Vehicle Side Sill Bending Resistance via Closed-Section Geometry
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Solution Overview
Problem
Existing lower vehicle-body structures face challenges in increasing the bending resistance of side sills without adding weight or increasing manufacturing costs, particularly when the cross-sectional width of the side sill is reduced to accommodate cabin space.
Innovation Solution
The proposed lower vehicle-body structure features a side sill with a closed-cross section formed by a side sill outer and a side sill inner. The side sill outer has upper and lower face portions with bending portions bent inward, while the side sill inner includes upper and lower face portions with secondary bending portions, which work together to generate a large reaction force during collisions, thus enhancing bending resistance without weight or cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the width of the cross section of the side sill is reduced to secure sufficient cabin space, then the cabin space is increased, but the bending resistance (bending rigidity) of the side sill decreases
Solution Approach 1:
The invention transitions from a conventional single-member side sill structure to a dual-member closed-cross section structure consisting of a side sill outer and a side sill inner. This dimensional change in structural configuration creates a closed-loop geometry that significantly enhances bending resistance and torsional rigidity while maintaining a compact cross-sectional width, thereby securing sufficient cabin space without sacrificing structural strength.
Solution Approach 2:
The side sill is constructed as a composite structure combining the side sill outer and side sill inner members into a closed-cross section assembly. This composite configuration leverages the geometric advantage of closed sections to achieve superior bending resistance and impact absorption performance compared to conventional open-section or single-member designs, resolving the contradiction between reduced width and maintained strength.
2Strength
If the side sill is reinforced by adding a reinforcing member or increasing the thickness to obtain sufficient bending resistance, then the bending resistance is improved, but the weight and manufacturing costs increase
Solution Approach 1:
Rather than increasing material thickness or adding reinforcing members within the existing single-member configuration, the invention employs a closed-cross section geometry formed by the side sill outer and side sill inner members. This geometric dimensionality change provides superior bending resistance and structural efficiency without requiring additional material or increased thickness, thereby avoiding weight and cost increases.
3Strength
If the side sill is reinforced by adding a reinforcing member or increasing the thickness to obtain sufficient bending resistance, then the bending resistance is improved, but the manufacturing costs increase
Solution Approach 1:
The closed-cross section configuration of the side sill outer and side sill inner members provides enhanced bending resistance through geometric efficiency rather than material quantity. This approach avoids the need for complex reinforcing members or increased plate thickness, simplifying the manufacturing process and reducing production costs while achieving the required structural performance.
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 structure effectively increases the bending resistance of the side sill by generating a large reaction force through the coordinated deformation of the side sill outer and inner components, thereby suppressing bending deformation and maintaining impact absorption performance without increasing weight or manufacturing costs.
Implementation Method 1
A pair of upper-and-lower side face portions of the side sill outer have bending portions which are bent toward an inside of the side sill, respectively. In a case where the vehicle has a side collision or the like, buckling of the side sill outer is caused with a starting point of the bending portion, so that the side sill outer can attain the impact absorption
Implementation Method 2
In a case where the vehicle has a side collision or the like, buckling of the side sill outer is caused with a starting point of the bending portion
Data Source
AI summary
A side sill comprises a side sill outer and a side sill inner. Each of an upper-side side face portion (upper face portion) and a lower-side side face portion (lower face portion) of the side sill outer comprises a first bending portion bent toward an inside of the side sill. The side sill inner comprises an upper-side side face portion with a first upper face portion, an upper-side slant face portion and a second upper face portion and a lower-side side face portion with a first lower face portion, a lower-side slant face portion and a second lower face portion. The side sill inner comprises a pair of upper-and-lower second bending portions which are bent toward an inside of the side sill at respective positions between the second upper face portion and the upper-side slant face portion and between the second lower face portion and the lower-side slant face portion.