Transient Force and Moment Computation for Non-Proportional Damping
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Solution Overview
Problem
Existing methods are inadequate for directly measuring interfacial forces and moments in the transient state or time domain, especially for structures with non-proportional damping, limiting the effectiveness of transfer path analysis (TPA) and power flow analysis.
Innovation Solution
A method to compute interfacial vibratory forces and moments using acceleration, material properties, and modal properties without direct measurement, applicable to both proportionally and non-proportionally damped structures, enabling true-transient TPA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement of force is used, then measurement precision is improved, but device complexity increases due to force sensor installation in series
Solution Approach 1:
The patent uses acceleration sensors as intermediaries to indirectly measure force. Instead of directly installing force sensors in series with the structure, acceleration sensors are placed on the structure surface, and force is computed through the equation of motion F = m*a, eliminating the need for complex series sensor installation while maintaining measurement capability
Solution Approach 2:
The patent replaces the mechanical force measurement approach (direct force sensors) with an indirect computational approach using acceleration data and mass properties. This substitution eliminates the need for physical force sensor installation while enabling force measurement through software computation based on measured acceleration and known mass characteristics
2Ease of operation
If frequency domain methods are used to compute force, then ease of operation is improved, but adaptability deteriorates for transient state analysis
Solution Approach 1:
The patent extends the force computation method from static/frequency domain to dynamic/time domain by using time-dependent acceleration data. The equation of motion F(t) = m*a(t) is applied at each time step, enabling the method to handle transient states, impacts, and time-varying conditions while maintaining operational simplicity through direct time-domain computation
3Device complexity
If existing indirect methods are used for force computation, then device complexity is reduced, but measurement precision deteriorates for non-proportional damping structures
Solution Approach 1:
The patent changes the approach from using frequency-domain parameters to using time-domain acceleration parameters. By computing force directly from time-dependent acceleration data through F(t) = m*a(t), the method achieves high precision for transient states and non-proportional damping conditions where traditional frequency-domain methods fail, while keeping the measurement system simple
Data Source
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AI summary
In example implementations described herein, there are systems and methods for computation of force and moment in the time domain for a physical system including one or more sensors, which can involve obtaining material properties and first modal properties of the physical system; generating a material property matrix from the material properties and second modal properties from the obtained modal properties; measuring, via the sensors, a set of motion responses of the physical system; obtaining first quantities based on the second modal properties and the material property matrix; calculating a first intermediate matrix from the second modal properties and the set of motion responses; recursively computing, for each time step during measurement of the response, a second intermediate matrix based on (1) the first quantities, (2) the second modal properties, (3) the first intermediate matrix, and (4) a previously computed second intermediate matrix from at least one previous time step; and calculating the force and the moment for each time step during the measurement of the set of motion responses based on the second intermediate matrix and the second modal properties.