1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
2、rom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2011 SAE International All rights reserved. No part of this publication ma
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4、A) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J1961_201105SURFACEVEHICLESTANDARDJ1961 MAY2011 Issued 1988-12Revised 2011-05Superseding J1961
5、MAR2002 Accelerated Exposure of Automotive Exterior Materials Using a Solar Fresnel Reflector Apparatus RATIONALEThis standard is being changed to make spray cycles specified in this standard in conformance with industry practice and with other SAE, ISO and ASTM standards which specify testing using
6、 Solar Fresnel Reflector Apparatus . 1. SCOPE 1.1 This test method specifies the operating procedures for using a solar fresnel reflector apparatus for the accelerated exposure of various automotive materials. 1.2 Sample preparation, test durations, and performance evaluation procedures are covered
7、in material specifications of the different automotive manufacturers. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this specification to the extent specified herein. 2.1.1 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, W
8、est Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org.ASTM D 859 Test Methods for Silica in Water ASTM D 4517 Test Method for Low-Level Total Silica in High Purity Water by Flameless Atomic Absorption SpectroscopyASTM E 891 Standard Tables for Terrestrial Direct Normal Solar Spectral Irra
9、diance for Air Mass 1.5 ASTM G 90 Standard Practice for Performing Accelerated Outdoor Weathering of Nonmetallic Materials Using Concentrated Natural Sunlight ASTM G 147 Standard Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests SAE J1961 Rev
10、ised MAY2011 Page 2 of 12 2.2 Related Publication The following publication is provided for information purposes only and is not a required part of this SAE Technical Report.2.2.1 ASTM Publication Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-29
11、59, Tel: 610-832-9585, www.astm.org.ASTM E 903 Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres3. DEFINITIONS 3.1 Black Panel Thermometer, n. A temperature measuring device, the sensing unit of which is covered with a black coating designed to
12、absorb most of the radiant energy encountered in fade/weathering testing. NOTE: This device provides an estimation of the maximum temperature a specimen may attain during exposure to natural or artificial light. 3.2 Irradiance, Spectral, n. The radiant power within a specified wavelength interval th
13、at falls upon a unit area of exposed surface (W/m2).3.3 Irradiance, Total, n. Radiant power integrated over all wavelengths falling upon a unit area of exposure at a point in time expressed in watts per square meter (W/m2).3.4 Irradiation, n. See radiant exposure. 3.5 Radiant Exposure, n. The time i
14、ntegral of irradiance expressed in joules per square meter (J/m2).3.6 Radiant Exposure, Spectral, n. The integration of spectral irradiance with respect to time. 3.7 Reference Materials, n. One or more light fastness standards selected for exposure as a check on a test apparatus and operating condit
15、ions. 3.8 Sample, Laboratory, n. A portion of material taken to represent the lot sample, or the original material, and used in the laboratory as a source of test specimens. 3.9 Specimen, n. A specific portion of a material or a laboratory sample upon which a test is performed or selected for that p
16、urpose. SAE J1961 Revised MAY2011 Page 3 of 12 3.10 Spectral Power Distribution, n. The variation of power due to the source over the wavelength span of the emitted radiation. 4. SIGNIFICANCE AND USE This test method is designed to simulate extreme environmental conditions encountered outside a vehi
17、cle due to sunlight, heat, and moisture (in the form of humidity, condensation, or rain) for the purpose of predicting the performance of automotive materials. 5. APPARATUS 5.1 The testing apparatus shall be a fresnel-reflecting device possessing 10 flat mirrors which focus direct sunlight onto an a
18、ir-cooled sample area. A more complete description of the apparatus may be found in ASTM G 90. See Figure 1. NOTE: The apparatus shall be operated in dry, sunny climates receiving approximately 3500 to 4000 h of sunshine per year and an average annual relative humidity of approximately 25 to 35%. FI
19、GURE 1 - SCHEMATIC OF FRESNEL REFLECTING CONCENTRATOR ACCELERATED WEATHERING MACHINE (SINGLE AXIS TRACKING) SAE J1961 Revised MAY2011 Page 4 of 12 5.2 If mirror reflectance cannot be measured directly, the apparatus shall be provided with a mounting area for affixing a removable optical-mirror sampl
20、e. This sample shall possess a minimum area of 2580 mm2(4 in2). The essential requirement is that the optical-mirror specimen be manufactured from the same batch and lot as the mirror stock-material used to irradiate the target sample area. This sample shall be labelled with a number which identifie
21、s which mirrors the sample applies to. The optical mirror sample is mounted at the same time as are the mirrors used to irradiate the sample area, and its specular, spectral reflectance is periodically measured. FIGURE 2 - DUAL AXIS TRACKING SAE J1961 Revised MAY2011 Page 5 of 12 FIGURE 3 - ACCELERA
22、TED EXPOSURE OF AUTOMOTIVE EXTERIOR MATERIALS USING A SOLAR FRESNEL REFLECTOR APPARATUS EXPOSURE REPORT FORM 5.3 A black panel thermometer may optionally be mounted onto the sample exposure area to assist in monitoring expected maximum sample temperatures. The device shall be constructed by affixing
23、 the sensing element to the front surface of a metal panel measuring 5 x 13 x 0.16 cm (2 x 5 x 0.06 in) or any other convenient size. The sensor can be attached using a thermally conductive epoxy such as Part Number EC-286 from Therm-X of California or equivalent. The front surface of the panel shal
24、l be then coated with DuPont 93 005 Delux Super Black Enamel, or other gloss black automotive coating. NOTE: ASTM Committee G03 on Durability is currently addressing the issue of Black Panel thermometers as a result of widely different temperature data reported by commercial testing agencies. 5.4 Wa
25、ter Quality 5.4.1 The purity of water used for specimen spray is very important. Without proper treatment to remove cations, anions, organics, and particularly silica, exposed panels will develop spots or stains that do not occur in exterior exposures.5.4.2 Water used for specimen spray shall leave
26、no objectionable deposits or stains on the exposed specimens. It is strongly recommended that the water contain a maximum of 1 ppm solids and a maximum of 0.2 ppm silica. Silica levels should be determined using the procedures defined in ASTM D 859 or ASTM D 4517. Prepackaged analysis kits are comme
27、rcially available that are capable of detecting silica levels of less than 200 parts per billion (ppb). A combination of deionization and reverse osmosis treatment can effectively produce water with the desired purity. If the spray water used is above 1 ppm solids, the solids and silica levels must
28、be reported. SAE J1961 Revised MAY2011 Page 6 of 12 6. CALIBRATION AND MAINTENANCE 6.1 At least every six months, measure the specular reflectance of each mirror in two places along the mirrors centerline using a portable specular reflectometer with narrow-band-pass filters centered at 310 nm wavele
29、ngth: (1) 15 cm (6 in) from the north edge, and (2) 15 cm (6 in) from the south edge. Visibly inspect each mirror and measure any additional areas which appear non-uniform. Update the value of Psemploying actual average values of specular reflectance. Replace individual mirrors if the average 310 nm
30、 specular reflectance is less than 0.65 (65%). 6.2 If measurement of specular reflectance of the mirrors used in exposure devices is not practical, mount small, representative specimens of the mirror material. Place the representative specimens next to the mirror locations described in 5.1. These re
31、presentative specimens must be of the same material and lot number as the mirrors used in the instrument. The representative specimens must also be installed at the same time as the mirrors. At least every six months, measure the specular reflectance of the representative specimens at 310 nm. Replac
32、e individual mirrors if the average 310 nm specular reflectance of the representative specimens is less than 0.65 (65%). 6.3 Mirrors shall be checked for mirror focus monthly in accordance with the procedure specified in ASTM G 90 and refocused if required at that time. 6.4 The safety mechanism used
33、 to protect samples in the event of a power outage shall be checked monthly to make sure it operates properly in all positions. 6.5 Clean mirrors (and removable mirror samples) at intervals necessary to maintain the reflectance specified in 6.1. To maintain optimum specular reflectance, it is recomm
34、ended that mirrors be cleaned on an established frequency to minimize the effects of surface deposits that may alter spectral irradiance at the target area. 6.6 Clean black panel thermometers at an interval necessary to maintain optical performance. 7. TEST PROCEDURES 7.1 To insure repeatability of
35、test, maintain the apparatus in accordance with Section 6 and the manufacturers specifications.7.1.1 Conditioning and handling of test, control, reference, and file specimens shall be according to ASTM G 147. 7.2 Mount samples in the exposure area using one of two methods: 7.2.1 Noninsulated Exposur
36、e Mount samples into sample holders constructed of a corrosion-resistant metal such as stainless steel or aluminum in an unbacked configuration such that panels can lose heat from back-side cooling. 7.2.2 Insulated Exposure Mount samples into sample holders such that samples are backed with an insul
37、ating water-resistant material such as 13 mm (1/2-in) thick exterior plywood. 7.3 Coated metal specimens shall be mounted using either of the two mounting methods in accordance with the schedule in Table 1: TABLE 1 - MOUNTING CONDITIONS Time Period Mounting Condition November 1 March 31 Insulated Ap
38、ril 1 October 31 Noninsulated SAE J1961 Revised MAY2011 Page 7 of 12 7.4 Specimens which are not coated metal shall be mounted for a noninsulated exposure. 7.5 If a black panel thermometer is mounted onto the sample area with the test samples to be exposed, it shall be mounted using the same mountin
39、g condition as the test samples. 7.6 Apparatus shall be set up to provide conditions in accordance with one of the cycles in Table 2: TABLE 2 - SPRAY CYCLES Cycle Daytime Nighttime Spray Duration Dry-Time Duration Cycles, h Spray DurationDry-Time Duration Cycles, h water is sprayed on the test speci
40、mens at:1 8 min 52 min 1 8 min 9:00 p.m. 12:00 midnight 3:00 a.m. 2 no water spray usedno water spray used3 no water spray used3 min 12 min 4 cycles per hour (from 7PM to 5 AM) NOTE: Prior to 2010, the spray cycles specified in this method were: Cycle 1 (same as Cycle 3 above), and Cycle 2 (same as
41、Cycle 2 above). These spray cycles were changed to be in conformance to ASTM and ISO standards. 7.7 Spray Orientation The apparatus shall be positioned so that specimens are sprayed at night either with specimens facing up or down. 7.7.1 Specimens Face Down The apparatus is oriented with the mirrors
42、 below the target specimen area such that nozzles spray high purity water in an upward direction onto the specimens. 7.7.2 Specimens Face Up The apparatus is oriented with the mirrors above the target specimen area such that nozzles spray high purity water in a downward direction onto the specimens.
43、 NOTE: No data has been presented indicating that exposures performed using different spray orientations provide equivalent results, and as such, may provide different test results. 7.8 Expose samples for a predetermined amount of ultraviolet radiant exposure measured in J/m2. Determine the solar ra
44、diant exposure of the test specimens in accordance with Equations 1 and 2: U N1idssHMH (Eq. 1) TU UM1iiscosM(Eq. 2) SAE J1961 Revised MAY2011 Page 8 of 12 where: TUHs= solar radiant exposure, J/m2M = number of mirrors Us= the cosine corrected specular reflectance U = the average energy-weighted spec
45、ular reflectance of the mirrors N = number of days of exposure TI= the angle of incidence of the irradiance from each mirror at the specimen target area Hd= direct-normal daily solar radiant exposure measured in a 6 degrees field of view To determine the ultraviolet (295 to 385 nm) solar radiant exp
46、osure, Hdin Equation 1 shall be determined as the integration of irradiance with respect to time. Irradiance shall be measured using two ultraviolet radiometers.1A black-painted permanent shading disk (see Figure 4) is positioned over one radiometer in order to provide a diffuse-only measurement (ex
47、cluding 6 degrees field of view). Hdis determined using Equation 3: dodHHH (Eq. 3) where:Hd= hemispherical daily solar radiant exposure Hdo= diffuse-only daily solar radiant exposure (excluding direct-normal radiant exposure in a 6 degrees field of view) The two ultraviolet radiometers shall be cali
48、brated at the same time at least annually against a standard source of spectral irradiance. Instrument calibration constants shall be checked by mounting both instruments at the same orientation for at least 1 h under clear sky conditions. If a difference of more than 2% exists between instruments,
49、they shall be recalibrated.At least monthly, for 1 h under clear sky conditions, both instruments shall be tracked off-altitude approximately 15 degrees with no shading on the normally shaded instruments diffuser. If the radiant exposure readings from the two instruments differ by more than 2%, the radiometers shall be recalibrated. Historical radiation data shall be checked on an annual basis to compare results
