Steel Pipe Waveform Design for Deformability
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Solution Overview
Problem
Existing techniques for improving the deformability of steel pipes to prevent buckling in earthquake-prone and non-permafrost areas increase labor and time in the pipe expansion process, as they require a smaller wavelength ratio and constant amplitude, which can lead to reduced deformability in certain situations.
Innovation Solution
A steel pipe with a waveform shape formed by a pipe expansion process, where the amplitude to wavelength ratio (a/w) is 0.038% or less, and a wavelength to Timoshenko's buckling wavelength ratio (w/λ) is greater than 0.8, allowing for improved deformability while reducing the labor and time required in the pipe expansion process, by determining the wavelength and amplitude based on the relationship between buckling-time bending angle and buckling wavelength ratio using Expression (1).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wavelength ratio of the waveform shape is reduced to improve deformability, then the deformability of the steel pipe is improved, but the labor and time required by the pipe expansion process increase
Solution Approach 1:
The invention changes the parameters of the waveform shape from the conventional approach (small wavelength ratio with constant amplitude) to a new parameter combination (wavelength ratio of 0.038% or less with amplitude of 0.06% or less of outer diameter). This parameter transformation resolves the contradiction by achieving improved deformability through a different parameter regime that does not require reduced die forwarding pitch, thus maintaining production efficiency.
2Ease of manufacture
If the amplitude of the waveform shape is kept constant throughout the pipe, then the manufacturing process is simplified, but the deformability may be lowered in some situations
Solution Approach 1:
The invention specifies both the wavelength ratio (0.038% or less) and amplitude (0.06% or less of outer diameter) parameters to be arranged throughout the pipe. This dual-parameter specification ensures that the waveform shape provides sufficient deformability while maintaining constant amplitude for manufacturing simplicity, resolving the contradiction between ease of manufacture and 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
This approach enhances the deformability of steel pipes, reducing the labor and time needed for the pipe expansion process, while maintaining a high level of buckling-time strain, making them suitable for severe environments like earthquake-prone areas.
Implementation Method 1
a pipe expansion process, by which a waveform shape is formed by outer diameters of the steel pipe
Data Source
AI summary
In a steel pipe having a waveform shape formed on an outer diameter thereof by a pipe expansion process, a value a/w is 0.038% or less, where a and w denote an amplitude and a wavelength of the waveform shape, respectively. A method of manufacturing a steel pipe having a waveform shape formed on an outer diameter thereof by a pipe expansion process includes a step of forming the waveform shape such that a value a/w is 0.038% or less, where a and w denote an amplitude and a wavelength of the waveform shape, respectively.