Closed Cross-Section Coupling Structure for Bolt Load Retention
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Solution Overview
Problem
Existing methods for coupling side members with closed cross-sections, such as welding or using a nut inside the cross-section, face challenges in terms of cost and strength, and can result in bearing surface depression and axial force decrease of bolts.
Innovation Solution
A coupling structure that includes pipes with opening portions at both ends, a patch with bolt holes smaller than the pipes, and a bracket with bolt holes in communication with the patch, allowing bolts to be inserted through the pipes, patch, and bracket, and fastened with nuts, while the pipes are not fixed to any member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding or nut fastening methods are used to couple side members, then coupling strength is improved, but manufacturing cost increases and bearing surface depression occurs
Solution Approach 1:
The coupling structure is divided into separate components: a bracket with bolt holes, bolts for fastening, and the side members with through holes. This segmentation allows each component to be manufactured independently using standard processes, reducing overall manufacturing cost while maintaining coupling strength through mechanical fastening rather than welding.
Solution Approach 2:
The bracket serves as an intermediary component that couples the first and second side members together. By introducing this intermediate element with pre-drilled bolt holes, the structure achieves strong coupling through bolt fastening without requiring direct welding between side members, thereby reducing manufacturing cost and preventing bearing surface depression.
2Ease of manufacture
If a bracket with bolt fastening is used to couple side members, then manufacturing cost is reduced, but bearing surface depression and axial force decrease of bolts occur
Solution Approach 1:
Through holes are pre-formed in the side members at appropriate positions and dimensions before assembly. These pre-prepared holes ensure that bolts can be properly inserted and fastened without causing bearing surface depression, thereby maintaining bolt axial force and reliability while keeping the manufacturing process simple and cost-effective.
Solution Approach 2:
The diameter of the through holes in the side members is specifically designed to be larger than the outer diameter of the bracket, and the patch material is positioned to fill the gap between the bracket and inner wall. This parameter optimization allows bolt fastening without bearing surface depression, maintaining bolt axial force while keeping the structure simple and manufacturable.
3Object-affected harmful factors
If the through hole diameter is made larger than the pipe outer diameter, then bearing surface depression is suppressed, but the structural rigidity may decrease
Solution Approach 1:
A patch made of filler material is introduced as an intermediary element to fill the gap between the bracket and the inner wall of the closed cross-section member. This patch reinforces the structure around the through hole, maintaining structural rigidity even when the through hole diameter is larger than the pipe outer diameter, thereby preventing bearing surface depression without compromising strength.
Data Source
AI summary
Provided is the coupling structure for coupling together closed cross-section members comprising a pair of opposing through holes wherein the coupling structure includes: a pipe that has an opening at one end arranged in one of the pair of through holes and an opening at another end arranged in the other of the pair of through holes; a patch provided to the exterior of each of the closed cross-section members; a bracket abutted against the patch; and bolts that in each of the closed cross-section members are inserted through the second bolt holes, the first bolt holes, and the pipe and are tightened with a nut. The pipe is not fixed to either the closed cross-section members or the patch, and the diameter of the pair of through holes is greater than the outer diameter of the pipe.