Fatigue Limit Stress Specification via Harmonic Temperature Analysis
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Solution Overview
Problem
Existing fatigue limit stress measurement systems lack precision in determining fatigue limit stress, particularly for objects with stress concentration, as they rely on subjective judgments and incomplete data analysis.
Innovation Solution
A fatigue limit stress specification system that uses a vibration generator, temperature sensor, and information processing device to measure temperature changes during stepwise loading, analyzing the relation between fundamental and second harmonic temperature amplitudes using quadratic approximate lines to accurately determine fatigue limit stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fatigue limit stress measurement methods are used, then the measurement process is simpler, but the measurement precision and reliability are insufficient due to subjective judgments and incomplete data analysis
Solution Approach 1:
The patent segments the temperature analysis into multiple frequency components (fundamental frequency and second harmonic frequency) to independently analyze different aspects of the fatigue behavior. This segmentation allows for more precise measurement of fatigue limit stress by examining specific frequency components separately rather than analyzing temperature data as a whole, thereby improving measurement precision while managing system complexity through structured data processing.
Solution Approach 2:
The patent introduces a new dimension of analysis by examining the relationship between fundamental frequency temperature amplitude and second harmonic temperature amplitude. This dimensional approach transforms the measurement from simple temperature monitoring to a multi-parameter analysis involving frequency-domain decomposition, which significantly improves fatigue limit stress measurement precision by capturing nonlinear thermal responses that conventional methods miss.
2Measurement precision
If only fundamental frequency temperature amplitude is analyzed, then the analysis is simpler, but the fatigue limit stress determination is less accurate
Solution Approach 1:
The patent segments the temperature signal into distinct frequency components using Fourier transform, separating the fundamental frequency response from the second harmonic response. This segmentation enables independent analysis of each frequency component's contribution to fatigue behavior, improving determination accuracy by capturing nonlinear thermal effects that appear primarily in the second harmonic while simplifying the analysis through frequency-domain separation.
Solution Approach 2:
The patent uses Fourier transform as an intermediary tool to convert time-domain temperature data into frequency-domain representations. This intermediary transformation facilitates the separation and independent analysis of fundamental and second harmonic components, making it easier to detect and measure their respective amplitudes without directly complex time-domain analysis, thereby improving accuracy while managing measurement difficulty.
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 system enables precise measurement of fatigue limit stress by objectively analyzing temperature changes, improving accuracy and reliability compared to conventional methods.
Implementation Method 1
The vibration generator repeatedly applies each of the loads to the object to be measured at a predetermined frequency
Implementation Method 2
The temperature sensor obtains a change in temperature indicating the change in temperature of the object to be measured
Implementation Method 3
The information processing device includes Fourier transform means for processing the temperature image of the object to be measured that has been obtained from the infrared camera
Implementation Method 4
dissipation energy measurement process for measuring dissipation energy
Data Source
AI summary
A fatigue limit stress specification system includes: a vibration generator that repeatedly applies a load to an object to be measured; a temperature sensor that measures a change in temperature of the object to be measured; and an information processing device that measures a fatigue limit stress of the object to be measured. The information processing device obtains a relation between a temperature amplitude of a fundamental frequency component of vibration for the object to be measured and a temperature amplitude of a second harmonic component of the vibration, performs fitting on the relation by using a first approximate line and a second approximate line, the first approximate line including a quadratic curve, the second approximate line including a quadratic curve, and obtains the fatigue limit stress of the object to be measured based on an intersection of the first approximate line and the second approximate line.