1、Designation: F 736 95 (Reapproved 2006)Standard Test Method forImpact Resistance of Monolithic Polycarbonate Sheet byMeans of a Falling Weight1This standard is issued under the fixed designation F 736; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case of revision, the year 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.1. Scope1.1 This test method covers the determination of the energyrequired to initiate failure in
3、 monolithic polycarbonate sheetmaterial under specified conditions of impact using a freefalling weight.1.2 Two specimen types are defined as follows:1.2.1 Type A consists of a flat plate test specimen andemploys a clamped ring support.1.2.2 Type B consists of a simply supported three-pointloaded be
4、am specimen (Fig. 1) and is recommended for usewith material which can not be failed using the Type Aspecimen. For a maximum drop height of 6.096 m (20 ft) anda maximum drop weight of 22.68 kg (50 lb), virgin polycar-bonate greater than 12.70 mm (12 in.) thick will probablyrequire use of the Type B
5、specimen.NOTE 1See also ASTM Methods: D 1709, D 2444 and D 3029.1.3 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 appli
6、ca-bility of regulatory limitations prior to use. For specific hazardstatement, See Section 7.2. Referenced Documents2.1 ASTM Standards:D 618 Practice for Conditioning Plastics for TestingD 790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Mate
7、rials3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 failure (of test specimen)failure is signified by thepresence of any crack or split in the impact-deformed area thatwas created by the impact of the falling weight and that can beseen by the naked eye.4. Summary of Test Meth
8、od4.1 The test procedure to cause failure covers a range ofimpact energies and differs with respect to geometry andsupport of test specimen Type A and test specimen Type B.Guidelines are established to control drop heights, impactvelocity, drop weights, impactor heads, impactor release,impactor rebo
9、und, impact location, and specimen configurationwhich are applicable to a falling weight impact tester designedto accommodate Type A or Type B test specimens, or both,fabricated from monolithic polycarbonate sheet material.5. Significance and Use5.1 This practice is applicable for qualitatively eval
10、uatingcoated and uncoated monolithic polycarbonate sheet material,for monitoring process control, for screening studies, and as anaid in the prediction of hardware performance when exposed toimpact service conditions.5.2 A limitation of Type A specimen testing is that a thicksheet may not fail since
11、 the available impact energy is limitedby the maximum drop height and falling weight capacity of thetest apparatus. Use Specimen TypeAfor material less than 12.7mm (0.50 in.) thick.5.3 Within the range of drop heights of this system, testsemploying different velocities are not expected to producedif
12、ferent results. However, for a given series of tests, it isrecommended that the drop height be held approximatelyconstant so that velocity of impact (strain rate) will not be avariable.5.4 As the polycarbonate specimen undergoes large plasticdeformation under impact, the down (opposite impact) side
13、isunder tensile loading and most influential in initiating failure.Polycarbonate sheet coated on one side may yield significantlydifferent test results when tested with the coated side downversus the coated side up.5.5 Direct comparison of specimen Type A and specimenType B test results should not b
14、e attempted. For test programsthat will require the comparison of interlaboratory test resultsthe specimen type and the approximate drop height must bespecified.5.6 Monolithic polycarbonate sheet is notch sensitive. Dataobtained from other test methods, particularly notched Izod/Charpy test results,
15、 and extremely high- or low-strain rate test1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 onTransparent Enclosures and Materials.Current edition approved Nov. 1, 2006. Published January 2007. Origina
16、llyapproved in 1981. Last previous edition approved in 2001 as F 736 95 (2001).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.results, should not be compared directly to data obtained fromthis method. It is noted that Type A specime
17、ns, free of flaws,have not experienced the characteristic ductile-to-brittle tran-sition between thin, less than 3.18 mm (18 in.), and thick,greater than 7.94 mm (516 in.), sheet as reflected by other testmethods.6. Apparatus6.1 Impact TesterThe apparatus shall be constructed es-sentially as shown i
18、n Fig. 2. Although not specified, materialscalled out have been found to be satisfactory.6.1.1 Drop HeightA lifting carrier shall be provided toraise or lower the falling weight impactor that will be adjust-able within the range of 0.305 m (1 ft) to maximum drop heightand measurable to the nearest 2
19、5.40 mm (1 in.).6.1.2 Drop WeightThe falling weights shall be detach-able, interchangeable, and variable in small known incrementsfrom a total of 0.45 kg (1 lb) to a maximum drop weight of 50kg (110 lb).6.1.3 ImpactorThe loading nose to be used with Type Aspecimens is shown in Fig. 3; with Type B sp
20、ecimens as shownin Fig. 4. The impactor surface shall be free of nicks or othersurface irregularities. The impactor geometry for Type Bspecimens corresponds to Test Method D 790.6.1.4 Impact LocationThe center of mass of the fallingweight shall be guided by a two cable system or other suitablemeans
21、to repeatedly strike within 2.54 mm (0.10 in.) of thecenter of the specimen support fixture as measured in the planeof the specimen, in order to assure uniform, reproducibledrops. Friction retarding the falling weight should be minimalso that the impact velocity approaches=2ghwhere:g = acceleration
22、of gravity, andh = drop height.6.1.5 SupportsClamp and support rings as shown in Fig.5 and Table 1 will be used to accommodate Type A platespecimens. Adjustable D 790Test Method 1 supports will beused to accommodate the Type B simply supported beamspecimens of 6 + 1 span-to-depth ratio. Specimens sh
23、all besupported so that the surface to be impacted is horizontal andat an angle of 90 (6 1) (p/2 radians) with respect to the fallingweight guides.6.1.6 ReleaseAn electromagnetic or mechanical releasingmechanism, capable of supporting the maximum fallingweight, will be provided to assure uniform and
24、 reproducibledrops.6.1.7 Rebound CatcherMeans must be provided to catchthe weight if it rebounds to prevent restriking the specimen andcausing further damage.6.1.8 Energy AbsorberAn energy absorbent material mustbe provided beneath the specimen to prevent damage to thefixture when the impactor penet
25、rates the specimen.FIG. 1 Type B Specimen Geometry and LoadingTABLE 1 Plate Support Ring GeometryNOTE 1Reference Fig. 5 for definition of “A” and “C.”Ring Size “A”“C” Spanmm (in.) mm (in.) mm (in.)1 88.9 (3.50) 127.0 (5.00) 101.6 (4.00)2 114.3 (4.50) 157.5 (6.20) 127.0 (5.00)3 190.5 (7.50) 254.0 (10
26、.00) 203.2 (8.00)4 292.1 (11.50) 381.0 (15.00) 304.8 (12.00)F 736 95 (2006)27. Hazards7.1 To reduce a hazard to the test operator or witness, orboth, a protective enclosure shall be placed around the testspecimen impact area to contain any flying particles which maybe generated during the test. No f
27、urther adjustments to thespecimen shall be made after positioning the falling weight atthe selected drop height.8. Test Specimens8.1 All specimens must be initially without flaws unless theflaws constitute variables under study. Type B specimens mustbe free of machining stresses. Edge stresses assoc
28、iated withstandard shop practice do not affect the test results for Type Aspecimens. If no combination of falling weight/drop height isavailable that will give satisfactory results using Type AFIG. 2 Falling Weight Impact TesterF 736 95 (2006)3specimens because of high impact resistance, the use of
29、TypeB specimens is recommended to produce failure at a lowerenergy level.8.1.1 Type AFlat plates shall be round or square and havethe physical dimensions specified in Table 2. These dimensionsprovide adequate edge distance for clamping on the platesupport rings.8.1.2 Type BFor beam specimens greater
30、 than 12.7 mm(0.50 in.) thick the support span shall be six times the thicknessof the beam, the specimen width shall be two times thethickness, not to exceed 50.80 mm (2.00 in.), and the overhangon each end shall be four times the thickness to prevent thespecimen from slipping through the supports.N
31、OTE 2With care, Type A plate specimens may be bandsawedwithout inducing failure from edge effects. Type B beam specimens musthave deburred finish-machined edges that are free of stress risers.9. Conditioning9.1 Unless otherwise specified, condition the test specimensin accordance with Procedure A of
32、 Methods D 618.10. Procedure10.1 Measure and record the thickness and geometry ofeach specimen.10.2 Choose a specimen at random from the sample.10.3 Lightly clamp (20 in.-lbs) plate specimens.10.4 Adjust the falling weight to that weight which isexpected to cause failure.10.5 Position the falling we
33、ight at the proper height toprovide the predicted failure energy at impact.10.6 Release the weight to strike the center of the specimen.If rebound occurs, prevent the impactor from restriking thespecimen.10.7 Examine the specimen to determine if it failed. Testeach specimen only once. If over (full
34、penetration) or under thethreshold of failure, remove or add an increment of weight asderived from results observed from the specimen tested imme-diately prior and repeat the test procedure.10.8 Use a sufficient number of specimens to determine thethreshold of failure, using trial and error test run
35、s. Test sixreplicates at failure energy so that at least two, and not morethan four, of the samples tested fail at the given energy level.10.9 Exercise care to avoid accidental exposure of polycar-bonate test samples to toluene, MEK vapors, and other harmfulsolvents. Degradation can occur with no vi
36、sual evidence ofdamage.11. Calculation11.1 The energy required to produce failure, expressed inJoules (foot-pounds), is obtained by multiplying the fallingweight in Newtons (pounds) by the drop height in meters(feet).12. Report12.1 The report shall include the following:12.1.1 Complete identificatio
37、n of the material,12.1.2 Type of specimen (either A or B),12.1.3 Specimen fabrication procedure,12.1.4 Thickness,12.1.5 Number of test specimens employed to determinethreshold of failure,12.1.6 Test conditions and material history,12.1.7 Failure energy,12.1.8 Drop height,12.1.9 Drop weight,12.1.10 F
38、ailure mode (ductile deformation, penetration, orbrittle fracture),TABLE 2 Type A Specimen GeometryASpecimen Thickness SpanB(“A”+2R) Diameter or WidthSpan/Thicknessmm (in.) mm (in.) mm (in.)3.175 (0.125) 7.94 (0.3125) 101.6 (4.00) 127.0 (5.00) 3212.87.95 (0.3130)12.80 (0.5040) 127.0 (5.00) 157.5 (6.
39、20) 169.912.81 (0.5045)19.30 (0.760) 203.2 (8.00) 254.0 (10.00) 15.910.519.31 (0.765)32.00 (1.26) 304.8 (12.00) 381.0 (15.00) 15.89.5ASpecified specimen thicknesses are nominal thicknesses. Tolerances on actual material thickness could cause specimens from a given group to fall in more than onethick
40、ness range. This should not be permitted. All specimens having the same nominal thickness should be tested at the same span.BReference Fig. 5.NOTE 1All loading surfaces to have surface roughness of 1.53.0 m(64128 in.).FIG. 3 Impactor Loading NoseType A Plate Specimen (StainlessSteel)F 736 95 (2006)4
41、12.1.11 Replicate data,12.1.12 Deviation(s) from test procedure, and12.1.13 Date of test.NOTE 1All loading surfaces to have surface roughness of 1.53.0 m (64128 in.).FIG. 4 Impactor Loading NoseType B Beam Specimen (Stainless Steel)NOTE 1Reference Table 1 for dimensions “A” and “C”.NOTE 2All loading
42、 surfaces to have surface roughness of 1.53.0 m (64128 in.).FIG. 5 Clamping and Support RingsType A Plate SpecimenF 736 95 (2006)513. Precision and Bias13.1 PrecisionThis test method does not yet contain anumerical precision statement. However, limited data from onelaboratory indicates repeatability
43、 to approximately 6 5 % foreither specimen Type A or Type B for material exhibitingductile behavior. The precision of this test method is underinvestigation by a task group of Subcommittee F07.08 via aninterlaboratory study. Anyone wishing to participate in thiswork may contact the Chairman, Subcomm
44、ittee F07.08,ASTM, 100 Barr Harbor Drive, West Conshohocken, PA,19428.13.2 BiasThe procedure in this test method for measuringresistance to a falling weight has no bias because the value forresistance to a falling weight is defined only in terms of this testmethod.14. Keywords14.1 falling weight; im
45、pact resistance; polycarbonateASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof in
46、fringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this stan
47、dard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your v
48、iews known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).F 736 95 (2006)6
