ASTM G214-15

Standard Test Method for Integration of Digital Spectral Data for Weathering and Durability Applications

SIGNIFICANCE AND USE
5.1 Weathering and durability testing often requires the computation of the effects of radiant exposure of materials to various optical radiation sources, including lamps with varying spectral power distributions and outdoor and simulated sunlight as in Test Methods E972, G130, and G207.  
5.2 The purpose of this test method is to foster greater consistency and comparability of weathering and durability test results between various exposure regimes, calculation of materials properties, and laboratories with respect to numerical results that depend upon the integration of spectral distribution data.  
5.3 Changes in the optical properties of materials such as spectral reflectance, transmittance, or absorptance are often the measure of material stability or usefulness in various applications. Computation of the material responses to exposure to radiant sources mentioned above requires the integration of measured wavelength-dependent digital data, sometimes in conjunction with tabulated wavelength-dependent reference or comparison data.  
5.4 This test method specifies and describes the Modified Trapezoid Rule as a single reasonably accurate and easily implemented integration technique for computing approximations of spectral source and optical property integrals.  
5.5 The method includes a procedure for estimating the approximate absolute and relative (percent) error in the estimated spectral integrals.  
5.6 The method includes a procedure to construct data sets that match in spectral wavelength and spectral wavelength interval, which does not have to be uniform over the spectral range of interest. Uniform spectral intervals simplify some of the calculations, but are not required.
SCOPE
1.1 This test method specifies a single relatively simple method to implement, common integration technique, the Modified Trapezoid Rule, to integrate digital or tabulated spectral data. The intent is to produce greater consistency and comparability of weathering and durability test results between various exposure regimes, calculation of materials properties, and laboratories with respect to numerical results that depend upon the integration of spectral distribution data.  
1.2 Weathering and durability testing often requires the computation of the effects of radiant exposure of materials to various optical radiation sources, including lamps with varying spectral power distributions and outdoor and simulated sunlight. Changes in the spectrally dependent optical properties of materials, in combination with exposure source spectral data, are often used to evaluate the effect of exposure to radiant sources, develop activation spectra (Practice G178), and classify, evaluate, or rate sources with respect to reference or exposure source spectral distributions. Another important application is the integration of the original spectrally dependent optical properties of materials in combination with exposure source spectral data to determine the total energy absorbed by a material from various exposure sources.  
1.3 The data applications described in 1.2 often require the use of tabulated reference spectral distributions, digital spectral data produced by modern instrumentation, and the integrated version of that data, or combinations (primarily multiplication) of spectrally dependent data.  
1.4 Computation of the material responses to exposure to radiant sources mentioned above require the integration of measured wavelength dependent digital data, sometimes in conjunction with tabulated wavelength dependent reference or comparison data.  
1.5 The term “integration” in the previous sections refers to the numerical approximation to the true integral of continuous functions, represented by discrete, digital data. There are numerous mathematical techniques for performing numerical integration. Each method provides different levels of complexity, accuracy, ease of implementation and computational efficiency, an...

General Information

• Status: Historical
• Publication Date: 30-Nov-2015
• ICS: 17.180.20 - Colours and measurement of light
• Technical Committee: G03 - Weathering and Durability
• Drafting Committee: G03.09 - Radiometry

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: G214 − 15
StandardTest Method for
Integration of Digital Spectral Data for Weathering and
1
Durability Applications
This standard is issued under the fixed designation G214; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope functions, represented by discrete, digital data. There are
numerous mathematical techniques for performing numerical
1.1 This test method specifies a single relatively simple
integration. Each method provides different levels of
method to implement, common integration technique, the
complexity, accuracy, ease of implementation and computa-
Modified Trapezoid Rule, to integrate digital or tabulated
tional efficiency, and, of course, resultant magnitudes.
spectral data. The intent is to produce greater consistency and
2
Hulstrom, Bird and Riordan (1) demonstrate the differences
comparability of weathering and durability test results between
2
between results for rectangular (963.56 W/m ), trapezoid rule
various exposure regimes, calculation of materials properties,
2 2
(962.53 W/m ), and modified trapezoid rule (963.75 W/m )
and laboratories with respect to numerical results that depend
integration for a single solar spectrum. Thus the need for a
upon the integration of spectral distribution data.
standard integration technique to simplify the comparison of
1.2 Weathering and durability testing often requires the
results from different laboratories, measurement
computation of the effects of radiant exposure of materials to
instrumentation, or exposure regimes.
various optical radiation sources, including lamps with varying
1.6 The values stated in SI units are to be regarded as
spectral power distributions and outdoor and simulated sun-
standard. No other units of measurement are included in this
light. Changes in the spectrally dependent optical properties of
standard.
materials, in combination with exposure source spectral data,
1.7 This standard does not purport to address all of the
are often used to evaluate the effect of exposure to radiant
safety concerns, if any, associated with its use. It is the
sources, develop activation spectra (Practice G178), and
responsibility of the user of this standard to establish appro-
classify, evaluate, or rate sources with respect to reference or
priate safety and health practices and determine the applica-
exposure source spectral distributions. Another important ap-
bility of regulatory limitations prior to use.
plication is the integration of the original spectrally dependent
optical properties of materials in combination with exposure
2. Referenced Documents
source spectral data to determine the total energy absorbed by
3
a material from various exposure sources. 2.1 ASTM Standards:
E275 Practice for Describing and Measuring Performance of
1.3 The data applications described in 1.2 often require the
Ultraviolet and Visible Spectrophotometers
useoftabulatedreferencespectraldistributions,digitalspectral
E424 Test Methods for Solar Energy Transmittance and
data produced by modern instrumentation, and the integrated
Reflectance (Terrestrial) of Sheet Materials
version of that data, or combinations (primarily multiplication)
E490 Standard Solar Constant and Zero Air Mass Solar
of spectrally dependent data.
Spectral Irradiance Tables
1.4 Computation of the material responses to exposure to
E772 Terminology of Solar Energy Conversion
radiant sources mentioned above require the integration of
E903 Test Method for Solar Absorptance, Reflectance, and
measured wavelength dependent digital data, sometimes in
Transmittance of Materials Using Integrating Spheres
conjunction with tabulated wavelength dependent reference or
E927 Specification for Solar Simulation for Photovoltaic
comparison data.
Testing
E971 Practice for Calculation of Photometric Transmittance
1.5 The term “integration” in the previous sections refers to
and Reflectance of Materials to Solar Radiation
the numerical approximation to the true integral of continuous
2
The boldface numbers in parentheses refer to a list of references at the end of
1
This test method is under the jurisdiction of ASTM Committee G03 on this standard.
3
Weathering and Durability and is the direct responsibility of Subcommittee G03.09 For referenced ASTM standards, visit the ASTM website, www.astm.org, or
on Radiometry. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Current edition approved Dec. 1, 2015. Published February 2016. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
G0214-15. the ASTM website.
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