Transfer Path Analysis Using Reciprocal Frequency Response Functions
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Solution Overview
Problem
Current methods for determining the proportions of individual transmission paths in the operational overall noise of a sound-transmitting structure, such as a vehicle, are time-consuming and prone to errors, particularly in measuring inertances and frequency response functions during transfer path analysis.
Innovation Solution
A method involving the definition of sound introduction and reception positions, simultaneous measurement of sound pressure and acceleration, calculation of sensitivity functions, and determination of inertances and frequency response functions to accurately assess the forces and proportions of individual transmission paths, while maintaining constant temperature and using reciprocal measurements to reduce errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional transfer path analysis is used to measure inertances and frequency response functions, then measurement completeness is achieved, but measurement time increases and error probability increases
Solution Approach 1:
The patent applies preliminary action by pre-heating the structure before measurements to establish stable thermal conditions, and by using previously measured inertances and transfer functions from off-road conditions to calculate on-road transmission paths without re-measuring all parameters, thus reducing measurement time while maintaining accuracy
Solution Approach 2:
The patent uses copying by measuring frequency response functions at off-road positions (where the structure is stationary and accessible) and then applying these measured functions to calculate transmission paths for on-road positions (where measurement would be difficult or impossible), thereby avoiding time-consuming on-road measurements while maintaining measurement completeness
2Measurement precision
If comprehensive measurements of all sound sources are performed, then measurement completeness and accuracy are improved, but measurement complexity and time increase
Solution Approach 1:
The patent applies segmentation by dividing the measurement process into distinct phases: off-road measurements for obtaining inertances and transfer functions, and on-road measurements for obtaining excitation forces and operating frequencies. This segmentation allows comprehensive sound source identification without requiring all measurements to be performed simultaneously under complex operating conditions
Solution Approach 2:
The patent uses intermediary elements (acceleration sensors and microphones placed at specific positions on the vehicle body) as mediators to capture vibration and acoustic signals from multiple sound sources. These intermediaries enable the system to identify individual sound source contributions through signal processing without requiring direct access to or measurement at each sound source location
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
This method significantly reduces measurement time and errors by using reciprocal frequency response functions and sensitivity functions, providing a more precise calculation of noise and vibration components, and allowing for the identification of sound sources' contributions to sound pressure and acceleration.
Implementation Method 1
carrying out at least one simultaneous measurement of the sound pressure or the acceleration at the receiving position and the acceleration and preferably the sound pressure at each sound introduction position during operation
Implementation Method 2
determining at least one acceleration-to-pressure or acceleration-to-acceleration sensitivity function and preferably at least one pressure-to-pressure sensitivity function on the basis of the measurement under e)
Data Source
AI summary
The method involves determining acceleration-to-pressure and/or acceleration-to-acceleration-selectivity functions and/or pressure-to-pressure-selectivity functions. Reciprocally measured frequency response functions between each sound initiation position and receiving position are determined. Forces are determined based on inertness and accelerations at the initiation positions. Proportions of individual transfer paths are determined based on the forces and the response functions and/or the pressure-to- pressure- selectivity functions and/or acoustic pressures at the initiation positions.