Dual-Layer Rubber-Reinforcing Cord for Predictable Fatigue Failure
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Solution Overview
Problem
Conventional rubber-reinforcing cords, whether made of high modulus fibers or multiple types of fibers, suffer from sudden fracture due to bending fatigue, leading to unexpected failure of rubber products and equipment breakdown, as the fibers break simultaneously without prior warning.
Innovation Solution
A rubber-reinforcing cord with a double-layer structure featuring a first fiber strand in the central portion and a plurality of second fiber strands with a higher tensile elastic modulus around it, ensuring that the second fiber strands bear the majority of the load and stress, thereby delaying the breakage of the first fiber strand and providing a warning before complete failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high modulus fibers are used to increase elastic modulus, then the elastic modulus is improved, but bending fatigue resistance deteriorates
Solution Approach 1:
The rubber-reinforcing cord is segmented into two distinct fiber layers: a high modulus fiber layer (carbon fibers) and a low modulus fiber layer (aramid or polyester fibers). This segmentation allows each layer to perform its specialized function - the high modulus layer provides stiffness while the low modulus layer provides flexibility and bending fatigue resistance, resolving the contradiction between elastic modulus and bending fatigue resistance.
Solution Approach 2:
Different regions of the rubber-reinforcing cord are assigned different material properties. The central high modulus fiber layer provides local stiffness where needed for dimensional stability, while the peripheral low modulus fiber layers provide local flexibility where needed for bending fatigue resistance. This local differentiation of material quality resolves the contradiction by optimizing properties at different locations.
2Reliability
If conventional double-layer structure with carbon fibers in center and glass fibers around is used, then balance between elastic modulus and bending fatigue resistance is improved, but sudden fracture prediction capability deteriorates
Solution Approach 1:
The low modulus fiber layer acts as a preliminary protective layer that undergoes progressive damage before the high modulus fiber layer. This preliminary action of the outer layer absorbs initial bending fatigue damage, preventing immediate failure of the inner high modulus layer and providing advance warning of impending fracture through gradual performance degradation.
Solution Approach 2:
The low modulus fiber layer serves as a cushioning layer that absorbs and dissipates bending fatigue stresses before they reach the high modulus fiber layer. This beforehand cushioning effect prevents sudden stress concentration on the carbon fibers, allowing progressive damage accumulation that can be detected and predicted before catastrophic failure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design prevents sudden fracture of the rubber-reinforcing cord and the rubber product, allowing for predictive maintenance and preventing equipment breakdown by creating a time lag between the breakage of the second and first fiber strands, thus enhancing the balance between elastic modulus and bending fatigue resistance.
Implementation Method 1
the second fiber strand has a tensile elastic modulus higher by 20 GPa or more than a tensile elastic modulus of the first fiber strand... the second fiber strand... provides the rubber-reinforcing cord with a high elastic modulus... the first fiber strand... provides the rubber-reinforcing cord with flexibility
Implementation Method 2
the first fiber strand... provides the rubber-reinforcing cord with flexibility, namely bending fatigue resistance... the second fiber strand having a higher elastic modulus is located in the peripheral portion and the first fiber strand having a lower elastic modulus is located in the central portion, is less likely to experience the phenomenon in which the first and second fiber strands are broken at almost the same time
Data Source
AI summary
A rubber-reinforcing cord (10) includes a first fiber strand (11) and a plurality of second fiber strands (12) disposed around the first fiber strand (11). The second fiber strand (12) has a tensile elastic modulus higher by 20 GPa or more than that of the first fiber strand (11).