Composite Leaf Spring Mounting to Prevent Torsion and Side Loads
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Solution Overview
Problem
Leaf springs made of fiber composite plastics are prone to breakage due to lateral deflections and torsion, which are not well tolerated by their unidirectional fiber structure, necessitating complex two-part designs to manage stress.
Innovation Solution
A leaf spring device with a fiber composite plastic leaf spring apparatus, featuring a first bearing point with three rotational degrees of freedom at one end and a second bearing point with one rotational degree of freedom at the other end, which helps prevent torsion and lateral forces from being introduced into the leaf spring apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If leaf springs are made of fiber composite plastics, then weight is reduced and corrosion resistance is improved, but the springs become susceptible to breakage due to lateral deflections and torsion
Solution Approach 1:
The invention divides the leaf spring into multiple individual leaf spring elements (at least two) that are connected to each other. This segmentation allows each element to independently absorb and distribute lateral deflections and torsional forces, preventing stress concentration that would lead to breakage of a single monolithic spring.
Solution Approach 2:
The invention uses fiber composite plastics with specifically oriented fiber structures. The fibers are arranged in multiple directions (not just unidirectional) to provide strength in both longitudinal and transverse directions, enabling the composite material to withstand lateral deflections and torsion while maintaining lightweight properties.
2Device complexity
If a single leaf spring element is used, then the design is simpler, but the spring cannot tolerate lateral deflections and torsion without breaking
Solution Approach 1:
The leaf spring is segmented into multiple connected elements rather than using a single element. This segmentation creates a structure where lateral deflections and torsion are distributed across multiple components, each experiencing reduced stress, thereby preventing breakage while maintaining a relatively simple overall design.
Solution Approach 2:
The invention changes the structural parameters of the leaf spring by connecting multiple elements with specific geometries and orientations. This parameter change enables the structure to tolerate lateral deflections and torsion that would be intolerable in a single-element design.
3Reliability
If two meander-shaped leaf springs are combined to form a leaf spring device, then lateral deflections and torsion are better managed, but the device complexity increases
Solution Approach 1:
The invention merges multiple leaf spring elements into a single integrated leaf spring device where the elements are connected to work together. This combining approach allows the device to manage lateral deflections and torsion effectively while presenting a unified structure rather than separate components.
Solution Approach 2:
The use of fiber composite plastics with multi-directional fiber orientation enables the merged structure to withstand complex stress states from lateral deflections and torsion, making the combined design more reliable than the sum of individual elements would suggest.
Data Source
AI summary
A leaf spring device for a vehicle, comprising a leaf spring apparatus made of a fiber composite plastic, a first bearing point provided at a first end section of the leaf spring apparatus for supporting the leaf spring device on the vehicle, the first bearing point comprising exactly three rotational degrees of freedom, and a second bearing point provided at a second end section of the leaf spring apparatus facing away from the first end section for supporting the leaf spring device on the vehicle, the second bearing point comprising exactly one rotational degree of freedom.