Thin-Wall Drive Shaft With Corrugated Web for Torque Buckling
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Solution Overview
Problem
Fiber-reinforced polymer-matrix composite drive shafts are prone to buckling under torque due to their thin walls, leading to the unnecessary addition of 'parasitic' layers that increase weight and cost without enhancing strength, limiting layup optimization opportunities.
Innovation Solution
A mechanical part design featuring a corrugated web and outer shell configuration that increases hoop stiffness without significantly increasing weight, achieved by affixing the corrugated web to the inner tube and outer shell, providing truss-type reinforcement along the length of the drive shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the wall thickness of composite drive shafts is reduced to achieve weight reduction, then weight decreases and material efficiency improves, but the risk of buckling under torque increases
Solution Approach 1:
The drive shaft is segmented into multiple functional layers: an inner structural tube, intermediate buckling-resistant layers with specific fiber orientations (including cross-ply and angle-ply configurations), and an outer shell. This segmentation allows each layer to contribute specifically to buckling resistance while maintaining overall light weight.
Solution Approach 2:
The invention employs multi-layer composite material construction with different fiber orientations and material properties in each layer. The combination of layers with varying stiffness and strength characteristics creates a synergistic effect that enhances buckling resistance without proportionally increasing weight.
2Reliability
If parasitic layers are added to increase wall thickness and prevent buckling, then buckling resistance improves, but weight increases and layup optimization opportunities are reduced
Solution Approach 1:
Different layers are designed with locally optimized fiber orientations and material properties tailored to specific stress states. For example, certain layers have fibers oriented at specific angles to resist compressive stresses during buckling, while other layers optimize for tensile strength or torsional resistance, achieving overall buckling protection without uniform thickness increase.
Solution Approach 2:
The invention changes key design parameters including fiber orientation angles, layer thickness ratios, and material selection for each layer to optimize the buckling resistance-to-weight ratio. By adjusting these parameters, the design achieves adequate buckling protection with minimal weight penalty compared to uniform thick-walled designs.
3Reliability
If wall thickness is over-designed to prevent buckling under torque, then buckling resistance improves, but manufacturing cost increases and layup optimization is limited
Solution Approach 1:
The multi-layer composite structure enables local optimization of fiber orientations and material properties in different layers, allowing manufacturers to tailor each layer's characteristics to specific functional requirements. This provides greater layup optimization flexibility compared to uniform thick-walled designs, as each layer can be independently optimized for its specific role in buckling resistance.
Data Source
Figure 1A~1C
Figure 1D~2B
Figure 3A~3B
AI summary
A mechanical part configured to be placed under torque. The mechanical part includes an inner tube having, a corrugated web (602), and an outer shell (206, 306, 406, 506). The inner tube has an outer tube circumference, a tube axial direction, and a tube length. The corrugated web (602) has a plurality of peaks (608) and a plurality of troughs (610), a height measured as a difference between one of the peaks and one of the troughs, and a web length perpendicular to the height and in the tube axial direction. The outer shell has an inner shell circumference, an outer shell circumference, and a shell length. The plurality of troughs (610) is affixed to the outer circumference of the inner tube. The plurality of peaks (608) is affixed to the inner shell circumference of the outer shell. The web length is aligned with the tube length and the shell length.