Composite Pressure Vessel Structure for Pinch-Off Durability
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Solution Overview
Problem
Pressure vessels face a challenge in achieving a balance between weight reduction, internal capacity, and durability, as increasing thickness to enhance strength compromises weight and capacity, while thinning for weight reduction and capacity sacrifices durability.
Innovation Solution
A pressure vessel design with a cylindrical straight body section and hemispherical dome sections, where the pinch-off regions are strategically positioned to reduce stress concentration, using a fiber-reinforced resin material with a specific distance ratio and direct blow molding method to maintain durability without excessive thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the main body is increased to enhance strength at the pinch-off region, then durability is improved, but weight increases and internal capacity decreases
Solution Approach 1:
The outer shell is designed with non-uniform thickness, providing localized reinforcement at the pinch-off region where stress concentration occurs. This allows the main body to maintain overall thinness for weight reduction while having targeted thickness enhancement only where structurally necessary, thus resolving the contradiction between durability and weight.
Solution Approach 2:
The pressure vessel employs a composite structure combining a thin resin main body with an outer shell of fiber-reinforced resin material. This composite design enables the thin-walled main body to achieve sufficient strength and durability through the reinforcing outer shell, avoiding the need to increase main body thickness and thereby preventing weight increase and capacity reduction.
2Reliability
If the thickness of the main body is increased to enhance strength at the pinch-off region, then durability is improved, but internal capacity decreases
Solution Approach 1:
The outer shell provides localized reinforcement at the pinch-off region through non-uniform thickness distribution, enabling the main body to remain thin throughout most of its volume. This preserves maximum internal capacity while providing targeted strength enhancement only where stress concentration occurs, resolving the contradiction between durability and internal capacity.
Solution Approach 2:
The composite structure of a thin resin main body combined with a fiber-reinforced outer shell allows the main body to maintain minimal thickness for maximum capacity, while the outer shell compensates for strength deficiencies at critical regions through material reinforcement rather than thickness increase.
3Weight of moving object
If the main body is thinned to reduce weight and increase internal capacity, then weight reduction and capacity are achieved, but durability is sacrificed
Solution Approach 1:
The thin-walled main body achieves sufficient durability not through increased thickness but through the composite effect of the fiber-reinforced outer shell. The carbon fiber or glass fiber reinforcement in the outer shell provides the necessary strength and damage resistance, allowing the main body to be thin without sacrificing durability.
Solution Approach 2:
The outer shell is designed with varying thickness to provide enhanced protection specifically at the pinch-off region where stress concentration and damage initiation are most likely. This localized quality enhancement ensures durability at critical points while maintaining overall thinness for weight reduction.
4Volume of moving object
If the main body is thinned to increase internal capacity, then capacity is improved, but durability is sacrificed
Solution Approach 1:
The fiber-reinforced outer shell compensates for the reduced durability that would normally result from thinning the main body. The composite structure allows the main body to be as thin as possible for maximum capacity while the outer shell provides the necessary strength and damage resistance to ensure durability.
Solution Approach 2:
The outer shell provides targeted reinforcement at the pinch-off region where thinning the main body would most critically impact durability. This localized quality enhancement ensures that capacity is maximized through overall thinness while durability is preserved at stress-concentration points through selective reinforcement.
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 achieves a lightweight pressure vessel with sufficient capacity and excellent durability, suppressing damage from internal pressure and extending the number of usable cycles.
Implementation Method 1
an outer shell formed of a fiber reinforced resin material including a reinforcing fiber and a matrix resin, the outer shell being provided on the outside of the resin main body
Implementation Method 2
The main body is generally formed by direct blow molding, rotational molding, injection molding, extrusion molding
Data Source
AI summary
A pressure vessel including: a cylindrical straight body section and dome sections provided at both ends of the body section, where: the body section and the dome sections are composed of a resin main body, and an outer shell made of a fiber reinforced resin material, the outer shell being on the outside of the main body; each of dome sections has pinch-off regions extending from a tip of the dome section toward the body section; and when an end of each of the pinch-off regions opposite to the tip of the dome section is located in a region where a distance from the tip of the dome section to the end of each of the pinch-off regions opposite to the tip of the dome section in the axial direction of the straight body section is less than a distance from the tip of each of the dome sections to a boundary between the straight body section of the main body and each of the dome sections in the axial direction of the straight body section.