This test method measures the system material properties of an insulated formed heat shield under invehicle conditions. While the material properties of the individual components can often be determined via existing test methods, the system properties of the entire composite is typically much harder to ascertain (especially for multi-layer shields). System material properties include thermal conductivity in the lateral or in-plane (x) direction, thermal conductivity through the thickness or perpendicular (y), surface emissivity on the top and bottom sides of the shield and specific heat of the shield material.
All properties are determined for the entire shielding material specimen as a composite of the entire structure. Properties are determined using a testing apparatus that allows for two-dimensional heat flow through the specimen. Due to this, the material property results from this test method may not agree with one-dimensional heat flow type testing methods, but is representative of most heat shield materials performance tested with a centralized heat source. Therefore, material property results from this test method may be more suited for multi-dimensional analytical studies.
This standard sets forth the general guidelines to construct and operate the testing apparatus to acquire a satisfactory set of test data. Designs conforming to this standard are included and must not be deviated from for sensitivity reasons that will be discussed in more detail later. Test parameters that cannot be deviated from include, but are not limited to; specimen size, distance between the source and the specimen, source diameter and environmental conditions around the apparatus.
This method ultimately determines the shield material properties by using the test data along with an analytical scheme, see Section 8.1.
This test method will evaluate both isotropic and anisotropic insulated shielding materials. This may also include multi-layer shielding structures which include embossed/corrugated solids, porous, fibrous, granulated and coated materials.