Vehicle Front Cross Member Recess Joint for Pole Collision Loads
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Solution Overview
Problem
Existing vehicle front structures are vulnerable to shearing loads during pole frontal-collisions, leading to detachment of the front cross member from the front side frame, which compromises collision-load absorption performance.
Innovation Solution
A vehicle front structure design featuring right-and-left front side frames with inward-facing recess portions and a cross member that fits into these recesses, supporting collision loads in the axial direction and preventing detachment, allowing the cross member to deform U-shaped and draw the frames inward for enhanced load absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cross member is fixed to the front side frame using a conventional joining structure, then the structure is simple to manufacture, but the joining portion is vulnerable to shearing loads during pole frontal-collision, leading to detachment
Solution Approach 1:
The front side frame is segmented into an inner wall portion and an outer wall portion, with the inner wall portion featuring a recess portion that receives the cross member. This segmentation allows the cross member to be positioned within the recess, transforming the loading path from shear-dominated to compression-dominated, thereby improving joining integrity without requiring complex additional fastening mechanisms.
Solution Approach 2:
The recess portion extends in the width direction of the vehicle, creating a three-dimensional receiving space for the cross member. This dimensional approach allows the cross member to be supported from the side rather than only from the front or rear, distributing the collision load more effectively and preventing detachment without adding complex multi-directional fastening systems.
2Reliability
If the cross member is designed to absorb collision load through deformation, then the collision-load absorption performance is improved, but the cross member may detach from the front side frame under shearing loads
Solution Approach 1:
The recess portion is designed in advance to receive and support the cross member during collision. By pre-positioning the cross member within the recess and designing the recess geometry to accommodate the deformed shape of the cross member, the structure provides built-in protection against detachment during the collision event, allowing the cross member to deform and absorb energy without compromising the joining integrity.
3Length of moving object
If the front edge of the inner wall portion is positioned forward, then the structure is compact in the longitudinal direction, but the cross member cannot be properly supported during pole frontal-collision, leading to shearing loads at the joining portion
Solution Approach 1:
Instead of extending the recess portion in the longitudinal direction (which would increase the front structure length), the recess is designed to extend in the width direction. This allows the cross member to be supported from the sides, transforming the force application from shear loading to compression loading, thereby reducing shearing loads at the joining portion while maintaining a compact longitudinal profile.
Data Source
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AI summary
The invention relates to a front structure of a vehicle comprises a pair of right-and-left front side frames (11) extending in a longitudinal direction and having a closed-cross section perpendicular to an extension direction thereof, respectively, and a cross member (12) extending in a width direction between the pair of right-and-left front side frames (11), wherein each of the front side frames (11) comprises an inner wall portion (11a) which is positioned on an inward side thereof, in the vehicle width direction, the inner wall portion (11a) has an inner recess portion (26), which is configured such that a front edge of the inner wall portion (11a) partially retreats rearward, and both-side portions, in the width direction, of the cross member (12) fit into said inner recess portions (26) of the inner wall portions (11a) from a forward side and are fixed to the inner wall portions (11a) of the front side frames (11).