Vehicle Structural Member Impact Deformation Control
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Solution Overview
Problem
Structural members with tubular portions tend to sharply bend and protrude when impacted, leading to significant deformation, and reducing wall thickness increases this protrusion, while existing techniques do not effectively minimize deformation upon impact.
Innovation Solution
A structural member with a closed-cross-section structure featuring a hat member and a reinforcing member, where the side walls have high-strength and low-strength portions with specific yield strength ratios, and the reinforcing member is positioned to overlap high-strength portions, dispersing deformation to low-strength areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the wall thickness of the structural member is reduced to decrease weight, then the weight is reduced, but the extent of protrusion upon impact increases
Solution Approach 1:
The side walls are designed with non-uniform thickness: thicker in the high-strength portions (at least 1.5 times the minimum thickness) and thinner in the low-strength portions. This local variation in quality allows the structure to maintain high impact resistance where needed while reducing overall weight by removing material from less critical areas.
Solution Approach 2:
The structural member combines materials or regions with different mechanical properties - high-strength portions with yield strength not lower than 500 MPa and low-strength portions with yield strength of 60-85% of the high-strength portion. This composite approach enables optimized weight-strength balance by placing appropriate material properties in appropriate locations.
2Ease of manufacture
If the structural member is designed with uniform strength throughout, then manufacturing is simplified, but the extent of protrusion upon impact increases
Solution Approach 1:
The side walls incorporate high-strength portions and low-strength portions with different thicknesses and mechanical properties at specific locations. The high-strength portions are positioned to overlap with the reinforcing member, creating localized strength enhancement that effectively reduces protrusion upon impact while maintaining manufacturing feasibility through defined geometric variations.
3Strength
If a reinforcing member is added to reduce protrusion, then impact resistance improves, but device complexity increases
Solution Approach 1:
The reinforcing member is integrated with the hat-shaped cross-section member such that both ends of the reinforcing member overlap the high-strength portions of the side walls. This merging approach combines the reinforcing function with the existing structural geometry, reducing protrusion upon impact while avoiding the need for completely separate reinforcement systems.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B~2C
AI summary
A structural member 10 includes a closed-cross-section structure having a hat member 1 and a closing plate 2, and a reinforcing member (supplementary strengthening member ("SSM")) 4. The hat member 1 includes two side walls 11 and 12, each of which includes a high-strength portion 11A, 12A with a yield strength not lower than 500 MPa and low-strength portions 11B, 12B with a yield strength of 60 to 85 % of the yield strength of the high-strength portion. As determined along the direction of extension of the ridges 123 of the hat member, both ends of the reinforcing member 4 overlap the high-strength portions 11A and 12B of the side walls 11 and 12. Adjacent to at least one of both ends of the reinforcing member 4, the border between the high-strength portions 11A and 12A and the low-strength portions 11B and 12B is positioned in a region starting at a position 1/3, and ending at a position 3/2, of the height H of the side wall 11 distant from that end of the reinforcing member 4 as determined along the direction of extension of the ridges 123 away from the reinforcing member 4.