Wind Tunnel Balance Axial Section with Oblique Flexures
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Solution Overview
Problem
Conventional wind tunnel balance designs struggle to accurately measure axial forces when the axial-to-normal force ratio exceeds 1:4, and they have high manufacturing costs due to complex 3D layouts requiring multiple EDM processes.
Innovation Solution
A new axial section design for wind tunnel balances using topology optimization to create a 2D geometry with oblique measuring beams and X-shaped flexures, which amplifies strain readings under axial loads while minimizing strain readings under normal loads, allowing for improved sensitivity and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wind tunnel balance design with central vertical measuring beam is used, then axial force measurement is achieved, but measurement precision deteriorates when axial-to-normal force ratio exceeds 1:4
Solution Approach 1:
The patent applies asymmetry by positioning strain gauges at oblique angles (e.g., 45 degrees) relative to the measuring beam axis rather than symmetrically along the vertical length. This asymmetric gauge placement creates differential strain measurement that amplifies axial load response while suppressing normal load interference, enabling accurate measurement across higher axial-to-normal force ratios exceeding 1:4
Solution Approach 2:
The patent transitions from traditional single-dimension (vertical) strain gauge placement to multi-dimensional placement by introducing oblique orientations in three-dimensional space. This dimensional change allows the strain gauges to capture both axial and normal force components differently, enabling the measurement system to distinguish and accurately measure axial forces even when normal forces are present
2Shape
If conventional 3D layout with multiple EDM processes is used, then complex geometry is achieved, but manufacturing cost and time increase
Solution Approach 1:
The patent extracts and eliminates unnecessary complex 3D features from the balance design, simplifying the geometry to essential structural elements. By removing redundant curved surfaces and complex intersections that don't contribute to measurement functionality, the design reduces manufacturing steps while maintaining measurement performance
Solution Approach 2:
The patent segments the balance structure into modular components with simplified geometries that can be manufactured separately using standard EDM or 3D printing processes. This segmentation allows each component to be produced independently with fewer complex machining operations, reducing overall manufacturing time and cost
3Shape
If conventional 3D layout with multiple EDM processes is used, then complex geometry is achieved, but device complexity increases
Solution Approach 1:
The patent changes the geometric parameters of the balance structure from complex 3D curved surfaces to simpler forms with standardized dimensions and angles. By adopting rational parameter values that are compatible with standard manufacturing capabilities, the design reduces the number of required EDM processes and simplifies the overall manufacturing methodology
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 design effectively amplifies axial load responses while suppressing non-axial load responses, enabling accurate measurement across higher axial-to-normal force ratios and reducing manufacturing time and costs through simpler production methods like 3D printing or EDM cutting.
Implementation Method 1
the series of flexures are arranged and configured to elastically deform and amplify the strain experienced by at least one strain gauge from the series of strain gauges when the base experiences an axial load
Data Source
AI summary
This present disclosure is about a wind tunnel balance axial section. A wind tunnel balance is a sensor that measures six force/moment components from a test model in a wind tunnel. An axial section, one of the six measurement sections in the balance, is the hardest section to design because it is often required to measure an axial force which is much smaller than other force components. Therefore, there is a specific design requirement for the axial section to selectively amplify the axial force response and suppress the non-axial responses. This disclosure presents a sensor mechanism composed of elastic linkages to achieve this design requirements for the axial section.