Guided Stress Engraving for Reproducible Coating Adhesion Tests
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Solution Overview
Problem
Existing methods fail to reliably assess the quality of coatings on components by locally applying defined stress and evaluating the resulting damage, particularly in cases where adhesion promoter layers fail, leading to potential detachment and propagation of damage.
Innovation Solution
A device is developed to apply a defined stress to test specimens using a guide and engraving means, ensuring identical stress application across multiple specimens, followed by exposure to a corrosive medium to simulate stress corrosion cracking, with optional engraving elements like saw blades or diamond-coated springs, and image analysis for damage assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual stress application is used, then device complexity is reduced, but measurement precision and reproducibility deteriorate
Solution Approach 1:
The patent replaces manual mechanical stress application with an automated mechanical testing system that includes a testing machine, fixture, and control unit. The control unit automatically controls the actuator to apply stress based on pre-set test parameters, eliminating manual operation while achieving precise and reproducible measurements.
Solution Approach 2:
The fixture is designed with universal features that can accommodate different test body geometries and configurations. The system can perform multiple types of stress tests (tension, compression, bending) using the same basic apparatus, reducing overall device complexity while maintaining measurement precision across various test scenarios.
2Reliability
If stress is applied until breakage, then measurement completeness is improved, but test body damage occurs
Solution Approach 1:
The testing system dynamically adjusts the stress application rate based on real-time feedback from load cells and displacement sensors. The control unit monitors test progress and automatically stops the test when predefined criteria are met, allowing flexible control over whether to continue to breakage or stop at intermediate stress levels based on test requirements.
Solution Approach 2:
The system incorporates feedback mechanisms through load cells that continuously monitor the applied stress and displacement sensors that track test body deformation. This feedback is fed to the control unit, which automatically adjusts the testing parameters and stops the test when predetermined conditions are achieved, ensuring reliable data collection while preserving test body integrity when needed.
3Productivity
If multiple test bodies are tested manually, then productivity decreases, but measurement accuracy is maintained
Solution Approach 1:
The system allows pre-programming of test parameters, fixtures, and test sequences before actual testing begins. Multiple test bodies can be queued and tested automatically according to pre-set protocols, eliminating repetitive manual setup and parameter adjustment while maintaining consistent measurement precision across all tests.
Solution Approach 2:
The automated system enables continuous testing of multiple test bodies without interruption. The control unit manages sequential testing, automatic fixture adjustment, and data collection across multiple samples, maintaining continuous productive operation while preserving measurement accuracy through consistent automated execution of test protocols.
Data Source
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Figure 3a~3b
AI summary
The invention relates to a device (1) for applying test bodies (2) with a defined stress, comprising a guide (3) having an inner perimeter (3b) with a shape corresponding to the shape of an outer perimeter (2a) of the test body (2), and with a size that permits a translational movement of the test body (2) through the guide (3) with only one degree of freedom into a processing position (4); and engraving means (5) which are designed to exert a predefined cutting application of force on the surface of said test body (2) in response to a test body (2) reaching the processing position (4).