Fiber-Composite Torsion Spring Layering to Reduce Shear Creep
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing torsion springs made from fiber-reinforced plastic face challenges in achieving low-cost, efficient production with optimal material utilization, particularly in distributing shear loads effectively, leading to suboptimal lightweight construction and increased creep due to shear stresses.
Innovation Solution
The design involves alternating layers of tension-loaded and compression-loaded fiber plies with specific fiber materials and angles to maximize loading limits, minimizing shear stresses and creep, using carbon fibers for tension and glass fibers for compression, and optimizing layer thicknesses and cross-sectional areas to achieve balanced group stiffness and energy storage density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fibers are wound at angles of +−45° to accommodate tensile and compressive forces, then material utilization is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies parameter changes by varying the fiber winding angles across different layers. Specifically, it uses +45° angles in some layers and -45° angles in other layers, rather than uniform angles throughout. This allows optimization of tensile and compressive force distribution while maintaining manufacturability through systematic parameter variation.
Solution Approach 2:
The patent employs composite materials by combining fiber-reinforced plastic layers with different fiber orientations and potentially different fiber types (e.g., carbon fibers, glass fibers). This multi-layer composite structure enables simultaneous optimization for both tensile and compressive loading conditions while managing manufacturing complexity through standardized layering procedures.
2Strength
If only tension-loaded fibers are used, then fiber potential for tension loading is optimized, but severe creep occurs due to shear stresses transmitted through the plastics matrix
Solution Approach 1:
The patent achieves homogeneity in stress distribution by symmetrically arranging fiber layers with alternating +45° and -45° orientations. This symmetric configuration ensures that shear stresses are evenly distributed across the structure, preventing localized stress concentrations that would cause creep in the plastics matrix while maintaining optimal tension loading capability.
Solution Approach 2:
The patent introduces intermediary compression-loaded fiber layers that act as mediators to bear shear stresses. These intermediate layers with -45° orientation counterbalance the shear stresses generated by +45° tension-loaded layers, thereby protecting the plastics matrix from excessive shear stress and preventing creep deformation.
3Reliability
If the number of compression fibers is increased relative to tension fibers, then material utilization is improved, but dependency on spring wire diameter remains
Solution Approach 1:
The patent applies dynamics by making the fiber layer configuration adaptable to different spring wire diameters. The number and arrangement of fiber layers are designed to scale with the wire diameter, allowing the same basic structural principle to be applied across different sizes. This dynamic adaptation maintains optimal material utilization while being versatile enough for various wire diameter specifications.
4Reliability
If alternating layers of tension-loaded and compression-loaded fiber plies are used, then shear stresses and creep are minimized, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the spring structure into distinct alternating layers, each with specific fiber orientations (+45° or -45°). This segmentation into functional layers simplifies the manufacturing process by allowing each layer to be produced and positioned independently according to standardized patterns, thereby reducing the overall precision requirements compared to a monolithic structure.
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 approach results in improved mass-based energy storage density and reduced creep, enabling cost-effective production of torsion springs with enhanced material utilization and reduced long-term deformation, suitable for vehicle construction.
Implementation Method 1
the plies are designed in such a way that the group stiffness of all of the compression-loaded groups is lower than the group stiffness of all of the tension-loaded groups
Implementation Method 2
minimizing shear stresses and creep, using carbon fibers for tension and glass fibers for compression
Data Source
AI summary
A torsion spring may be configured as a torsion bar or a helical spring made of a spring wire made of fiber-composite material. The torsion spring may have a plurality of layers of fiber reinforcement that have been saturated with a matrix material, wherein the layers may have fibers that are tension-loaded and fibers that are compression-loaded. The at least one compression-loaded group may have a lower group stiffness than the tension-loaded group with the highest group stiffness. Methods for designing or making torsion springs made of fiber-composite material are also disclosed.