Tubular Vibration-Damping Device Bracket Stress Distribution
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Solution Overview
Problem
The use of synthetic resin outer tube members in tubular vibration-damping devices leads to damage of metal tubular brackets due to localized rigidity increases and stress concentration during press-fitting, compromising the press-fitting fixing force and durability.
Innovation Solution
Integrally forming inward projections on the outer tube member and providing gaps between the outer tube member and tubular bracket at the projection sites to distribute stress and prevent damage, while maintaining the design flexibility and load-bearing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an inside projection is integrally formed on the outer tube member made of synthetic resin, then the rigidity and toughness of the outer tube member are increased, but the tubular bracket is damaged during press-fitting due to stress concentration
Solution Approach 1:
The patent applies local quality by providing a gap between the inside projection and the inner peripheral surface of the tubular bracket at specific locations. This creates a localized difference in rigidity distribution - the outside projection maintains structural strength where needed, while the gap region allows stress relief and prevents concentration at critical points, thereby preventing bracket damage during press-fitting
Solution Approach 2:
The gap acts as an intermediary element between the inside projection and the tubular bracket. Instead of direct contact that would cause stress concentration and damage, the gap mediates the interaction by allowing controlled deformation and stress distribution, preventing harmful stress transfer to the bracket while maintaining the structural benefits of the inside projection
2Object-affected harmful factors
If the press-fit rate of the outer tube member into the tubular bracket is decreased to avoid bracket damage, then the damage risk is reduced, but the press-fitting fixing force becomes insufficient
Solution Approach 1:
The patent uses local quality by strategically positioning gaps only at specific locations where inside projections contact the bracket, rather than uniformly reducing press-fit rate across the entire interface. This localized approach allows full press-fit force to be applied at non-gap regions (providing sufficient fixing force) while avoiding stress concentration at gap regions (preventing bracket damage)
Solution Approach 2:
The patent segments the press-fitting interface by creating discrete gap regions between inside projections and the bracket, rather than having uniform contact. This segmentation allows different regions to serve different functions: gap regions prevent stress concentration and bracket damage, while non-gap regions provide adequate fixing force through full contact
Data Source
AI summary
A tubular vibration-damping device having a bracket including a tubular vibration-damping device press-fitted and attached into a tubular bracket, the tubular vibration-damping device including an inner shaft member, an outer tube member made of synthetic resin and disposed on an outer peripheral side of the inner shaft member, and a main rubber elastic body connecting the inner shaft member and the outer tube member. An inside projection is integrally formed with the outer tube member so as to project radially inwardly. A gap is provided between an outer peripheral surface of the outer tube member and an inner peripheral surface of the tubular bracket at a position in a peripheral wall part of the outer tube member where the inside projection is formed.