solution Approach 1:
The patent modifies the geometric parameters of the shoulder ribs, specifically optimizing the curvature radius, thickness, and length ratios. These parameter changes increase the rib's flexural rigidity to resist top load forces while preserving its ability to absorb vacuum forces. The specific ratio of rib length to container diameter and rib thickness to wall thickness are carefully controlled to achieve the desired balance.
3Reliability
If the shoulder rib is made more rigid to prevent ovalization under top load, then top load performance improves, but the rib becomes too stiff to absorb vacuum forces effectively
Solution Approach 1:
The shoulder rib design incorporates dynamic characteristics that allow it to adapt to different loading conditions. Under top load, the rib's geometry provides sufficient rigidity to prevent ovalization. Under vacuum conditions, the same geometry allows controlled deformation for energy absorption. The rib acts dynamically, changing its effective stiffness based on the type of force applied.
Data Source
AI summary
A polymeric container including a finish defining an opening of the container. A shoulder of the container is between the finish and a body of the container. A base of the container is at an end of the body opposite to the shoulder. The base is configured to support the container upright. A plurality of body ribs are at the body. A shoulder rib is between the shoulder and the body. The shoulder rib has a maximum height that is about 5 times greater than a maximum depth of the shoulder rib.