1、Designation: C 203 05aStandard Test Methods forBreaking Load and Flexural Properties of Block-TypeThermal Insulation1This standard is issued under the fixed designation C 203; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 These test methods cover the de
3、termination of thebreaking load and calculated flexural strength of a rectangularcross section of a preformed block-type thermal insulationtested as a simple beam. It is also applicable to cellular plastics.Two test methods are described as follows:1.1.1 Test Method IA loading system utilizing cente
4、rloading on a simply supported beam, supported at both ends.1.1.2 Test Method IIA loading system utilizing twosymmetric load points equally spaced from their adjacentsupport points at each end with a distance between load pointsof one half of the support span.1.2 Either test method is capable of bei
5、ng used with the fourprocedures that follow:1.2.1 Procedure A Designed principally for materials thatbreak at comparatively small deflections.1.2.2 Procedure B Designed particularly for those mate-rials that undergo large deflections during testing.1.2.3 Procedure C Designed for measuring at a const
6、antstress rate, using a CRL (constant rate of loading) machine.Used for breaking load measurements only.1.2.4 Procedure D Designed for measurements at a con-stant crosshead speed, using either a CRT (constant rate oftraverse) or CRE (constant rate of extension) machine. Usedfor breaking load measure
7、ments using a fixed crosshead speedmachine.1.3 Comparative tests are capable of being run according toeither method or procedure, provided that the method orprocedure is found satisfactory for the material being tested.1.4 These test methods are purposely general in order toaccommodate the widely va
8、rying industry practices. It isimportant that the user consult the appropriate materialsspecification for any specific detailed requirements regardingthese test methods.1.5 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are provided forinformation on
9、ly.1.6 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-bility of regulatory limitations prior to use. For specifi
10、cprecautionary statements, see Section 11.2. Referenced Documents2.1 ASTM Standards:2C 133 Test Methods for Cold Crushing Strength and Modu-lus of Rupture of RefractoriesC 168 Terminology Relating to Thermal InsulationC 390 Practice for Sampling and Acceptance of PreformedThermal Insulation LotsC 87
11、0 Practice for Conditioning of Thermal Insulating Ma-terialsD76 Specification for Tensile Testing Machines for TextilesE4 Practice for Force Verification of Testing Machines3. Terminology3.1 Terminology C 168 shall be considered applied to theterms used in this method.4. Summary of Test Methods4.1 A
12、 bar of rectangular cross section is tested in flexure asa beam as follows:4.1.1 Test Method IThe bar rests on two supports and isloaded by means of a loading fitting or piece midway betweenthe supports (see Fig. 1).4.1.2 Test Method IIThe bar rests on two supports and isloaded at the two quarter po
13、ints (by means of two loadingfittings), each an equal distance from the adjacent support1These test methods are under the jurisdiction of ASTM Committee C16 onThermal Insulation and are the direct responsibility of Subcommittee C16.32 onMechanical Properties.Current edition approved Nov. 1, 2005. Pu
14、blished December 2005. Originallyapproved in 1945. Last previous edition approved 2005 as C 203 05.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Doc
15、ument Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.point. The distance between the loading fittings is one half ofthe support span (see Fig. 2).4.2 The specimen is deflected until rupture occurs, un
16、lessthe materials specification indicates termination at a particularmaximum strain level.NOTE 1One criteria used is to limit the strain to 5 %. If failure doesnot occur at 5 % strain, the strain rate is increased and the test repeated ona new specimen.4.3 Procedures A and B allow for testing at two
17、 differentstrain rates. Procedure C specifies a stress rate. Procedure Dspecifies a rate of extension or traverse.4.3.1 Procedure A specifies a strain rate of 0.01 in./in.(mm/mm) that is useful for testing insulations that are very stiffor break at quite low deflections.4.3.2 Procedure B specifies a
18、 strain rate of 0.1 in./in.(mm/mm) which is useful for testing insulations that arerelatively flexible or break at higher deflections.4.3.3 Procedure C specifies a stress rate of 550 psi (3.79MPa)/min except as applicable in the materials specification.4.3.4 Procedure D specifies a CRE machine with
19、a fixedcrosshead speed, or a CRT machine with a movable loadclamp, such as the Scott tester. Because the strain rate is afunction of specimen geometry, this procedure does not give aconstant strain rate for specimens of different thicknessestested on the same loading fixture.5. Significance and Use5
20、.1 These test methods are to be used to determine theresistance of some types of preformed block insulation whentransverse loads are normally applied to the surface. Values aremeasured at the maximum load or breaking point underspecified conditions or specimen size, span between supports,and rate of
21、 load application. The equations used are based onthe assumption that the materials are uniform and presume thatthe stress-strain characteristics below the elastic limit arelinearly elastic. These assumptions are not strictly applicable tothermal insulations of certain types in which crushing occurs
22、before failure is obtained in transverse bending; however,depending upon the accuracy required, these procedures arecapable of providing acceptable results.5.2 Test Method I is especially useful when testing only forthe modulus of rupture or the breaking load. This informationis useful for quality c
23、ontrol inspection and qualification forspecification purposes.5.3 Test Method II is useful in determining the elasticmodulus in bending as well as the flexural strength. Flexuralproperties determined by these test methods are also useful forquality control and specification purposes.5.4 The basic di
24、fferences between the two test methods is inthe location of the maximum bending moment, maximum axialfiber (flexural or tensile) stresses, and the resolved stress statein terms of shear stress and tensile/compression stress. Themaximum axial fiber stresses occur on a line under the loadingfitting in
25、 Test Method I and over the area between the loadingfittings in Test Method II. Test Method I has a high shear stresscomponent in the direction of loading, perpendicular to theaxial fiber stress. Sufficient resolved shear stress is capable ofproducing failure by a shear mode rather than a simpletens
26、ion/flexural failure. There is no comparable shear compo-nent in the central region between the loading fittings in TestMethod II. Test Method II simulates a uniformly loaded beamin terms of equivalent stresses at the center of the specimen.5.5 Flexural properties are capable of varing with specimen
27、span-to-thickness ratio, temperature, atmospheric conditions,and the difference in rate of straining specified in Procedures Aand B. In comparing results it is important that all parametersbe equivalent. Increases in the strain rate typically result inincreased strengths and in the elastic modulus.6
28、. Apparatus6.1 Testing Machine A properly calibrated testing ma-chine that is capable of being operated at either constant loadrates or constant rates of crosshead motion over the rangeindicated, and in which the error in the load-measuring systemshall not exceed 61 % of maximum load expected to bem
29、easured. The load-indicating mechanism shall be essentiallyfree of inertial lag. The accuracy and calibration of the testingmachine shall be verified in accordance with Practice E4.Ifstiffness or deflection measurements are to be made, then themachine shall be equipped with a deflection-type measuri
30、ngdevice. The stiffness of the testing machine shall be such thatthe total elastic deformation of the system does not exceed 1 %of the total deflection of the test specimen during test, orappropriate corrections shall be made.6.2 Bearing Edges The loading fittings and supports shallhave cylindrical
31、surfaces. In order to avoid excessive indenta-tion, or failure due to stress concentration directly under theloading fitting or fittings, the diameter of these bearing edgesshall be 114 614 in. (32 6 6 mm). The bearing cylinders shallbe straight and parallel to each other, and they shall beself-alig
32、ning to maintain full contact with the specimenthroughout the test. They shall have a length at least equal tothe width of the specimen.6.3 Bearing cylindrical supports are described in Test Meth-ods C 133.6.4 See Fig. 1 for Test Method I; Fig. 2 for Test Method II.6.4.1 CRL machines are described i
33、n Specification D76.FIG. 1 Loading System for Test Method IFIG. 2 Loading System for Test Method IIC 203 05a26.4.2 CRE and CRT machines are described in SpecificationD76.7. Safety Precautions7.1 Safety precautions consistent with the normal usage ofany universal testing machine shall be observed. Sa
34、fety glassesshould be worn when testing all brittle samples.7.2 Smoking and open flames shall be avoided when work-ing with flammable or combustible specimens.7.3 Respirators shall be worn during preparation of speci-mens that are friable or composed of compacted powder whendust levels are above per
35、missible limits. Laboratory clothesand gloves shall be used when working with such materials ormaterial that is abrasive or a skin irritant.8. Test Specimens8.1 The number of specimens to be tested shall be given inthe materials specification. In the absence of such specification,test at least four
36、samples.8.2 The specific materials specification shall be consultedfor the test specimen geometry and specific directions concern-ing selection or cutting of specimens. In the absence of suchguidance, the preferred test specimen shall be 1 in. thick by 4in. wide by 12 in. long (25 by 100 by 300 mm)
37、tested on a 10in. (250 mm) support span. The test specimens shall be 4 in.(100 mm) unless otherwise specified, but in no case less than3 in. (75 mm) in width, and 1 in. (25 mm) thick. The testspecimens shall be long enough to accommodate a supportspan of 10 in. (25 mm) in length. The width and thick
38、ness oftest specimens shall be recorded to the nearest 0.01 in. (0.3mm).NOTE 2When comparing test results, such data must be obtainedusing a common specimen size and the same procedure.8.3 The following are commonly used and minimum re-quirements for the test specimen geometry and test setup:Common
39、L/d = 10 Require 20 $ L/d $ 2(Common requirement that the support span be ten times the thickness.)Common L/b = 2.5 Require L/b $ 0.8(Common requirement that support span be two and a half times thewidth.)Common b/d = 4 Require b/d $ 1(Common requirement that the width be four times the thickness.)w
40、here:L = support span, in. (or mm),d = thickness of specimen, in. (or mm), andb = width of specimen, in. (or mm).NOTE 3Examination of the minimum test requirements shows theyare not compatible. They represent a compromise of industrial practiceswith the emphasis toward the commonly used parameters.
41、This incom-patibility precludes a simple table of commonly used and minimumdimensions.8.4 The selection of the samples shall conform to PracticeC 390. The specimens shall be cut from larger blocks orirregular shapes in such a manner to preserve as many of theoriginal surfaces as acceptable. Only one
42、 sample shall be cutfrom a single block or board. Multiple specimens are capableof being cut from a sample such as a large bun of insulationmaterial. If the test specimen is cut to obtain a narrower widththan as received, the cut shall be made lengthwise of the block.For anisotropic materials, flexu
43、ral tests are capable of beingrun in other than the length direction, such as the crossdirection of the sample. When comparative tests are to be madeon preformed materials, all specimens shall be of the samethickness, except as applicable in the materials specification.The bearing faces of the test
44、specimens shall be approximatelyparallel planes. In preparing specimens from pieces of irregularshape, any means such as a band saw, or any method involvingthe use of abrasives such as high-speed abrasion wheel orrubbing bed, that will produce a specimen with approximatelyplane and parallel faces (p
45、arallel within 1) without weakeningthe structure of the specimen is capable of being used. Thevalue obtained on specimens with machined surfaces will differfrom those obtained on specimens with original surfaces.Consequently, the report must state if original surfaces wereretained and when only one
46、original surface was retained,whether it was on the tension or compression side of the beam.9. Conditioning9.1 Dry and condition specimens prior to test, followingapplicable specifications for the material. In the absence ofdefinitive drying specifications, follow accepted practices forconditioning
47、in Practice C 870. Where circumstances or re-quirements preclude compliance with these conditioning pro-cedures, exceptions agreed upon between the manufacturer andthe purchaser shall be made, and will be specifically listed inthe test report.10. Procedure10.1 Test Method I, Procedure A:10.1.1 Use a
48、n untested specimen for each measurement.Measure the width and depth of the specimen to the nearest0.01 in. (0.3 mm) at the center of the support span. Eachdimension is to be measured at three points along the centerline of the span and to use the average value of thesemeasurements in order to get a
49、 better value in case the sides arenot truly parallel.10.1.2 Determine the support span to be used and set up thesupport span to within 1 % of the determined value. Measurethis support span to the nearest 0.1 in. (3.0 mm) at three pointsand record this measurement.10.1.3 Calculate the rate of crosshead motion as follows andset the machine for the calculated rate:R 5 ZL2/6d(1)where:R = rate of crosshead motion, in./min. (or mm/min.),L = support span, in. (or mm),d = depth of beam, in. (or mm), andZ = rate of straining of the outer fiber, in./in.min (ormm/mmmin). Z sh
