Anti-Stiffness Rhombus Frame for Modal Test Support
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Solution Overview
Problem
Conventional support tools struggle to meet the test requirements for large and highly flexible structures during modal tests, leading to reduced test credibility due to their inability to accurately replicate the natural frequency of these structures.
Innovation Solution
A support apparatus for modal tests is designed, comprising a suspension structure and a support structure with an anti-stiffness rhombus-shaped frame, a scalable sleeve, a horizontal elastic component, and a base, which are configured to achieve zero stiffness, thereby accurately supporting low-frequency structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional support tools are used for modal testing of large and highly flexible structures, then the support structure provides sufficient strength and stability, but the stiffness of the support apparatus is too high, which alters the natural frequency of the test unit and reduces test credibility
Solution Approach 1:
The patent applies parameter changes by modifying the stiffness characteristics of the support apparatus through the anti-stiffness rhombus-shaped frame mechanism. The rhombus frame with articulated hinges and elastic components creates a system where the effective stiffness can be tuned to match the low stiffness requirements of large flexible structures, thereby preserving natural frequency characteristics and improving test credibility
Solution Approach 2:
The support apparatus uses a composite structure combining rigid rhombus-shaped frame members with elastic components (springs or dampers). This composite approach allows the support structure to provide necessary strength while maintaining low overall stiffness, resolving the contradiction between support strength and test accuracy for flexible structures
2Reliability
If the support apparatus stiffness is reduced to match low-frequency structures, then test credibility is improved, but the support structure may become insufficiently stable
Solution Approach 1:
The anti-stiffness rhombus-shaped frame employs a counterbalancing mechanism where the elastic components and articulated hinges work together to offset stiffness in a controlled manner. This allows the support apparatus to maintain stability while presenting low stiffness to the test unit, effectively resolving the contradiction between support stability and test accuracy
3Measurement precision
If a complex support structure is designed to achieve zero stiffness, then test accuracy is improved, but the device complexity increases
Solution Approach 1:
The support apparatus is segmented into modular components: the anti-stiffness rhombus-shaped frame with its articulated hinges, the elastic components, and the base structure. This segmentation allows for easier fabrication, assembly, and adjustment of each component independently, reducing overall device complexity while achieving the zero-stiffness requirement for accurate natural frequency measurement
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 support apparatus achieves low stiffness, effectively meeting the modal test requirements of low-frequency structures, thereby enhancing test credibility, simplicity, reliability, robustness, and ease of operation.
Implementation Method 1
a first elastic component and a second elastic component, the first elastic component and the second elastic component are horizontally connected to the suspension crossbeam and configured to suspend the test unit
Implementation Method 2
the suspension structure and the support structure being matched to cause a stiffness of the support apparatus for a modal test to be zero
Data Source
AI summary
A support apparatus for a modal test and a using method thereof. The support apparatus includes: a suspension structure (1) configured to suspend a test unit (2); and a support structure disposed under the suspension structure (1) and configured to support the test unit (2). The suspension structure (1) and the support structure are matched to cause a stiffness of the support apparatus for a modal test to be zero. The support structure includes an anti-stiffness rhombus-shaped frame (4), a scalable sleeve, a horizontal elastic component (49), and a base (6). The scalable sleeve is connected to the anti-stiffness rhombus-shaped frame (4) and the base (6) respectively, and the horizontal elastic component (49) connects two diagonal points of the anti-stiffness rhombus-shaped frame (4).