Dash Cross Member Load Path for Vehicle Body Stiffness
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Solution Overview
Problem
Existing vehicle body structures face challenges in suppressing deformation while maintaining a reduced weight, particularly during front collisions, as the load redirection increases the weight and complexity of the structure.
Innovation Solution
A vehicle body structure design that includes a dash lower panel between left and right front pillars, with a dash upper panel and a floor panel, where the dash cross member bridges the pillars and is supported by a tunnel frame and dash upper panel, effectively transmitting loads to the dash frame and suppressing deformation, while also integrating a bulkhead and tire-load-bearing portion to distribute loads and reduce weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the load redirection path is increased to suppress deformation of the dash lower panel, then the deformation resistance is improved, but the weight of the vehicle body structure increases
Solution Approach 1:
The vehicle body structure is divided into distinct functional segments: the dash lower panel, dash upper panel, floor panel, tunnel frame, dash frame, and dash cross member. Each segment is optimized to handle specific loads, allowing the structure to suppress deformation without requiring a monolithic heavy design. The dash cross member specifically segments the load path by bridging between front pillars and connecting to the dash frame, creating an efficient load distribution network.
Solution Approach 2:
The patent introduces a third dimension to the load path by adding the dash cross member that extends in the vehicle-body width direction. This cross member creates a spatial load distribution system that redirects loads from the dash lower panel through the dash frame to the tunnel frame and floor tunnel, utilizing the vertical and lateral dimensions to suppress deformation without increasing weight.
2Strength
If the dash cross member is connected to the floor tunnel and dash frame to transmit loads, then the load transmission capability is improved, but the device complexity increases
Solution Approach 1:
The dash cross member serves multiple functions simultaneously: it bridges the left and right front pillars, connects to the dash frame for load transmission, and provides structural support for the dash lower panel. This multi-functionality allows efficient load transmission without requiring separate dedicated components for each function, thereby reducing overall structural complexity.
Solution Approach 2:
The patent merges the functions of load bearing, load transmission, and structural support into integrated components. The dash frame combines vertical support and lateral load transmission functions, while the dash cross member integrates pillar bridging and load distribution functions. This merging reduces the number of separate parts needed compared to a design where each function has a dedicated component.
3Strength
If the size of the load redirection portion is increased to reduce bending moment, then the deformation resistance is improved, but the weight of the vehicle body structure increases
Solution Approach 1:
The patent optimizes the geometric parameters of the dash frame and dash cross member connections to minimize bending moments. By carefully designing the connection points, angles, and dimensions of these components, the structure achieves high deformation resistance at load redirection portions without requiring increased size or additional material, thereby avoiding weight increase.
Data Source
AI summary
A vehicle body structure includes a left tunnel frame extending along a floor tunnel to a dash lower panel, a left dash frame extending upward from a front end of the left tunnel frame to a dash upper panel, and a dash cross member extending in a vehicle-body width direction and across the left dash frame. The left dash frame is provided on a vehicle-cabin-side surface of the dash lower panel. The dash cross member is provided on an engine-room-side surface of the dash lower panel. The dash cross member bridges a left front pillar and a right front pillar.