Thermal Test Fixture With Laser Heating And Insulation
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Solution Overview
Problem
Conventional test fixtures for thermal contact resistance (TCR) are inadequate for simulating high temperature loads necessary for emulating hypersonic thermal environments, which are critical for predicting the thermal survivability of hypersonic vehicles.
Innovation Solution
A test fixture design that includes a housing with an axial cavity, an isolation container for the sample pair, and a compressor to apply axial pressure, while also providing thermal insulation and allowing for radiative heating using a laser emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional resistance heaters are used in simple TCR test fixtures, then the device complexity is low and ease of manufacture is good, but the temperature capability is insufficient to emulate hypersonic thermal environments
Solution Approach 1:
The test fixture is divided into distinct functional segments: a heating section with laser emitter, an insulation section with thermal barrier, and a compression section with adjustable pressure mechanism. Each segment handles a specific function, allowing the system to achieve high temperature capability while maintaining manageable complexity through modular design
Solution Approach 2:
A thermal insulation layer acts as an intermediary between the high-temperature laser heating zone and the sample compression zone. This intermediary protects the compression mechanism from direct thermal exposure, enabling the system to achieve both high temperature capability and mechanical functionality without requiring the entire fixture to be thermally resistant
2Temperature
If simple fixture designs with hydraulic presses are used, then ease of operation is good, but the fixture cannot provide the necessary thermal insulation for high temperature loads
Solution Approach 1:
The thermal insulation layer serves as a protective intermediary that allows the sample compression mechanism to operate at room temperature while the laser heating zone reaches high temperatures. This enables the compression mechanism to remain simple and easy to operate without direct exposure to thermal stress
Solution Approach 2:
The fixture is segmented into thermally isolated zones: a heated zone for laser irradiation and a cool zone for sample compression. This segmentation allows different parts of the fixture to have different thermal conditions, maintaining ease of operation for the compression mechanism while achieving high temperature capability in the heating zone
3Reliability
If conventional fixtures without thermal insulation are used, then device complexity is low, but they cannot maintain thermal conditions necessary for accurate TCR measurement under hypersonic conditions
Solution Approach 1:
The thermal insulation layer acts as a thermal barrier that maintains distinct temperature zones within the fixture. This intermediary ensures that the sample compression zone remains thermally stable for accurate measurement while the laser heating zone can achieve high temperatures, thereby improving measurement accuracy without requiring the entire fixture to be thermally resistant
Solution Approach 2:
Different parts of the fixture have different thermal properties: the laser heating zone is designed for high temperature exposure, while the sample compression zone is thermally insulated to maintain stable conditions. This local differentiation of thermal properties enables accurate TCR measurement under hypersonic conditions while managing overall device complexity
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 test fixture effectively emulates hypersonic thermal environments by applying high temperature loads and measuring temperature gradients, enabling accurate calculation of TCR values for materials under extreme conditions.
Implementation Method 1
The fixture receives exposure to laser emission for radiative heating
Implementation Method 2
The isolation container provides thermal insulation from the housing and the compressor
Implementation Method 3
The compressor has circular cross-sections for insertion into the axial cavity and includes an external helical thread portion for engaging the internal helical thread portion of the housing. Axial pressure applies to the isolation container by turning the compressor inside the axial cavity.
Data Source
AI summary
A test fixture is provided for containing a pair of test samples (i.e., sample pair) that contact each other along an interface. The fixture receives exposure to laser emission for radiative heating while providing compression to the sample pair. The text fixture includes a housing, an isolation container, and a compressor. The housing has an axial cavity with annular cross-sections including an internal helical thread portion and a window for receiving the laser emission. The isolation container receives the sample pair. The container inserts into the axial cavity and including an opening for disposition adjacent to the window. The compressor has circular cross-sections for insertion into the axial cavity and includes an external helical thread portion for engaging the internal helical thread portion of the housing. Axial pressure applies to the isolation container by turning the compressor inside the axial cavity. The isolation container provides thermal insulation from the housing and the compressor. In additional embodiments, the isolation container comprises a cup with the opening to isolate the sample pair from the housing, and a washer to isolate the sample pair from the compressor.