Torque Transmission Axial Compliance Flexure
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Solution Overview
Problem
Existing torque transfer systems in orthopedic device wear test machines face challenges in providing high torsional stiffness with minimal deflection error while maintaining low axial stiffness to prevent cross-talk and frictional forces, which is crucial for precise and repeatable wear testing.
Innovation Solution
A torque transfer transmission system that combines high torsional stiffness with axial compliance, utilizing a rotational element with a flexible connector that is torsionally stiff and axially compliant, allowing for friction-free axial translation and rigid torque transfer, employing a friction-free axial actuator and flexible connectors like flexure plates to achieve precise force and motion control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid torque transfer system is used, then torsional stiffness is improved, but axial compliance deteriorates
Solution Approach 1:
The torque transfer system is segmented into multiple functional components: a rotational element for torque transfer, a flexible connector for axial compliance, and a friction-free axial actuator. This segmentation allows each component to specialize in one function (torque transfer or axial movement) without compromising the other, resolving the contradiction between rigid torque transfer and axial compliance.
Solution Approach 2:
A flexible connector acts as an intermediary element between the rotational element and the axial actuator. This intermediary component specifically addresses the contradiction by being torsionally stiff to maintain torque transfer integrity while being axially compliant to allow friction-free axial translation, thus mediating between the conflicting requirements of rigidity and compliance.
2Object-affected harmful factors
If axial compliance is increased to reduce friction, then cross-talk prevention is improved, but torque transfer rigidity deteriorates
Solution Approach 1:
The flexible connector exhibits local quality by having different mechanical properties in different directions: it is torsionally stiff to maintain torque transfer rigidity while being axially compliant to reduce friction. This directional differentiation of mechanical properties allows the system to simultaneously achieve rigid torque transfer and friction reduction through axial compliance.
Solution Approach 2:
The system employs dynamic characteristics through the flexible connector which allows axial translation when needed (during axial loading phases) while maintaining torsional stiffness for torque transfer. The friction-free axial actuator also introduces dynamic control, allowing the system to adapt its axial stiffness dynamically to prevent cross-talk while maintaining torque transfer integrity.
3Measurement precision
If high torsional stiffness is maintained for precise torque control, then deflection error is reduced, but axial translation freedom deteriorates
Solution Approach 1:
The system segments the functional requirements by separating the rotational element (for precise torque control with high torsional stiffness) from the axial actuator (for friction-free axial translation). This segmentation allows precise torque control to be maintained while axial translation freedom is enabled through the dedicated axial actuator and compliant flexible connector.
Solution Approach 2:
The flexible connector serves as an intermediary that couples the rotationally stiff element with the axially compliant actuator. It mediates between the conflicting requirements by transmitting torque rigidly while allowing axial compliance, thus enabling both precise torque control and axial translation freedom without compromise.
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
The system enables precise and repeatable torque transmission with minimal deflection error and reduced frictional forces, ensuring consistent wear conditions across test specimens and preventing cross-talk at the load cell, thereby enhancing the validity of testing results.
Implementation Method 1
A flexible connector, which is flexible along the axis of rotation but is torsionally stiff, is coupled between the rotational transfer link and the rotational element
Data Source
Figure 1~2
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AI summary
A transmission for torque transfer with axial compliance and a test machine employing the transmission has a flexible connector that provides high torsional stiffness and high axial compliance while inducing no frictional forces. The transmission includes an axial portion allowed to translate freely along its axis due to a high axial compliance of the transmission while the transmission simultaneously facilitates rigid torque transfer.