1、Designation: D349 13Standard Test Methods forLaminated Round Rods Used for Electrical Insulation1This standard is issued under the fixed designation D349; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover the procedures for testing rigidround rods used in electrical insulation. These round rodsinclude many types
3、 made from fibrous sheets of basicmaterials, such as cellulose, glass, or nylon in the form ofpaper, woven fabrics, or mats, bonded together by natural orsynthetic resins, or by adhesives. Such round rods includevulcanized fiber and thermosetting laminates as well as roundrods made from cast, molded
4、, or extruded natural or syntheticresins, with or without fillers or reinforcing materials.1.2 The procedures appear in the following sections:SectionCompressive strength (axial) 2025Density 2830Dielectric strength 3139Flexural strength 1319Tensile strength 712Water absorption 26-271.3 The values st
5、ated in inch-pound units are to be regardedas the standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bi
6、lity of regulatory limitations prior to use. For a specificwarning statement see 36.2.2. Referenced Documents2.1 ASTM Standards:2D149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating Materialsat Commercial Power FrequenciesD570 Test Method for Water
7、Absorption of PlasticsD668 Test Methods of Measuring Dimensions of Rigid Rodsand Tubes Used for Electrical InsulationD792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD1711 Terminology Relating to Electrical InsulationD6054 Practice for Conditioning El
8、ectrical Insulating Mate-rials for Testing (Withdrawn 2012)33. Terminology3.1 DefinitionsUse Terminology D1711 for definitions ofterms used in these test methods and associated with electricalor electronic insulation materials.4. Selection of Test Specimens4.1 Specimens for tests shall be selected f
9、rom portions ofmaterial that are free of obvious defects unless the purpose ofthe test is to evaluate the effect of these defects.5. Conditioning5.1 In order to eliminate the effects of previous history ofhumidity exposure and to obtain reproducible results (Note 1),in all cases of dispute give the
10、test specimens of laminated rodsa conditioning treatment for physical test as follows:5.1.1 Tensile, Flexural, and Compressive Strengths, andDensityPrior to test, condition the machined specimens inaccordance with Procedure B of Practice D6054.All specimensshall be tested at room temperature maintai
11、ned at 23 6 5 C.NOTE 1The following are potential reasons to undertake conditioningof specimens: (a) for the purpose of bringing the material into equilibriumwith normal or average room conditions of 23 C and 50 % relativehumidity; (b) simply to obtain reproducible results, irrespective ofprevious h
12、istory of exposure; or (c) to subject the material to abnormalconditions of temperature or humidity in order to predict its servicebehavior.The conditions given here to obtain reproducible results will givephysical values which could be somewhat higher or somewhat lower thanvalues under equilibrium
13、at normal conditions, depending upon theparticular material and test. To ensure substantial equilibrium undernormal conditions of humidity and temperature, however, will requirefrom 20 to 100 days or more depending upon thickness and type ofmaterial and its previous history. Consequently, conditioni
14、ng for repro-ducibility must of necessity be used for general purchase specificationsand product control tests.1These test methods are under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and are the direct responsibility ofSubcommittee D09.07 on Flexible and
15、 Rigid Insulating Materials.Current edition approved Nov. 1, 2013. Published November 2013. Originallyapproved in 1932. Last previous edition approved in 2007 as D349 07. DOI:10.1520/D0349-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at ser
16、viceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM Inter
17、national, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Dimensional Measurements6.1 Make dimensional measurements of rods in accordancewith Test Methods D668.TENSILE STRENGTH7. Significance and Use7.1 This test method is designed to provide data for thecontro
18、l and specification of materials and for characterizationpurposes in research and development of new materials. It ispossible that the tensile properties will vary with the size ofspecimens and the speed of testing. Consequently, these factorsalong with others noted herein must be controlled wherepr
19、ecise comparative results are desired.8. Apparatus8.1 Any testing machine is acceptable for use provided it isaccurate to 1 % of the lowest breaking force to be applied. Usejaws which tighten under load, such as wedge grip jaws, withthe specimen properly aligned.9. Test Specimens9.1 Prepare the test
20、 specimen as shown in Fig. 1. The length,L, is as shown in Table 1. Machine a groove around thespecimen at the center of its length so that the diameter of themachined portion is 60 % of the original nominal diameter.This groove consists of a straight section 214 in. (57 mm) inlength with a radius o
21、f 3 in. (76 mm) at each end joining it tothe outside diameter.10. Procedure10.1 Adjust the crosshead speed of the testing machine notto exceed 0.050 in. (1.27 mm)/min when running idle and testfive specimens.11. Report11.1 Report the following information:11.1.1 The average diameter of the specimen,
22、 expressed tothe nearest 0.001 in. (0.0254 mm), determined from at leasttwo measurements 90 apart,11.1.2 The average diameter of the reduced section, ex-pressed to the nearest 0.001 in. (0.025 mm), determined fromat least two measurements 90 apart,11.1.3 Crosshead speed in inches per minute (or mill
23、ime-tres).11.1.4 The breaking load of each specimen in pounds-force(or newtons),11.1.5 The tensile strength of each specimen in pounds-force per square inch, (or pascals), and11.1.6 The room temperature in degrees Celsius.12. Precision and Bias12.1 PrecisionThis test method has been in use for manyy
24、ears, but no statement of precision has been available and noactivity is planned to develop such a statement.12.2 BiasA statement of bias is not applicable in view ofthe lack of a standard reference material for this property.FLEXURAL STRENGTH13. Significance and Use13.1 Flexural strength data are u
25、seful for the control andspecification of materials and to provide guidance in the designof electrical equipment. Flexural properties have the potentialto vary with the size of the specimens and the speed of testing.Consequently, these factors, together with others noted herein,must be controlled wh
26、ere precise comparative results aredesired.14. Apparatus14.1 Any testing machine is acceptable for use provided it isaccurate to 1 % of the lowest breaking force to be applied.15. Test Specimens15.1 Prepare the test specimen with a diameter equal to thatof the rod and a length eight times the diamet
27、er, plus 1 in. (25.4mm) for rods under12 in. (12.7 mm) in diameter. For rods over12 in. and up to 2 in. (50.8 mm) in diameter, machinespecimens to a diameter of12 in. and cut to a length of 6 in.(152.4 mm).Metric Equivalentsin. mm2 50.8214 57.13 76.2312 88.9FIG. 1 Diagram Showing Location of Rod Ten
28、sion TestSpecimen in Testing MachineD349 13215.2 When the rod being tested is not circumferentiallyisotropic, prepare specimens for testing in both of the principaldirections, and identify them as to directionality. This particu-larly includes rods machined from stripmolded or sheet stock.16. Proced
29、ure16.1 Test five specimens for each laminate orientation, eachas a simple beam loaded at the center. The distance between thesupports shall be eight times the diameter of the rod. Thesupports shall have contact edges rounded to a radius of18 in.(3.2 mm). Adjust the crosshead speed of the testing ma
30、chinenot to exceed an idle speed of 0.050 in./min (1.27 mm/min) andapply the load through a steel block having a semi-circularcontact edge of the same radius as the rod, with edges roundedto a radius of18 in. (3.2 mm).17. Calculation17.1 Calculate the maximum fiber stress, S, as follows:S 5 8 WL/d3(
31、1)where:W = breaking load, lbf (N),L = distance between supports, in. (mm), andd = diameter, in (mm).18. Report18.1 Report the following information:18.1.1 The diameter of the specimen expressed to thenearest 0.001 in. (0.0254 mm), determined from at least twomeasurements 90 apart,18.1.2 Crosshead s
32、peed in inches per minute (ormillimetres),18.1.3 The breaking load of each specimen in pounds-force(or newtons),18.1.4 The maximum fiber stress S, in pounds-force persquare inch (pascals), and18.1.5 The direction of loading relative to the direction ofthe laminate if the rods are ground from strip-m
33、olded stock,sheet stock, and vulcanized fiber.19. Precision and Bias19.1 PrecisionThis test method has been in use for manyyears, but no statement of precision has been available and noactivity is planned to develop such a statement.19.2 BiasA statement of bias is not applicable in view ofthe lack o
34、f a standard reference material for this property.COMPRESSIVE STRENGTH (AXIAL)20. Significance and Use20.1 Compression tests, properly interpreted, provide rea-sonably accurate information with regard to the compressiveproperties of rigid round rods when employed under conditionsapproximating those
35、under which the tests are made. Thecompressive strength values have the potential to vary with thesize of the rigid round rod, and with temperature and atmo-spheric conditions. Compression tests provide data potentiallyuseful for research and development, engineering design,quality control, and acce
36、ptance or rejection under specifica-tions.21. Apparatus21.1 Any testing machine is acceptable for use provided it isaccurate to 1 % of the lowest breaking force to be applied. Oneend of the specimen shall bear upon an accurately centeredspherical bearing block, located, whenever practicable, at thet
37、op. The metal bearing plates shall be directly in contact withthe ends of the test specimen.22. Test Specimens22.1 Unless otherwise specified in the test method orspecification for that material, test the samples as received. Forrods18 to 1 in. (3.2 to 25.4 mm) in diameter, prepare the testspecimen
38、with a diameter equal to the diameter of the rod, andlength conforming to the following requirements:Diameter, in. (mm)Length, in.(mm)SlendernessRatio18 to14 (3.2 to 6.4) incl12 (12.7) 16 to 8Over14 to12 (6.4 to 12.7) incl 1 (25.4) 16 to 8Over12 to 1 (12.7 to 25.4) incl 2 (50.8) 16 to 8TABLE 1 Dimen
39、sions of Rod SpecimensNominal Diameter,in. (mm)Length of Radial Sections2 RS, in. (mm)Total Calculated MinimumLength of Specimen,in. (mm)Standard Length, L, of Speci-men to be Used for 312 in.(88.9 mm) JawsA18 (3.2) 0.773 (19.63) 14.02 (35.61) 15 (381.0)316 (4.8) 0.946 (24.03) 14.20 (36.06) 15 (381.
40、0)14 (6.4) 1.091 (27.71) 14.34 (36.42) 15 (381.0)38 (9.5) 1.333 (33.86) 14.58 (37.03) 15 (381.0)12 (12.7) 1.563 (38.01) 14.79 (37.56) 15.75 (400.0)58 (15.9) 1.714 (43.56) 14.96 (37.99) 15.75 (400.0)34 (19.0) 1.813 (46.05) 15.12 (38.40) 15.75 (400.0)78 (22.1) 2.019 (51.28) 15.27 (38.78) 15.75 (400.0)
41、1 (25.4) 2.154 (54.71) 15.40 (39.11) 16.5 (414.0)114 (31.8) 2.398 (60.90) 15.65 (39.75) 16.5 (414.0)112 (38.0) 2.615 (66.42) 15.87 (40.31) 16.5 (414.0)134 (44.5) 2.812 (70.41) 16.06 (40.79) 16.5 (414.0)2 (50.8) 2.993 (76.02) 16.24 (41.25) 17 (432.0)AFor other jaws greater than 312 in. (88.9 mm), the
42、 standard length shall be increased by twice the length of the jaw minus 7 in. (177.8 mm). The standard length permitsa slippage of approximately14 to12 in. (6.35 to 12.7 mm) in each jaw while maintaining maximum length of jaw grip.D349 13322.2 For rods over 1 in. (25.4 mm) in diameter, specimensare
43、 standard12 by12 by 1-in. (12.7 by 12.7 by 25.4-mm) rightparallelepiped, cut from the rods so as to be representative oftheir cross sections both at the center and near the edges.22.3 Accurately cut or grind the ends of each specimenparallel to each other.23. Procedure23.1 Adjust the crosshead speed
44、 of the testing machine notto exceed an idle speed of 0.050 in./min (1.27 mm/min), andtest five specimens with the load applied perpendicular to thefaces or ends of the specimen.23.2 Discard specimens that break at some obvious flaw andmake retests unless such flaws constitute a variable, the effect
45、of which it is desired to study.24. Report24.1 Report the following information:24.1.1 The diameter of the specimen expressed to thenearest 0.001 in. (0.0254 mm), determined from at least twomeasurements 90 apart,24.1.2 The load on each specimen in pounds at the first signof rupture, and24.1.3 The c
46、ompressive strength in pounds-force per squareinch (or pascals) calculated from the data obtained on theapplication of the load perpendicular to the face of thespecimen.25. Precision and Bias25.1 PrecisionThis test method has been in use for manyyears, but no statement of precision has been availabl
47、e and noactivity is planned to develop such a statement.25.2 BiasA statement of bias is not applicable in view ofthe lack of a standard reference material for this property.WATER ABSORPTION26. Significance and Use26.1 The moisture content of a rigid round rod has a definiteinfluence on the electrica
48、l properties, mechanical strength,dimensional stability, and appearance. The effect upon theseproperties of changes in moisture content, due to waterabsorption, depends largely upon the inherent properties of therigid round rod. It is possible that the rate of water absorptionwill be widely differen
49、t through each edge and surface.Awaterabsorption determination will provide data useful for researchand development, engineering design, quality control, andacceptance or rejection under specifications.27. Procedure27.1 Determine and report the rate of water absorption inaccordance with Test Method D570, immersing specimens for24 h in distilled water at 23 6 1 C after preliminaryconditioning for1hat105to110C.27.2 For some types of materials, or for special applications,it will be desirable to employ longer periods of water imm
