Vehicle Lower Body Frame Member Deformation Control
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Solution Overview
Problem
In existing vehicle lower body structures, the frame member and floor panel have different rigidities, leading to excessive deformation of the floor panel during a side collision, which causes the joined portion to break and reduces the support effect for the side sill, resulting in inward falling deformation.
Innovation Solution
Incorporating a deformation facilitating portion, such as beads or holes, in the frame member's first face portion to facilitate deformation in the vehicle width direction, ensuring the deformation amount matches that of the floor panel, thereby maintaining the closed cross-section and support for the side sill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the frame member has higher rigidity than the floor panel, then the frame member can provide sufficient structural support, but the floor panel experiences excessive deformation during side collision causing the joined portion to break
Solution Approach 1:
The patent applies local quality by forming a deformation facilitating portion (such as a recess or groove) at a specific location on the first face portion of the frame member. This localized structural feature allows the frame member to have different rigidity characteristics in different regions: the majority maintains high rigidity for structural support, while the deformation facilitating portion has reduced rigidity to accommodate floor panel deformation during side collision, preventing joined portion breakage
Solution Approach 2:
The patent changes the rigidity parameter locally by introducing a deformation facilitating portion with modified geometric parameters (such as reduced thickness or altered cross-section). This parameter change allows the frame member to transition from a uniformly high-rigidity structure to a differentiated structure where specific regions can deform more easily, matching the deformation characteristics of the floor panel during collision
2Strength
If the frame member maintains high rigidity, then structural support is sufficient, but excessive shearing strain occurs in the joined portion during side collision
Solution Approach 1:
The deformation facilitating portion creates a localized region with different mechanical properties, allowing the frame member to absorb and distribute collision forces more effectively. This local modification reduces the concentration of shearing strain in the joined portion while maintaining overall structural support capability
3Strength
If the first face portion has higher rigidity than the floor panel, then the frame member provides adequate support, but the deformation amount of the floor panel becomes excessively large compared to the frame member
Solution Approach 1:
The deformation facilitating portion creates a localized region where the frame member's rigidity is reduced, allowing it to deform by an amount comparable to the floor panel during side collision. This local differentiation in rigidity enables coordinated deformation between the frame member and floor panel, preventing excessive floor panel deformation
Data Source
AI summary
A lower vehicle-body structure of a vehicle may include: a floor panel; a side sill; and a frame member that extends in the front-rear direction on the vehicle-width-direction inner side of the side sill and includes a front-rear extended portion that is in abutment against the side sill on the vehicle-width-direction inner side and extends in the vehicle front-rear direction along the side sill. The front-rear extended portion may include: a bottom face portion; an inner wall portion; and an inner-side flange that extends to the vehicle-width-direction inner side from a distal end portion of the inner wall portion and is joined to the floor panel. Deformation facilitating facilitators that facilitate deformation of the bottom face portion in the vehicle width direction when a collision load in the vehicle width direction is input may be formed in the bottom face portion.