1、Designation: C203 05a (Reapproved 2012)Standard Test Methods forBreaking Load and Flexural Properties of Block-TypeThermal Insulation1This standard is issued under the fixed designation C203; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 metho
3、ds cover the determination 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
4、utilizing centerloading 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
5、 capable of being 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 measu
6、ring at a constantstress 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 breaki
7、ng load measurements 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 toaccommodat
8、e the widely varying 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 fo
9、rinformation only.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 u
10、se. For specificprecautionary statements, see Section 11.2. Referenced Documents2.1 ASTM Standards:2C133 Test Methods for Cold Crushing Strength and Modu-lus of Rupture of RefractoriesC168 Terminology Relating to Thermal InsulationC390 Practice for Sampling and Acceptance of ThermalInsulation LotsC8
11、70 Practice for Conditioning of Thermal Insulating Ma-terialsD76 Specification for Tensile Testing Machines for TextilesE4 Practices for Force Verification of Testing Machines3. Terminology3.1 Terminology C168 shall be considered applied to theterms used in this method.4. Summary of Test Methods4.1
12、A 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 p
13、oints (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 March 1, 2012.
14、Published May 2012. Originallyapproved in 1945. Last previous edition approved 2005 as C203 05a. DOI:10.1520/C0203-05AR12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, ref
15、er to the standards Document 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 u
16、ntil rupture occurs, unlessthe 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 a
17、llow for testing at two 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
18、Procedure B specifies a 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 specif
19、ies a CRE machine with 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
20、. Significance and Use5.1 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 betwe
21、en supports,and rate of 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 i
22、n which crushing occursbefore 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 information
23、is useful for quality control 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 pu
24、rposes.5.4 The basic differences 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 unde
25、r the loadingfitting in 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 r
26、ather than a simpletension/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
27、of varing with specimenspan-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 i
28、n the elastic modulus.6. 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 maxim
29、um load expected to bemeasured. 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
30、deflection-type measuringdevice. 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
31、 shallhave cylindrical 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
32、 they shall beself-aligning 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 C133.6.4 See Fig. 1 for Test Method I; Fig. 2 for Test Method II.6.4.1 CRL ma
33、chines are described in Specification D76.FIG. 1 Loading System for Test Method IFIG. 2 Loading System for Test Method IIC203 05a (2012)26.4.2 CRE and CRT machines are described in SpecificationD76.7. Safety Precautions7.1 Safety precautions consistent with the normal usage ofany universal testing m
34、achine shall be observed. Safety 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 w
35、hendust levels are above permissible 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 speci
36、fication,test at least four 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.
37、 long (25 by 100 by 300 mm) 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. (250 mm) i
38、n length. The width and thickness 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 ge
39、ometry and test setup:Common 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 b
40、e four times the thickness.)where: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 t
41、he commonly used parameters. This incom-patibility precludes a simple table of commonly used and minimumdimensions.8.4 The selection of the samples shall conform to PracticeC390. The specimens shall be cut from larger blocks orirregular shapes in such a manner to preserve as many of theoriginal surf
42、aces as acceptable. Only one 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
43、anisotropic materials, flexural 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.Th
44、e bearing faces of the test 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 approximatel
45、yplane and parallel faces (parallel 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 wer
46、eretained and when only one 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 accepte
47、d practices forconditioning in Practice C870. 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
48、I, Procedure A:10.1.1 Use an 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 thesemea
49、surements in order to get a 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.
