Asymmetrical Stretch Composite Pipe Liner for Axial Length Stability
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Solution Overview
Problem
Existing pipe liners expand radially but also stretch in the axial direction, making it difficult to cut them to the appropriate length for insertion into pipes, leading to issues with fitting and stability.
Innovation Solution
A fibrous composite material with an asymmetrical stretch profile is developed, where the material is extensible in the cross-machine direction and substantially inextensible in the machine direction, achieved through the use of filament yarns or scrims, allowing for greater radial expansion without unwanted lengthwise extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible liner material is expanded radially to fit into the pipe, then the liner can be installed in situ, but the liner also expands in the axial direction making it difficult to cut to the appropriate length
Solution Approach 1:
The patent applies asymmetry by creating a fibrous composite with different stretch characteristics in different directions. The composite has an asymmetrical stretch profile where the ratio of cross-machine direction (CMD) to machine direction (MD) percent elongation is at least 3:1, allowing radial expansion while preventing axial stretching
Solution Approach 2:
The patent uses local quality by incorporating specific fibrous materials with directional properties. The composite includes materials that provide extensibility in the CMD while maintaining inextensibility in the MD, creating localized functional differences within the same structure
2Ease of operation
If the liner is made extensible to facilitate installation, then radial expansion is enabled, but axial stretching occurs causing fitting and stability issues
Solution Approach 1:
The asymmetrical stretch profile with CMD/MD elongation ratio of at least 3:1 creates directional dependency where radial expansion is facilitated while axial stability is maintained, resolving the contradiction between ease of installation and dimensional reliability
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 fibrous composite material allows for accurate cutting and fitting of pipe liners, ensuring they expand radially while maintaining stability in the axial direction, thus improving the installation process and reducing the risk of shrinkage or extension issues.
Implementation Method 1
the fibrous composite may be extensible in the cross-machine direction and substantially inextensible (i.e., may have little or no extensibility) in the machine direction
Implementation Method 2
the liner also tends to expand in the lengthwise or axial direction, thereby making it difficult to cut the liner to the appropriate length
Data Source
AI summary
A fibrous material or composite including a plurality of layers joined to one another, for example, by needlepunching, is disclosed. The fibrous composite generally has an asymmetrical stretch profile, such that the fibrous composite is more extensible in the cross-machine direction than in the machine direction. The fibrous composite may find particular use in forming a cure-in-place pipe liner.