Quadrangular Metal Pipe with Local Strength Zones for Impact Resistance
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Solution Overview
Problem
Metal pipes with quadrangular cross sections used as structural members tend to protrude excessively when subjected to impacts exceeding their yield strength, particularly when their wall thickness is reduced for weight reduction, leading to significant deformation and potential damage.
Innovation Solution
A metal pipe design featuring a quadrangular cross section with high-strength and low-strength portions, where the high-strength portions have a yield strength of at least 500 MPa and the low-strength portions have a yield strength of 60 to 85% of the high-strength portions, strategically positioned to absorb and distribute impact loads, reducing the extent of deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the wall thickness of the metal pipe is reduced to reduce weight, then the weight of the metal pipe is reduced, but the extent of protrusion occurring when the pipe is sharply bent by an impact increases
Solution Approach 1:
The side walls are designed with non-uniform thickness distribution, featuring thicker portions at specific locations and thinner portions at other locations. This local quality variation allows the pipe to maintain lower overall weight while providing enhanced impact resistance at critical areas where protrusion is most likely to occur during sharp bending.
2Weight of moving object
If the wall thickness of the metal pipe is reduced to reduce weight, then the weight of the metal pipe is reduced, but the impact resistance of the metal pipe deteriorates
Solution Approach 1:
The side walls are designed with non-uniform thickness distribution, featuring thicker portions at specific locations and thinner portions at other locations. This local quality variation allows the pipe to maintain lower overall weight while providing enhanced impact resistance at critical areas where protrusion is most likely to occur during sharp bending.
3Ease of manufacture
If the metal pipe is designed with uniform strength distribution, then the manufacturing process is simplified, but the extent of deformation under impact increases
Solution Approach 1:
The side walls are designed with non-uniform thickness distribution, featuring thicker portions at specific locations and thinner portions at other locations. This local quality variation allows the pipe to maintain lower overall weight while providing enhanced impact resistance at critical areas where protrusion is most likely to occur during sharp bending.
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3
AI summary
A metal pipe 1 has a quadrangular cross section. The metal pipe 1 includes a pair of side walls 11 and 12 facing each other and having a height H, a top portion 13 connected to an upper edge of each of the pair of side walls 11 and 12, and a bottom portion 14 connected to a lower edge of each of the pair of side walls 11 and 12. The metal pipe 1 has a length six times the height H of the side walls 11 and 12 or more. Each of the pair of side walls 11 and 12 includes a high-strength portion 11A or 12A and a pair of low-strength portions 11B or 12B. Each high-strength portion 11A or 12A has a dimension not less than (2/3) H and not more than 3H as measured in the longitudinal direction of the metal pipe, the high-strength portions forming opposite portions of the pair of side walls 11 and 12, each high-strength portion having a yield strength not less than 500 MPa. The low-strength portions 11B or 12B sandwich the high-strength portion 11A or 12A as determined along the longitudinal direction of the metal pipe, each low-strength portion having a yield strength of 60 to 85 % of that of the high-strength portion 11A or 12A.