Vehicle Body Rear Structure With Offset Stiffener Connections
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Solution Overview
Problem
Existing vehicle body rear structures face issues with stress concentration at connecting portions, leading to increased weight and reduced collision safety due to the alignment of connecting points, necessitating additional reinforcement.
Innovation Solution
A vehicle body rear structure design featuring separate forward and rearward stiffeners aligned in the front-rear direction, with offset connections and a distributed load transmission system, including a wheel house reinforcing member and gussets, to distribute collision loads and reduce weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bracing member and upper wall portion are connected at the same position where two separated members are joined, then the structural integrity is improved, but stress concentration occurs leading to increased weight for reinforcement
Solution Approach 1:
The upper wall portion is divided into two separated members (first and second members) that are positioned at different locations in the vehicle width direction. The bracing member connects to these separated members at different positions, avoiding stress concentration at a single point while maintaining structural integrity through distributed connection points.
2Reliability
If additional reinforcement is added to the connecting portions, then the collision safety is improved, but the vehicle weight increases
Solution Approach 1:
The connection structure utilizes the vehicle width direction dimension by positioning the first and second members at different lateral locations. This spatial distribution of connection points in the width direction allows stress to be dispersed across multiple locations rather than concentrated at a single point, achieving collision safety without additional reinforcement weight.
3Ease of manufacture
If the connecting portions are aligned at the same position, then the manufacturing process is simplified, but stress concentration occurs reducing collision safety
Solution Approach 1:
The upper wall portion is segmented into two separate members positioned at different locations in the vehicle width direction. This segmentation naturally separates the connection points of the bracing member, preventing stress concentration while maintaining relatively simple manufacturing processes through standardized connection structures at each separated location.
Data Source
AI summary
A vehicle body rear structure includes: a rear frame extending in a vehicle front-rear direction on a vehicle width direction end side of a floor panel; a rear wheel house extending upward from a vehicle width direction outer portion of the rear frame; a rear cross member extending in a vehicle width direction on the floor panel; a wheel house reinforcing member extending in an up-down direction along the rear wheel house; and an upper stiffener covering an opening of the rear frame. The upper stiffener includes forward and rearward stiffeners. The wheel house reinforcing member has a lower portion connected to the upper stiffener and to the rear cross member. The forward and rearward stiffeners are connected to each other at a connecting portion located offset in the front-rear direction from a connecting portion where the upper stiffener and the wheel house reinforcing member are connected to each other.