Composite Torsion Spring Layered Fiber Architecture
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Solution Overview
Problem
Current torsion springs made of fiber-reinforced plastics, such as carbon fiber reinforced plastics (CFRP) and glass fiber reinforced plastics (GRP), face challenges in effectively utilizing material load-bearing capacity due to the inability of fibers to transmit shear loads, leading to inefficient material utilization and potential weak points under torsional stress.
Innovation Solution
A method for designing torsion springs where the inner layers support both tension and compression, with the matrix transmitting minimal shear forces to avoid creep, and the fiber arrangement is optimized to ensure even load distribution across all cross-sectional areas, utilizing different fiber materials and angles to achieve homogeneous material utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fibers are wound at +/-45° angle to transmit tensile and compressive forces, then material load-bearing capacity is improved, but shear stresses must be transmitted through the plastic matrix leading to creep under continuous loading
Solution Approach 1:
The spring wire is segmented into multiple fiber layers with different orientations. The outer layers are wound at +/-45° angles to handle tensile and compressive forces, while inner layers have fiber orientations closer to 0° or 90° relative to the spring axis to handle shear stresses, dividing the stress transmission function among different layers
Solution Approach 2:
Different regions of the spring wire cross-section are assigned different fiber orientations tailored to the local stress state. Outer regions experience primarily tensile/compressive loads and have +/-45° fibers, while inner regions experience higher shear stresses and have fibers oriented to better resist shear, creating a non-uniform but optimized fiber architecture
2Strength
If only tensile fibers are used to optimize tensile load utilization, then tensile strength is improved, but shear stresses transmitted through the plastic matrix cause strong creep phenomena
Solution Approach 1:
The spring wire uses a composite structure combining fiber-reinforced plastic layers with different fiber orientations. By integrating multiple fiber directions (not just tensile fibers) within the composite architecture, the system maintains high tensile load utilization while distributing shear stress transmission to fibers better suited for shear resistance, reducing reliance on the plastic matrix and thereby reducing creep
3Productivity
If the number of compression fibers is increased compared to tensile fibers to ensure even load distribution, then material utilization is improved, but the dependence of material utilization on spring wire diameter is not eliminated
Solution Approach 1:
The fiber layer configuration is made dynamic and adaptive rather than fixed. The number of layers, fiber orientations, and material properties are adjusted based on the specific spring wire diameter and application requirements. This allows the design to optimize material utilization for each diameter while maintaining scalability across different sizes through systematic parameter adjustment
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 approach enhances the mass-related energy storage density and reduces the tendency for creep, allowing for more efficient and uniform load distribution, thereby improving the overall lightweight construction and durability of the springs.
Implementation Method 1
a bar or coil spring made of fiber-reinforced plastic, which ensures improved utilization of the load-bearing capacity of all material layers
Implementation Method 2
the shear stress components being carried by the matrix material or by compressive stresses in the core
Data Source
Figure 1a~1b
Figure 2
Figure 3~4
AI summary
The invention relates to a torsion spring, which is preferably designed as a bar spring or coil spring made from spring wire composed of fiber composite material. Said torsion spring has a plurality of layers (Sj) of fiber reinforcement, which are impregnated with a matrix material, wherein the layers have fibers that are loaded in tension and fibers that are loaded in compression. The torsion spring is characterized in that groups (Gk) of layers (Sj) of the same loading direction exist, and the group stiffness of at least two groups, as viewed from the inside out, differs. The invention further relates to a method for designing a torsion spring composed of fiber composite material.