Thermomechanical Analysis Correction for Thermal Expansion
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Solution Overview
Problem
Current thermomechanical analysis methods struggle to accurately calculate the corrected reversible component of length variation and coefficient of thermal expansion, especially when a sample undergoes thermally induced conversion processes during modulated temperature programs, due to temperature gradients and heat conduction lag within the sample.
Innovation Solution
The method involves a temperature program with a first segment for calculating a correction parameter in a region without thermally induced conversion, which is then used in a second segment with a lower heating rate to calculate the corrected reversible components, utilizing a temperature-dependent function for extrapolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a modulated temperature program with high heating rate is used to perform thermomechanical analysis, then the analysis time is reduced and productivity is improved, but temperature gradients and heat conduction lag within the sample increase, leading to decreased measurement precision
Solution Approach 1:
The temperature program is segmented into a first segment with high heating rate for rapid analysis and a second segment with low heating rate for precise measurement. This segmentation allows the method to achieve both high productivity during the first segment and high measurement precision during the second segment, resolving the contradiction between analysis time and measurement precision.
Solution Approach 2:
The first segment with high heating rate performs preliminary heating to bring the sample to the target temperature range quickly. The correction parameter is preliminarily determined in this segment, and then the second segment uses low heating rate to achieve precise measurements while applying the preliminary correction, thus resolving the time-precision trade-off.
2Productivity
If the heating rate is increased to improve analysis efficiency, then productivity is improved, but temperature-dependent effects and heat conduction lag become more significant, causing errors in determining reversible components
Solution Approach 1:
The heating rate is made dynamic rather than constant. The method uses high heating rate in the first segment when the sample is not undergoing thermally induced conversion, and switches to low heating rate in the second segment when conversion occurs. This dynamic adjustment of heating rate maintains both high efficiency and high reliability throughout the analysis.
Solution Approach 2:
The heating rate parameter is changed between segments to optimize different phases of the analysis. By changing from high to low heating rate, the method accounts for temperature-dependent effects and heat conduction lag, ensuring reliable determination of reversible components while maintaining overall analysis efficiency.
3Ease of operation
If a single heating rate is used throughout the temperature program, then the device operation is simplified, but accurate determination of corrected reversible components during thermally induced conversion cannot be achieved
Solution Approach 1:
The temperature program is divided into segments with different heating rates. The first segment uses high heating rate for efficiency, and the second segment uses low heating rate for precision during thermally induced conversion. This segmentation resolves the contradiction between ease of operation and measurement precision by automating the segment transition.
Solution Approach 2:
The method uses feedback from detection of thermally induced conversion to automatically switch between heating rates. When conversion is detected in the first segment, the system transitions to the second segment with low heating rate, ensuring accurate determination of corrected reversible components while maintaining operational simplicity through automated control.
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 approach allows for accurate determination of corrected reversible components even during thermally induced conversion processes, reducing errors by accounting for temperature-dependent behavior and heat conduction effects.
Implementation Method 1
heat conduction lag within the sample
Implementation Method 2
temperature gradients and heat conduction lag within the sample
Implementation Method 3
reversible component of the length variation (caused by temperature variation)
Data Source
AI summary
A method for the thermomechanical analysis of a sample (P) of a material including (a) controlling the temperature of the sample (P), (b) recording data representative for a length variation (dL) of the sample (P), (c) evaluating the data in order to determine a reversible component (dLrev), (d) calculating a corrected reversible component (dLrev-corr; αrev-corr) and/or of the coefficient of thermal expansion (α).