Teardrop Pressure Vessel Wall Profile for Lower Stress in AM
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Solution Overview
Problem
Existing additive manufacturing processes for pressure vessels require internal support structures for round passages, leading to stress concentrations and increased weight when converting to teardrop profiles, which are necessary to comply with manufacturing constraints.
Innovation Solution
A non-uniform wall thickness profile for pressure vessels, featuring a teardrop shape with a curved segment, thickened regions, and transition regions, reduces stress concentrations without the need for internal support structures, using additive manufacturing to form thin-walled structures with minimal material addition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If round passages are converted to teardrop profile to comply with additive manufacturing constraints, then support structures are eliminated, but stress concentrations increase significantly
Solution Approach 1:
The wall thickness is varied locally around the teardrop passage: thickest at the apex (opposite the rounded end), thinnest at the rounded end, and intermediate at the sides. This local quality variation reduces stress concentrations at critical locations while maintaining the teardrop profile needed for additive manufacturing compliance.
Solution Approach 2:
The wall thickness parameter is changed from uniform to non-uniform distribution around the teardrop passage. By adjusting the thickness parameter at different angular positions, the design achieves both manufacturing compliance and reduced stress concentrations through optimized material distribution.
2Strength
If wall thickness is uniformly increased to reduce stress concentrations, then structural strength improves, but component weight increases undesirably
Solution Approach 1:
Instead of uniform wall thickening, the solution applies local quality by concentrating material where stress concentrations occur (apex and sides of teardrop) while maintaining thinner walls at the rounded end where stresses are lower. This optimizes structural strength while minimizing weight.
Solution Approach 2:
The wall thickness parameter is optimized to vary around the passage perimeter, creating a non-uniform distribution that provides enhanced strength at critical stress locations without the penalty of uniform weight increase throughout the entire component.
3Ease of manufacture
If teardrop profile is used with uniform wall thickness, then additive manufacturing is enabled, but stress concentrations occur at tight radii
Solution Approach 1:
The wall thickness is made non-uniform with specific emphasis on thickening at the apex and side regions where the teardrop profile creates stress concentrations, while keeping the rounded end region thinner. This local differentiation addresses stress issues without compromising the additive manufacturing compliant teardrop geometry.
Data Source
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AI summary
A pressure vessel includes a body (12) defined by a cross-sectional shape (14) along a plane transverse to a centerline (22). The cross-sectional shape includes an inner surface (16) defining an interior void and a wall (20) extending from the inner surface to an outer surface (18) defining an exterior of the body. The inner surface includes an arcuate region (24) and a gabled region (26). The gabled region forms a curved interior peak (28) opposite a center of the arcuate region. The arcuate region and the gabled region together define a teardrop shape. The wall includes a curved segment (32) along the arcuate region having a curved segment minimum thickness at a location opposite the interior peak, an apex (34) aligned with the interior peak and having an apex thickness, and thickened regions adjacent intersections between gabled region and the arcuate region and having greater radial thickness than the curved segment minimum thickness.