Composite Test Piece for Flame-Resistance Evaluation
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Solution Overview
Problem
Existing methods for flame-resistance evaluation of composite members formed by combining different materials, such as metal and rubber, in railway vehicles are inadequate as they cannot properly evaluate the composite member as a whole due to the inability to cut out a test piece locally.
Innovation Solution
A preparation method for a test piece that involves setting a predetermined region to maximize the surface area of the portion exposed to a heat source with the lowest flame resistance, calculating the surface area ratio of each member, and preparing the test piece using test members made of the same materials, exposed at the same ratios as in the actual use state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test piece is cut out from a molded article or sheet for flame-resistance evaluation, then the evaluation can be performed under exposed surface condition same as actual use condition, but it becomes impossible to properly evaluate composite members formed by combining different materials as a whole
Solution Approach 1:
The composite member is divided into multiple test members corresponding to different material portions, allowing each material to be evaluated separately while maintaining the composite structure's exposure ratios. This segmentation enables the evaluation of composite members that cannot be cut out locally.
Solution Approach 2:
Test members are prepared as copies of the actual composite member portions, reproducing the same material composition and exposure ratios. This copying approach allows evaluation of the composite member as a whole without needing to cut out the actual component.
2Measurement precision
If the test piece reproduces the actual use state with proper surface area ratios of different materials, then accurate flame-resistance evaluation is achieved, but the test piece preparation becomes more complex
Solution Approach 1:
The method changes the parameter of surface area ratio to define the test piece configuration. By specifying that test members should be exposed at ratios corresponding to their surface area ratios in the actual composite member, the preparation process becomes systematic rather than complex.
Data Source
AI summary
A preparation method of a test piece 100 with respect to an axle beam bush formed of metal and rubber with different material properties includes: setting a predetermined region S, so that a surface area of a portion exposed to a heat source at a predetermined position and having a lowest flame resistance is maximized in an actual use state of the axle beam bush; calculating the surface area ratio of each member in the region; and preparing the test piece 100 by using a metal member 103 and a rubber member 104 as materials same as respective members in the region, so that the metal member 103 and the rubber member 104 are exposed at ratios same as the calculated surface area ratios.