Composite Coil Spring Fiber Orientation for Buckling Resistance
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Solution Overview
Problem
Current coil springs face limitations in energy storage and release capacity due to non-uniform stress distribution, leading to underutilization of material and potential failure from cracks initiated at the inner side, especially under compressive loads.
Innovation Solution
A composite coil spring design featuring a core wire with strategically angled fiber layers around the spring axis, optimized based on winding direction to enhance natural frequency, resistance to buckling, and tensile and compressive stress components, fabricated using a method involving uncured preforms and selective curing to achieve tailored stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional steel coil springs are used to meet target mechanical stress and fatigue characteristics, then reliability is improved, but weight increases
Solution Approach 1:
The patent applies composite materials by combining a steel core wire with carbon fiber layers wrapped around it. The carbon fiber layers provide enhanced mechanical properties including fatigue resistance and strength-to-weight ratio, while the steel core provides structural support. This composite structure achieves the required reliability and fatigue characteristics while reducing overall spring weight compared to traditional solid steel springs.
2Ease of manufacture
If material is uniformly distributed in traditional springs, then manufacturing is simplified, but energy storage capacity is reduced due to non-uniform stress distribution
Solution Approach 1:
The patent implements local quality by varying the angular positioning and orientation of carbon fiber layers at different locations along the spring wire. The fiber angles are specifically optimized for different stress regions: longitudinal fibers in high-tensile areas, spiral fibers in high-compression areas, and circumferential fibers in high-shear areas. This localized optimization of fiber orientation maximizes energy storage capacity by ensuring material properties match the local stress state, while the overall manufacturing process remains feasible through standardized wrapping procedures.
3Strength
If fiber layers are added to enhance stress resistance, then strength is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the reinforcement structure into distinct functional layers: an inner layer with specific fiber orientations for handling certain stress components, and an outer layer with different fiber orientations for handling other stress components. This segmented approach allows each layer to be optimized for specific mechanical demands while maintaining a manageable overall structure that can be manufactured through systematic wrapping processes.
Data Source
AI summary
A composite spring made of a wire of a longitudinal axis curved around a spring axis in a winding direction and a method of fabrication thereof, the spring, the wire comprising a core; and fibers layers wound around the core, and an angular positioning, relative to the spring axis, of each one of the fiber layers being selected, along a length of the core, depending on the winding direction of the wire about the spring axis, to adjust at least one of: high natural frequency of the spring, resistance to buckling and resistance to tensile and compressive stress components induced by a compressive load on the spring.